How to do a good job in rural domestic sewage treatment project

Rural domestic sewage treatment method (strongly recommended) rural domestic sewage purification pool technology?

This technology adopts multistage gravity flow process, which is suitable for decentralized treatment of domestic sewage, and has the characteristics of saving investment, no operating cost and convenient management. This technology is different from the traditional biogas digester technology, and the sewage can reach the standard after treatment. ?

1. Use and function?

Biogas digester for purifying domestic sewage is a new structure for decentralized treatment of domestic sewage, which is suitable for rural areas where sewage treatment plants cannot be built in the near future. Domestic sewage includes kitchen cooking water, bath water, washing water and toilet flushing water, which has three characteristics: first, toilet flushing water contains feces, which is the source of infection for many diseases; Second, the concentration of domestic sewage is low; Third, domestic sewage has good biodegradability and is suitable for anaerobic nitrification to produce biogas. Domestic sewage purification tank is a treatment device designed according to the above characteristics of domestic sewage, which integrates anaerobic nitrification, precipitation filtration and other treatment technologies. ?

2. Structure and working principle of the pool?

The biogas digester for purifying domestic sewage is a multipolar baffled digestion system integrating hydraulic biogas digester, anaerobic filter and facultative anaerobic tank. After coarse solids are removed from the manure through the grid, it enters the pretreatment area 1 through the grit chamber, where the manure undergoes biogas fermentation and gradually returns. The generated sludge suspended matter is precipitated in the second half area and slides back to the front along the inclined bottom of the tank body, and then mixed with the newly entered feces for biogas fermentation. On a clear night, the overflow enters the pretreatment zone 2, where it is mixed with other domestic sewage except feces for biogas fermentation and partially refluxed through anaerobic filtration. The key bacteria attached to the biofilm on the filler further carry out anaerobic nitrification on the sewage, and then overflow into the post-treatment tank. Pretreatment area 1 and pretreatment area 2 are both improved hydraulic biogas digesters. The post-treatment area is a three-stage baffling and aerobic tank, which is communicated with the atmosphere, and the upper part is equipped with a foam filter to intercept suspended solids, thus improving the effluent quality. ?

According to whether the fecal sewage and other domestic sewage pipelines are sub-systems or combined systems, the sewage flow direction can be divided into two types. ?

ⅰ confluence system?

The indoor sewage pipeline is a combined sewage flow as follows: domestic sewage-> grid intercepting well-> grid intercepting well; Grit chamber -> 60% pretreatment area -> 40% post-treatment area-> discharge or aerobic treatment. ?

Ⅱ shunt system?

It is suitable for sewage treatment of fecal sewage and other domestic sewage. The sewage flow is as follows: other domestic sewage-> grid intercepting well-> grit chamber-> fecal sewage-> grid intercepting well-> grit chamber-> pretreatment area1(40%)->; Pretreatment zone 2 (30%)->; Post-treatment area (30%)->; Discharge or aerobic treatment. ?

3. Process parameters?

The design of biogas digester for purifying domestic sewage is based on the amount of sewage treated every day, and the amount of sewage is 100L/ (person? Day), in which the water consumption for flushing toilets is 20 ~ 30l/ (person? Day) calculation, other domestic sewage volume is 70 ~ 80l/ (person? God). Sewage retention time is 2 ~ 3 days, and sludge cleaning cycle is 300 days. ?

4. Operation management?

Reasonable design, reliable construction and careful management are the three main links to ensure the normal operation of domestic sewage purification biogas digesters. Among them, the daily management work must be as follows: a. Where the domestic sewage purification pool is set, professional construction and contract management should be implemented to ensure normal operation; B. Establish engineering archives and management records; C. remove sludge once a year; D. Polyurethane filter foam board shall be updated every 4 ~ 5 years, and soft filler shall be updated every 10 years (semi-soft filler shall not be replaced); E. Pay attention to safety and avoid fire and suffocation accidents. ?

2. Unpowered multi-stage anaerobic composite ecological treatment system?

This technology is suitable for the treatment of low-concentration rural domestic sewage such as kitchen, laundry and bathing in retail stores, especially for rural domestic sewage in retail stores or 2-5 households with different topography.

Professor G, an expert in anaerobic biology, asserts that anaerobic treatment biotechnology can become the core means of decentralized domestic sewage treatment mode if it is matched with suitable post-treatment methods. This model is more sustainable and vital than the traditional centralized treatment method, especially suitable for developing countries. ?

1. Basic principle?

In view of the shortage of funds, energy and pollution in China, anaerobic treatment technology is a technology especially suitable for China's national conditions. However, because anaerobic itself has no ability to remove nutrients such as nitrogen and phosphorus, nitrogen and phosphorus in sewage will make water eutrophication. At the same time, simple anaerobic treatment can not remove germs well, and the anaerobic effluent can not meet the national discharge standard as a whole. Therefore, anaerobic treatment alone can only be used as pretreatment, and appropriate subsequent treatment units must be selected. ?

Based on the above background, a set of mature anaerobic treatment combined with ecological bed has been basically formed for the treatment of single-family or joint-family domestic sewage, which is called unpowered multi-stage anaerobic composite ecological treatment system for short. ?

The system is mainly composed of 2 ~ 3 grids of anaerobic ponds and 65,438+0 grids of compound ecological beds with large specific surface areas such as gravel and fine soil, among which the ponds are connected by pipes, and the sewage stays in the ponds for 5 ~ 7 days. After anaerobic treatment, suspended solids in domestic sewage can be precipitated, and refractory organic pollutants are transformed into small molecular organics by anaerobic microorganisms. Aquatic organisms can be planted on the surface of the compound ecological bed. ?

The compound ecological bed can not only filter, but also improve the treatment effect of organic matter. First, the growth of plants changes the flow pattern of the ecological bed, and the obstacles of growing plants' roots and stems to the water flow are beneficial to uniform water distribution and prolong the hydraulic retention time; Second, the roots of plants create a microenvironment conducive to the growth of various microorganisms. The extension of plant roots will form an aerobic micro-area near the plant roots, and the anaerobic area far from the roots contains a lot of available carbon sources, which provides denitrification conditions; Third, plant growth can absorb various nutrients, especially nitrate nitrogen. ?

After anaerobic "coarse" treatment, the load of the subsequent "fine" treatment unit is relatively small, which can save the occupied area of the ecological bed. After the sewage is treated by anaerobic reactor, most of the suspended solids can be effectively removed and the ecological bed can be prevented from being blocked. Therefore, this combination can not only effectively remove organic matter, but also effectively solve the problem that nitrogen and phosphorus can not meet the standard in sewage treatment at present. ?

2. Technical process?

The technological process of unpowered multistage anaerobic composite ecological treatment system is as follows:

Sewage-sewage collection system (pipeline) -3-cell anaerobic fermentation treatment tank compound ecological bed?

The process is described as follows:

(1) sewage collection system?

The system generally treats the sewage generated in the kitchen and bathroom, connects the sewer and sewage pipe with a culvert, and sets a grid at the wellhead to remove larger particles. ?

(2) The treatment tank consists of an anaerobic fermentation tank and a compound ecological bed, forming an integrated structure?

Anaerobic fermentor consists of three units. Anaerobic fermentation of 1 cell is mainly used to adjust water quantity, and also has a certain degree of water quality uniformity and initial sedimentation; The second and third grids can effectively degrade the organic matter in sewage, which is beneficial to the treatment of compound ecological bed. ?

Calculation of total volume of treatment tank?

V=Q*T？

Where the design volume of upflow pool (m)?

Q—— Estimated water treatment capacity of upflow water tank (m /h)?

T—— Retention time of sewage in the rising pool (h)?

T generally takes 6 ~ 7 days, and V—— At present, there are 3 m and 4.5m pools successfully demonstrated in rural areas. ?

(3) Composite ecological bed structure?

The compound ecological bed is the main structure in the treatment system, which is a rectangular brick structure composed of one or two infiltration filters. The pond is filled with substrates such as gravel and artificial soil. ?

(4) Composition and thickness of sand and artificial soil?

Ⅰ Gravel layer is composed of gravels with different particle sizes, generally divided into 3-4 layers?

Gravel adopts porous inorganic matrix with large specific surface area. ?

Ⅱ. Selection of artificial soil?

There are many kinds of bacteria, fungi, actinomycetes, algae, protozoa and so on. They are indispensable components of material and energy transformation in maintaining soil and completing ecosystem functions. They are decomposers and converters of material and energy cycle in soil ecosystem. Therefore, artificial soil should choose sand, high fertility topsoil and peat as raw materials. The thickness of artificial soil is generally 10 ~ 20 cm. ?

3. Technical features?

The treatment system has the advantages of simple process flow, good effluent quality, strong impact resistance, no need of artificial aeration, sludge reflux, mixing and stirring, no need of large-scale treatment machinery and complex operation control system, so it is extremely simple to operate and does not need a large number of trained operation management personnel, which is very suitable for the sewage treatment technology and technology urgently needed in rural areas of China at present. ?

3. Soil infiltration ecological treatment system?

This technology is a bio-ecological combination technology, which is suitable for rural areas with less land but suitable soil conditions. Soil infiltration includes slow infiltration and rapid infiltration, and different infiltration methods can be selected according to different rural conditions. ?

The sewage in-situ soil infiltration treatment system consists of septic tank and soil infiltration. ?

1.

The basic principle of the system is that domestic sewage enters the distribution box after sedimentation and anaerobic treatment in septic tanks and flows into various soil infiltration pipes. The sewage flowing out of the pipeline uniformly percolates to the anaerobic filter layer, then rises under the action of surface tension, crosses the outlet weir of the anaerobic filter layer, and continuously penetrates into the upper aerobic filter layer through siphon phenomenon. In the above process, water is separated from pollutants, and the water is collected by percolation through the water collection pipeline, and the pollutants are trapped in the soil by physical and chemical adsorption; Due to anaerobic and aerobic processes, part of carbon and nitrogen is decomposed into inorganic carbon, which remains in the soil, and the other part becomes nitrogen and carbon dioxide, which is dispersed into the air. Phosphorus is absorbed by the soil in physical and chemical ways, stays in the soil, and is used by lawns or other plants. ?

2. Process flow?

Sewage-anaerobic biogas digester-water distribution tank-soil infiltration treatment process-collecting well-effluent?

3. Process characteristics?

Compared with other sewage treatment systems, the soil infiltration ecological treatment system has the following characteristics:

(1) The system runs stably and reliably, and has strong impact load resistance; ?

(2) The effluent quality is good, and it has a good treatment effect on organic matter, especially organic chloride and ammonia nitrogen; ?

(3) Small one-time investment, low operation cost and energy saving; ?

(4) Planting plants on the land treatment pond can not only improve the sewage purification efficiency of the system, but also enhance the landscape effect. ?

4. Is there any problem?

(1) septic tank problem?

Septic tank, as the pretreatment device of sewage soil infiltration system, provides water with low pollutant concentration and high biodegradability for the subsequent soil infiltration system, which plays the role of degrading pollutants and eliminating harmful bacteria, so that the feces in sewage can be treated harmlessly to a certain extent. At present, brick or concrete pouring is widely used in China, which has high cost, poor sealing performance, poor biochemical effect and inconvenient construction. With the increase of chemicals used by people, the composition of domestic sewage becomes more complicated. In order to improve the purification effect of sewage, these septic tanks need to be improved. ?

(2) Soil infiltration?

Sewage flows out from the infiltration pipe and enters the soil in the infiltration ditch, and some of it moves to the surface to reach the roots of plants, and the other part percolates downward. When these two parts move, which part of the sewage reaches deeper is related to the depth of the infiltration pipe buried in the soil. ?

(3) The influence of temperature on the system?

Because the microorganisms in the soil infiltration ecological treatment system are basically in the natural environment, they change with the change of environmental temperature and climate. When the temperature is high in summer, the microbial activity is high; When the temperature is low in winter, the activity of microorganisms is greatly reduced and the sewage treatment capacity of the system is greatly reduced. Especially in the northern region, how to operate normally in winter is worth studying. ?

(4) The influence of precipitation on the system?

The drainage design of the system must consider the influence of precipitation to ensure that the precipitation entering the system is discharged in time and reduce its influence on hydraulic load. ?

5. Development prospects?

Soil infiltration ecological treatment system is a technology suitable for treating dispersed domestic sewage. Making full use of the purification ability of the soil-plant-microorganism system has the advantages of not affecting the ground landscape, simple operation and management, low construction cost and good effluent quality. With the continuous development of rural areas in China, this sewage treatment system can be transformed from a simple "treatment type" to a "utilization type" combining treatment and utilization, and the treated sewage can be used for irrigation to alleviate the water shortage problem in rural areas. ?