RU2148033C1 - Improved method for treating waste waters - Google Patents

Abstract

FIELD: waste water treatment. SUBSTANCE: waste water containing suspended solid particles, ammonia nitrogen, phosphate, and biologically degradable substances is passed consecutively through aerobic biooxidation zone, intermediate sedimentation zone, oxygen-free zone, aerobic mixing zone, and final sedimentation zone wherein purified water and final sludge are separated. Part of final sludge is fed into oxygen-free anaerobic zone which receives volatile acid to release phosphate. Part of sludge and waste water recycle from oxygen-free anaerobic zone into oxygen-free zone. Another part of sludge is fed into fermentation zone to form volatile acid. EFFECT: improved separation of solids, reduced oxygen biological demand, and increased nitrogen and phosphorus removal. 32 cl, 33 dwg, 8 tbl, 2 ex

Description

 The invention relates in a broad sense to technological improvements in wastewater treatment methods using drip biological filters. More specifically, this invention relates to methods for increasing the removal efficiency of particulate matter in the implementation of purification methods by contacting drip biological filters with particulate matter. More specifically, this invention relates to the implementation of such methods in order to significantly increase the efficiency of removal of suspended solids and reduce the biochemical oxygen demand in existing methods. In addition, the invention makes it possible to reduce the levels of nitrogen and phosphorus in wastewater.

 Background to the invention.

 Methods of treating wastewater using drip biological filters include the step of passing wastewater into a system with a wastewater supply in a downward flow in contact with biomass attached to the filter material. For the absorption of soluble and colloidal material into the biomass, a sufficient contact time of wastewater with filter material is provided. As a result of the oxidation or oxidative respiration phase, a new biomass is created. In addition, biomass is restored through endogenous respiration.

 Wastewater treatment methods using drip biological filters are simple to operate and maintain, and are considered energy efficient with respect to wastewater treatment methods using activated sludge, since they do not require expensive air supply. However, the quality of the treated wastewater is low, and they usually contain 20–40 mg / L of biochemical oxygen demand (BOD) and suspended solids (VHF (SS)).

Although up to the forties of the twentieth century, drip biological filters were most often used in the implementation of secondary wastewater treatment methods, the use of drip biological filters has gradually decreased in recent years due to their inability to meet the standard of maintaining the level of 30 mg / l BHPK ₅ and VHF for 30 days. This occurs mainly due to the large amount of HPM in treated wastewater. To ensure that high-quality treated wastewater is obtained, effective removal of particulate matter from treated wastewater is necessary.

Numerous modifications of purification methods have been used to improve the performance of drip biological filters. One such option is to replace the drip biological filter with activated sludge or a rotating biological contactor (IBD (RBC)). The second option is to use a tertiary treatment method, such as filtration or chemical treatment, to purify the treated wastewater from existing plants with drip biological filters. The third option is to replace the existing mineral filter materials of the drip biological filters with plastics to improve the performance of the drip biological filter. A fourth option is to modify the purification method using a drip biological filter by combining it with activated sludge wastewater treatment method. Each of these alternative measures can provide a means of satisfying the existing regulatory restriction imposed on the release of treated wastewater and expressed in the amount of 30 mg / l BHPK ₅ and VTCh, but each of these measures is associated with additional investment and operating costs.

 In the early eighties of the twentieth century, Norris et al. [1, 2] and Fedotoff [3] proposed a simple way to produce high-quality treated wastewater without the need for expensive tertiary or associated treatment. In this modification, the treated wastewater of a drip biological filter is mixed with recycled sludge from a final sump, and then treated in an aerated tank or channel with a short hydraulic capture time. These modifications, as a rule, relate to the cleaning method by contacting a drip biological filter with solid particles (to the CBF / PM (TF / SS) -contact method).

 The advantages of modifications of drip biological filters for the CBF / PM contact method according to the works of Norris et al. [1, 2], Fedotoff et al. [3] and Niku et al. [4] include: (1) less capital investment, than in the case of full-scale methods for wastewater treatment with activated sludge and rotary biological contactors (VBK), (2) lower operating costs and maintenance and repair costs, (3) ease of operation, (4) ease of deposition of activated sludge, (5) adaptability to existing drip biological filters, and (6) equivalence Performance performance process wastewater by activated sludge.

 In accordance with the foregoing, CBF / PM-contact installations allowed to obtain the quality of treated wastewater that exceeds the quality of treated wastewater of secondary treatment plants or comparable to the quality of treated wastewater of tertiary treatment plants. Obtaining high-quality treated wastewater is associated with increased flocculation and increased removal of soluble organic substances, manifested by sludge in contact with aerated solids. However, the kinetics of the process and the structural parameters of the solid particles at the contacting stage are not fully understood.

 As in other methods of biological wastewater treatment, the performance of the final sump has a great influence on the efficiency of the treatment produced by the drip biological filter. Most of the dissolved organic substances and colloidal solids in the wastewater fall into biological droplets and are precipitated by absorption and biological flocculation on the biological film of a droplet biological filter. The film itself is modified by decomposition, and the net removal (net remonal) of solid particles in wastewater changes and is associated with the holding capacity of the biomass in the filter. Despite its importance, information on the stage of sludge deposition in a drip biological filter is much scarcer than information on the method of treating wastewater with activated sludge.

 It is known that various physical, electrochemical and biochemical factors influence the flocculation of biological sludge. Physical factors include flake size, degree of aditation in the system, flake surface area, bound water, and particulate concentration. The electrochemical factor includes the surface charge of the flakes. The polymer content in the sludge is a biochemical factor.

 Although flocculation is closely related to sedimentation of sludge, there is no direct way to determine the degree of flocculation in biological sludge. The sludge volumetric index (SVI), which reflects the sedimentation of sludge, is actually a measure of the volume of sludge deposited as a result of the complex interaction of flocculation and compaction during the deposition process. Although the importance of the effect of the polymer material on the sludge sedimentation is a recognized factor in the method of treating wastewater with activated sludge, studies of the effect of the polymer material on the sludge sedimentation in the treatment method using a drip biological filter have so far been limited.

 Objectives of the invention.

 Thus, the primary objective of this invention is to increase the efficiency of the use of wastewater treatment methods using drip biological filters.

 Another primary objective of this invention is to improve purification methods by contacting drip biological filters with solid particles.

 Another primary objective of this invention is to improve the sludge deposition step in wastewater treatment methods using drip biological filters by determining process parameters and operating conditions so that high-quality wastewater can be obtained.

 Another related priority task of this invention is to develop technological modifications of existing cleaning methods using drip biological filters and existing cleaning methods by contacting biological droplet filters with solid particles, which makes it possible to meet the requirements of BHPC and VHF standards to similar installations, or to exceed these requirements.

 Another related priority task of this invention is to develop technological modifications of existing methods of wastewater treatment using drip biological filters and existing purification methods by contacting biological droplet filters with solid particles, which makes it possible to satisfy the requirements of nitrogen concentration standards and phosphates for such installations, or exceed these requirements and provides the opportunity to reduce the levels of nitrogen and phosphorus in cing waters.

 A brief description of the invention.

 The invention, in a broad sense, consists in methods for increasing the sedimentation of suspended solids in treated wastewater for methods of wastewater treatment using drip biological filters, including those in which drip biological filters are an integral part of the implementation of the cleaning method by contact with solid particles. In a broad sense, the invention consists in the discovery that if the biological sludge obtained by sedimentation of suspended solids is held in an oxygen-free / anaerobic zone for a period of time sufficient for the growth of the extracellular polymer contained in the sludge, and then comes into contact with the purified with wastewater from a drip biological filter with stirring and maintaining aerobic conditions, the sedimentation of suspended particles and a decrease in biochemical oxygen demand (BHPC) are significantly increased. It was also found that it is possible to remove nitrogen and / or phosphorus from wastewater and to increase the sedimentation of suspended solids and to reduce BCP in purified wastewater by mixing sludge from an oxygen-free / anaerobic zone with treated wastewater obtained from a drip biological filter or from an intermediate precipitation stage , in an oxygen-free pre-mixing zone, followed by exposure to mixed or mixing under aerobic conditions.

 In addition, it was found that the removal of phosphorus can be facilitated by supplying volatile acid to a zone in which additional oxygen was not introduced into the stream from the main aerobic biological oxidation zone, for example, a drop biological filter, or into an oxygen-free / anaerobic zone, and that nitrogen removal can be facilitate by oxidizing ammonia nitrogen to nitrate nitrogen in the aerobic biological oxidation zone, for example in a drip biological filter, and, optionally, by reducing nitrate nitrogen to molecular nitrogen (gas figurative nitrogen) in the zone where oxygen is not introduced.

 The invention provides significant flexibility in modifying the existing drip biological filter and purification methods by contacting the drip biological filters with solid particles due to the fact that it is possible to create an oxygen-free / anaerobic zone for treating recycled or intermediate sludge obtained during the cleaning process, moreover, the sludge from oxygen-free / the anaerobic zone is mixed with treated wastewater obtained from a drip biological filter or from the intermediate precipitation stage, in aero pre-mixing / mixing zone or an oxygen-free pre-mixing zone, which is located upstream than the aerobic / mixing zone. In addition, you can install a bioreactor for particulate matter, designed to treat either primary sludge, or intermediate sludge, or the final sludge obtained in the purification process, in order to obtain volatile acid to remove phosphorus. The existing aerobic biological oxidation zone can be used to nitrify nitrogen and, optionally, the zone into which no additional oxygen has been introduced can be used to denitrify or remove nitrogen. Accordingly, the proposed method can be used in existing plants or in new plants with a significant increase in the sedimentation of solid particles and the recovery of BHPC, and by introducing an oxygen-free pre-mixing zone, which is located upstream than the aerobic / mixing zone, and / or by introducing a source of volatile acids can reduce the levels of nitrogen and phosphorus in wastewater.

 A brief description of the drawings.

 In FIG. 1 is a schematic diagram of a purification method by contacting a drip biological filter with solid particles.

 In FIG. 2 is a schematic diagram of three different methods for treating treated wastewater of a drip biological filter, including a method according to the invention.

 In FIG. 3 is a schematic diagram of a laboratory workflow for investigating a method for treating treated wastewater of a drip biological filter according to the invention.

 In FIG. Figure 4 shows a graph of the effect of the hydraulic retention time (HRT) of an aerobic / mixing tank on the concentration of HFC in the final treated wastewater, the total chemical oxygen demand (total chemical oxygen demand (TCOD)) and the chemical need for dissolved oxygen (CLCD) (soluble chemical oxygen demand - SCOD)) of finally treated wastewater.

 In FIG. Figure 5 shows a graph of the effect of the VSU aerobic / mixing tank on the HWP and the HPW in the finally treated wastewater.

 In FIG. Figure 6 shows a graph of the effect of the VSU aerobic / mixing tank on the extracellular polymer (VKP (extracellular polymer - ECP) and OPI.

 In FIG. Figure 7 shows a graph of the effect of the HHP of an oxygen-free / anaerobic tank on the quantitative characteristics of the finally treated wastewater, including the concentration of HFC, OCPK and KhPRK.

 In FIG. Figure 8 shows a graph of the effect of the HVAC of an oxygen-free / anaerobic reservoir on the HWP and HPW in the finally treated wastewater.

 In FIG. Figure 9 shows a graph of the effect of the CPSU on OPI under various oxygen-free conditions.

 In FIG. 10 shows a graph of the content of the CPSU depending on the IPI.

 In FIG. 11 is a flow diagram of a preferred method including the invention.

 In FIG. 12 depicts a second process flow diagram of a preferred method including the invention.

 In FIG. 13 depicts a third process flow diagram of a preferred method including the invention.

 In FIG. 14 depicts a fourth process flow diagram of a preferred method including the invention.

 In FIG. 15 is a diagram of a preferred method including the invention.

 In FIG. 16 is a schematic diagram of a preferred method incorporating the invention.

 In FIG. 17-27 are schematic diagrams of alternative specific embodiments of the preferred method of FIG. 16, including the invention.

 In FIG. 28 is a diagram of yet another preferred method comprising the invention.

 In FIG. 29 and 30 are diagrams of alternative specific embodiments of the preferred method of FIG. 28, including the invention.

 In FIG. 31 is a diagram of another preferred method comprising the invention.

 In FIG. 32 and 33 are diagrams of alternative specific embodiments of the preferred method of FIG. 31.

 DETAILED DESCRIPTION OF THE INVENTION

 The invention relates in a broad sense to technological methods of wastewater treatment, and more particularly, to such methods that use drip biological filters, or to drip biological filters as parts of a purification method by contact with solid particles. The invention can be used for the treatment of domestic, agricultural and / or industrial wastewater. Some types of industrial waste are difficult to clean biologically because they lack some nutrients such as nitrogen and phosphorus. For biological treatment of such wastes, nutrients such as nitrogen and phosphorus can be added to compensate for their limited concentration or complete absence. Purification of papermaking wastes could serve as an example of how nitrogen and phosphorus are introduced for biological treatment with activated sludge in order to maintain relations corresponding to 1 part nitrogen per 20 parts BHPK and 1 part phosphorus 75 parts BHPK. Figure 1 shows a schematic diagram of such a cleaning method by contacting a drip biological filter with solid particles, which is known in the art.

 To date, it has been found, in a broad sense, that the sedimentation of suspended solids in treated wastewater with such methods can be significantly increased and that the biochemical oxygen demand (BHPC) in treated wastewater can be significantly reduced when implementing the method, when the used sludge is held in an oxygen-free / anaerobic zone (defined below) for a time sufficient to improve the precipitation characteristics of suspended solids in the treated wastewater of the process plant, after by contacting the sludge from an oxygen-free / anaerobic zone with treated wastewater from a drip biological filter under mixing and under anaerobic conditions (defined below).

 It has also been found that the removal of nitrogen and / or phosphorus can be facilitated, in addition to the foregoing, by a method in which volatile acid, such as an acid obtained from a particulate bioreactor (defined below), is supplied to an oxygen-free / anaerobic one to remove phosphorus zone, and / or to remove nitrogen, ammonia nitrogen is oxidized to nitrate nitrogen in the aerobic biological oxidation zone, and optionally, in the oxygen-free zone (defined below), nitrate nitrogen is reduced to molecular nitrogen (nitrogen gas).

 In a preferred embodiment of the method of FIG. 11, wastewater containing suspended solids and biodegradable organic matter is transported through line 10 through an aerobic biological oxidation zone 12, in which part of the BCCP is converted to additional suspended solids. Treated wastewater from aerobic biological oxidation zone 12 is passed through line 14 to aerobic / mixing zone 16, where it is mixed with treated wastewater transported through line 18 from an oxygen-free / anaerobic zone 20. Treated wastewater from zone 16 of aeration mixing passes through line 22 to the deposition zone 24. The treated wastewater with reduced BCF and suspended solids content leaves the deposition zone 24 through the pipe 26, and the sludge containing suspended solids leaves through boprovodu 28. The double lines in FIG. 11 and FIG. 13-15 depict sludge flow, while single lines depict fluid flow. Part of the sludge containing suspended solids is recycled through line 30 to an oxygen-free / anaerobic zone 20. In an oxygen-free / anaerobic zone 20, the content of extracellular polymer in the sludge increases, and the treated wastewater from zone 20 is recycled through line 18 to the aerobic / mixing zone, as indicated above.

 The following terms used throughout the description have the following meanings.

 By “aerobic biological oxidation zone” is meant any of the known aerobic biological treatments, such as purification operations using a drip biological filter, or by contacting a drip biological filter with solid particles, or methods for treating wastewater with activated sludge. Such aerobic biological oxidation zones include any operation in which the main emphasis is on the reduction of BCP through aerobic biological treatment. Such treatment operations may include treatment in stabilizing ponds, lagoons and oxidation steps in ditches.

 Under "aerobic conditions", i.e. conditions in the aerobic / mixing zone, it is understood the conditions of aeration oxidation, which can be provided on the well-known technological equipment, including aerators, mixers, etc. "Aerobic" means "containing a finite amount of dissolved oxygen (PK (DO))." Preferred aerobic conditions are those in which the RK content is more than one milligram per liter.

 By “oxygen-free conditions” we mean conditions under which dissolved oxygen (RK) is absent in liquid products stored in tanks, but chemically bound oxygen, such as nitrate, is available for microbial metabolism.

 Under "anaerobic conditions" we mean conditions under which there is no RC in liquid products stored in tanks and under which nitrate is also absent, so only anaerobic microorganisms can survive.

 By “oxygen-free / anaerobic conditions” are meant conditions that are at least oxygen-free, i.e. dissolved (free) oxygen is absent, but bound oxygen in the form of nitrate may or may not be present.

 The term "precipitation" in the sense that is used here, refers in a broad sense to any method of separation of solid particles known in the art, for example, to filtration and centrifugation.

 The term “volatile acid,” as used herein, refers to water-soluble fatty acids that can be distilled at atmospheric pressure, and encompasses water-soluble fatty acids containing up to 6 carbon atoms in a molecule. The term also encompasses the corresponding water soluble carboxylates of volatile acids.

 The type of reactor used in any of the zones described in this invention (in the main aerobic biological oxidation zone, aerobic zone, oxygen-free zone, oxygen-free / anaerobic zone and anaerobic zone) can be classified as a biological suspension reactor or a film reactor attached to a stretched film cells. In addition, it is possible to combine these two types in the form of a reactor with a suspension and with cells attached to the stretched film. An example of a slurry reactor is an aeration tank of the type used in activated sludge treatment. An example of a film reactor with cells attached to a stretched film is a drip biological filter or a rotating biological contactor (IBC). Combined reactors with a suspension and with cells fixed on a stretched film can be of various types, including IBD in an aeration tank, feeding a suspension into a film reactor with cells fixed on a stretched film, or feeding precipitated suspended biological solids into a film reactor with cells fixed on a stretched film.

 In preferred particular embodiments of the method shown in FIG. 11, a portion of the treated wastewater can be separated in the precipitation zone and recycled to the aerobic / mixing zone as a diluent. In another preferred particular embodiment, the wastewater supplied to the aerobic biological oxidation zone can first be passed through the primary particulate separation zone, in which part of the suspended solids is removed and BCPK is reduced. Process conditions in several treatment zones in the method shown in FIG. 11 are described in detail above.

 In a broad sense, the ratio of sludge recycled to an oxygen-free / anaerobic zone to sludge either removed from the purification process or recycled back to the aerobic biological oxidation zone is in the range 1: 99-99: 1. Such a wide range gives considerable flexibility to the method of the invention.

 Another specific embodiment of the invention is shown in FIG. 12. Reference numeral 50 relates to a pipeline through which wastewater containing suspended solids and biodegradable organic matter is transported to aerobic biological oxidation zone 52. In zone 52, part of the BHPC is converted to additional suspended solids. The treated wastewater from zone 52 of the aerobic biological oxidation is transported through line 54 to the intermediate deposition zone 56, where the intermediate clarified wastewater is separated from the intermediate sludge containing suspended solids. The clarified treated wastewater flows through line 58 to the aerobic / mixing zone 60, and the sludge is transported through line 62 to the anaerobic zone 64. The treated wastewater from the aerobic / mixing zone 60 passes through line 66 to the secondary deposition zone 68, where the treated wastewater with reduced BCF and a reduced content of suspended solids are separated from the sludge containing suspended solids. The treated wastewater is transported through pipeline 70 from the secondary deposition zone 68, and the sludge containing suspended solids is removed and recycled back to the aerobic biological deposition zone 52 through the pipeline 72. The intermediate sludge contained in the oxygen-free / anaerobic zone 64 is held therein. sufficient time to increase the extracellular polymer content of the specified sludge, and treated wastewater from an oxygen-free / anaerobic zone having a high content of extracellular polymer, transpo they are pumped through line 74 to the aerobic mixing zone 60, where it is mixed with intermediate clarified wastewater transported through line 58. The process conditions in several treatment zones for the method shown in FIG. 12 are described in detail below.

 In FIG. 13, the wastewater is piped 100 to an aerobic biological oxidation zone 102, where a portion of the BCCP is converted to suspended solids. The treated wastewater from zone 102 is transported through a pipeline 104 to an intermediate deposition zone 106, and the intermediate clarified wastewater is discharged from zone 106 through a pipeline 108, and the intermediate sludge containing suspended solids is removed or recycled back to the aerobic biological oxidation zone 102 through a pipeline 110. Intermediate clarified wastewater flows into aerobic / mixing zone 112, where it is mixed with treated wastewater from an oxygen-free / anaerobic zone 114. Purified wastewater from aero The bean / mixing zone 112 is transported via line 116 to the secondary deposition zone 118. In this zone, treated wastewater having a reduced BHPC and a reduced suspended solids content is separated from the sludge containing suspended solids. The former are removed through line 120, and the latter is recycled to an oxygen-free / anaerobic zone 114 through line 122. The sludge containing suspended solids that is introduced into the oxygen-free / anaerobic zone 114 is held therein for a time sufficient to increase the content of extracellular sludge polymer, and then recycled through conduit 124 to the aerobic / mixing zone 112. Conditions in several cleaning zones for the method shown in FIG. 13 are further described below.

 In FIG. 14, the wastewater is piped 150 to the aerobic biological oxidation zone 152, where a portion of the BCPC is converted to suspended solids. Treated wastewater from zone 152 is transported via pipeline 154 to intermediate deposition zone 156. Intermediate clarified wastewater is transported from zone 156 via line 158 to aerobic / mixing zone 160. Intermediate sludge containing suspended solids is transported through line 162. Intermediate sludge (activated sludge) can be transported through line 164 to remove waste or can be transported by pipeline 166 to the anoxic / anaerobic zone 168. The treated wastewater from the aerobic / mixing zone 160 is transported through pipeline 170 to the secondary deposition zone 172. In this zone, treated wastewater having a reduced BHPC and a reduced suspended solids content is separated from the sludge containing suspended solids. The first stream is discharged from the process chain through line 174, and the last stream is transported from the secondary deposition zone 172 via line 176. Secondary sludge can be removed from the process line through lines 176, 178 and 164, or can be recycled through line 180 to an oxygen-free / anaerobic zone 168, in which it can be mixed with an intermediate sludge containing suspended solids transported via line 166. The sludge is held in an oxygen-free / anaerobic zone for a time sufficient to increase the content of the extracellular polymer of such sludge, and then recycled through line 182 to the aerobic / mixing zone 160, where it is mixed with intermediate clarified treated wastewater in line 158. Conditions in several treatment zones for the method shown in FIG. 14 are further described below.

 Another additional and important feature of the invention is that the methods described above can be further modified by setting certain conditions in the mixing zone, located upstream than the aerobic / mixing zone. Turning to FIG. 11-15, we note that the advantages of mixing treated wastewater from the aerobic biological oxidation zone, transported via pipeline 14, with treated wastewater from an oxygen-free / anaerobic zone having a high content of extracellular polymer in an oxygen-free pre-mixing zone were found. Such an oxygen-free pre-mixing zone is indicated by 200 in FIG. 15. The pipelines leading to the premixing zone 200 are pipelines 14 and 18 shown in FIG. 11. By holding and pre-mixing the sludge species in zone 200 for a period of time further indicated below and then passing the mixed sludge species through conduit 202 to the aerobic / mixing zone 204, it has been found that additional important improvements in the solids separation performance and additional improving performance in terms of reducing BCF and the area of treated wastewater. The aerobically mixed sludge in zone 204 passes through line 22, as described above and shown in FIG. eleven.

 All methods depicted in FIG. 11, 12, 13 and 14 can be modified by introducing an oxygen-free pre-mixing zone located upstream than the aerobic / mixing zone described above in connection with FIG. 11. Therefore, pipelines 58 and 74, as shown in FIG. 12, pipelines 108 and 124, as shown in FIG. 13, or pipelines 158 and 182, as shown in FIG. fourteen.

 As for the methods depicted in FIG. 11-14 and modified as shown in FIG. 15, it was found that suitably adapted methods may be effective in removing nutrients — nitrogen and phosphorus — from waste streams. Aerobic biological oxidation is known to lead to the oxidation of nitrogen in the form of ammonia to nitrogen in the form of nitrate. As a result of the implementation of the processes in question, nitrate nitrogen can be removed by denitrification to nitrogen gas in an oxygen-free pre-mixing zone or an oxygen-free / anaerobic zone.

 Turning now to the specific embodiments illustrated in FIG. 16-33, note that these specific options facilitate the removal of nitrogen by passing treated wastewater from the main zone of aerobic biological oxidation (where ammonia nitrogen was oxidized to nitrate nitrogen) to anaerobic (Fig. 22-24) or oxygen-free (Fig. 16- 21, 25-27, 31-33) the zone where the nitrate nitrogen is reduced to molecular nitrogen (nitrogen gas) due to microbial exposure.

 As for phosphorus, its removal begins in an oxygen-free / anaerobic zone, where phosphorus is released from the sludge into the liquid, and ends in the aerobic / mixing zone by the abundant introduction of phosphorus obtained by aerobic biological oxidation into the biomass under aerobic mixing.

 Specific embodiments of the present invention illustrated in FIG. 16-33 further facilitate the removal of phosphates by introducing volatile acid into the anoxic / anaerobic zone. In this aspect of the present invention, the absorption of volatile acid by suitable microorganisms under oxygen-free, anaerobic or oxygen-free / anaerobic conditions causes these organisms to energetically release phosphorus from the liquid, thereby removing it as part of the process biomass.

 Therefore, it was found that it is possible to implement a flexible wastewater treatment method that not only has improved particulate separation and reduced BCPF, but also provides effective removal of nitrogen and / or phosphorus from the wastewater. This is achieved not only due to the above modification of the method described above in connection with FIG. 15, but also due to the specific embodiments illustrated in FIG. 16-33. The method can be implemented to effectively improve the characteristics of the separation of solid particles and reduce BHPC or to achieve the same goals along with the removal of phosphorus or the removal of nitrogen.

 Table 1 shows the conditions characterizing the time spent in various cleaning zones and affecting the desired results.

 It was found that the sedimentation of sludge on a drip biological filter is a function of the content of extracellular polymer and its graph is plotted according to the corresponding data of OPI. In FIG. 9 shows that the best precipitated sludge, represented by a low OPI, has a higher VKP content. In FIG. 10 also shows that the sludge sedimentation begins to decrease when the content is less than 90 mg VKP per gram of the average suspended solids (MSSP) (mean level suspended solids (MLSS)) and decreases sharply when the content is less than 60 mg VKP / g MSSP. At a level of less than 60 mg VKP / g SSHTV, the change in IPI is very sensitive to a change in VKP. Obviously, the content of the CPS in the drip biological filter depends on the determination of the degree of biofloculation, a measure of which is the OPI.

 The effect of VSU (hydraulic retention time) in an aerobic / mixing tank.

 The effect of the change in the HVG in the aerobic / mixing tank on the sedimentation of sludge and the quality of the treated wastewater is shown in FIG. 5 and 6, which depicts the relationship between OPI, VKP and HPF filtrate, when the VSU of the aerobic / mixing tank changes from 15 minutes to 60 minutes. VSU for more than 60 minutes does not improve the parameters of VTCh or OPI. The reason for this may be the fragmentation of particles caused by extensive aeration, as well as a small formation of VKP in the sludge.

VSU in the aerobic / mixing tank for 15.5 minutes gave a CPRK of treated wastewater of 39 mg / L (equivalent to the biochemical need for dissolved oxygen (BCPR ₅ ) 10 mg / L). The CHRK in the filter, when the HHC was more than 30 minutes, was less than 30 mg / L (or the equivalent of BHPC ₅ less than 5 mg / L), indicating that most of the soluble organic substances from the treated wastewater of the drip biological filter were removed by HHW in aerobic / mixing tank for more than 30 minutes.

 VSU in the aerobic / mixing tank for more than 62 minutes did not improve the quality of the high-frequency water treatment of the finally treated wastewater. Experimental results showed that the quality of the high-temperature water treatment of finally treated wastewater was reduced due to the high flow rate due to the low concentration of HCP in the sludge. An extended aeration period can reduce sludge settling. Thus, the aeration period in an aerobic mixing tank to remove organic substances in a drip biological filter should be maintained, for example, equal to 30 minutes, but prolonged aeration, for example, for 60 minutes, should be avoided to prevent its undesirable effect on the sedimentation of sludge.

 The effect of HHU in an oxygen-free / anaerobic tank.

The experimental results also demonstrated the positive effect of supplementing the treatment of decontaminated wastewater with a drip biological filter, an oxygen-free / anaerobic treatment. In FIG. Figures 8 and 9 show the relationship between the OPI, VKP, and VHF of the final treated wastewater when using various HLP in an oxygen-free / anaerobic tank during the treatment of treated wastewater. VSU in the aerobic / mixing tank was maintained at 30 minutes, because at 30 minutes most of the soluble organic substances should be removed from the treated wastewater by a drip biological filter when loading organic substances at 41 pounds COD / day / 1000 cubic feet (0, 67 kg COD / day / m ³ ). The graphs showed that the OPI was the smallest at VSU in an oxygen-free / anaerobic tank for 45 minutes.

 Better precipitated sludge may be a sign of a high concentration of VKP in the sludge. The VKP content in the sludge was greatest at 45 minutes of HHP in an oxygen-free / anaerobic tank, as shown in FIG. 9. The content of VKP in the sludge after passing more than 45 minutes of VSU in an oxygen-free / anaerobic tank did not increase. Experimental results show that extensive oxygen-free / anaerobic treatment does not allow more VKP in sludge to be obtained. Sludge sedimentation during periods of oxygen-free / anaerobic treatment more than 45 minutes actually decreased due to the lower content of VKP. A decrease in the VKP content in the sludge could be the result of decomposition of the VKP due to the extensive lytic effect associated with the hydrolysis of polymers or polymeric materials. At 91 minutes of anoxic / anaerobic treatment, the CPC of the final treated wastewater actually increased to 32.2 mg / L, as shown in FIG. 7. An increase in CPRK can be caused by the formation of refractory materials during prolonged oxygen-free / anaerobic treatment. Therefore, the results show that VSU in an oxygen-free / anaerobic tank, which is less than 45 minutes, allows to achieve maximum deposition efficiency in connection with the formation of VKP.

Turning now to the method of the invention and illustrated in FIG. 16, note that untreated wastewater enters the primary sedimentation zone or reservoir 300, where suspended solids are separated from the wastewater. Wastewater as treated wastewater flows into the main zone 310 of aerobic biological oxidation (which introduces and maintains the characteristics of the aerobic biological oxidation zone corresponding to the specific embodiments depicted in Figs. 11-15) through the sewage liquid pipeline 302. In the main aerobic biological oxidation zone 310, part of the biochemical oxygen demand is removed by oxidation and at least part of the ammonia nitrogen (NH ₃ -N) contained in the wastewater is oxidized to nitrate nitrogen (NO ₃ -N). This nitrogen conversion is called nitrification. In order to be able to carry out nitrification by microbial oxidation, the biochemical oxygen demand should be significantly reduced, for example, to a level of 14 mg / l or less. This is due to the fact that autotrophic bacteria such as Nitrosommonas and Nitrobacter species are responsible for the conversion of ammonia nitrogen to nitrate nitrogen. Initially, heterotrophic bacteria, such as Bacillus spp., Dominate in the aerobic biological oxidation zone 310, since these heterotrophs metabolize BHPC. This heterotrophic activity successfully limits the activity of nitrifying autotrophs until BHPK decreases to a level low enough so that heterotrophic activity is limited and autotrophic activity can dominate. The same effect, i.e., in essence, autotrophic domination, can be achieved in the case of wastewater with an initial sufficiently low BCP, such as 14 mg / L or less.

 The treated wastewater from the main zone 310 of aerobic biological oxidation passes into the zone into which additional oxygen, such as an oxygen-free zone 315, is not introduced, through the liquid sewage pipe 312. The treated wastewater from the oxygen-free zone 315 passes into the aerobic / mixing zone 320 (which introduces and maintains the characteristics of the aerobic / mixing zone corresponding to the specific embodiments depicted in Figs. 11-15) through the sewage liquid pipe 317.

 One or more volatile acids are present in the oxygen-free zone 315, and bacteria, in the presence of such volatile acids and under conditions where no additional oxygen is introduced, release phosphate in zone 315.

 In the aerobic / mixing zone 320, bacteria quickly remove phosphate from the treated wastewater, affecting not only the contained phosphate released in the oxygen-free zone 315, but also the phosphate contained in the treated wastewater obtained from the main aerobic biological oxidation zone 310. The treated wastewater from the aerobic / mixing zone 320 passes through a pipe 322 to the final deposition zone 330 (which introduces and maintains the characteristics of the final deposition zone corresponding to the specific embodiments depicted in Figures 11-15), where suspended solids are separated from the treated wastewater water and out of the system through a pipe 334 fluid. A portion of the suspended solids from the final deposition zone 330 is recycled back to the main stream (passing from the main aerobic biological oxidation zone 310 to the liquid line 312, the oxygen-free zone 315, the liquid line 317, the aerobic mixing zone 320, the liquid line 322, and the final settling zone 330) as sludge through the pipelines 332 and 334 'of solid particles in order to facilitate the implementation of the method and to obtain the advantages provided by the present invention. The remainder of the suspended solids from the final deposition zone 330 exits the sludge treatment via a particulate line 336.

 The oxygen-free zone 315 has a significant effect on phosphorus removal. At least a portion of the sludge formed from the suspended solids is removed using the primary sedimentation zone 340 and passes to the primary sludge fermentation zone 340 through the particulate pipe 303. Fermentation zone 340 provides for the formation of volatile acids, such as acetic, n-propionic, n-butyric and / or lactic acids and / or their carboxylates, such as sodium acetate, due to short-term anaerobic fermentation, lasting from about 0.5 days to about 3 days. An example of the production of volatile acid by fermentation of both primary sludge and sludge from a rotating biological contactor from both an industrial wastewater treatment plant and laboratory methods is shown in Table 2.

Table 2 shows that the volatile acid in the form of acetic acid, which was discussed here, can be obtained using primary sludge and sludge industrial rotary biological contactor, as well as sludge laboratory rotary biological contactor. After fermentation, the spent solid particles are separated from the liquid in the sludge fermentation zone 340 and are discharged from the system through a pipe 342 of solid particles. The treated wastewater fluid from the primary sludge fermentation zone 340, with a concomitant volatile acid content, is supplied to the oxygen-free zone 315 as part of the treated wastewater passed through the liquid pipe 312. In the oxygen-free zone, 315 volatile acids are collected by bacteria, causing them to release phosphate into treated wastewater. In addition, oxygen-free conditions in oxygen-free zone 315 restore nitrate nitrogen (NO ₃ —N) to molecular nitrogen (carry out denitrification), which may be present in the treated wastewater in the form of a gas, thereby reducing the nitrogen content in the treated wastewater. The treated wastewater from the main aerobic biological oxidation zone 310, containing suspended solids from the final precipitation zone 330, is purified by being in the oxygen-free zone 315, and the volatile acid and bacteria cleaning in this way are introduced into the aerobic / mixing zone 320 via a fluid line 317. In the aerobic / mixing zone 320, the bacteria aerobically exposed to the phosphate of the treated wastewater obtained from the main zone 310 of aerobic biological oxidation, as well as the phosphate released in the oxygen-free zone 315, quickly select the phosphate contained in the treated wastewater, introducing it into biomass. Suspended solids from the final deposition zone 330 are recycled back to the main stream (flowing from the main aerobic biological oxidation zone 310 to a pipe 312, an oxygen-free zone 315, a pipe 317, an aerobic / mixing zone 320, a liquid pipe 322 and a final deposition zone 330) 332 and 334 'in order to facilitate the implementation of the method. An advantage of the particular embodiment depicted in FIG. 16 is that, in addition to the advantages of the specific embodiments depicted in FIG. 11-15, ammonia nitrogen is converted to nitrate nitrogen (nitrification takes place), and then to molecular nitrogen (denitrification takes place), due to which the amount of nitrogen in the pipeline 334 of treated wastewater is significantly reduced, and the dissolved phosphate is removed from the treated wastewater in due to microbial uptake into biomass, the phosphate being captured in the form of solid particles.

 In FIG. 16-33, various respective zones and pipelines of liquid and solid particles are denoted by the same reference numerals from drawing to drawing to facilitate understanding. It should be understood that the various respective zones and pipelines in the specific embodiments depicted in FIG. 17-33 operate and function in the same manner as discussed with respect to FIGS. 16, unless you take into account the exceptions that can be noted when discussing a particular embodiment.

 In the particular embodiment depicted in FIG. 17, suspended solids from the final deposition zone 330 are used as a source to produce volatile acid rather than primary sludge, as in the particular embodiment depicted in FIG. 16. When a portion of the suspended solids from the final deposition zone 330 passes directly to the liquid line 312 and to the oxygen-free zone 315 through the solid lines 332, 333, 335 and 337, the second part passes to the final silt fermentation zone 350 through the solid lines 332 and 338 particles. Suspended solids in the final fermentation zone 350 undergo anaerobic fermentation from about half a day to about three days, resulting in one or more of the aforementioned volatile acids and / or carboxylates. The treated wastewater from the zone 350 of the final sludge fermentation (with volatile acid and fermented suspended solids) enters the oxygen-free zone 315 through the pipelines 339, 337 and 312 of the liquid / solid particles, where they along with suspended solids from the pipelines 332, 333, 335 and 337 solids are treated in the same way as treated wastewater from the primary sludge fermentation zone 340 and suspended solids from the final sedimentation zone 330 in the particular embodiment shown in FIG. 16. The advantage of the particular embodiment depicted in FIG. 17, different from the advantages of the particular embodiment depicted in FIG. 16, the use of finally precipitated biological sludge as a source of volatile acids for increased phosphorus removal does not add additional BCPK and additional solid particles to the main sewage stream, as in the case of the primary sludge fermentation approach in a particular embodiment, depicted in FIG. 16. In addition, biological sludge is easier to handle than primary sludge. Further, part of the biomass with suspended solids is fermented or hydrolytically decomposed into a liquid form that is easier to move. However, fermentation of primary sludge introduces some additional nitrogen and phosphorus into the system along with volatile acids and, therefore, increases the load of nitrogen and phosphorus in the wastewater treatment plant. When using fermented products of finally precipitated biological sludge, no such load of nitrogen and phosphorus should be. Thus, if an increase in the loading of nitrogen and phosphorus is not allowed by the guidelines, the finally precipitated biological sludge should be a very valuable feature in the production of volatile acids.

 In the particular embodiment depicted in FIG. 18, volatile acid is supplied as an additive of sodium acetate from a source of 360 sodium acetate. Sodium acetate is supplied in the form of an aqueous solution in order to provide a concentration of 30-150 mg / L in the oxygen-free zone 315, or preferably 50-100 mg / L in the liquid pipe 362 to the liquid pipe 312, and therefore to the oxygen-free zone 315, where the same effect as the introduction of volatile acid in the specific embodiments depicted in FIG. 16 and 17. In situations where there is insufficient anaerobically fermentable substrates in the untreated wastewater to obtain an adequate level of volatile acid and / or phosphate removal, it may be desirable to use the particular embodiment depicted in FIG. 18. Further, when anaerobic fermentation is used, as in the specific embodiments depicted in FIG. 16 and 17, but for a long or short period of time additional volatile acid is needed, it may be desirable to supply additional volatile acid, as shown in FIG. 18.

 It should be understood that the specific embodiments depicted in FIG. 16-18, it is possible to combine in such a way that it will be possible to obtain volatile acid using zone 340 of primary sludge fermentation and zone 350 of final sludge fermentation, or using zone 340 of primary sludge fermentation and source 360 of sodium acetate, or using zone 350 of final fermentation sludge and a source of 360 sodium acetate, or using all three sources.

 The particular embodiment depicted in FIG. 19 differs from the specific embodiment depicted in FIG. 16, in that the treated wastewater from the main aerobic biological oxidation zone 310 passes through a liquid pipe 314 to an intermediate sedimentation zone 370, where suspended solids are separated from the treated wastewater and pass through a solid pipe 372 to an intermediate sludge fermentation zone 380. The treated wastewater from the intermediate sedimentation zone 370 passes through a liquid pipe 374 to an oxygen-free zone 315. The sludge from the intermediate deposition zone 370 undergoes anaerobic fermentation from about half a day to about three days in the intermediate sludge fermentation zone 380 to produce volatile acid. The treated wastewater from the sludge intermediate fermentation zone 380 containing volatile acid is transported through a liquid line 382 to a liquid line 374, and hence to an oxygen-free zone 315, where phosphate removal is facilitated, as described above. The fermented sludge is removed from the intermediate sludge fermentation zone 380 and discharged from the processing through the pipeline 382 solid particles. Primary sludge is removed from the primary sedimentation tank 300 and discharged from processing through the particulate pipe 304. In this particular embodiment, intermediate sludge rather than primary sludge or final sludge is used as the source of volatile acid, as in the particular embodiment depicted in FIG. 16 and 17. The advantages this gives are that the intermediate sludge contains biologically active solids already prior to any biological treatment, which should not have been the case with finally precipitated solids. Intermediate sludge should have a higher content of organic substances for better fermentation in order to obtain volatile acid.

 The particular embodiment depicted in FIG. 20 differs from the specific embodiments depicted in FIG. 16 and 19, in that the treated wastewater from the sludge primary fermentation zone 340 (from the specific embodiment shown in FIG. 16) containing volatile acid passes into the intermediate sludge fermentation zone 380 (from the specific embodiment shown in FIG. 19), where anaerobic fermentation of intermediate sludge replenishes its volatile acid content. The combined now treated wastewater from the primary sludge fermentation zone 340 and the intermediate sludge fermentation zone 380 passes to an oxygen-free zone 315 through fluid lines 382 and 374. An advantage of this particular embodiment is the introduction of unused organic substances from the primary sludge fermentation zone, with the goal of sludge fermentation, into the intermediate sludge fermentation zone to produce volatile acid.

 The particular embodiment depicted in FIG. 21 is a variation of the particular embodiment depicted in FIG. 20, which consists in the fact that the treated wastewater from the zone 340 of primary sludge fermentation enters directly into the oxygen-free zone 315 through liquid pipelines 348 and 374, and does not enter the intermediate sludge fermentation zone 380. The advantage is that each zone is separated from the other and therefore cannot interfere with other biological fermentations in order to produce volatile acid. While in the particular embodiment depicted in FIG. 20, primary sludge fermentation zone 340 is connected in series with intermediate sludge fermentation zone 380, in the particular embodiment shown in FIG. 21, these two zones are connected in parallel to each other.

 Turning now to the specific embodiment depicted in FIG. 22, note that the treated wastewater from the main zone 310 of aerobic biological oxidation is supplied to the anaerobic zone 390 through a pipe 312. In the anaerobic zone 390, at least a portion of the nitrate nitrogen content in the treated wastewater is restored to molecular nitrogen (nitrogen gas), the treated wastewater Water from the anaerobic zone 390 is supplied to the aerobic / mixing zone 320 via a fluid line 392. In this embodiment, the treated wastewater from the oxygen-free / anaerobic zone 400 is supplied to the anaerobic zone 390 through fluid lines 402 and 312. Further, part of the treated wastewater from the sludge primary fermentation zone 340 with its volatile acid content is supplied to the anaerobic zone through pipelines 347, 347A and 312, while the remainder passes to the anoxic / anaerobic zone 400 through pipelines 347, 347B and 334 '. Thus, the volatile acid from the primary sludge fermentation zone 340 and the suspended solids from the final sedimentation zone 330 are processed in an oxygen-free / anaerobic zone 400, where the volatile acid is initially absorbed and phosphate is released, and another portion of the volatile acid from the primary sludge fermentation zone 340 and the filtrate from the anoxic / anaerobic zone 400 is treated in the anaerobic zone 390, where a second absorption of volatile acid and a second release of phosphate occurs.

 Therefore, the absorption of phosphate in the aerobic / mixing zone 320 is even more energetic. An additional advantage of the particular embodiment depicted in FIG. 22, it is possible that additional phosphate can be released by introducing an anaerobic zone in front of the aerobic / mixing zone. This can provide a means of increasing the total removal of phosphate, as well as the removal of nitrate formed in the main zone of aerobic biological oxidation, by reduction to molecular nitrogen. Volatile acids from the primary sludge fermentation zone 340 can be passed to both the anoxic / anaerobic zone 400 and the anaerobic zone 390. The use of the anaerobic zone shown in FIG. 22-24, has the advantage of combining nitrate reduction and phosphate release in the same process unit. In normal practice, nitrate can inhibit phosphate release. However, it has been found that by introducing volatile acid into the anaerobic zone, it is possible to ensure that both can be carried out in the same reservoir or zone.

 The particular embodiment depicted in FIG. 23 is similar to the particular embodiment depicted in FIG. 22, except that volatile acid is supplied from the sludge final fermentation zone 350, and not from the primary sludge fermentation zone 340, as in the particular embodiment depicted in FIG. 22. In this embodiment, part of the treated wastewater from the sludge final fermentation zone 350 is supplied to the anaerobic zone 390 through the fluid lines 339, 352 and 312, while the rest of the filtrate passes to the anoxic / anaerobic zone 400 through the liquid lines 339 and 354. In addition, a portion of the treated wastewater from the final sedimentation zone 330 is transported through the particulate pipelines 332, 336 and 336 'to the oxygen-free / anaerobic zone 400 for purification in the above manner. Thus, the initial absorption of volatile acid and the release of phosphate in the anoxic / anaerobic zone 400 occurs, followed by the second absorption of volatile acid and the release of phosphate in the anaerobic zone 390, as in the particular embodiment depicted in FIG. 22. An advantage of this particular embodiment is that phosphate removal is further facilitated, as in the embodiment depicted in FIG. 22, combined with the advantage of fermentation of biological sludge. An advantage of the particular embodiment depicted in FIG. 17, which differs from the advantages of the particular embodiment depicted in FIG. 16, it is the fact that the use of finally precipitated biological sludge as a source of volatile acids intended for increased phosphorus removal does not introduce additional BCPK and additional solid particles outside the biological treatment zone into the main stream of treated wastewater and allows applying the approach of primary fermentation sludge, as in the particular embodiment depicted in FIG. 16. In addition, biological sludge is easier to handle than primary sludge. Further, part of the biomass with suspended solids undergoes fermentation or hydrolytic decomposition with the transition into a liquid form, which is easier to move. However, primary sludge fermentation introduces some additional nitrogen and phosphorus along with volatile acids into the system and, therefore, increases the loading of nitrogen and phosphorus in the wastewater treatment plant. When using fermented products of finally precipitated biological sludge, no such load of nitrogen and phosphorus should be. Thus, if an increase in the loading of nitrogen and phosphorus is not allowed by the guidelines, the finally precipitated biological sludge should be a very valuable feature in the production of volatile acids.

 The particular embodiment depicted in FIG. 24 is similar to the particular embodiment depicted in FIG. 22 and 23, with the exception that volatile acid is supplied to the anaerobic zone 390 from both the primary sludge fermentation zone 340 and the final sludge fermentation zone 350. Therefore, a part of the filtrate containing volatile acid from the final sludge fermentation zone 350 is fed directly to the anaerobic zone 390 directly via the liquid lines 347, 347A and 312 and the liquid lines 339, 352 and 312, respectively. The remaining treated wastewater containing volatile acid from these two fermentation zones is transported to an oxygen-free / anaerobic zone 400 via liquid lines 347 and 347B, liquid / particulate lines 347C and liquid lines 339 and 354, respectively. Thus, as in the specific embodiments depicted in FIG. 22 and 23, the initial absorption of volatile acid and the release of phosphate in the anoxic / anaerobic zone 400 occurs, followed by the second absorption of volatile acid and the release of phosphate in the anaerobic zone 390, as well as the removal of nitrate formed in the main aerobic biological oxidation zone by reduction to molecular nitrogen. An advantage of this particular embodiment is that phosphate removal is further facilitated, as in the particular embodiment depicted in FIG. 22 and 23, combined with the advantage of converting biomass into liquid form, as in the particular embodiment depicted in FIG. 23.

 The particular embodiment depicted in FIG. 25 is similar to the particular embodiment depicted in FIG. 22, except that the treated wastewater from the main aerobic biological oxidation zone 310 is supplied to the anoxic zone 315 via a pipe 312. In the anoxic zone 315, at least a portion of the nitrate nitrogen contained in the treated wastewater is reduced to molecular nitrogen (nitrogen gas) ) The treated wastewater from the oxygen-free zone 315 passes into the anaerobic zone 390 through a fluid pipe 317. Anaerobic zone 390 restores another part of the nitrate nitrogen contained in the treated wastewater to molecular nitrogen (nitrogen gas). A portion of the treated wastewater from the anoxic / anaerobic zone 400 is supplied to the anoxic zone 315 through the fluid lines 403 and 404, while the remaining treated wastewater flows into the anaerobic zone 390 through the fluid lines 402 and 406. In addition, part of the treated wastewater from the sludge primary fermentation zone 340 with the volatile acid contained therein is supplied to the anaerobic zone 390 through the fluid lines 347, 347A and 317, while the remaining treated wastewater passes to the anoxic / anaerobic zone 400 through the pipes 347B and 334 '. As in the particular embodiment depicted in FIG. 20, a portion of the treated wastewater from the primary sludge fermentation zone 340 passes to the anaerobic zone 390, and the remaining treated wastewater goes to the anoxic / anaerobic zone 400 with the same effect as in the particular embodiment shown in FIG. 22. Depicted in FIG. 22-24, the anaerobic reservoir serves as both a zone for nitrate reduction and a zone for phosphate release. However, it is likely that these conditions may cause longer hydraulic retention times, which may be unnecessary or may create the need for excessive levels of volatile acid content. Therefore, in FIG. 25-27 nitrate reduction and phosphate release are separated by introducing an oxygen-free zone in front of the anaerobic zone. This makes it possible to separate the reduction of nitrate carried out in the oxygen-free zone and the release of phosphate carried out in the anaerobic zone. In this case, the need to introduce volatile acid may not be such an important factor.

 The particular embodiment depicted in FIG. 26 is similar to the particular embodiment depicted in FIG. 25, except that volatile acid is supplied from zone 350 of the final sludge fermentation. Part of the treated wastewater from the sludge final fermentation zone 350 is fed into the anaerobic zone 390 directly via the fluid pipelines 339, 352 and 317, while the remaining wastewater flows into the anoxic / anaerobic zone 400 through the fluid pipelines 339 and 354 with the same effect as and in the particular embodiment depicted in FIG. 23. While part of the final sludge from the final precipitation zone 330 is fed to the final fermentation zone 350 through pipelines 332 and 338 of solid particles as a substrate for anaerobic fermentation to volatile acid, the other part is supplied to the oxygen-free / anaerobic zone 400 via pipelines 332, 336 and 336 'particulate matter for the above purposes. An advantage of the particular embodiment depicted in FIG. 17, which differs from the advantages of the particular embodiment depicted in FIG. 16, it is the fact that the use of finally precipitated biological sludge as a source of volatile acids intended for increased phosphorus removal does not introduce additional BCPK and additional solid particles outside the biological treatment zone into the main stream of treated wastewater and allows applying the approach of primary fermentation sludge, as in the particular embodiment depicted in FIG. 16. In addition, biological sludge is easier to handle than primary sludge. Further, part of the biomass with suspended solids undergoes fermentation or hydrolytic decomposition with the transition into a liquid form, which is easier to move. However, primary sludge fermentation introduces some additional nitrogen and phosphorus along with volatile acids into the system and, therefore, increases the loading of nitrogen and phosphorus in the wastewater treatment plant. When using fermented products of finally precipitated biological sludge, no such load of nitrogen and phosphorus should be. Thus, if an increase in the loading of nitrogen and phosphorus is not allowed by the guidelines, the finally precipitated biological sludge should be a very valuable feature in the production of volatile acids.

 The particular embodiment depicted in FIG. 27 is similar to the particular embodiment depicted in FIG. 25 and 26, with the exception that volatile acid is supplied from both the primary sludge fermentation zone 340 and the final sludge fermentation zone 350, in the same way as in the particular embodiment depicted in FIG. 24, with a portion of the volatile acid from each zone entering the anaerobic zone 390, and the remainder entering the anoxic / anaerobic zone 400. In addition, as in the specific embodiments depicted in FIG. 25 and 26, part of the treated wastewater from the oxygen-free / anaerobic zone 400 is supplied to the oxygen-free zone 315 through the liquid pipelines 402 and 404, while the remaining treated wastewater flows into the anaerobic zone 390 through the liquid pipelines 402 and 406 with the same effect as in the specific embodiments depicted in FIG. 25 and 26. By using both the zone of primary sludge fermentation and the zone of final sludge fermentation, the final volatile acid content increases and the possibility of achieving greater removal of nitrogen and phosphorus, as well as BHPC and HPF, is achieved.

 Turning now to the specific embodiment depicted in FIG. 28, note that the treated wastewater enters the reservoir or primary sedimentation zone 300 where suspended solids are separated from the treated wastewater. The treated wastewater then passes into the main aerobic biological oxidation zone 310 (which introduces and maintains the characteristics of the aerobic biological oxidation zone corresponding to the specific embodiments depicted in FIGS. 11-15) through a fluid line 302. In the main aerobic biological oxidation zone 310, part of the biochemical oxygen demand is removed by oxidation and at least part of the ammonia nitrogen contained in the wastewater is oxidized to nitrate nitrogen. In addition, at least a portion of biochemical oxygen is converted to suspended solids, the treated wastewater from the main zone 310 of aerobic biological oxidation then passes to the aerobic / mixing zone 320 (which introduces and maintains the characteristics of the aerobic / mixing zone corresponding to particular embodiments, depicted in Fig. 11-15) through the pipeline 312 fluid.

 In the aerobic / mixing zone 320, bacteria quickly remove phosphate from the liquid, acting to remove the phosphate contained in the treated wastewater from the main aerobic biological oxidation zone 310. The treated wastewater from the aerobic / mixing zone 320 passes through the liquid pipe 322 to the final deposition zone 330 (which introduces and maintains the characteristics of the final deposition zone corresponding to the specific embodiments depicted in Figs. 11-15), where sludge species containing suspended solids particles are separated from the treated wastewater and exit the system through a fluid line 334. At least a portion of the sludge containing suspended solids from the final deposition zone 330 is fed via pipelines 332 and 334 ′ to the oxygen-free / anaerobic zone 400 (which introduces and maintains the characteristics of the oxygen-free / anaerobic zone corresponding to the particular embodiments depicted in FIG. 11 -fifteen). From this point on, suspended solids are recycled back to the main stream (passing from the main zone 310 of aerobic biological oxidation to line 312, aerobic / mixing zone 320, line 322 and final deposition zone 330) through lines 332 and 334 ', through the oxygen-free / aerobic zone 400 and a fluid conduit 402 so as to facilitate the implementation of the method and obtain the advantages provided by the present invention. In addition, the oxygen-free / anaerobic zone 400 performs an additional function in the removal of phosphorus. At least a portion of the sludge removed through the primary sedimentation zone 300 passes into the primary sludge fermentation zone 340 through a particulate pipe 303. Zone 340 primary sludge fermentation allows you to get volatile acid by short-term anaerobic fermentation, lasting from about 0.5 days to about 3 days.

 After fermentation, the crushed solid particles are separated from the liquid in the primary sludge fermentation zone 340 and are discharged through the solid particle pipe 342. The treated wastewater fluid from the primary sludge fermentation zone 340 with the associated volatile acid content is supplied to the oxygen-free / anaerobic zone 400 via a fluid / solid pipe 347 '. In the anoxic / anaerobic zone, 400 volatile acids are selected by bacteria, causing them to release phosphate. The treated wastewater from the oxygen-free / anaerobic zone 400 containing suspended solids from the final sedimentation zone 330 is treated by being in the oxygen-free / anaerobic zone 400, and the volatile acid and bacteria cleaning in this way are introduced into the aerobic / mixing zone 320 through a liquid line 402 / particulate matter and fluid line 312. In the aerobic / mixing zone 320, bacteria subjected to aerobic treatment of treated wastewater phosphate obtained from the main aerobic biological oxidation zone 310, under aerobic conditions, both the phosphate contained in the main aerobic biological oxidation zone 310 and the previously released phosphate contained in treated wastewater by introducing it into the biomass. Suspended solids from the final deposition zone 330 are recycled back to the main stream (passing from the main aerobic biological oxidation zone 310 to conduit 312, aerobic / mixing zone 320, conduit 322 and final deposition zone 330) through conduits 332 and 334 'through oxygen-free / anaerobic zone 400 and conduits 402 and 312 in order to facilitate the implementation of the method as described above with respect to specific embodiments, the advantage of the particular embodiment depicted in FIG. 28, is that, in addition to the advantages of the specific embodiments depicted in FIG. 11-15, ammonia nitrogen is converted to nitrate nitrogen, due to which the amount of ammonia nitrogen released by the proposed method is significantly reduced, and the dissolved phosphate is removed from the treated wastewater due to microbial absorption into the biomass.

 In the particular embodiment depicted in FIG. 29, sludge containing suspended solids from the final deposition zone 330, rather than primary sludge, is used as a source of volatile acid. Part of the sludge, which is a suspended solid particles, passes directly into the oxygen-free / anaerobic zone 400 through pipelines 332, 333 and 335 of solid particles. The remainder passes to the zone 350 of final fermentation of sludge through pipelines 332 and 338 of solid particles. Sludge in the zone 350 of final fermentation of sludge undergoes anaerobic fermentation lasting from about half a day to about three days, thereby providing the aforementioned volatile acids. The treated wastewater from the final sludge fermentation zone 350 (with volatile acid and fermented suspended solids) is supplied to the oxygen-free / anaerobic zone 400 via the fluid / solid particles pipe 339, where they are treated in the same way along with the suspended solids from the 335 solid particles pipe as treated wastewater from the sludge primary fermentation zone 340 and suspended particles from the final sedimentation zone 330 in the particular embodiment shown in FIG. 28.

 An advantage of the particular embodiment depicted in FIG. 29, the use of the finally precipitated sludge as a source of volatile acids to remove phosphorus does not introduce additional BCPK and additional solid particles outside the biological treatment zone, as is the case with primary sludge fermentation products in the specific embodiment depicted in FIG. 28. In addition, biological sludge is easier to handle than primary sludge. Further, the fermentation of primary sludge tends to introduce additional amounts of nitrogen and phosphorus along with volatile acids into the process, and hence to increase the load of nitrogen and phosphorus corresponding to the wastewater treatment method. When using fermented products of finally precipitated biological sludge, no such load of nitrogen and phosphorus should be. Thus, if an increase in the loading of nitrogen and phosphorus is not allowed by the guidelines, the finally precipitated biological sludge should be a very valuable feature in the production of volatile acids.

 In the particular embodiment depicted in FIG. 30, both primary sludge from the primary deposition zone 300 and sludge containing suspended solids from the final deposition zone 330 are used to produce volatile acid. For example, if the biological sludge from the final precipitation zone 330 does not have an organic content sufficient or suitable for satisfactory removal of phosphorus, fermented primary sludge can be used as a source of volatile acid, in addition to biological sludge or in addition to an external source of volatile acid such as sodium acetate, which can also be used. Part of the final sludge containing suspended solids is fed through pipelines 332 and 338 to the zone 350 of final sludge fermentation, where it is subjected to anaerobic fermentation lasting from half a day to three days, and the resulting filtrate containing volatile acid is then fed to an oxygen-free / anaerobic zone 400 through a pipeline 339. Another part of the final sludge is supplied to an oxygen-free / anaerobic zone 400 through pipelines 347 ', 347C and 339. Since the treated wastewater from zone 340 of primary sludge fermentation and zone 330 eye sediments are transported together in pipelines 347C and 339, both streams are mixed until they enter the oxygen-free / anaerobic zone 400. Similarly, since both of these streams and treated wastewater from the final sludge fermentation zone 350 are transported together in pipelines 339, all three are mixed flows until they enter the oxygen-free / anaerobic zone 400. An advantage of this particular embodiment is that it combines volatile acid from the primary and final zones fermentation to better release phosphorus and restore nitrate in an oxygen-free / anaerobic zone.

 Turning now to the specific embodiments depicted in FIG. 31-33, respectively, note that these specific embodiments are different from the specific embodiments depicted in FIG. 28-30, respectively, by the fact that the filtrate from the main zone 310 of aerobic biological oxidation is fed through a pipe 312 to the oxygen-free zone 315 where denitrification takes place (the reduction of nitrogen of the nitrate contained in the solvent obtained from the main zone 310 of aerobic biological oxidation to molecular nitrogen) and nitrogen is removed from the treated wastewater in the form of gas. In addition, the oxygen-free conditions prevailing in the oxygen-free zone 315 and the additional phosphate content in the treated wastewater from the main zone 310 of aerobic biological oxidation contribute to the additional release of phosphate by bacteria in the oxygen-free zone 315. The purified wastewater from the oxygen-free zone 315 is fed into the aerobic / mixing zone 320 through pipeline 317, where aerobic conditions and dissolved phosphate contained in the treated wastewater contribute to the bacterial selection of phosphate dissolved in the effluent suspended waters. At least a portion of the sludge containing suspended solids from the final deposition zone 330 is fed via lines 332 and 334 ′ to the anoxic / anaerobic zone 400 (which introduces and maintains the characteristics of the anoxic / anaerobic zone corresponding to the particular embodiments depicted in FIG. 11 -fifteen). From this moment, suspended solids are recycled back to the main stream (passing from the main zone 310 of aerobic biological oxidation to line 312, aerobic / mixing zone 320, line 322 and final deposition zone 330) through lines 332 and 334 ', through an oxygen-free / anaerobic zone 400 and fluid conduits 402 and 312 and an oxygen-free zone 315 in order to facilitate the implementation of the method and to obtain the advantages provided by the present invention. In addition, the oxygen-free / anaerobic zone performs an additional function in the removal of phosphorus. In all other aspects, the particular embodiment depicted in FIG. 31 corresponds to the particular embodiment depicted in FIG. 28, the embodiment depicted in FIG. 32 corresponds to the particular embodiment depicted in FIG. 29, and the specific embodiment depicted in FIG. 33 corresponds to the particular embodiment depicted in FIG. 30. The advantage of the specific embodiments depicted in FIG. 31-33, consists in the fact that due to the sequential arrangement of the zones into which oxygen is not introduced - the oxygen-free / anaerobic zone 400 and the oxygen-free zone 315 - sequentially carried out stages of phosphate release are provided, which is manifested in a greater extraction of phosphate and introduction into the biomass at a subsequent stage - in the aerobic / mixing zone 320. This will also be manifested in additional subsequent reduction of nitrate.

 Example 1

 Comparison of the method of wastewater treatment using a drip biological filter.

In order to investigate the effect of the mixing step under aerobic conditions and oxygen-free / anaerobic conditions on the treatment of treated wastewater of a drip biological filter, the treated wastewater of a drip biological filter was subjected to three different operating conditions:
1. Drip biological filter (CBF (TF)) + sedimentation tank (PO (ST)).

 2. CBF + reservoir for contact during mixing under aerobic conditions (aerobic / mixing tank, ACP (AMT)) + PO.

 3. CBF + ASR + PO + oxygen-free / anaerobic treatment of recycled sludge.

 In all three technological schemes, a sludge return pump was used to direct the precipitated sludge from the sedimentation tank to any place in the technological chain of processing the filtrate of a drip biological filter.

 The units of drip biological filters and sedimentation tanks used throughout the experiment had identical dimensions and technological dimensions. Schematic diagrams of methods for treating treated wastewater of a drip biological filter are shown in FIG. 2.

 Equipment and working conditions.

 Three identical blocks of drip biological filters 1.2 meters (4 feet) high were constructed. In FIG. 3 shows the experimental equipment, and table 3 shows the detailed dimensions of the unit of the drip biological filter. Flowing wastewater was supplied to the top of a drip biological filter. There was no recirculation of the treated wastewater stream. A uniform distribution of the flow rate was ensured by installing a flow distributor 15 cm above the surface of the (filtering - approx. Transl.) Material. The flow distributor was made on the basis of a nylon mesh filter with small mesh holes (the hole size was 0.16 cm or 1/16 inch). Due to the presence of a liquid column 30 cm high between the inflowing fluid inlet and the flow distributor, the wastewater droplets hit the flow distributor, which resulted in uniform spraying of small droplets over the entire cross-section of the surface (filtering - approx. Transfer) of the material. It was necessary to clean the flow distributor every three days of operation due to the build-up of excess mucus on the dispenser, accompanied by a reduced efficiency of uniform flow distribution. Another hallmark of installing a drip biological filter was the use of a strainer with small mesh holes (the hole size was 0.03 cm or 1/32 inch) in the upper and lower parts of the filter, which becomes necessary due to the possible accumulation of flies. The strainer provided ventilation while preventing the entry of flies.

 The improved sludge deposition properties and kinetics of the purification steps were investigated in a laboratory flow chart. The installation included a calibrated feed tank containing synthetic wastewater for the system and the drip biological filter unit. The treated wastewater of a drip biological filter containing non-metabolized substrates and discharged biomass was mixed with recycled sludge from an oxygen-free / anaerobic tank in the aerobic / mixing zone. The sedimentation tank contained treated wastewater from the aerobic / mixing tank. The supernatant or treated wastewater was collected in a calibrated tank for final purification. Precipitated sludge from the sedimentation tank was passed into an oxygen-free / anaerobic tank.

 The oxygen-free / anaerobic tanks were made of transparent acrylic plates with a thickness of 1/4 inch (0.635 cm). Aeration and complete mixing in the aerobic / mixing tank was carried out using an air pump (15 W power) and a diffusing donkey.

 The oxygen-free / anaerobic process conditions were provided by installing an oxygen-free / anaerobic tank, which was made of a transparent acrylic cylinder with an inner diameter (ID) of 7.62 mm or 3 inches. A 3/4 inch (1.5 cm) magnetic rod was placed inside the tank to ensure complete mixing. A 5/8 inch (1.6 cm) thick acrylic plate at the bottom of the oxygen-free / anaerobic tank shielded excess heat from the magnetic mixer. Platinum electrodes were inserted into the top of the reactor to measure the level of electrode potential in the tank.

 The deposition tank was made of a transparent acrylic cylinder with an inner diameter (ID) of 10.2 cm or 4 inches, and a plastic cone was fixed in its lower part. In laboratory facilities, a gravity flow diagram (gravity flow) was implemented from the wastewater inlet to the treated wastewater outlet, except for the supply of wastewater and the return of sludge from the sedimentation tank, which were carried out by Masterflex multi-channel pumps (model "Cole Parmer Model 7567" (Cole Parmer Model 7567)).

Reference loads of organic substances were based on industrial processing data reported by Norris et al. [1,2], which showed a maximum load of 35 pounds (15.876 kg) for BHPC and HFC less than 10 mg / L. In this study, the flow rates through the drip biological filters were maintained such that they could provide an equivalent load of organic substances of 0.66 kg COD / day / m ³ (approximate base of BHPC ₅ 0.46 kg BHPC / day / m ³ ) and hydraulic loading speed 50 gallons per day per square meter ft (gal / day / ft ² ) (2 m ³ / day / m ² ).

 The hydraulic retention time (HUA) in the aerobic / mixing tank in units 2 and 3 was initially maintained at 15 minutes, and 15 minutes of the HUA were provided for an oxygen-free / anaerobic tank in unit 3. The feed to the aerobic / mixing tank was one unit of treated wastewater biological filter mixed with one unit of treated wastewater of an oxygen-free / anaerobic tank. The operation of the three units was compared on the basis of steady state data collected over a period of one month.

 Steady-state sampling and experimental periods.

 Samples of inflowing wastewater were taken from a calibrated feed tank, and fresh samples of purified wastewater from a drip biological filter were collected from a hole for discharging the filtrate of a drip biological filter for analysis. Sludge samples were taken from the aerobic / mixing tank for testing for the level of OPI, VKP and absorption of RK. Immediately after measurements of the OPI and oxygen absorption rate, the sludge species were returned to the system.

 Wastewater.

A soluble synthetic substrate was supplied. The composition of the synthetic wastewater solution, which simulates the composition of domestic wastewater, is presented in Table 4. The organic composition of this substrate was used by Simons et al. [13] for laboratory studies of activated sludge treatment and Wend and Molor were used. [14] for laboratory studies of purification using a film reactor with cells attached to the stretched film,
Considering this composition to be ordinary, easy to use and approximately reflecting the concentration of fats, carbonates and proteins in domestic wastewater. Protein is present as a nutrient broth representing 65% of the chemical oxygen demand (COD), carbonate is present as glucose representing 25% COD, and fatty acid is present as sodium oleate, representing 10% COD.

Analytical methods
COD of the samples was determined by the method of calorimetry of the return flow according to the Standard Methods [15]. However, samples for the determination of COD at low levels were back titrated with a standard solution of iron-ammonium alum using a ferroin indicator.

The concentration of HPV in the samples was determined according to the Standard Methods [15]. Used Whatman glass filters, grade 934H, which had a diameter of 47 mm and a nominal mesh size of 1.2 μm. A drying oven (Precision Scientific, Model 18) maintained a temperature of 103 ^° C (± 1 ^° F). Volatile suspended solids (LVSS (VSS)) were determined using a muffle furnace (Thermolyne, model F-A1738, Cybron Corp.) at 550 ^o C. Gravity analysis was performed on a laboratory balance ("Mettler", model "Type 15").

An analytical method for determining the concentration of ATP in the sludge sample from an oxygen-free / anaerobic reservoir was an object of intensive search) [16, 17, 18], and its various modifications were developed [5, 6, 7, 8, 9, 10, 11, 12, 16, 17]. Analytical measurements of the content of extracellular polymeric materials from a sludge sample were carried out on the basis of gravitational measurement of the content of insoluble biological polymers in a solvent after centrifugation and ultrasonic treatment of sludge. The control method was as follows. Forty milliliters of a sludge sample was taken from each reactor and carefully placed in centrifugation tubes (with a capacity of 50 ml) using a wide-neck pipette. Tubes with samples were placed in a high speed centrifuge (WCC (ICE) model NT) and centrifuged for 15 minutes at 2700g. The supernatant was carefully drained from the tubes, and a suspension was obtained from the remaining solid particles by adding distilled water to obtain a volume of 40 ml. The re-weighed sludge varieties were carefully poured into 100 ml glass beakers and subjected to ultrasound in a ultrasonic destructive device (Heat-System Ultrasonic Inc., Model W 200) at rated output 20E for 20 minutes. A drop of ultrasonically treated sludge was removed from a beaker to check the viability of the microorganisms using a microscope. Immediately after checking under a microscope, sludge was placed in centrifugation tubes and centrifuged for more than 10 minutes at 7000g. A variety of sludge was carefully transferred to a conical flask and 80 ml of a mixture (1: 1) of acetone and ethyl alcohol was added. The contents of the flasks were thoroughly mixed. Then the plugs were closed and the flasks were placed overnight in a refrigerator with a temperature inside of 5 ^o C. After cooling, insoluble precipitates were filtered through a glass fiber filter (Whatman AH937, diameter 47 mm), and filter paper was placed in aluminum dishes and covered with a Petri dish. Drying was carried out at 80 ^° C. for 1 hour in a drying oven (Precision Science, Model 18). (At the drying stage in a convection oven, filter paper should be placed in a Petri dish to prevent possible losses of the CWP due to convection of heated air). Solvent-free extracellular polymer (VKP) collected on a glass fiber filter was analyzed on an analytical balance (Mettler model 15).

 The sludge volume indicator (OPI) is the volume in milliliters that takes 1 g of suspension after 30 minutes of precipitation. Due to the limited sample volume, the OPI was monitored using a graduated cylinder with a capacity of 100 ml (Kimax grand, Fisher Cat. (Kymax grand, Fisher Cat), # 08-554E). The OPI data obtained from a cylinder with a capacity of 100 ml is slightly higher than the standard test data for determining the OPI using a graduated cylinder with a capacity of 1 liter.

 The test procedure for determining BHPC was recommended by the "Standard Methods" [15]. Each test to determine BHPC was performed using a nitrification inhibitor and a solution of glucose and glutamic acid as a reference sample.

 Initial operation.

 To initiate biofilm growth on the filter media, an activated sludge seed sample was taken from a wastewater treatment plant in Rockland Colunty, New York, mixed with synthetic wastewater and introduced into laboratory biological droplets. The biofilm was yellow to light brown in color. COD and the flow rate of the starting filtrate were maintained at about 200 ml / L and 20 L per day, respectively. The surfaces of the filter material in the drip biological filters were finally coated with a dark brown biofilm in four weeks of operation. The concentration of COD and the flow rate of the effluent was increased to 400 ml / l and 24 l / day, respectively, to operate in steady state, as described above. A microscopic examination of the treated wastewater of a droplet biological filter at a 100-fold increase revealed the presence of protozoa (free-floating cilia and stalked cilia), as well as some filamentous microorganisms. The purified wastewater of a drip biological filter was subjected to various treatment conditions described in experimental methods.

 Comparison of the treatment of treated wastewater drip biological filter.

 Schematic diagrams of installations 1, 2, and 3 are shown in FIG. 2. Laboratory installation 1 was a single-stage system of a drip biological filter and worked as a control device. An aerobic / mixing tank was introduced into laboratory unit 2 to simulate a cleaning method by contacting a drip biological filter with solid particles. In addition to the aerobic / mixing tank, an oxygen-free / anaerobic tank was introduced into laboratory unit 3 to control the influence of oxygen-free / anaerobic conditions in the treatment of treated wastewater using a drip biological filter.

During the experiment, the hydraulic loading rates were maintained at the level of 40.2-41.2 gal / day / sq. Ft (2.03-2.05 m ³ / day / m ² ), bringing the flow rate to 23.6-23.9 l / day (6.2-6.3 gal / day). The COD of the fluid flowing into the drip biological filter was maintained at about 200 ml / L for acclimatization, but increased in the range to about 400 ml / L for normal operation. Thus, the organic loading of the drip biological filters when operating in the steady state was in the range of 0.44-0.46 kg COD / day / m ³ (49.8-50.4 pounds COD / day / 1000 cubic feet). The hydraulic retention time (HHC) in aerobic / mixing tanks in plants 2 and 3 was maintained at 15 minutes, and the HHC in an oxygen-free / anaerobic tank in installation 3 was also maintained at 15 minutes. Detailed operating conditions are summarized in table 5.

 The experimental results obtained by considering methods of treating treated wastewater of drip biological filters are summarized in table 6. Each given value is an average of 7 experimental data sampling points.

 The chemical need for dissolved oxygen (CLCD) in the treated wastewater of the drip biological filter remained mainly in the range of 83-88 mg / L, indicating that the rates of removal of dissolved organic substances for the three plants of drip biological filters were comparable in level. However, the total COD (OCPC) and the concentration of HPV in the treated wastewater of drip biological filters varied from 177 mg / L to 208 mg / L and from 80 mg / L to 95 mg / L, respectively. Changes in the VHF and OHPC parameters of the treated wastewater of the drip biological filters show that the slough-off biofilms in the three drip biological filter plants were at different levels under identical operating conditions of the drip biological filters. The results also suggest that the final sedimentation tank in the drip biological filter installation can accept different solids loads under the same conditions of organic matter and hydraulic loading. Therefore, the successful operation of the final sedimentation tanks in the drip biological filter plants should depend on good flocculation of sludge, as well as on the proper design of the sedimentation tank, which makes it possible to level fluctuations in the loading of solid particles under normal operating conditions.

 The efficiencies of reducing CPRD and removal of HPV were calculated for three different treatment methods for treated wastewater, which are presented in table 7.

 Drip biological filters had similar efficiencies in reducing CRPC in the range of 83-88%. However, the effectiveness of the reduction of CPRC of the three methods for treating treated wastewater was noticeably different. For example, control unit 1, which had a sedimentation tank, used only for treatment of treated wastewater, showed only a 20.7% reduction in CRPC; this parameter is calculated on the basis of the parameters of the treated wastewater of the drip biological filter (the value of 83.2 mg / l decreased to 66.0 mg / l). Conversely, approximately 21% of the metabolized organic matter in the treated wastewater of a drip biological filter was recovered by microorganisms during the precipitation periods.

 However, the reduction efficiency of CPRK at the aeration stage in laboratory installation 2 was 55.9%, being determined on the basis of the CPRP of treated wastewater of a drip biological filter. An additional 35% reduction in the treated wastewater of the drip biological filter was achieved during a 15-minute aeration, and a decrease in CPRK of over 21% was provided by a sedimentation tank.

 The reduction in CLCD during the aeration stage during oxygen-free / anaerobic treatment was excellent and amounted to 73.2% based on the parameters of the treated wastewater drip biological filter. The introduction of the oxygen-free / anaerobic treatment step in Unit 3 reduced the CPRK by an additional 17% compared to Unit 2. The results show that the CPRP in the treated wastewater of the drip biological filter decreased due to the sludge formed during the 15 minutes of the oxygen-free / anaerobic treatment stage in addition to the aerobic mixing step.

 The beneficial effect of oxygen-free / anaerobic treatment has also affected the efficiency of the removal of HPV. The efficiency of the removal of HPM at the deposition stage in laboratory installation 1 was 69.9% with a content of HPM in the finally treated wastewater of 14.3 mg / L. This fully complies with the 30 mg / L limit on secondary treatment. Installations 2 and 3 showed the efficiency of removal of HFCs of 89.2 and 92.5%, respectively, and this means that such cleaning methods in the finally treated wastewater of a drip biological filter allow a significantly lower content of HFC to be obtained than the secondary treatment standard, expressed as 30 mg / l Removing the HF in the installation with the aerobic mixing and oxygen-free / anaerobic cleaning step provided the best performance, showing that the additional oxygen-free / anaerobic cleaning was more effective at lowering the HF content along with the removal of organic substances.

 The aerobic mixing stage in plants 2 and 3 also positively affected the microbiological quality of the final filtrate. During the experiment, a slight growth of fungi and water mold appeared on the surface of the sedimentation tank in Unit 1. However, brown color was observed in the sedimentation tanks in treatment plants 2 and 3, the presence of protozoa (stalked cilia and free-floating cilia) and high levels of animal species (nematodes) were noted. In contrast, the precipitated sludge from control plant 1 was dark brown to black in color, and the microbial species were not as abundant as those from plants 2 and 3.

The levels of phosphate (PO ₄ -P) in the oxygen-free / anaerobic sludge of the treated wastewater of the drip biological filter and the final treated wastewater were determined by the filtered sample. 45 minutes of HHU in an oxygen-free / anaerobic reservoir provided a release of up to 10.6 mg / L PO ₄ -P. The released PO ₄ -P was then sampled by sludge in an aerobic / mixing tank (30 minutes of HHP), and the data of the finally treated wastewater showed 11.1 mg / L of PO ₄ -P removed during the treatment of the treated wastewater. At the stage of purification of treated wastewater, 75 mg / L of CPRK was removed (basis BHPC ₅ 54 mg / L). Therefore, the metabolic phosphorus requirement was less than 2 mg / L, indicating that over 4 mg / L, PO ₄ -P was removed during the treatment of the treated wastewater.

 Example 2

 The wastewater treatment method was implemented in accordance with the flow chart shown in FIG. 18. The main zone of aerobic biological oxidation was a single-stage laboratory (0.5 ft (152.4 mm in diameter)) rotating biological contactor (VBK). After VBC, an oxygen-free tank, an aerobic / mixing tank, and a final sedimentation tank were installed in the process chain. The only source of volatile acid was sodium oleate, which was introduced into an anoxic tank.

 The hydraulic retention time in the oxygen-free tank was 6.7 minutes; it was 30 minutes in the aerobic / mixing tank, and 72 minutes in the final sedimentation tank. Inoculum sludge for research was obtained from a technological plant for purifying waste water containing nutrients using an antioxidant (AO) located in Warminster, Pennsylvania, USA. The rate of solids recirculation from the final deposition tank back to the oxygen-free tank was set 2 times higher than the feed rate, so that the deposition level in the laboratory final deposition tank could be kept low.

 The addition of sodium acetate to the oxygen-free tank was set at 50 mg / L. Sodium acetate at this level ensured both phosphate release and nitrate reduction. The released phosphate was then removed in an aerobic / mixing tank.

 The experimental results are shown in table 8. The reduction results are based on the concentration of treated wastewater from the main aerobic biological oxidation unit.

Literature
1. Norris, DP, Parker, DP, Daniels, ML, and Owens, EL 1980. Efficiences of advanced waste treatment obtained with upgraded trickling filters. J. Wat. Poll. Cont. Fed. 48: 96-101.

 2. Norris, D.P., Parker, D.P., Daniels, M.L., and Owens, E.L. 1982. High quality trickling filter effluent without tretiary treatment. J. Wat. Poll. Cont. Fed., 54: 1087 - 98.

 3. Fedotoff, R.C. 1983. The trickling filter finds new parthner. Water Engineering & Management, June: 28.

 4. Niku, S., et al. 1982. Reliability and stability of trickling filter process. J. Wat. Poll. Cont. Fed., 54: 129 - 34.

 5. Forster, C.F. 1971. Separation of activated sludge using natural and synthetic polymers. Water Pollution Control, 71: 363 - 71.

 6. Wilkinson, J.F. 1958. The extracellular polysaccharides of bacteria. Bacteriol. Rev. 22: 46.

 7. Tenny, M. W., and Stumm, W. 1965. Chemical flocculation of microorganisms in biological waste treatment. J. Wat. Poll. Cont. Fed., 37: 1370 - 88.

 8. Gulas, V., Bons, M., and L. Benefield. 1979. Use of exocellular polymers for thickening and dewatering activated sludge. J. Wat. Poll. Cont. Fed., 51: 798 - 807.

 9. Pavoni, J., Tenny, M., and Echelberger, Jr., W. 1972. Bacterial exocellylar polymers and biological flocculation. J. Wat. Poll. Cont. Fed., 44: 414-31.

 10, Friedman, B., et al. 1970. Structure of exocellylar polymers and their relationships to bacterial flocculation. J. Wat. Poll. Cont. Fed., 98: 1328 - 88.

 11. Kiff, R.H. 1978. A study of the factors affecting bioflocculation in the activated sludge process. Water Pollution Control, 77: 464 - 70.

 12. Harris, R. H., and Mitchell, R. 1975. Inhibition of the bioflocculation of bacteria by biopolymers. Water Research, 9: 993-99.

 13. Symons, J., McKinney, R., and Hassis, H. 1960. A procedure for determination of industrial wastes. J. Wat. Poll. Cont. Fed. 32: 841-52.

 14. Weng, C., and Molof, A.H. 1974. Nitrification in the biological fixed-film rotating disk system. J. Wat. Poll. Cont. Fed., 46: 1676.

 15. Standard Methods. 1985.15th ed. APHA-AWWA-WPCF.

 16. Gener, R., and Henry, J.G. 1983. Removal of extracellular materials: techniques and pitfalls. Water research, 17: 1743 - 48.

 17. Novak, J.E., and Haugan, B.E. 1981. Polymer extraction from activated sludge. J. Wat. Poll. Cont. Fed., 53: 1420-24.

 18. Brown, M.J., and Lester, J.N. 1980. Comparison of extracellular polymer extraction methods. Appl. & Environ. Microbiol., 40: 170 - 86.

 19. Fuchs G.M. and M. Chen, 1975. Microbial Basis for Phosphate Removal in the Activated Sludge Process for the Treatment of Wastewater. Microb. Ecol., 2: 119.

 20. Venter, S.L.V. et al. 1978. Optimization of Johannesburg Olifantsvlei Extended Aeration Plant for Phosphorus Removal. Prog. in wat. Technology, 10: 279.

 21. Nichols, H.A. and D.W. Osborn 1979. Bacterial Stress: Prerequisite far Removal of Phosphorus. JWPCF 51 (3): 557, 1979.

 22. Barnard, J. L., 1984. Activated Primary Tanks for Phosphate Removal. Water SA, 10 (3): July, 1984.

Claims (32)

 1. The method of wastewater treatment, characterized by improved characteristics of the separation of solid particles, reduced biological oxygen demand (BHPC) in the treated wastewater and increased removal of nitrogen and phosphate, characterized in that the following stages are carried out: a) incoming wastewater containing suspended solid particles, ammonia nitrogen, phosphate and biodegradable substances through the zone of aerobic biological oxidation and in it oxidize part of BHPK and transform part of BHPK into additional suspended s hard particles and oxidize at least a portion of the ammonia nitrogen to nitrate nitrogen; b) pass the wastewater from the aerobic biological oxidation zone into the intermediate sedimentation zone and intermediate wastewater and intermediate sludge containing suspended solids are separated therein; c) passing (i) intermediate-treated wastewater, and (ii) wastewater from the oxygen-free / anaerobic zone from step (g) to the zone to which no additional oxygen is added, and in it part of the ammonia nitrogen and nitrate are reduced to molecular nitrogen; (d) passing the wastewater from the zone in which there is no additional oxygen of step (c) into the aerobic / mixing zone, in which the wastewater is mixed under aerobic conditions with a sludge mixture consisting mainly of solid particles that have undergone anoxic / anaerobic treatment, from step (f) below; f) passing the wastewater from the aerobic / mixing zone into the final precipitation zone and then (i) treated wastewater having reduced biochemical oxygen demand and reduced phosphate and nitrogen content and (ii) final sludge containing suspended solids and phosphate; f) at least a portion of the final sludge formed in step (e) is fed into the anoxic / anaerobic zone for a time sufficient to obtain solid particles that have undergone anoxic / anaerobic treatment, then a portion is fed into step (e) to improve the deposition efficiency in the precipitation zone and then at least one volatile acid is added to the oxygen-free / anaerobic zone to isolate phosphate; and g) recycle an effective amount of wastewater from the oxygen-free / anaerobic zone to the zone to which additional oxygen is not added, steps (c).  2. The method according to claim 1, characterized in that the wastewater supplied to the main zone of aerobic biological oxidation, first pass through the zone of primary separation of solid particles, in which part of the suspended solid particles and BHPC are separated.  3. The method according to claim 1, characterized in that the ratio of sludge recycled to an oxygen-free / anaerobic zone to sludge either removed from the treatment or recycled back to the main aerobic biological oxidation zone is in the range from 1: 99 to 99: 1.  4. The method of wastewater treatment, characterized by improved characteristics of the separation of solid particles, reduced biological oxygen demand (BHPC) in the treated wastewater and increased removal of nitrogen and phosphate, characterized in that the following stages are carried out: a) incoming wastewater containing suspended solid particles, ammonia nitrogen, phosphate and biodegradable substances through the aerobic biological oxidation zone, in it oxidize part of BHPK and transform part of BHPK into additional weighted e solid particles and oxidize at least a portion of the ammonia nitrogen to nitrate nitrogen; b) pass the wastewater from the aerobic biological oxidation zone into the intermediate sedimentation zone and intermediate wastewater and intermediate sludge containing suspended solids are separated therein; c) passing (i) intermediate-treated wastewater and (ii) wastewater from the oxygen-free / anaerobic zone of step (g) into the zone to which no additional oxygen is added, and thereby reducing part of the ammonia nitrogen and nitrate into molecular nitrogen; d) pass the wastewater from the zone of stage (c), in which there is no additional oxygen, to the aerobic / mixing zone, where the wastewater is mixed under aerobic conditions with a sludge mixture consisting mainly of solid particles that underwent anoxic / anaerobic treatment of stage (f ) below; f) pass the wastewater from the aerobic / mixing zone into the final precipitation zone and then separate (i) the treated wastewater having a reduced biochemical oxygen demand and a low phosphate and nitrogen content; and (ii) final sludge containing suspended particles and phosphate; f) a part of the sludge obtained in stage (b) is passed and a part of the final sludge formed in stage (e) is passed into the anoxic / anaerobic zone for a time sufficient to form solid particles that underwent anoxic / anaerobic treatment, then a part of the obtained sludge to stage (e) to improve the efficiency of the deposition in the zone of final deposition and then add at least one volatile acid to an oxygen-free / anaerobic zone to separate phosphate; and g) recycle an effective amount of wastewater from the oxygen-free / anaerobic zone to the zone to which additional oxygen is not added, steps (c).  5. A method of wastewater treatment, providing increased separation of nitrogen, phosphate and biological oxygen demand, characterized in that the following stages are carried out: a) pass wastewater containing ammonia nitrogen, phosphate and biochemical oxygen demand through the main zone of aerobic biological oxidation and in it at least a portion of the ammonia nitrogen is oxidized to nitrate nitrogen and at least a portion of the biochemical oxygen demand and at least a portion of the biochemical oxygen demand is converted into suspended solids; b) allow (i) wastewater from the aerobic biological oxidation zone and (ii) wastewater and the anoxic / anaerobic zone of step (e) to the zone to which no additional oxygen is added, and in which part of the ammonia nitrogen and nitrate are reduced to molecular nitrogen ; c) passing the wastewater from the zone of step (b) into the aerobic / mixing zone where the wastewater is mixed under aerobic conditions and molecular nitrogen and phosphate are removed from the wastewater; d) allow wastewater from the aerobic / mixing zone to the final precipitation zone and (i) treated wastewater having reduced biochemical oxygen demand and phosphate and nitrogen content is separated; and (ii) final sludge containing suspended solids and phosphate; e) at least a portion of the final sludge is recycled to the oxygen-free / anaerobic zone and at least one volatile acid is added to the oxygen-free / anaerobic zone to release phosphate; f) supply wastewater from an oxygen-free / anaerobic zone to the zone of stage (b).  6. The method according to claim 5, characterized in that the main zone of aerobic biological oxidation is a drip biological filter or a rotating biological reactor.  7. The method according to claim 5, characterized in that the wastewater supplied to the main zone of aerobic biological oxidation, first pass through the zone of primary separation of solid particles, in which part of the suspended solid particles and BHPC are separated.  8. The wastewater treatment method according to claim 5, characterized in that the primary sludge obtained from the primary precipitation zone, which precedes the main zone of aerobic biological oxidation, and / or the final sludge obtained from the final precipitation zone, is fermented to form volatile acid and part of the fermentation product containing volatile acid is fed to an oxygen-free / anaerobic zone.  9. The wastewater treatment method according to claim 8, characterized in that the primary sludge is fermented in the zone of primary sludge fermentation and the final sludge is fermented in the zone of final sludge fermentation.  10. The wastewater treatment method according to claim 9, characterized in that the zone to which additional oxygen is not added is an oxygen-free zone.  11. The wastewater treatment method according to claim 9, characterized in that the zone to which additional oxygen is not added is an anaerobic zone.  12. The wastewater treatment method according to claim 11, characterized in that part of the product from the zone of primary sludge fermentation is fed into the anaerobic zone.  13. The wastewater treatment method according to claim 5, characterized in that volatile acid is also added to the zone to which additional oxygen is not added.  14. The wastewater treatment method according to claim 5, characterized in that the zone to which additional oxygen is not added is an oxygen-free zone.  15. The wastewater treatment method according to claim 5, characterized in that the wastewater introduced into the main zone of aerobic biological oxidation is first passed through the primary sedimentation zone to separate the primary sludge, primary sludge is fermented to produce volatile acid in the primary sludge fermentation zone, and a portion of the primary sludge-containing fermentation zone containing volatile acid is added to the oxygen-free / anaerobic zone.  16. The wastewater treatment method according to clause 15, wherein the zone to which additional oxygen is not added is an oxygen-free zone.  17. The method of wastewater treatment according to clause 15, wherein the zone to which additional oxygen is not added is an anaerobic zone.  18. The method of wastewater treatment according to 17, characterized in that the second part of the zone of primary fermentation of sludge is fed into the anaerobic zone.  19. The wastewater treatment method according to claim 5, characterized in that a part of the final sludge containing suspended solids and phosphate is fermented in the zone of final sludge fermentation and the first part of the final sludge fermentation is fed to an oxygen-free / anaerobic zone.  20. The wastewater treatment method according to claim 19, characterized in that the zone to which additional oxygen is not added is an oxygen-free zone.  21. The wastewater treatment method according to claim 19, wherein the zone to which additional oxygen is not added is an anaerobic zone.  22. The wastewater treatment method according to item 21, characterized in that the second part of the product of the zone of primary sludge fermentation is served in the anaerobic zone.  23. A method of wastewater treatment, providing increased separation of nitrogen, phosphate and lowering the biological oxygen demand, characterized in that the following steps are carried out: a) passing wastewater containing ammonia nitrogen, phosphate and biochemical oxygen demand through the main aerobic biological zone oxidation and in it oxidize at least a portion of the ammonia nitrogen to nitrate nitrogen and at least a portion of the biochemical oxygen demand and convert at least a portion of the biochemical demand to oxygen to suspended solids; b) pass (i) wastewater from the main aerobic biological oxidation zone and (ii) recirculated sludge from the oxygen-free / anaerobic zone of step (e) into the anaerobic zone and treat it; c) allow wastewater from the anaerobic zone to the aerobic / mixing zone, where they are mixed under aerobic conditions; d) allow wastewater from the aerobic / mixing zone to the final precipitation zone and (i) treated wastewater having reduced biochemical oxygen demand and phosphate and nitrogen content is separated; and (ii) final sludge containing suspended solids and phosphate; e) recycle at least a portion of the final sludge into an oxygen-free / anaerobic zone and treat it with at least one volatile acid to liberate phosphate; f) supply wastewater from the oxygen-free / anaerobic zone to the anaerobic zone.  24. The wastewater treatment method according to item 23, wherein the primary sedimentation step is preceded in the main zone of aerobic biological oxidation, part of the primary sludge formed in the primary precipitation zone is fermented, and part of the fermentation product is fed to the anaerobic zone and / or to oxygen-free anaerobic zone.  25. The wastewater treatment method according to item 23, wherein the part of the sludge obtained in the zone of final precipitation is fed to the zone of final fermentation of sludge to obtain a fermented final sludge and part of the fermented final sludge from the zone of final sludge fermentation is fed into the anaerobic zone and / or anoxic / anaerobic zone.  26. A method of wastewater treatment, providing increased separation of nitrogen, phosphate and lowering the biological oxygen demand, characterized in that the following steps are carried out: a) passing wastewater containing ammonia nitrogen, phosphate and biochemical oxygen demand through the main aerobic biological oxidation zone , it oxidizes at least a portion of ammonia nitrogen into nitrate nitrogen and at least a portion of the biochemical oxygen demand and transform at least a portion of the biochemical oxygen demand lorode into suspended solids; b) pass (i) the wastewater from the main aerobic biological oxidation zone and (ii) the wastewater from the anoxic / anaerobic zone of step (f) into the anoxic zone and recover at least a portion of ammonia nitrogen and nitrate into molecular nitrogen; c) pass the wastewater from the oxygen-free zone to the anaerobic zone together with volatile acid and thereby separate the phosphate; d) the wastewater is passed from the aerobic zone of step (c) to the aerobic / mixing zone, the wastewater is mixed under aerobic conditions and molecular nitrogen and phosphate are removed; e) pass the wastewater from the aerobic / mixing zone into the final precipitation zone and (i) treated wastewater having a reduced biochemical oxygen demand and a low phosphate and nitrogen content, and (ii) the final sludge containing suspended solids; f) recycle at least a portion of the final sludge to an oxygen-free / anaerobic zone; and g) recycle waste water from an oxygen-free / anaerobic zone to an oxygen-free zone and / or anaerobic zone.  27. The wastewater treatment method according to p. 26, characterized in that the primary zone of aerobic biological oxidation is preceded by a primary sedimentation zone, the primary sludge obtained therein is fermented in the primary sludge fermentation zone and the product of the primary sludge fermentation zone is introduced into the anaerobic zone and / or to an oxygen-free / anaerobic zone.  28. The wastewater treatment method according to p, characterized in that part of the final sludge is fed into the zone of final sludge fermentation and a part of the product of the zone of final sludge fermentation is introduced into the anaerobic zone and / or into an oxygen-free / anaerobic zone.  29. The wastewater treatment method according to p. 26, characterized in that the wastewater introduced into the main zone of aerobic biological oxidation is first passed through the primary sedimentation zone to separate the primary sludge, primary sludge is fermented in the zone of primary sludge fermentation to obtain volatile acid and the first part of the primary sludge fermentation zone containing volatile acid is added to the anaerobic zone, and the second part of the primary sludge fermentation zone is added to the anoxic / anaerobic zone.  30. The wastewater treatment method according to clause 29, wherein a part of the final sludge containing suspended solids and phosphate is fermented in the zone of final sludge fermentation and a part of the product of the zone of final sludge fermentation containing volatile acid is introduced into an oxygen-free / anaerobic zone and / or into the anaerobic zone.  31. The wastewater treatment method according to p, characterized in that part of the final sludge is fed into the zone of final sludge fermentation and the product of the zone of final sludge fermentation containing volatile acid is introduced into the anaerobic zone and / or into an oxygen-free / anaerobic zone, and / or to an oxygen-free zone.  32. The wastewater treatment method according to p, characterized in that the volatile acid is sodium acetate.

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