RU2736187C1 - Method and device for cleaning domestic waste water - Google Patents

Abstract

FIELD: water purification.

SUBSTANCE: group of inventions is intended for purification of domestic waste water treatment of suspended substances, compounds of nitrogen, phosphorus and hard-to-oxidize organic compounds. Method comprises feeding effluents, first purified from coarse impurities, into chamber 1, at the stage of anaerobic purification in the presence of anaerobic bacteria of floating silt with content of 2.5–3.0 g/l and dissolved oxygen of not more than 1.0 mg/l. Through overflow hole 7 waste water from chamber 1 together with the sludge part is supplied to chamber 3 for the aerobic cleaning stage, performed when air is supplied from compressor via hose 18 on cassette 6 with biofilters located in area of overflow hole 7. Then, afterpurification of waste water in chamber 3 on cassette 6 with biofilters arranged in area of overflow hole 7 into chamber 4. Part of clarified flow carrying active sludge is supplied from chamber 3 by submersible pump 5 into basket of aerator 11 for reflux of loading 12, from which liquid is distributed through holes in plates 15 so that 10–15 % of flow is returned to chamber 1, and 85–90 % of flow is fed into chamber 3. Clarified effluent passes final sludge in pyramidal truncated part of chamber 4 and is brought out of device by means of drain pipe or submersible pump 5. In another embodiment, a device is provided, which is a cylindrical container with sewage water inlet branch pipes and clarified water outlet, divided into four chambers by vertical partitions, in which holes are made, through which sewage circulation inside device is performed. In the top part of the device there is a basket of aerator 11 with loading 12 and plate 15 with holes for distribution of liquid flowing down on the loading into chambers 1 and 3 of the device. Inlet branch pipe is located in anaerobic cleaning chamber 1. Chamber 2 of aerobic cleaning includes hose 18 of air supply from compressor and cassette 6 with bio filters, located in area of overflow hole 7 into chamber 3. Afterpurification chamber 3 includes biofilter cassette 6 located in the area of overflow hole 7 into chamber 4, as well as submersible pump 5 to supply part of clarified flow carrying active sludge into basket of aerator 11. Chamber 4 comprises clarified water outlet pipe and submersible pump 5.

EFFECT: group of inventions provides reduction of device dimensions, as well as quality of treated water according to BOD, COD, compounds of nitrogen, phosphorus, difficult-to-oxidize organic compounds corresponding to maximum allowable concentration for discharge into fisheries for fishery purposes.

6 cl, 2 dwg, 3 tbl

Description

A variety of methods, structures and devices for the treatment of domestic wastewater are known, including multistage anaerobic-aerobic treatment of the flow using both attached and suspended microflora. A variety of stationary and mobile devices, stations and installations for biological wastewater treatment are also known.

A known method for purifying wastewater from nitrogen ammonium compounds in a steel-reinforced plastic tank, divided into 3 communicating chambers. Biofilters in them are located in the first and third chambers. The first chamber contains anaerobic bacteria to remove organic compounds. The second chamber contains an air diffuser and aerobic bacteria to remove nitrogen-containing compounds. The third chamber contains the pump assembly and outlet filter. The resulting purified water is selectively discharged from the third chamber through an outlet. (US patent 8372274 B2, CO2F 3/06, 2013).

The disadvantages of this method are limited functionality, since it is aimed at purifying wastewater from nitrogen ammonium salts and does not contribute to the removal of phosphates, the absence of an aeration unit in the device does not allow improving the quality of treated effluents.

The known method and device for wastewater treatment from a residential building. The device additionally contains a storage chamber for waste water coming from the house and a disinfecting chamber. Cleaning from organic compounds and nitrogen-containing substances takes place in two chambers equipped with biofilters. The liquid is pumped by a pump (Patent US 5868927 A, CO2F 9/00, 1999).

The disadvantage of this method is the multistage nature, the complexity of the equipment, the use of additional disinfectants, increased costs of maintaining the system, the presence of an unpleasant odor.

Known small-sized installation for wastewater treatment of individual houses, residential buildings, hotels, etc., consisting of an aeration chamber, a sedimentation chamber and a disinfection chamber. The deposition chamber is divided into a number of functional compartments (Patent EP 1451115 B1, C02F 3/1242, 2004).

The disadvantage of this installation is the low efficiency of wastewater treatment due to poorly organized flow circulation.

The known method and installation of wastewater treatment, providing for the accumulation of wastewater, removal of phosphorus and nitrogen-containing compounds, aerobic treatment by microorganisms to capture heterotrophic bacteria in the aeration section of the installation, additional purification from autotrophic bacteria in the second aeration section. Thus, nitrogen and hydrogen sulfide are absorbed (Patent WO 2005026064 A1, C02F 3/1215–2005).

The disadvantage of this method is the possibility of flooding the installation in the event of failure of the submersible pump, which provides both direct and reverse flow.

A three-stage compact wastewater treatment plant is known for use in homes and buildings that are not connected to city sewer networks. In a cylindrical container made of concrete, the processes of sedimentation and biological wastewater treatment are carried out using anaerobic and aerobic microorganisms. The chlorination of effluents is provided after the completion of the anaerobic purification process. The aerobic cleaning process is carried out in the next compartment, where air is supplied and turbulence is created. The installation is effective in purifying wastewater from nitrogen-containing compounds (Patent US 6406619 B1, CJ2F 3/1242, 2008).

The disadvantage is the operation of chlorination of effluents in the treatment process, which increases the environmental load and requires additional solutions to reduce it.

A known method of purification of ammonium-containing wastewater. It is implemented in an activated sludge wastewater treatment plant. First, with the help of aerobic oxidizing bacteria (AOB), ammonium is converted to nitrite, and then, with the help of anaerobic oxidizing bacteria (AMOCS), ammonium and nitrite are converted into elemental nitrogen. The method provides complete removal of nitrogen (RF Patent 2477709, CO2F 3/30, 2013).

The disadvantage of this method is its low efficiency in the purification of wastewater from phosphorus compounds and high oxygen consumption. In this case, the sludge loses carbon and its activity. For the separation of light and heavy sludge fraction, an additional hydrocyclone is required.

Known installation for the treatment of domestic wastewater on oil and gas production platforms, terminals and ships, which is a module of series-connected units: a sump-homogenizer, a device for receiving initial wastewater, an anaerobic unit, a membrane filtration unit and auxiliary equipment. In this case, the anaerobic block is configured to supply return activated sludge together with waste water from the oxide block. The oxide block is configured to supply return sludge from the membrane block to it and is equipped with an aerator; the membrane filtration unit is also equipped with an aerator and a vacuum device for removing purified water for discharge. The installation is reliable in operation and allows the quality of cleaning to comply with the requirements of existing regulatory documents on the concentration of pollutants (RF Patent 2537611, C02F 9/14, 2015). However, the installation is metal-consuming, cumbersome and expensive, which limits its widespread use for individual use in cottage villages.

Known installation for biological treatment of domestic wastewater, containing sequentially located in the direction of flow of the accumulator-homogenizer, sand trap, two blocks of biological treatment, tertiary settling tank and a system of technological pipelines. Each of the biological treatment units contains a two-section submersible drum biofilter with flat loading and a secondary clarifier. The latter is an open container that includes 2-4 transverse cassette filters with a fixed loading of fractionated zeolite and settling chambers. The number of settling tanks in each block is from 1 to 3. Such a device allows you to quickly build up the biomass of microorganisms and efficiently absorb phosphorus and nitrogen-containing substances (RF Patent 2323891, CO2F 3/06, CO2F 9/00, 2008).

The disadvantage of this system is the lack of compactness, the presence of resistance to the movement of liquid through pipelines, a significant number of settling tanks in the device that impede circulation, the presence of sieve grates that require frequent replacement, inconvenience in operating the installation in the conditions of individual farms.

Close in technical essence to the proposed invention is a small-sized wastewater treatment plant, consisting of three tanks connected in series. Purification of effluents from phosphorus and nitrogen-containing compounds and hydrocarbons occurs in the specified installation using anaerobic and aerobic microorganisms and microorganisms of activated sludge (Patent DE 10041665 A1, C02F 3/1242, 2002).

The disadvantage of the installation is that it is not assembled in a single unit and requires constant maintenance during operation.

Closest to the proposed invention is a mini installation for wastewater treatment with a low flow (from 1 to 8 m ³ / day), which has a single metal body with a cover. The internal volume is divided by partitions into compartments for primary sedimentation, compartments with anaerobic and aerobic microorganisms. Internal recirculation of treated water with sediment sludge occurs between the sedimentation compartment and the primary sediment compartment. Air is pumped between the compartments by a low-power silent compressor. In the upper part of the unit there is a light-loading aerator made of polymeric materials. The cleaning efficiency is within 80-86% of the initial concentrations of harmful substances. (US Patent 6,210,578 B1; C02F 3/1242; 2001). The disadvantage of such an installation is that it is made of metal, and with constant contact with an aggressive environment, it quickly breaks down. Giving it corrosion resistance requires additional costs. The quality of the treated water for a number of indicators does not meet the sanitary and hygienic requirements and standards of the Russian Federation.

The technical result of the claimed invention is to reduce the size, eliminate metal parts and assemblies, place all elements of the device in a single cylindrical container made of polymer material, stable operation of the device without the intervention of its owner. The degree of domestic wastewater treatment is provided by at least 98-99% according to the main controlled parameters (suspended solids and BOD - COD).

The technical result is achieved by the fact that the purified water according to a given circulation regime, due to the design of the device, divided into four chambers by vertical partitions, is sequentially passed through the anaerobic and aerobic stages of treatment with activated sludge and microorganisms with different enzymatic respiration. The supply of oxygen to microorganisms is carried out by an aerating device that allows saturating the liquid when spraying, returning it in the required volumes to the indicated processing stages so that the liquid is most effectively purified from the organic substances contained in it, phosphorus and ammonium-containing compounds, nitrites and nitrates.

The method is carried out as follows: Initial waste water, previously purified from coarsely dispersed impurities, with indicators: suspended matter, mg / l 281.9; ammonium nitrogen, mg / l 26.9; total nitrogen, mg / l 29-30; phosphates 3.6 mg / l; BOD, mgO ₂ / l 77.2; COD, mgO ₂ / l 89.3 is fed into chamber 1 (Fig. 2) to the stage of anaerobic purification, where, in the presence of anaerobic bacteria, floating sludge (content 2.5-3.0 g / l due to its partial return from chamber 3 and aerator 11) and dissolved oxygen not exceeding 1.0 mg / l, glycolysis of easily oxidized organic substances, ammonolysis of ammonium salts and the development of phosphate-accumulating microorganisms and, as a consequence, biological absorption of phosphorus to a maximum concentration of 0.18 mg / l. This is possible because in addition to the main incoming fluid flow, chamber 1 receives periodically (as the submersible pump 5 is turned on in chamber 3) 1 / 7-1 / 10 of the clarified flow from the aerator, which carries activated sludge and increases the content of the resulting low molecular weight fatty acids. In this case, the load on the activated sludge according to the BOD is 2.5-3.5 mgO ₂ / g. In the process of life of heterotrophic anaerobic microorganisms, enzymatic hydrolysis of hydrocarbons takes place with the formation of low molecular weight compounds, in particular simple linear low molecular weight acids and aldehydes, the reduction of oxidized forms of nitrogen and the consumption of phosphorus (phosphates) by microorganisms as food. The return of a certain volume of purified water from the aerator is necessary for the recovery of nitrate nitrogen. The load on activated sludge in terms of nitrogen is in the range of 3.5-4.2 mg / g.

Through the overflow hole in chamber 1, the liquid, together with the sludge part from chamber 1, enters chamber 2, where there is a cassette 6 with biofilters and where air from the external compressor is supplied through a hose 18 so that the incoming oxygen mostly falls on the resulting biofilm on the surface of the filters located in the area of the overflow hole from chamber 2 to chamber 3. The load on the activated sludge in this case reaches values for BOD up to 12 mgO ₂ / g. Here, in chamber 2, the aerobic stage of liquid purification takes place. The concentration of dissolved oxygen in this chamber is maximum 4.0-4.5 mg / l. A mixed biocenosis of heterotrophic and autotrophic microorganisms consumes almost the entire organic part of wastewater. The load on the activated sludge in terms of nitrogen is 0.8-1.3 mg / g, in terms of synthetic surfactants - 0.15-0.25 mg / g. The organic compounds remaining after the anaerobic stage are completely oxidized, the processes of the transition of nitrites to nitrates and further to free nitrogen are intensified. The duration of the aerobic stage is determined by the load on the activated sludge in terms of nitrogen, surfactants and fats, some cyclic difficult-to-oxidize organic compounds. At this stage, almost 80-90% of the liquid is purified from the specified contaminants (see table. 1).

Additional wastewater treatment takes place in chamber 3, where there is also a cassette 6 with biofilters, located in the area of the overflow from chamber 3 to chamber 4, and a submersible pump 5, mounted on a vertically movable shelf with the ability to install the pump in the most optimal position. The pump is designed for periodic supply of liquid and sludge to the basket with aerator 11, where with the help of the original sprayer 13 the liquid and sludge are enriched with air oxygen, uniform irrigation of the load located in the basket takes place 12. The liquid drain from the load is arranged so that its main part returns back to chamber 3 (85-90%), and only 10-15% returns to chamber 1. At this stage, the concentration of dissolved oxygen in the range of 3.2-4.0 mg / l is provided, which makes it possible to implement the processes of additional oxidation of some remaining in the liquid difficult oxidizable organic compounds. The submersible pump 5 is turned on by means of an electrical switching device upon receiving signals from the liquid level sensors in the chamber. As a result of additional treatment, the composition of the water is brought to the standard indicators.

The liquid purified from impurities with small amounts of sludge enters through the overflow opening of chamber 3 into chamber 4, where a pyramidal sump 9, truncated to the bottom, is arranged, into which the branch pipe 8 of the drain pipe 10 directly enters from above to evacuate the treated effluent outside the device. Water entering chamber 4 enters the sump from below, slows down, accumulates in an inverted truncated pyramid and is freed from silt. In this case, the outlet pipe 8 is located at a level from the surface of the earth below the inlet pipe 16, so the drain leaves the device by gravity. However, in case of situations when there is a need to free the chamber 4 from liquid, an option is provided with the help of a submersible pump 5 built into the sump with an autonomous outlet pipeline 10. The duration of the process of cleaning domestic waste water is 4 hours.

Table 2 shows the indicators of the quality of the treated water and the efficiency of the device for the treatment of domestic wastewater.

Thus, the obtained data on the quality of the treated waste water, the design of the device, labor and material costs according to the proposed method as a whole indicate the advantages over the known method (see Table 3).

The body of the proposed device, made of impact-resistant polypropylene sheet, and the absence of metal assemblies and parts distinguishes it favorably from the prototype assembled in a metal container and saturated with metal corrosive partitions. The service life of the proposed device is much higher, and the energy consumption for assembly and operation is lower.

The data obtained and presented in the tables indicate that the claimed indicators ensure the achievement of the quality of purified water in terms of BOD, COD, nitrogen, phosphorus compounds, difficult-to-oxidize organic compounds, corresponding to the MPC for discharge into fishery water bodies.

Claims (10)

1. A method of biological treatment of domestic wastewater, including the separation of the flow into a purified liquid and a solid mass of pollution, characterized in that the supply of wastewater, previously purified from coarse impurities, into chamber 1, at the stage of anaerobic purification in the presence of anaerobic bacteria of floating sludge with a content of 2.5-3.0 g / l and dissolved oxygen no more than 1.0 mg / l; - feeding through the overflow hole 7 wastewater from the chamber 1 together with the sludge part, where, when air is supplied from the compressor through the hose 18 on the cassette 6 with biofilters, located in the area of the overflow hole 7 into the chamber 3, the aerobic stage of cleaning is carried out; - post-treatment of wastewater is carried out in chamber 3 on a cassette 6 with biofilters, located in the area of the overflow hole 7 into chamber 4; - in this case, part of the clarified flow carrying activated sludge from chamber 3 with the help of a submersible pump 5 is fed into the basket of the aerator 11 for irrigation of the load 12, from where the liquid is distributed through the holes in the plates 15 in such a way that 10-15% of the flow returns to chamber 1, and 85-90% of the flow into chamber 3; - the clarified effluent passes the final sludge in the pyramidal truncated part of the chamber 4 and is discharged outside the device using a drain pipe or a submersible pump 5. 2. A device for the treatment of domestic wastewater, which is a cylindrical container with sewage inlet and clarified water outlet, divided into four chambers by vertical partitions, in which holes are made through which the wastewater circulates inside the device, characterized in that it contains in the upper part of the basket of the aerator 11 with loading 12 and plate 15 with holes for distributing the liquid flowing down the loading into chambers 1 and 3 of the device; the inlet pipe is located in the anaerobic cleaning chamber 1; the aerobic cleaning chamber 2 includes a hose 18 for supplying air from the compressor and a cassette 6 with biofilters located in the area of the overflow hole 7 into the chamber 3; the post-treatment chamber 3 includes a biofilter cassette 6 located in the area of the overflow opening 7 into the chamber 4, as well as a submersible pump 5 for supplying a part of the clarified stream carrying activated sludge to the aerator basket 11; chamber 4 contains a branch pipe for the outlet of clarified water and a submersible pump 5. 3. The device according to claim 2, characterized in that the overflow holes in the partitions between the chambers are located at different levels so that the level of the overflow hole of the chamber 1 is higher than the level of the overflow hole of the chamber 2, the level of the overflow hole of the chamber 3 is higher than the level of the overflow hole and the drain pipe of the chamber 4, which circulates the liquid in the device. 4. The device according to claim 2, characterized in that inside chambers 2, 3 there are brackets for attaching removable cassettes 6 with biofilters, and inside chambers 3 and 4 there are removable shelves for attaching submersible pumps with the possibility of adjusting the depth of their immersion and extraction in case necessity. 5. The device according to claim. 2, characterized in that the outside of the cylindrical body has a rim 17 along the entire surface of the cylinder to increase the structural strength of the device. 6. The device according to claim. 2, characterized in that the aeration module is equipped with a round flat diffuser for irrigation of the load with liquid coming from the chamber 3, while the uniform distribution of the runoff over the load occurs due to a system of radial recesses on the lower surface of the diffuser.

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