RU189953U1 - INSTALLATION FOR BIOLOGICAL PURIFICATION OF COMMUNAL WASTEWATER FROM NITROGEN AND Phosphorus compounds - Google Patents

Abstract

The plant for biological treatment of municipal wastewater from nitrogen and phosphorus compounds contains primary and secondary clarifiers, anaerobic, anoxide and aerobic tanks, a coagulant tank, a sludge thickener and a dewatering unit equipped with inlet and outlet pipes and connecting pipes. Characterized by the fact that the above-mentioned containers form a flow system of wastewater in the following sequence: primary clarifier-fermenter 1, anaerobic tank 2, anoxide reservoir 3, aerobic reservoir 4, secondary clarifier 5, and the secondary settler 5 has an upper sedimentation zone of active sludge and a lower zone excess sludge compaction, equipped with a circulating activated sludge outlet pipe, a compacted excess sludge outlet pipe and a purified water outlet pipe, with the said secondary sedimentation zone the sump 5 via a circulating activated sludge pipeline is connected to the anaerobic tank 2 and the anoxide tank 3; from which the thick excess sludge has the ability to move through the pipeline of excess sludge into the dewatering unit 8, and the sludge liquid has the ability through pipes wire interstitial fluid flow into the anoxic tank 3 for reprocessing, the dehydrated sludge from the dewatering unit 8 is output from the unit and formed by a conduit of supernatant centrate is fed to the anaerobic tank 2 for reprocessing. The installation includes three main elements: an anaerobic treatment unit for a mixture of wastewater and sludge for the process of dephosphatization; anoxide block for denitrification; oxide (aerobic) unit for nitrification. Dephosphatization is achieved mainly by using phosphorus accumulating (PAOs) bacteria, denitrification - by microorganisms that can use oxides of nitrogen as a source of vital activity in the absence of oxygen or its low concentration. Nitrification proceeds as a two-stage process carried out by groups of chemo-autotroph bacteria. Nitrifiers oxidize ammonium nitrogen to nitrite, and then to nitrate. Technical result achieved - increasing the efficiency of purification of municipal wastewater from nitrogen and phosphorus. 1 hp f-ly, 1 ill.

Description

The utility model relates to the field of biological treatment of communal and close to them composition of wastewater from nitrogen compounds and phosphorus, can be used in the treatment of effluent settlements and small industries.

A variety of schemes for the device of biological treatment units are caused, first of all, by different performance requirements, to the quality of treated water and the reliability level of the facilities by seasons of the year in different climatic conditions.

The “Plant for biological purification and removal of nitrogen and phosphorus wastewater compounds” [1] is known, containing a cylindroconic sand trap and a primary sedimentation tank, with which the denitrifier is combined with an irregular load, designed to accumulate biomass in it, which purifies wastewater from contamination, and containing several biofilters. The “Method of biological treatment of domestic, municipal and industrial wastewater” [2] is known, which includes the supply of wastewater to the corridor type aeration tank and the treatment of water with activated sludge in the anaerobic, anoxide and aerobic zones, the separation of activated sludge and its recirculation. In the anaerobic and anoxid zones on alternating flat and corrugated sheets of resistant polymeric material, microorganisms are immobilized and the sludge mixture is mixed by means of aerators.

A common drawback of installations and cleaning methods using carriers for the development of immobilized biomass on their surface is the uncontrolled mode of biomass accumulation on ruffs and sheets, leading to negative phenomena: rotting with proliferation of filamentous and branched forms of microorganisms, including mold fungi, as a result - development in the biofilm of helminth parasites. Excessive sludge from biofilm requires mandatory disinfection, which leads to additional costs. In cases where, according to the conditions of phosphorus excretion in the composition of excess sludge, it is required to observe an increased content of polyphosphates in the cell body, it becomes necessary to create optimal parameters of acidic fermentation in the anaerobic compartments. If there is a lack of an organic substrate, reagent phosphorus removal is used - the coagulation process. Coagulants are added directly to the bioblock. When a reagent is introduced into a bioblock with a constant and proportional sludge consumption dose, the reaction occurs under conditions of elevated phosphate content in the sludge.

The “Domestic wastewater treatment system and purification processes” [3] is known. It includes the steps of adding a coagulant to the sewage system, obtaining a pool of pre-treated sludge and the first supernatant, introducing it into the anaerobic fermentation reactor, forming a fermentation broth and a second supernatant, then a phosphor-collecting plant for the recovery of phosphate fertilizers, as well as a stage of biological purification of the first and / or second supernatant.

The disadvantage of this system is the limited introduction of coagulant in the first stage of treatment into the wastewater; it is not possible to mix the coagulant intensively with the entire volume of effluent, which leads to an increase in the consumption of coagulant.

As a prototype, an installation used in the biological treatment method for the removal of nitrogen and phosphorus [4] was selected, in which, after the primary clarifier, using a switchgear, sends 0-30% of wastewater to the anoxide tank, 70-100% to the anaerobic tank, after 100% of the wastewater is sent to the secondary clarifier, and part of the sludge from the secondary clarifier is returned to the anoxide tank.

One of the drawbacks of this method is the location of the anoxide tank in front of the anaerobic one, due to which the supply of organic matter with the source wastewater is limited. In addition, with this arrangement of the anoxide tank, the flow of circulating sludge is limited. During the passage of wastewater through this system, there is a sharp decrease in the concentration of phosphates in the aerobic tank. Dosing of coagulant is made in anoxic or aerobic tanks. Since the reaction of coagulant binding to phosphates occurs only in the anoxide tank, the phosphate content in the aerobic tank is not high, therefore, it is difficult to achieve high cleaning efficiency. In the anoxide tank, incomplete mixing of the coagulant and wastewater occurs, since it is not possible to intensively mix the coagulant with the entire fluid flow in the tank, which leads to an increase in the consumption of coagulant and a decrease in efficiency during the removal of phosphorus.

The technical objective of the proposed installation for the biological treatment of municipal wastewater from nitrogen compounds and phosphorus is to increase the efficiency of wastewater treatment from nitrogen and phosphorus.

The problem is solved due to the fact that in the declared installation containing primary and secondary settlers, anaerobic, anoxide and aerobic tanks, coagulant tank, sludge thickener and dehydration unit, equipped with inlet and outlet nozzles and connecting pipes, unlike the prototype, the mentioned tanks connected by sewage pipelines in the following strict sequence: primary clarifier-fermenter 1, anaerobic tank 2, anoxide tank 3, aerobic tank 4, secondary clarifier 5, the secondary settling tank 5 has an upper sedimentation zone of activated sludge and a lower compaction zone of excess sludge, is equipped with a circulating activated sludge outlet pipe, a compacted excess sludge outlet pipe and a clarified water outlet pipe, the above-mentioned sedimentation zone of the secondary settler 5 is connected via a circulating activated sludge pipe to anaerobic tank 2 and anoxide tank 3, the said pipeline circulating active sludge in its initial part is connected to the solution tank and coagulant 6, the said sealing zone of the secondary settling tank 5 is connected by a pipeline of excess sludge to the inlet of the thickener of sludge 7, from which thick excess sludge has the ability to move through the pipeline of excess sludge to the dewatering unit 8, and the sludge liquid has the ability to flow into the anoxide through the pipeline of sludge tank 3 for re-treatment, while the dewatered sludge from the dehydration unit 8 is removed from the plant, and the resulting fugate is fed to the anaerobic tank 2 for re-treatment weavers.

The primary clarifier-fermenter 1 can be equipped with a sediment outlet pipe connected to the dewatering unit 8, which allows working with concentrated streams.

Common features with the prototype are: the presence of primary and secondary clarifiers, the presence of interconnected anoxide, anaerobic and aerobic reservoirs into which activated sludge is introduced, the presence of circulating sludge pipeline. Coagulant, as in the claimed installation, is added to the anoxide or anaerobic tanks.

Salient features:

the use of a strict sequence of anaerobic, anoxic, aerobic tanks interconnected by pipelines and supplying a secondary settling tank separator, with the placement of an aerobic tank at the final stage of bioprocessing.

equipment of the secondary settling tank, which has a liquid sedimentation zone and a zone of excess sludge compaction, with a pipeline of active sludge circulation through anaerobic and anoxide tanks, which allows for repeated biological cleaning of the liquid;

the presence of excess sludge thickener at the final stage of biological treatment with discharge of sludge liquid for additional treatment in the anoxide tank.

The principle of operation and the essence of the device are illustrated in the attached diagram (Fig. 1).

Numbers in the diagram denote:

(1) primary clarifier-fermenter

(2) anaerobic tank

(3) anoxide tank

(4) aerobic tank

(5) secondary settling tank

(6) coagulant solution tank

(7) excess sludge thickener

(8) dehydration unit

As can be seen in the diagram, the bioreactors form a flow system of design performance, after which the drains are sent for separation. The coagulant solution tank is connected to the circulating sludge pipeline that returns part of the sludge from the settling tank separator 7 to the anaerobic and anoxide tanks, with the coagulant being supplied in the initial part of the pipeline, which ensures active mixing in the stream before it enters the anaerobic and anoxide tanks; the discharge pipe of excess sludge from the secondary clarifier-separator 5 is connected via a pipeline to a thickener of sludge 7; Excess sludge thickener 7 is equipped with an excess sludge discharge pipe that is connected to the excess sludge dewatering unit 8; the pipe silt liquid thickener 7 is connected to the anoxide tank 3, the pipe of centrate (formed liquid component) of the dehydration unit 8 is connected to the anaerobic tank 2.

Example of the installation:

The plant for the biological removal of nitrogen and phosphorus includes three main elements: an anaerobic unit 2 for treating a mixture of wastewater and sludge for the process of dephosphating; anoxide block 3 for denitrification; oxide (aerobic) unit 4 for nitrification. Dephosphatization is achieved mainly by using phosphorus accumulating (PAOs) bacteria, denitrification - by microorganisms that can use oxides of nitrogen as a source of vital activity in the absence of oxygen or its low concentration. Nitrification proceeds as a two-stage process carried out by groups of chemo-autotroph bacteria. Nitrifiers oxidize ammonium nitrogen to nitrite, and then to nitrate.

Source wastewater enters the clarifier-fermenter (1), where the sedimentation of suspended substances and the fermentation of organic pollutants with the formation of volatile fatty acids. Next, the wastewater is sequentially treated in anaerobic (2), anoxic (3) and aerobic (4) tanks. Secondary sump 5 serves to separate wastewater into circulating sludge, excess sludge and clarified liquid. Circulating sludge is sent for additional purification from nitrates and phosphates. The clarified liquid is removed from the installation and can be directed to the post-treatment facility (bioreactors, biofilters, filtration fields, etc.). Organic matter-rich fugate from sediment dewatering unit (8) also enters the anaerobic reservoir (2), where further fermentation of organic substances occurs with the formation of volatile fatty acids, which serve as an additional source of easily oxidized organic matter to increase the intensity of denitrification processes. In the anoxide reservoir (3) biological processes of nitrate reduction to molecular nitrogen are carried out. The source of nitrates is the circulating activated sludge coming from the secondary clarifier (5), which is mixed with the coagulant coming from the coagulant solution tank (6) and the sludge liquid coming from the excess sludge thickener (7). In the aerobic tank (4) aeration is carried out, organic substances and nitrogen compounds are oxidized by microorganisms to carbon dioxide and nitrates.

From the zone of the sealer of the activated sludge from the secondary settling tank (5), sludge water and circulating sludge are directed to anoxic (3) and anaerobic (2) tanks. The limiting factor in the process of wastewater treatment from phosphorus is the low concentration of phosphates interacting with coagulants. Under anaerobic conditions, the concentration of phosphates increases, so the highest concentration of phosphates is formed in the circulating sludge, namely, in the sludge mixture in the anaerobic (2) and anoxide (3) tanks, so it is advisable to place the aerobic tank (4) after the anoxide tank. Phosphates bind, for example, Fe + 3 and Al + 3 cations to poorly soluble FePO4 and AlPO4 complexes, supplying the coagulant from the tank (6) to the circulating sludge promotes the chemical reaction of phosphates with the coagulant, which saves coagulant efficiency and improves wastewater treatment efficiency. Insoluble phosphorus compounds through the secondary clarifier (5) are removed from the biological treatment system along with excess sludge, which enters the thickener (7). Condensed activated sludge is sent for dehydration (8). The sediment-fermenter sludge (1) is also added here. The dehydrated sediment is discharged from the installation and disposed of, and the liquid purified from nitrogen and phosphorus compounds can be discharged into the catchment system.

The technical result of the utility model is to increase the efficiency of purification of municipal wastewater from nitrogen and phosphorus.

Used sources:

1. RU 58529 U1; IPC C02F3 / 02; publ. November 27, 2006;

2. RU 2294899 C1; IPC C02F3 / 00, C02F101 / 16, C02F101 / 30; publ. March 10, 2007;

3. CN 108675548 A; IPC C02F9 / 14, C02F101 / 10, C02F101 / 16, C02F101 / 30; publ. 10/19/2019;

4. KR 20000039706 A; IPC C02F3 / 30; publ. 07.07.2000.

Claims (2)

1. Installation for biological treatment of municipal wastewater from nitrogen and phosphorus compounds, containing primary and secondary settling tanks, anaerobic, anoxide and aerobic tanks, coagulant tank, sludge thickener and dewatering unit, equipped with inlet and outlet nozzles and connecting pipes, characterized in that the above-mentioned tanks are connected by sewage pipelines in the following strict sequence: primary clarifier-fermenter 1, anaerobic tank 2, anoxide tank 3, aerobic tank 4, secondary settling tank 5, the secondary settling tank 5 has an upper sedimentation zone of active sludge and a lower compaction zone of excess sludge, is equipped with a circulating activated sludge outlet pipe, a compacted excess sludge outlet pipe and a purified water outlet pipe, with the above-mentioned sedimentation zone of the secondary settler 5 through a circulating pipeline activated sludge is connected to the anaerobic reservoir 2 and the anoxide reservoir 3, the above mentioned circulating activated sludge pipeline in its initial part with a tank of coagulant solution 6, said compaction zone of the secondary settling tank 5 is connected by a pipe of excess sludge through the outlet pipe to the inlet pipe of sludge thickener 7, from which thick excess sludge can be transferred to the dewatering unit 8, and the sludge liquid can pipeline sludge flow into the anoxide tank 3 for re-processing, while dehydrated sludge from the dehydration unit 8 is removed from the installation, and the resulting fugate through the pipe After withdrawal of the centrate, the centrifuge line is fed to the anaerobic tank 2 for re-treatment. 2. Installation according to claim 1, characterized in that the primary clarifier-fermenter 1 is equipped with a pipe output sludge connected by pipeline with the unit dewatering excess sludge 8.

Images