RU2181703C2 - Complex of domestic sewage treatment facilities - Google Patents

Abstract

FIELD: treatment of sewage and biological purification of waste water followed by tertiary treatment through filtration; treatment of waste water at low flow rate and at increasing flow rate at different degree of contamination. SUBSTANCE: proposed complex includes, grate, sand trap, settler-balancing reservoir, aerotank unit and biological ponds made in form of multi-sectional biological pond. Besides that, complex includes biosorption filter filled with mixture of inert coarse-dispersed material by 50%, for example, gravel: fractions of 1 to 5 mm, 30 %: fractions of 5 to 15 mm, 50% and fractions of 15 to 25 mm, 20%, biosubstrate on base of waste bark, for example, softwood disbarking of size 10 to 100 mm, 70%; sawdust, 20% and excessive activated sludge, 10 %. Filter is provided with perforated pipes mounted below freezing level. Biofilter surface is planted with Salix alba. Cat-tail and reed are planted on banks of multisectional biopond. Eichornia crassipes are planted in pond proper. Filtering dams are provided between sections of biopond; floating aerator is mounted in first section. Filtering dams have non-filtering bases made from waterproofing soil, for example clay at distance of 0.75 from normal headwater level and filtering crest made from inert coarse-dispersed materials, for example gravel. EFFECT: enhanced efficiency of sewage treatment; improved quality of stable purification at dynamic change in flow rate and degree of contamination. 4 cl, 2 dwg

Description

 The invention relates to wastewater treatment, is intended for mechanical and biological wastewater treatment with post-treatment by filtration and can be used in the treatment of both small wastewater costs with a low degree of pollution, and for wastewater treatment of developing objects with increasing consumption and degree of wastewater pollution .

 When constructing residential and industrial facilities, the legislation in force in the country provides for the early commissioning of a full range of biological wastewater treatment plants already at the initial stage of residential construction, when wastewater costs and the content of biologically cleaned pollutants in them are insufficient.

 The generally accepted classical schemes for wastewater treatment include various combinations of mechanical and biological treatment devices, for example for settlements: grate - sand trap - 2-tier sedimentation tank - aeration tank - secondary sedimentation tank - disinfection; for small objects: grate - sand trap - sedimentation tank - biopond.

 A known scheme of wastewater treatment, including mechanical treatment, biological treatment and post-treatment by filtration. The technological scheme includes the following equipment: grates, sand trap, primary sump, aeration tank, secondary sump, activated sludge regenerator, strainer, grain filter, chlorination unit, contact tank, wash water discharge tank, wash water storage tank and sand pads (see A.M. Kaganovsky, N.A. Klimenko, etc. Purification and use of wastewater in industrial water supply, M .: Chemistry, 1983, p.238).

 The disadvantage of this complex of facilities is that the treated water cannot be used to feed completely closed (blow-off) cycles of reverse water supply, because colloidal and especially dissolved contaminants cannot be removed from wastewater.

The main disadvantages for newly constructed facilities of generally accepted schemes of treatment facilities based on aeration tanks of various modifications are:
- non-adaptability to changing conditions, the impossibility of changing the functions performed;
- the complexity of reconstruction in the event of an increase in consumption and an increase in the degree of pollution of wastewater, requiring a change in the set of treatment facilities, their capacity and functions of individual elements.

 In some cases, the prospect of an object under construction is being reviewed, while the constructed treatment facilities, as a rule, cease to correspond to the changed parameters and require radical reconstruction.

 As shown by the practice of operating the above facilities designed for rural settlements with long construction periods, normative wastewater treatment, especially in the initial period, is not provided. This is due to the fact that at the beginning of the development of the settlement, a small amount of wastewater with a minimal degree of pollution arrives at the treatment plant, which does not ensure the normal operation of biological treatment plants, in particular aeration tanks. In this case, the activated sludge formed is mineralized and does not increase to the required volumes. Thus, biological treatment in aeration tanks does not occur, insufficiently treated wastewater is supplied to the aftertreatment facilities, which leads to disruption of the wastewater treatment process.

 Thus, with a long development period of facilities, the standard level of wastewater treatment in these initial periods is practically not achieved, the treatment facilities are inefficient, their maintenance is unsatisfactory, the equipment fails, the structures become unusable and the treatment facilities need to be cleaned after a few years overhaul.

 The closest in technical essence and the achieved result to the claimed technical solution is the scheme of wastewater treatment using a complex of devices described in the book B.O. Botuk. Purification of domestic wastewater, Moscow: Ministry of Agriculture of the RSFSR, 1949, p. 39.

 This scheme contains a grate, a sand trap, a settling tank, aeration tanks and biological ponds successively installed along the flow.

 The disadvantage of the prototype device is that the purified water cannot be used to feed completely closed (without purging) cycles of reverse water supply, because colloidal and especially dissolved contaminants cannot be removed from wastewater.

 The task to which the proposed technical solution is directed is to create a complex of facilities that allows to increase the degree of wastewater treatment due to post-treatment of water at the output of the biocomplex, to ensure high-quality stable wastewater treatment in the face of dynamic changes in the flow rate and degree of water pollution during the development period of developing facilities .

 The task is achieved using the features specified in the 1st paragraph of the claims common to the prototype, such as: a complex of facilities for treatment of domestic wastewater, containing a grate, a sand trap, a settling tank, aeration tank, aeration tank unit and biological ponds , and distinctive, essential features, such as: ponds are made in the form of a multi-section biopond, and the complex additionally contains an underground biosorption filter, the body of which is filled with a mixture of inert coarse material by 50%, for example gravel: 30% fractions 1-5 mm; 50% - 5-15 mm; 20% - 15-25 mm, biosubstrate based on bark waste, for example, waste debarking coniferous wood with a grain size of 10-100 mm - 70%; sawdust - 20%; excess activated sludge - 10%, and the filter contains perforated pipes installed below the freezing level. This allows us to provide high-quality stable wastewater treatment under conditions of dynamic changes in the flow rate and degree of water pollution during the development period of developing facilities.

 Paragraph 2 of the formula indicates the peculiarity of vegetation placement of the biosorption filter, namely: the surface of the biosorption filter is planted with Salix alba willows.

 Peculiarities of the implementation of the biopond are reflected in paragraph 3, formulas, namely: the shores of a multi-section biopond are planted with cattail, reed, and water hyacinth (eichornia) is planted in the pond itself, and filter dams are installed between the sections of the biopond, and a floating aerator is installed in the first section of the biopond.

 The design of filtering dams is reflected in paragraph 4 of the formula, namely, filtering dams have a non-filtering base constructed of waterproofing soil, such as clay, at a distance of 0.75 from the normal retaining level and a filter ridge made of inert coarse materials, such as gravel.

The advantages of the claimed complex with the above signs of domestic wastewater treatment for developing facilities with increasing consumption and degree of pollution are:
- ensuring high-quality and stable wastewater treatment under conditions of a dynamic change in their flow rate and degree of pollution in the initial and intermediate periods of development of a developing facility;
- low capital and operating costs in the first stages of wastewater treatment (reduced costs for the construction and operation of treatment facilities);
- the possibility of changing the final capacity of the treatment facilities of the facility when changing the prospects for its development.

 The invention is illustrated by the following drawings: in figure 1. The scheme of the proposed complex is presented; in FIG. 2 shows a diagram of a filter dam.

 At the initial stage of development of the facility, when the volumes and degree of pollution of domestic wastewater are minimal, mechanical treatment with additional disinfection will be sufficient - stage I of the input of treatment facilities. Household wastewater in order to extract coarse and medium-sized contaminants is treated on the grate 1, sand trap 2 and then goes to the settling pond-averager 3, where further treatment takes place, and then it is fed to the disinfection unit 4. As the consumption and degree of pollution of household wastewater increase water, when mechanical cleaning is not enough to ensure a standard level, add a single-section bio pond 5, in which the cleaning occurs due to ongoing anaerobic and aerobic processes. The settling pond-averager 3 also performs the functions of a storage tank - stage II.

 With the further development of the facility with increasing costs and the degree of pollution of domestic wastewater, there is a need to intensify the treatment process. For this purpose, sections of the biopond are added, filtering dams 6, consisting of 2 parts, are constructed between the sections of the pond: non-filtering base 7, constructed from waterproofing soil (for example, clay) at 0.75 normal retaining level and filtering comb 8 made of coarse inert materials (for example, gravel) (figure 2).

 In the 1st section (figure 1), artificial aeration 9 is introduced, for example, in the form of a floating aerator - stage III. It is possible to use PM 22-09 or PM 55-1.03 aerators, developed by Lenhimmash and manufactured by the Marshan Chemical Engineering Plant.

 With a further increase in the flow rate and the degree of pollution of domestic wastewater sufficient to ensure the normal operation of the aeration tanks, after the pond-sump-averager-accumulator 3, a block of aeration tanks 10 is introduced in front of the multi-section bio-pond 10. Aeration tanks are used according to SNIP 2.04.03-85; Standard design decisions of the Central Institute for Standard Design 902-03-16. Thus, domestic wastewater after the pond-sump-averager-accumulator 3 enters the aeration tanks 10, and then for additional treatment in a multi-section bio-pond 5 - stage IV of the input of treatment facilities.

At stage V, in order to remove specific pollutants (for example, wastewater containing oils and various other petroleum products was added to household wastewater), species changes are introduced into the biocenosis of a multi-section biopond:
- along the banks of the pond is planted with cattail, reed 11;
- water hyacinth (eichornia) is planted in the pond itself 12.

 Finally, at the final stage of the facility’s development, with the maximum volume and degree of pollution of domestic wastewater, an underground biosorption filter 13 is put into operation as a post-treatment, the body of which is filled with a 50% mixture of inert coarse material (for example, gravel: 30% fraction of 1-5 mm ; 50% - 5-15 mm; 20% - 15-25 mm) and 50% biosubstrate based on bark waste (for example, debarking coniferous wood debarks with a grain size of 10-100 mm) - 70%; sawdust - 20%; excess activated sludge - 10%.

 In order to ensure year-round operation, the wastewater enters the biofilter through perforated pipes 15 located below the freezing level. The surface is planted with willows 14 (Salix alba) - stage VI. Elements of the complex of structures are interconnected by pipelines (gravity and pressure) 16.

 The complex of structures (figure 1) works as follows.

 Wastewater through pipeline 16 enters the grate 1, where it is cleaned of coarse particulate contaminants, then flows through the pipeline to a sand trap 2, where it is cleaned of medium-sized contaminants. Here, at relatively low fluid velocities, heavy mechanical impurities (sand) are deposited and air bubbles float, which float small organic substances and keep them in suspension, thereby improving the quality of the sludge in the sand trap 2. Then, the sewage flows through a pipeline to settling pond-averager 3, where further purification takes place. When the mixture enters the settling zone of pond 3, simultaneous processes of flocculation and deposition of suspended particles and sludge occur, and all excess sludge precipitates. Then the clarified waste fluid is fed to the disinfection unit 4 (used in stage I).

 Then, the clarified wastewater after the settling pond-averager 3 enters the aeration tanks 10, which are structurally a Typical project 902-03-16, and then to the multi-section bio pond 6, in which the treatment takes place due to the occurring anaerobic and aerobic processes. In block 6, water is purified from organic and mineral compounds, oils and oil products; her disinfection. At the same time, species changes are introduced into the biocenosis of a multi-section pond 6 — cattail, reed, and water hyacinth (eichornia) are used if necessary. Next, the water enters the underground biosorption filter 13, where there is a post-treatment.

 The wastewater treated at stages I-VI of the complex is used in the reverse cycle or discharged into an open reservoir.

Claims (4)

 1. A complex of facilities for treating household wastewater, containing a grate, a sand trap, a settling tank-averager, aeration tanks and biological ponds sequentially installed along the flow, characterized in that the ponds are made in the form of a multi-section biopond, the complex additionally contains an underground biosorption filter, whose body is filled with a mixture of inert coarse material by 50%, for example, gravel: 30% of a fraction of 1-5 mm; 50% - 5-15 mm; 20% - 15-25 mm, biosubstrate based on bark waste, for example, debarking coniferous wood debarks with a grain size of 10-100 mm - 70%; sawdust - 20%; excess activated sludge - 10%, moreover, the filter contains perforated pipes installed below the freezing level.  2. The complex according to claim 1, characterized in that the surface of the biosorption filter is planted with Salix alba willows.  3. The complex according to claim 1, characterized in that the shores of the multi-section biopond are planted with cattail, reed, and water hyacinth (eichhornia) is planted in the pond itself, and filter dams are installed between the sections of the biopond, and a floating aerator is installed in the first section of the biopond.  4. The complex according to paragraphs. 1 and 3, characterized in that the filtering dams have a non-filtering base constructed of waterproofing soil, such as clay at a distance of 0.75 normal retaining level and a filter ridge made of inert coarse materials, such as gravel.

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