RU2552558C1 - Method for aerobic biological oxidation of biodegradable organic compounds in waste water - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: waste water is fed to the input of a sealed multi-stage filter module comprising at least three series-mounted chambers separated by partition walls, which allow the overflow of the waste water from the previous chamber to the next. The chambers have a floating load on which there is a biocenosis of microorganisms. The waste water passes through said multi-stage filter module with forced aeration and maintenance of acidic and ionic conditions, which are optimum for sustaining the microorganisms. The optimum ionic conditions are maintained using a salt concentrate obtained by demineralising water on reverse-osmosis apparatus, which is fed into a storage container.

EFFECT: high efficiency of treating industrial waste water from highly concentrated organic impurities without uncontrolled emission of volatile organic compounds from the apparatus into the atmosphere.

6 cl

Description

The invention relates to the field of wastewater treatment, preferably containing organic biodegradable compounds, and can be used in the purification of industrial wastewater containing organic compounds, as well as municipal wastewater.

It was proposed to use the technology of aerobic biological oxidation of organic compounds (microbiological filtration, biofiltration) without any additional oxidizing agents (ozone, chlorine, etc.), the use of which leads to the uncontrolled formation of new chemical compounds, including toxic to bacterial cells (ozone, active chlorine, organochlorine compounds, etc.). To neutralize the effects of such compounds, the wastewater treatment system must include additional devices, which increases both capital costs and the cost of operating the system.

The microbial component of the biofilter for wastewater treatment is formed in the form of a consortium of stably effective microorganisms that exhibit highly specific biocatalytic activity with respect to the components of the effluents, proved during preliminary tests. For the formation of the consortium using exclusively non-pathogenic strains of natural origin.

Known (Jp, application 49/021951, publ. 1992) a method of treating wastewater containing organic compounds by exposing the wastewater to the combined action of ultraviolet rays, as well as activated chlorine or hypochlorite, followed by purification with activated carbon.

The disadvantage of this method should recognize the technological complexity of the method, as well as the formation during the processing of chlorine and ultraviolet rays of organochlorine compounds, peroxides and quinones.

Known (RU, patent 2117639, publ. 1998) is a method of reducing the content of organic chemicals in wastewater containing organic compounds with a chemical oxygen demand (COD) by chemical oxidation in the presence of chlorine, and the wastewater is fed to at least one reactor, purified at a temperature of more than 15 ° C with a chlorine-containing and / or chlorine-releasing substance, chlorine is supplied in an amount of more than 1 g of chlorine per 1 g of COD with the expectation of the chlorine content in the chlorine-containing and / or chlorine-releasing substance at a molar ratio of OH ^- Cl more than 1.5 and a pH of the wastewater of more than 6 for more than 0.4 h, and the organic compounds are at least partially oxidized, then the wastewater is purified in a subsequent cycle, and / or discharged and / or discharged from the reactor .

The disadvantage of this method should recognize the formation of organochlorine compounds in the water to be purified during the cleaning process.

Known (US patent 5861095, publ. 1999) is an aerobic-anaerobic method for treating wastewater from organic compounds and suspended solids by aeration in a closed reactor with constant stirring, re-aeration in the next aerobic reactor with periodic stirring; after a predetermined period of time, water is supplied to the third reactor for its treatment under anaerobic conditions and then, in the fourth, for nitrification.

The disadvantage of this method is its complexity due to multi-stage, and increased energy consumption due to the need for constant mixing.

Known (Jp, application 62-295838, publ. 1994) a method of treating wastewater from organic compounds and suspended solids by aerobic treatment in the presence of a floating load with attached microorganisms to lower BOD. After aeration, water is sedimented to separate activated sludge, clarified water is subjected to secondary aeration on a nozzle with attached microorganisms for the purpose of nitrification and then anaerobic treatment with stirring for denitrification. Further aeration in the presence of a floating carrier with attached microorganisms removes phosphorus and then settles to clarify the water.

The disadvantages of this method are its complexity, due to the multi-stage process, the difficulty of retaining a floating carrier in the cleaning system and the need to use mixing devices, which leads to increased energy costs.

Known (RU, patent 2136614, publ. 1999) is an aerobic-anaerobic method for biological treatment of wastewater from organic compounds and suspended solids, which consists in mixing the source water and activated sludge, saturating the mixture with air, sorbing contaminants from the resulting air-water mixture during its passage through a suspended layer of activated sludge with clarification of water, separation of organic sediment and its destruction under anaerobic conditions; clarified water is subjected to aeration in a suspended layer of activated sludge to remove organic contaminants with further nitrification at a charge with immobilized microorganisms and denitrification with the release of free nitrogen. The sludge mixture saturated with air is subjected to post-aeration and flotation with removal of the released air for aeration. The treated water flows in a downward flow through a suspended layer of activated sludge aeroflocles, being cleaned of contaminants and nitrogen released, and then with the remaining part of activated sludge passes through a charge with nitrifying agents, and in an upward flow passes through a fluidized bed of granular material with an optional biocenosis. Anaerobic treatment of purified water is carried out by passing it through a dense suspended layer of activated sludge to restore nitrate nitrogen; purified water is defended to remove sludge residues, followed by saturation of clarified water with air oxygen for the final removal of nitrogen.

The disadvantage of this method is its complexity, due to the multi-stage process and, as a consequence, its complex design.

Known (US, application 95116354, publ. 1995) is an aerobic-anaerobic method for treating household and biodegradable industrial wastewater by aeration of a mixture of purified water and a suspension of suspended solids returned from the sump on surfaces of a stationary charge immersed in water with attached microorganisms; The created circulating water-air flow “washes” the upper and lower surfaces of the charge, promoting intensive oxidation of organic substances and their fermentation under the influence of biomass, and suspended solids and particles of biomass remaining in the water are removed by settling.

The disadvantage of this method is the insufficiently high degree of wastewater treatment.

Known (RU, patent 2137720, publ. 1999) is a method of biological treatment of domestic and similar in composition industrial wastewater, which consists in settling, anaerobic treatment, aerobic biological treatment of pre-clarified wastewater by aeration on a volumetric, porous, shaped charge, in the process which, as a result of saturation of water with atmospheric oxygen and the creation of intense circulation in the aeration zone, the oxidation of organic substances occurs; after aeration, the water is subjected to secondary sedimentation with separation of the biofilm returned to the primary sedimentation stage, and the water, which has undergone a complete biological treatment, is subjected to post-treatment by biofiltration at the charge, followed by disinfection.

The disadvantage of this method is the duration of the process - about 85 hours due to insufficient use of the anaerobic zone, devoid of loading, a one-stage process of aerobic treatment (only at the load with attached microorganisms) and the unsatisfactory mode of circulation of the water-air mixture both during the aerobic treatment and in the process tertiary treatment with a downward movement of water, and insufficiently high degree of removal of ammonium nitrogen.

Known (RU patent 2225368, publ. 2004) is a method of deep biological wastewater treatment in an installation divided into four series-connected zones using anaerobic and aerobic conditions, followed by separation of activated sludge and purified water by settling and discharging activated sludge and purified water, at the same time, wastewater treatment in the first two zones of the installation is carried out under anaerobic conditions with stirring using microflora attached to an inert loading material reinforced with metal, in the absence of The amount of dissolved oxygen in the first zone and the concentration of dissolved oxygen in the second zone not exceeding 1.0 mg / L, the cleaning in the third and fourth zones is carried out under aerobic conditions, while the cleaning in the third zone is carried out using microflora attached to an inert loading material when the concentration of dissolved oxygen is 2-3 mg / l, and the purification in the fourth zone is carried out using free-floating microflora while maintaining an excess of dissolved oxygen more than 4.0 mg / l, purified water after settling It is poured into two streams, one of which in an amount of not less than 50% of the total amount of purified water is sent to the first zone, and the second is sent for additional treatment under aerobic conditions using microflora attached to an inert loading material.

The disadvantage of this method is the use at several stages of processing immobilized on an inert loading material microflora, which significantly increases the cost of the process due to the need for periodic regeneration of the load.

A common drawback of all the technical solutions listed above is the need to recognize the impossibility of their use for preliminary biological treatment of industrial effluents in a compact design that allows their installation directly in the premises of the enterprise.

The closest analogue of the developed technical method can be recognized (UA, patent 9640, publ. 30/09/1996) a method of aerobic biological oxidation of biodegradable organic compounds in wastewater. According to a known method, wastewater is supplied to the input of a cascade filtration module containing at least three successively installed chambers separated by partitions installed to ensure the flow of treated effluents from the previous chamber to the subsequent chamber, and the overflow from the chamber with an odd number to the chamber with an even number occurs at the bottom of the cameras, and transfer from an even-numbered camera to an odd-numbered camera occurs at the top of the cameras, a floating load is placed in the cameras and with a community of microorganisms attached to it, and the effluent to be cleaned is passed through the indicated cascade filter module during forced aeration and maintaining the acid and ionic regime, optimal for the life of microorganisms.

The disadvantage of this method should be recognized as the insufficient efficiency of wastewater treatment from organic biodegradable contaminants due to leaks in the equipment used, leading to additional pollution of wastewater by microorganisms from the atmosphere, as well as the need to use additional sources of mineral components.

The technical problem solved by using the developed design is to expand the range of primary wastewater treatment products containing various organic components, toxic to most microorganisms and / or contained in effluents at dangerously high concentrations.

The technical result obtained by the implementation of the developed method consists in increasing the efficiency of purification of industrial effluents from highly concentrated organic impurities, toxic to ordinary microflora (including microflora of standard urban wastewater treatment plants), without uncontrolled emission of vapors of volatile organic compounds into the atmosphere from the installation volume.

To achieve the specified technical result, it is proposed to use the developed method of aerobic biological oxidation of biodegradable organic compounds in wastewater. According to the developed method, the wastewater is fed to the inlet of a hermetically sealed cascade filtration module containing at least three successive chambers separated by partitions installed to ensure the flow of treated effluents from the previous chamber to the subsequent chamber, and the overflow from the chamber with an odd number to the chamber with an even number occurs at the bottom of the cameras, and transfer from an even-numbered camera to an odd-numbered camera occurs at the top of the cameras, while in cameras ene floating loading from fixed thereto microbial community, and cleaned waste water is passed through said cascade filter module when implementing forced aeration and maintaining the acidic and ionic optimum operating conditions for the microorganisms.

The number of chambers in the used filtration module depends on the degree of contamination in the treated effluents. It was experimentally established that there should be at least three cameras. In a most preferred embodiment, the filter module comprises eight chambers. The design of a hermetically sealed filtration module ensures that vapors of volatile organic compounds do not enter the atmosphere. The flow of treated effluents in this way prevents the mixing of more contaminated portions of effluents with effluents that have already undergone partial biological treatment, which actually increases the contact time of the contaminants with the community of microorganisms that remove these pollutants from the effluent, and also ensures a continuous course of oxidative biodegradation of pollutants even during periods lack of supply for cleaning new portions of treated effluents. The use of forced aeration, as well as maintaining the acid and ionic regime in the chambers that is optimal for the life of microorganisms, ensure the normal growth and development of the community of microorganisms present in the chambers, which, in turn, guarantees an improvement in the quality of wastewater treatment.

Preferably, the wastewater is supplied for treatment from a storage tank into which wastewater is previously collected from various sources.

Since the composition of the organic impurities of the effluents is a priori known or can be determined using well-known methods of chemical analysis, cultures of microorganisms with established physiological and biochemical properties, including the absence of toxicity and pathogenicity isolated from natural sources and adapted for oxidative decomposition of the target ones, are usually used to create a starting community of microorganisms organic components of treated wastewater. If necessary, they additionally check the resistance of microorganism cultures that are supposed to be included in the initial community to the action of a complex of organic compounds that make up the wastewater.

In the case where a reverse osmosis water purification process is used in a plant whose wastewater is to be treated, the concentrate obtained by reverse osmosis water purification can be used in the chambers of the filtration cascade module to maintain the optimal ion mode.

Periodically, as the accumulated sediment accumulates in the chambers of the cascade filtration module during the purification of effluents from the chambers of the cascade filtration module, it is preferable to remove the formed sediment. The amount of sediment accumulated in the chambers of the cascade filtration module is determined by any known method applicable in this case. In particular, a piezoelectric sensor or an optical level sensor can be used.

In the case of a small volume of wastewater, wastewater from various production sites can be pre-mixed in a storage tank. The treatment of pre-mixed wastewater in the storage tank is carried out in a constant or pulse-flow mode, depending on the production conditions and the total volume of wastewater.

Since in the process of wastewater accumulation in the storage tank, vapors of organic compounds are formed, as in the process of aeration of the chambers of the filtration cascade module, these vapors of organic compounds are preferably removed from the exhaust air before being discharged into the atmosphere. The removal of vapors from the exhaust air can be carried out by any known method.

The developed method of wastewater treatment from organic components in the basic version is implemented as follows.

The developed method was applied to purify enterprise effluents containing organic amides, organic amines, as well as substituted organic acids and their salts. A reverse osmosis unit was used at the enterprise to obtain demineralized water.

The microbial component of the biofilter for wastewater treatment was formed in the form of a consortium of stably effective microorganisms that exhibit highly specific biocatalytic activity with respect to the components of the effluents, proved during preliminary tests. For the formation of the consortium used exclusively non-pathogenic strains of natural origin.

The effluents to be treated were collected in containers located at production sites. Submersible drainage pump as the accumulation of effluents pumped effluents through the pipeline from these tanks in the storage tank. To prevent the emission of vapors of organic components to be cleaned into the atmosphere, a system for adsorption purification of gas-air emissions from waste collection tanks at production sites, as well as from a storage tank, was used. The specified system contains a duct fan and an adsorption filter with a small differential pressure.

In the process of deep demineralization of water, salt concentrate is formed on reverse osmosis membranes, the volume of which is 25-30% of the volume of water received for purification. The resulting salt concentrates were transported via pipelines to a storage tank.

The storage tank, as noted earlier, is designed to accumulate all untreated effluents. Due to the arrival in the tank of aqueous solutions of various origins, containing both technogenic pollutants and salt concentrates, and mixed pollution of various nature, wastewater was mixed, as a result of which the concentration of pollutants and dissolved salts was averaged. In the storage tank, due to wastewater mixing, the mineral composition of the averaged runoff entering the treatment was restored to the level of tap water, which favorably affected the maintenance of the bacterial component and reduced the need for additional mineral dressing. In the storage tank, due to the receipt of the concentrate obtained during the post-treatment of tap water at the reverse osmosis unit, the residual concentrations of pollutants returned to the biological treatment system, which excluded uncontrolled entry of pollutants in any concentration into the sewage system. The averaged wastewater was sent for cleaning by a drainage pump. To improve the mixing of aqueous solutions in the tank, either a recirculation line of the drain pump or an additional recirculation pump can be additionally used. When filling the tank with drains, air is displaced from the tank. Since at this moment degassing of technogenic pollutants from the liquid can occur, a forced exhaust ventilation system is provided for the tank, which excludes the ingress of gas-air emissions containing vapors of organic substances from the tank volume into the atmosphere.

The wastewater collected in the storage tank was fed into the filtration cascade module. The filtration module has several working chambers of the transfer type, combined in a common volume. The volume of the working chambers can be either equal or different, which allows you to adjust the speed and volume of oxidative reactions at different stages of treatment. The working chambers are equipped with an effective aeration system (bubblers), forming small air bubbles, and a drainage pipe. The volume of the working chamber is partially filled with a floating load (inert mechanical carrier), on which a biofilm is formed during the operation of the biofilter. The main function of a floating load is to provide contact between contaminants contained in water and active microbial cultures immobilized on a carrier and / or present as a biofilm on the surface of the carrier. To ensure high system efficiency, the working chambers can be filled with various types of floating loading, and during operation, one type of loading can be replaced by another in a specific chamber (for example, to prevent excessive growth of biomass leading to the formation of bottom sediments). In the process of wastewater treatment, the optimal salt composition, temperature and volume of air supply for aeration were automatically or manually maintained in the chambers.

Purified water was collected in a second storage tank, which is designed to accumulate purified effluents. The water accumulated in the tank overflow enters the sewer. Since the water stored in the tank can be used for technical and technological needs, a drainage pump is provided in the tank to supply water to the distribution unit equipped with valves with actuators. From the distribution node, water from the tank can be directed to technological needs and technical needs (including for wet cleaning of a biological treatment room, washing equipment, washing automotive equipment, etc.) or, if necessary, returned to the first storage tank. Since when the tank is filled with water, man-made pollutants will not be degassed from the liquid, a respiratory ventilation system is provided in the tank associated with the volume of the biological treatment room to maintain the temperature of the tank.

When using the developed method, at least 90% of the starting organic compounds are removed from wastewater containing dimethylformamide, metaphenylenediamine, triethylamine, campharosulfonic acid and sodium lauryl sulfate.

Claims (6)

1. The method of aerobic biological oxidation of biodegradable organic compounds in wastewater, including the supply of wastewater to the input of a cascade filtration module containing at least three sequentially installed chambers separated by partitions installed to ensure the flow of treated effluents from the previous chamber to the subsequent chamber moreover, the overflow from the camera with an odd number to the camera with an even number occurs at the bottom of the cameras, and the overflow from the camera with an even number to the camera with an odd the number occurs in the upper part of the chambers, a floating charge with a community of microorganisms is mounted in the chambers, and the treated effluent is passed through the indicated cascade filter module during forced aeration and maintaining the acid and ionic regimes optimal for the life of microorganisms, characterized in that they are used hermetically sealed cascade module, while to maintain the optimal ionic regime, they use, inter alia, the salt concentrate obtained by demine alization water in reverse osmosis plants, which is sent to the holding tank. 2. The method according to p. 1, characterized in that to create a starting community of microorganisms, cultures of microorganisms with established physiological and biochemical properties are used, including the absence of toxicity and pathogenicity isolated from natural sources and adapted to the oxidative decomposition of the target organic components of the treated wastewater. 3. The method according to p. 1, characterized in that in the process of wastewater treatment from the chambers of the cascade filtration module, the precipitate formed is removed. 4. The method according to p. 1, characterized in that previously in the storage tank produce a mixture of effluents of various origins. 5. The method according to p. 4, characterized in that the cleaning of the pre-mixed effluents is carried out in a constant or pulse-flow mode. 6. The method according to claim 1, characterized in that the vapors of organic compounds formed during the mixing of the effluents and during the cleaning and aeration process are removed from the exhaust air before being discharged into the atmosphere.