CN107055754B - Circulating zero-valent iron biofilter for strengthening treatment of rural domestic sewage - Google Patents

Abstract

The invention discloses a circulating zero-valent iron biological filter for strengthening the treatment of rural domestic sewage. Its structure is that a plurality of sewage disposal units are arranged underground; Intensified treatment, the treated domestic sewage is used as agricultural irrigation water or supplements groundwater or is directly discharged into the river; the sewage treatment unit includes: pretreatment tank, circulation tank and zero-valent iron biological filter three parts, each treatment unit structure They are independent of each other and communicate with each other through pipes. Advantages: low maintenance, low energy consumption, resistance to water quality and quantity impact, and high sewage treatment efficiency; only one pump couples the respective advantages of the two technical routes of intensive and ecological, which can easily cope with the complex drainage situation in rural areas and ensure the quality of the effluent. At the same time, it saves surface land resources, is simple and applicable, easy to operate and manage, and low cost.

Description

A circulating zero-valent iron biological filter for strengthening the treatment of rural domestic sewage

technical field

The invention relates to a circulating zero-valent iron biological filter for strengthening the treatment of rural domestic sewage, which can be directly applied to the treatment of rural domestic sewage or small-scale domestic sewage in villages and towns, and can also be used for the degradation of rural non-point source pollutants and water quality purification. It belongs to the field of environmental protection sewage treatment.

Background technique

Due to scattered areas, large population, and difficulty in collection, rural sewage has become an important source of pollution of rivers and lakes, as well as an important part of rural non-point source pollution; rural sewage contains a large amount of organic matter and nitrogen, phosphorus and other organic matter. Salt and untreated rural domestic sewage are directly discharged into natural water bodies, which not only affects crop yields, but also brings serious harm to the ecological environment and water quality of rivers and lakes. Therefore, the treatment of rural domestic sewage is very urgent and of great significance.

The treatment mode of domestic sewage includes centralized treatment and decentralized treatment mode; the centralized treatment technology and process are very mature, mainly urban sewage treatment plants, and their daily operation can achieve relatively stable treatment efficiency; while rural areas are generally located in remote areas, The sewage collection pipe network is difficult to cover. Therefore, the rural sewage generally adopts the decentralized treatment mode; the mainstream technologies used for rural domestic sewage abroad include: biological contact oxidation method, SBR activated sludge method and membrane bioreactor, etc.; these processes, technologies The requirements are high, the process control is difficult, and the operation cost is high, which is not suitable for the treatment mode of rural sewage in my country. At present, the technologies adopted for rural sewage in my country mainly include biological treatment technology that miniaturizes the process of sewage treatment plants, and artificial wetlands as the core. Ecological treatment technology and coupled treatment technology that combines the two. Similarly, these processes also have some problems, such as the high energy consumption per unit of the miniaturization of the sewage treatment plant process, and the lack of technical personnel in rural areas; the artificial wetland covers a large area, and the treatment effect is unstable; It will cause an impact on the water quality and quality of the treatment facilities in a short time. In addition, the concentration of nitrogen and phosphorus in rural domestic sewage in my country is relatively high, and the general treatment process is not effective in removing total nitrogen. For example, the publication number CN104098223B discloses a rural decentralized domestic sewage treatment system and method, which couples "biology" and "ecology", integrates the advantages of technologies such as ecological floating islands and artificial wetlands, and creatively proposes ecological floating islands— Constructed wetland technology combines new technology, makes full use of the remediation effect of aquatic plants, does not require land occupation, has low cost and good treatment effect, and controls the dosing of sewage into the filler that is often saturated, and the sewage flows in a certain direction. , Under the physical and chemical synergy of the filler, the organic matter in the sewage can effectively purify the sewage through filtration, adsorption and absorption, and promote the decomposition of facultative microorganisms. However, due to the lack of carbon source supply and the creation of anaerobic environment, the denitrification capacity of the system is weak, and the effluent effect is unstable. At present, the rural domestic sewage treatment system that has been put into practical application still has certain limitations.

The invention summarizes the deficiencies in the existing rural domestic sewage treatment technology in China, fully considers the needs and characteristics of rural sewage treatment in my country, and innovatively proposes low maintenance, low energy consumption, resistance to water quality and water impact, and stable effluent effect. Coupling intensive and Circulating zero-valent iron biofilter technology for enhanced water quality treatment.

SUMMARY OF THE INVENTION

The invention proposes a circulating zero-valent iron biological filter for strengthening the treatment of rural domestic sewage. It has the characteristics of high sewage treatment efficiency, stable effluent quality, simple application, convenient operation and management, and low cost. It can be widely used in the circulating zero-valent iron biological filter for intensive and intensive treatment of rural domestic sewage.

The technical solution of the present invention: a circulating zero-valent iron biological filter for strengthening the treatment of rural domestic sewage, which is characterized in that: a plurality of sewage disposal units are arranged underground; rural domestic sewage is collected to the sewage disposal unit through a water pipeline system Circulation and intensive treatment are carried out inside the treated domestic sewage, and the treated domestic sewage is used as agricultural irrigation water or supplementary groundwater or directly discharged into the river; the sewage treatment unit includes: a pretreatment tank, a circulation tank and a zero-valent iron biological filter. The three parts are connected in sequence; multiple sewage treatment unit structures are independent of each other, and communicate with each other through pipelines; the zero-valent iron biological filter is divided into two parts: ordinary biological filter and built-in zero-valent iron enhanced reaction tank.

Advantages of the present invention:

(1) Only one pump couples the respective advantages of the two technical routes of intensive and ecological, which can cope with the complex drainage situation in rural areas freely, and ensure the stability of the effluent quality;

(2) Construct aerobic-anoxic-anaerobic conditions of different depths, which are beneficial to the removal of total nitrogen. In the zero-valent iron reaction box in the anaerobic zone, rice straw or wood chips can be used as a solid carbon source to enhance heterotrophy. The growth of microorganisms with denitrification performance finally forms a zero-valent iron/microbial coupling system, which strengthens the removal of NO ₃ ^- , and the generated Fe ³⁺ /Fe ²⁺ has good flocculation performance, which strengthens the anaerobic release of phosphorus. remove;

(3) The zeolite layer is set above the zero-valent iron reaction box, which ensures the water quality of the effluent, creates an anaerobic environment for the lower layer, and prolongs the service life of the zero-valent iron;

(4) The entire circulating biological filter has low maintenance, low energy consumption, resistance to water quality and water impact, and high sewage treatment efficiency;

(5) The treatment structure is buried underground to save ground resources, and planted bricks are laid on the top of the disposal unit to create a good ecological environment;

(6) The zero-valent iron reaction box is easy to check and replace, which is convenient for management and maintenance;

(7) The whole project materials are cheap, easy to obtain and will not cause secondary pollution to the environment;

(8) The whole project is simple in structure, convenient in construction, stable in function, low in cost and easy to use.

Description of drawings

Figure 1 is a schematic diagram of a circulating zero-valent iron biological filter for intensive treatment of rural domestic sewage.

Figure 2 is a schematic plan view of a circulating zero-valent iron biological filter for intensive treatment of rural domestic sewage.

Figure 3 is a schematic diagram of a zero-valent iron reaction box.

1 is the water pipeline, 2 is the pretreatment tank, 3 is the 10-40mm middle grid, 4 is the circulation tank, 5 is the sludge collection tank, 6 is the circulating dissolved air pump, 7 is the sludge discharge pipe, and 8 is the Sludge pump, 9 is zero-valent iron biological filter, 10 is water distribution area, 11 is biological filler (one of crushed stone, pebble, slag or coke), 12 is pebble support layer, 13 is return pipeline, 14 is zero-valent iron reaction box, 15 is zeolite filler, 16 is overflow plate, 17 is drainage pipe, 18 is steel frame of φ15, 19 is steel mesh surface, 20 is zero-valent iron filler (made of sponge iron, iron shavings) 21 is wood chips (straw), 22 is a ring hook.

Detailed ways

A circulating zero-valent iron biological filter for strengthening the treatment of rural domestic sewage, the structure of which is that a plurality of sewage disposal units are arranged underground; The latter domestic sewage is used as agricultural irrigation water or supplements groundwater or is directly discharged into the river; the sewage treatment unit includes three parts: a pretreatment tank, a circulation tank and a zero-valent iron biological filter, and the structures of each treatment unit are independent from each other. The said zero-valent iron biological filter is divided into two parts: ordinary biological filter and built-in zero-valent iron enhanced reaction tank.

The plurality of sewage treatment units are arranged underground in a fully-buried or semi-buried type.

The pretreatment tank mainly removes the suspended solids in the raw sewage and other pollutants that can block the filter material, and homogenizes the water quality; the pretreatment tank has a built-in grille to intercept larger domestic garbage and impurities.

The circulating pool has a built-in circulating dissolved air pump for sewage circulation and oxygen enrichment; only one pump couples the respective advantages of the two technical routes of intensive and ecological, which can freely cope with the complex drainage situation in rural areas and ensure the quality of the effluent. At the same time, the dissolved air pump has its own oxygen-enriching function, which provides aerobic conditions for ordinary biological filters; a sludge collection tank and a sludge discharge pipe are set in the circulation tank near the side wall of the zero-valent iron biological filter; the sludge collection tank It is mainly used for enriching and concentrating the fallen off and aging biofilms discharged through the return pipe, and at the same time, the supernatant from the upper layer flows back into the circulation tank; a sludge discharge pipe is set on the side wall of the circulation tank near the bottom of the collection tank, and the sludge is discharged through the sludge discharge pump. Concentrated sludge.

The zero-valent iron biological filter has a nearly circular shape, and the circular design can eliminate "dead corners"; the outermost wall is treated with anti-seepage; the middle is a common biological filter, and the inner layer is zero-valent iron Reaction tank; the water inlet and outlet of the zero-valent iron biological filter is "weekly in and out", the sewage enters the water distribution area through the water pipeline, and is evenly sprayed by the water distributor into the ordinary biological filler tank and the zero-valent iron enhanced reaction tank; ordinary The construction of the biological filter material tank is as follows: the upper layer is provided with a working layer, and the filler of the working layer can be one of crushed stone, pebbles, slag or coke that is easily obtained locally, with a particle size of 25~40mm, and the thickness of the working layer is 1.5~ 1.8m; the lower layer is provided with a supporting layer, the particle size is 70~100mm hard pebble, and the thickness of the supporting layer is 0.2m. A large number of microorganisms are attached to the surface of the filler in the ordinary biological filter tank, forming a biofilm system, which plays a role in biodegrading the pollutants in the sewage; and because the dissolved oxygen is continuously consumed in the biodegradation process of the pollutants, from the top Aerobic zone and anoxic zone are gradually formed to the bottom. The inner ring is a zero-valent iron-enhanced reaction pool, and the bottom is also a 0.2m-thick supporting layer; a return pipe is set in the center of the bottom of the supporting layer, and the other end of the return pipe is connected to the circulation tank to connect the returned sewage and the falling biofilm. It is discharged into the sludge collection tank. In addition, the advantage of setting the zero-valent iron reaction zone in the return pipe is that the concentration of NO ₃ ^- in the anaerobic zero-valent iron reaction zone can be guaranteed; Mobile zero-valent iron reaction box, the zero-valent iron reaction box is cylindrical, with φ15 steel bar as the support frame, its diameter is equal to the inner diameter of the zero-valent iron-enhanced reaction pool, and the height is about 30cm. The zero-valent iron reaction box is set to be openable A ring hook is set at the center of the upper surface for inspection and replacement; the filler in the zero-valent iron reaction box is composed of one or more of sponge iron, iron shavings and scrap iron filings. 10% by volume sawdust or straw. The zero-valent iron reaction box is the core area of the whole system, which can strengthen the removal of pollutants in the sewage, especially nitrogen and phosphorus; the zero-valent iron reaction box is located in the anaerobic area of the entire biological filter, plus a carbon source , which is beneficial to the growth of denitrifying microorganisms. In the zero-valent iron reaction box, the microorganisms adhere to the iron carrier to form a zero-valent iron/microorganism coupling system, which strengthens the removal of NO ₃ ^- and generates Fe ³⁺ /Fe ^{2 +} has good flocculation performance, which strengthens the removal of phosphorus released by anaerobicity; the upper layer of the zero-valent iron reaction box is laid with zeolite to adsorb micro-pollutants in the effluent, which ensures the quality of the effluent, and also creates a new zero-valent iron reaction box for the lower layer. The anaerobic environment is adopted; the effluent of the zero-valent iron reaction tank is in the form of overflow.

The technical solutions of the present invention are further described below in conjunction with the accompanying drawings:

As shown in Fig. 1, Fig. 2 and Fig. 3, water pipelines 1 are laid at the places where sewage generated by scattered users in rural areas is used to collect rural domestic sewage; pre-treatment tanks 2 are dug underground in sequence by using fully buried or semi-buried type. , circulating pool 4 and zero-valent iron biological filter 9; the middle grid 3 of 10-40mm is arranged inside the pretreatment pool 2; one side of the pretreatment pool 3 is communicated with the circulation pool 4 through the water pipeline 1; A sludge collection tank 5 and a sludge discharge pipe 7 are arranged on the side wall near the zero-valent iron biological filter 9; the concentrated sludge in the sludge collection tank 5 is discharged through a sludge discharge pump 8; a circulating dissolved air pump is built in the circulation tank 6 (with its own oxygen-enriching function), the sewage in the circulation pool is raised to the zero-valent iron biological filter 9 through the water pipeline; the zero-valent iron biological filter 9 is divided into the outermost wall, and the ordinary biological filter in the middle layer. There is an anti-seepage treated wall between the material tank and the zero-valent iron reaction tank in the inner layer, the ordinary biological filter material tank and the zero-valent iron reaction tank; The surface of the biological filler 11 of the biological filter material tank; the design height of the filler layer 11 is about 1.5-1.8m, the particle size of the filler is 25-40mm, and the selected filler (one of crushed stone, pebbles, slag or coke) should be Uniform and consistent, and local materials are used for processing and transportation; 0.2m of pebble support layer 12 is laid under the filler layer 11, and the particle size of the pebble support layer 12 is between 70 and 100mm; the bottom center of the support layer 12 A return pipe 13 is set up, and the other end of the return pipe is connected to the sludge collection tank 5 in the circulation tank 4; the construction of the inner zero-valent iron reaction tank is to fill 5 to 6 zero-valent iron reaction tanks with a height of about 0.3m. The box 14, the zero-valent iron reaction box 14 is cylindrical, the steel bar of φ15 is used as the support frame 18, and the steel mesh surface 19 is used as the outer surface, and the aperture of the steel mesh surface is slightly smaller than the particle size of the iron filler; the zero-valent iron reaction box The diameter of the circular surface is equal to the inner diameter of the zero-valent iron reaction tank, and the filler in the zero-valent iron reaction box 14 is composed of zero-valent iron filler 20 (one or more combinations of sponge iron, iron shavings and scrap iron filings) and Add 10% volume of wood chips (straw) 21; the zero-valent iron reaction box is set to be openable, and a ring hook 22 is set at the center of the upper surface, which is convenient for carrying and inspection and replacement; the upper layer of the zero-valent iron reaction box 14 A 0.3m zeolite filler 15 is laid, and an overflow plate 16 is arranged at the water outlet of the zero-valent iron reaction tank; the overflowed water is recycled or directly discharged through the drainage pipe 17 . Flowers and trees can be planted above the structures to create a good ecological environment.

A circulating zero-valent iron biological filter for strengthening treatment of rural domestic sewage, and a method for treating sewage, comprising the following steps:

1) Pretreatment tank: The domestic sewage discharged by rural retail households is collected through the water pipeline 1 and discharged into the pretreatment tank 2. The pretreatment tank 2 is equipped with a 10-40mm middle grille 3 to intercept larger domestic garbage. At the same time, the sewage stays in the pretreatment tank for a short time, mainly to remove the suspended solids in the raw sewage and other pollutants that can block the filter material, and to homogenize the water quality;

2) Circulation pool: The sewage homogenized by the pretreatment tank 2 enters the circulation tank 4 through the water pipeline 1; the circulation tank 4 has a built-in circulating dissolved air pump 6 for sewage circulation and oxygen enrichment, which is coupled by only one pump Taking advantage of the respective advantages of the two technical routes of intensive and ecological, it can freely cope with the complex drainage conditions in rural areas and ensure the stability of the effluent water quality. A sludge collection tank 5 is arranged on the side wall of the near-zero valent iron biological filter 9 in the circulating pool to receive the return sewage from the zero valent iron biological filter and the biofilm that has fallen off due to aging; the concentrated biofilm passes through the sludge discharge pipe 7 Discharged through sludge pump 8;

3) Zero-valent iron biological filter: The sewage in the circulation tank 4 is transported to the upper water distribution area 10 of the zero-valent iron biological filter through the dissolved air pump 6, and the sewage is evenly distributed on the upper surface of the biological filler 11 through the water distributor, and the biological filter material A large number of microorganisms are attached to the surface of the tank filler to form a biofilm system, which plays a role in biodegrading the pollutants in the sewage; because the oxygen-enriched sewage enters the biological filter material tank, the upper layer of the filter material mainly adheres to aerobic microorganisms. In the process of microbial degradation of pollutants, the dissolved oxygen in the water needs to be consumed, and the dissolved oxygen in the sewage gradually decreases from top to bottom, forming an anoxic zone in the lower layer; the sewage treated by the biological filter enters the middle anaerobic area through the supporting layer 12 Oxygen zero-valent iron reaction box 14; aerobic-anoxic-anaerobic conditions are favorable for the removal of total nitrogen, zero-valent iron and microorganisms in the anaerobic zone form a zero-valent iron/microorganism coupling system, which strengthens the removal of NO ₃ ^- , and the Fe ³⁺ /Fe ²⁺ produced at the same time has good flocculation performance, which strengthens the removal of phosphorus released by anaerobic release; a zeolite layer 15 is arranged on the upper layer of the zero-valent iron reaction zone to adsorb micro-pollutants in the effluent to ensure A return pipe 13 is arranged at the bottom center of the supporting layer 12 for returning sewage and falling biofilms. The advantage of the return pipe before the zero-valent iron reaction zone is set is that it can ensure the entry into the anaerobic zero-valent iron reaction. zone NO ₃ ^- concentration.

Claims (5)

1. a circulating zero-valent iron biological filter for strengthening the treatment of rural domestic sewage, is characterized in that: multiple sewage disposal units are set underground; rural domestic sewage is collected in the sewage disposal unit by the water delivery pipeline system to circulate and strengthen Treatment, the treated domestic sewage is used as agricultural irrigation water or supplements groundwater or is directly discharged into the river; the sewage treatment unit includes: a pretreatment tank, a circulation tank and a zero-valent iron biological filter. The three parts are connected in sequence. The structures of each sewage treatment unit are independent of each other and communicated with each other through pipes; the zero-valent iron biological filter is divided into two parts: ordinary biological filter and built-in zero-valent iron enhanced reaction tank; the circulation tank has a built-in one Circulating dissolved air pump for sewage circulation and oxygen enrichment; sludge collection tank and sludge discharge pipe are set on the side wall of the circulation pool near the zero-valent iron biological filter; The zero-valent iron biological filter has a nearly circular shape, the outermost layer is a wall, the middle is an ordinary biological filter, and the inner ring is a zero-valent iron-enhanced reaction tank. The second pass through the ordinary biological filter and the zero-valent iron enhanced reaction tank, and a return pipe is set at the bottom center of the zero-valent iron biological filter, and the other end of the return pipe is connected to the sludge collection tank in the circulation tank. 2. a kind of circulating zero-valent iron biological filter for strengthening treatment of rural domestic sewage according to claim 1, is characterized in that the upper layer of described common biological filter is a working layer, and the filler of the working layer is a local easily-obtained crushed material. One of stone, pebbles, slag or coke, with a particle size of 25-40mm and a thickness of 1.5-1.8m; the lower layer is a supporting layer, hard crushed stone or pebbles with a particle size of 70-100mm and a thickness of 0.2m . 3. a kind of circulating zero-valent iron biological filter for strengthening the treatment of rural domestic sewage according to claim 1, is characterized in that the movable zero-valent iron reaction box of different filling quantities in the described zero-valent iron strengthening reaction tank ; The zero-valent iron reaction box is cylindrical, with φ15 steel bar as its supporting frame, its diameter is equal to the inner diameter of the zero-valent iron-enhanced reaction pool, and the height is about 30cm; the zero-valent iron reaction box is set to be openable, and on the upper surface A ring hook is set at the center for easy inspection and replacement; zeolite is laid on the upper layer of the zero-valent iron reaction tank; the side wall of the zero-valent iron reinforced reaction tank is treated with anti-seepage. 4. a kind of circulating zero-valent iron biological filter for strengthening the treatment of rural domestic sewage according to claim 3, is characterized in that the filler in the described zero-valent iron reaction box is composed of three kinds of sponge iron, iron shavings and scrap iron filings One or more of them are combined, and at the same time, wood chips or straws are added in a certain proportion. 5. a kind of circulating zero-valent iron biological filter for strengthening treatment of rural domestic sewage according to claim 1, is characterized in that treating sewage comprises the steps: 1) Pretreatment tank: Rural domestic sewage is collected by the pipe network and discharged into the pretreatment tank to remove the suspended pollutants in the raw sewage that can block the filter material, and to homogenize the water quality; 2) Circulating pool: a built-in circulating dissolved air pump for sewage circulation and oxygen enrichment. Only one pump is used to couple the respective advantages of the two technical routes of intensive and ecological. The water quality is stable; at the same time, the dissolved air pump has its own oxygen-enriching function to provide aerobic conditions for ordinary biological filters; a sludge collection tank is set on the side wall of the near-zero valent iron biological filter in the circulation pool to receive the zero valent iron biological filter. The backflow sewage of the tank and the biofilm that has fallen off, and the enrichment and concentration of the biofilm that has fallen off is carried out; a sludge discharge pipe is set on the side wall of the circulation tank near the bottom of the collection tank to discharge the concentrated sludge; 3) Zero-valent iron biological filter: The sewage in the circulating tank is transported to the upper part of the ordinary biological filter through the dissolved air pump, and the sewage is evenly spread on the surface of the filter material through the water distributor. A large number of microorganisms are attached to the surface of the ordinary biological filter filler to form a biofilm The system plays a role in biodegrading the pollutants in the sewage; because the oxygen-enriched sewage enters the ordinary biological filter, the aerobic microorganisms are mainly attached to the upper layer of the filter material, and the microbial degradation process of the pollutants needs to consume water. The dissolved oxygen in the sewage gradually decreases from top to bottom, forming an anoxic zone in the lower layer; the sewage treated by the ordinary biological filter enters the middle anaerobic zero-valent iron reaction zone through the supporting layer; aerobic- The anoxic-anaerobic conditions are favorable for the removal of total nitrogen. The zero-valent iron and microorganisms in the anaerobic zone form a zero-valent iron/microorganism coupling system, which strengthens the removal of NO ₃ ^- and generates Fe ³⁺ /Fe ²⁺ at the same time. It has good flocculation performance, which strengthens the removal of phosphorus released by anaerobicity; a zeolite layer is arranged on the upper layer of the zero-valent iron reaction zone to absorb micro-pollutants in the effluent and ensure the quality of the effluent; in the zero-valent iron biological filter There is a return pipe at the bottom for returning sewage and falling off biofilm, and the return pipe is arranged before the zero-valent iron reaction zone to ensure the concentration of NO ₃ ^- entering the anaerobic zero-valent iron reaction zone.

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