Sewage treatment

For the reuse of urban raw sewage, the advantages are: energy saving and environmental protection, no pollution.

Processing method:

Village sewage is mainly composed of domestic sewage and agricultural wastewater. The composition of domestic sewage is relatively fixed, mainly containing carbohydrates, proteins, amino acids, fats and other organic matter, which is more suitable for the growth of bacteria, and become a place for bacteria and viruses to survive and reproduce; However, domestic sewage generally does not contain toxicity, and has a certain fertilizer effect, which can be used to irrigate farmland. The composition of agricultural wastewater is diverse, different seasons, different places, different development goals of the villages and towns, the wastewater needs to use different treatment methods. In the treatment of sewage, in order to reduce the discharge of sewage and its complexity, it should be combined with the construction of biogas digester that is being vigorously promoted by the country, and the flushing water (black water) in domestic water and other domestic water (gray water) should be separated. Gray water is treated with natural purification system, black water and human and animal feces are treated by anaerobic biogas digester, which can not only reduce the discharge, complexity and treatment cost of sewage, but also have important significance for the development of rural clean new energy, protect the living environment, and promote the sustainable development of rural economy and society.

The function of the sewage treatment station is to treat the production and domestic sewage, meet the prescribed discharge standards, and is an important facility to protect the environment. Sewage treatment stations in industrialized countries have been very common, and there are few sewage treatment stations in villages and towns in China, but they will gradually increase in the future. In order to make these sewage treatment stations really play a role, it also needs to rely on strict discharge system, organization and management system to ensure.

Where conditions exist, sewage treatment stations should be built in villages or single villages. And shall comply with the following provisions:

① When rain and pollution are divided, the sewage is transported to the sewage treatment station for treatment;

(2) When the rain and pollution are combined, the combined sewage is transported to the sewage treatment station for treatment; In front of the sewage treatment station, it is advisable to set up interceptor Wells to remove the combined sewage in the rainy season.

③ The sewage treatment station can use biochemical treatment technologies such as constructed wetlands, biological filters or stabilization ponds, or other treatment technologies with engineering examples or mature experience can be used according to local conditions.

Constructed wetland is suitable for treating pure domestic sewage or rain-polluted combined sewage, which covers a large area and should adopt two-stage series; The plane shape of the biological filter should be circular or rectangular. The filler should be solid, corrosion resistant, high strength, large specific surface area, high porosity, and should use inorganic filter materials such as gravel, pebbles, slag, coke, etc. When the geographical environment is suitable and the technical conditions allow, the village sewage can be considered to use wasteland, waste land, pits, depressions and other stable pond treatment system. The stabilization pond system used for secondary treatment should not be larger than 5000m3/d.

The site selection of the station should be arranged in the summer under the dominant wind direction, the downstream of the village water body, the lower terrain, to facilitate the sewage to flow into the sewage treatment station, do not pollute the village water, and facilitate the downstream discharge after treatment. It has a protective distance from the residential area of the village to reduce the pollution to the residential area. If the sewage is considered for farmland irrigation and sludge fertilization, its location should be correspondingly close to the farmland irrigation area and easy to transport. The sewage of medical institutions must be strictly disinfected and discharged into the sewage network after meeting the prescribed discharge standards, and should comply with the relevant provisions of the current national standard "Hospital sewage treatment design Code" (CECS07:2004). When using reclaimed water, the water quality should conform to the relevant provisions of the current national standards "Code for the Design of Water in Buildings" (GB50336-2002) and "Code for the Design of Sewage recycling Engineering" (GB503352002), and the opening and closing device should be set up to stop the use of public health emergencies.

The effluent from the sewage treatment station shall comply with the relevant provisions of the current national standard "Pollutant Discharge Standard for Urban Sewage Treatment Plants" (GB18918-2002); When the effluent from the sewage treatment station is used for farmland irrigation, it should comply with the relevant provisions of the current national standard "Water Quality Standard for Farmland Irrigation" (GB5084-2005). There are many methods for sewage treatment and utilization, and the following factors should be considered in the selection of the scheme: