1 Present situation of sewage treatment in rural living environment in China
Rural domestic sewage is mainly produced in the process of residents' life, such as feces and its washing water, bath sewage and kitchen sewage. , and its treatment is difficult, the main reasons are as follows:
First, most villagers have a weak awareness of environmental protection and insufficient understanding of the harm of domestic sewage.
Second, the economic strength of villages and towns is relatively weak, and the government has less investment in rural domestic sewage treatment, which makes rural areas lack sewage treatment systems and leads to low rural domestic sewage treatment rate.
Third, rural environmental protection institutions are not perfect, and there is a lack of professional environmental protection talents.
Fourth, it is difficult to popularize rural domestic sewage treatment technology. The choice of sewage treatment technology is restricted by the local social and economic development level, and resisted by local protectionism or other humanistic factors.
Fifth, the local natural ecological conditions (temperature, precipitation, wind direction, soil, etc. ) has a negative impact on the selected treatment process and technology, making it unable to function normally.
Sixth, the pressure of rural immigrants on rural domestic sewage treatment has increased. In rural areas, due to the relatively scattered residence of floating population, difficult management and weak awareness of environmental protection, it has brought great inconvenience to township managers, so the floating population has increased the pressure on rural domestic sewage treatment to a certain extent.
2 rural living environment sewage treatment countermeasures and suggestions
2. 1 Strengthen the propaganda of rural ecological environment protection and raise farmers' awareness of environmental protection.
The masses are producers, victims and beneficiaries of environmental pollution. Therefore, the government must increase the intensity and breadth of environmental protection propaganda, and go deep into rural areas, communities and even every farmer's family through TV and radio, so that they can deeply realize that protecting the rural ecological environment means protecting their health, and protecting their homes means benefiting themselves and future generations.
2.2 Improve rural environmental management institutions
Establish laws and regulations on rural environmental protection. It is suggested that all towns and villages should set up environmental protection offices to be responsible for the supervision and management of environmental protection under the leadership of the local government. The administrative villagers' committee shall implement the special person responsible for the environmental protection management of the village, and report and exchange environmental protection information in a timely manner. While perfecting rural environmental management institutions, we should also formulate laws and regulations on rural environmental protection as soon as possible. In China's current legal system, rural environmental protection is rarely involved, even if it is involved, it is limited to principled provisions, and rural, agriculture and resource protection are not unified. So I suggest to speed up the formulation of corresponding laws and regulations.
2.3 The government increased capital investment to build a rural domestic sewage treatment system.
Local governments should increase capital investment in the construction of rural domestic sewage treatment systems. It is suggested that towns and villages contribute money to send a trash can to each household, so that farmers can put their domestic garbage into the trash can, and each production team has a sanitation worker to transport the garbage; Each village should set up a garbage dump, and each village should have several people to clean up the garbage on the river. Every town has a garbage truck to transport the domestic garbage in the town to the comprehensive garbage treatment station to prevent the domestic garbage from being directly thrown into the river to pollute the river.
2.4 Strengthen the construction of rural domestic sewage pipe network
According to the overall planning and actual situation of new rural construction, the following measures can be taken for rural domestic sewage discharge pipes: first, there is no sewage pipe network in the community, and the smaller open ditches are closed with cover plates, and the rainwater is flooded; For large ditches, the collection pipe will be installed in the ditch. When necessary, the original confluence ditch can be dug, and the rainwater ditch or irrigation ditch can be rebuilt after the sewage collection pipe is installed. Secondly, if there is enough space to lay a sewage pipe network in the community, the sewage pipe should be built next to the original ditch, and the buried depth should be reduced as much as possible to reduce the cost while meeting the drainage elevation requirements.
2.5 Local treatment of rural domestic sewage
First, for single village or joint village with relatively dense village layout, large scale and good economic conditions, it is suggested to adopt centralized treatment mode, that is, collect the sewage generated by all farmers and build a treatment facility to treat all the sewage in the village in a unified way, so as to achieve the effects of small floor space, safe and reliable operation and good effluent quality.
The second is to use "three-stage purification" to treat rural sewage. Build a three-cell pond with three functions of sedimentation, biochemistry and clean water, and put pebbles, sand and alum charcoal into the pond to carry out biochemical treatment of sewage; Plants with developed roots are planted above the pool to absorb the decomposed organic matter in the sewage and purify the pollution.
Third, biogas is used in the domestic sewage purification pool. Using anaerobic fermentation technology, the organic matter in domestic sewage is decomposed into CH4, CO2 and water under anaerobic and facultative anaerobic conditions, so as to achieve the purpose of purifying domestic sewage. Its treatment process: domestic sewage → grid pond → anaerobic fermentation → discharge. The characteristics of this "three-stage purification" domestic sewage treatment facility are: on the one hand, it can be built independently or jointly by several households, and it is not limited by topography; On the other hand, the investment is small, the operation and maintenance are simple, and it can be cleaned once every 2-3 years. At the same time, the treated sewage can be used to water flowers and grow grass, which is very suitable for scattered rural farmers.
The fourth is the buried unpowered purification treatment device. Underground unpowered purification treatment device is developed on the basis of cylindrical facultative filter, and its treatment process is: domestic sewage → anaerobic acidification → facultative filtration → ecological ditch (natural ventilation) → discharge. The biggest feature of this process is the addition of ecological ditch, which aims to oxidize the sewage after anaerobic fermentation and further improve the effluent quality. However, due to the poor effect of natural oxygenation, the treatment effect is similar to that of ordinary septic tanks, and the investment is much higher than that of septic tanks, so it is used less.
The fifth is to use oxidation pond. Oxidation pond is a natural pond with the ability to treat sewage and wastewater after artificial transformation. It is a purification system with simple structure, convenient maintenance and management, stable treatment effect and energy saving. Organic pollutants and other pollutants are degraded and removed through the metabolic activities of microorganisms, the interaction between bacteria and algae or the comprehensive action between bacteria and algae and aquatic organisms after long-term stay and storage in ponds.
Sixth, the contact oxidation technology of falling water and oxygenation is adopted. The contact oxidation technology of falling water and increasing oxygen is to use the sewage lifting pump to lift the sewage or use the terrain difference to make the sewage drop in stages, form a water curtain and naturally increase oxygen droplets, without aeration device, and remove pollutants such as nitrogen and phosphorus while reducing organic matter.
Seventh, the domestic sewage treatment technology of constructed wetland is adopted. Wetlands generally refer to low-lying land with a temporary or long-term coverage depth of less than 2 m and coastal areas with a depth of less than 6 m at low tide. According to the conditions of wetland formation, wetlands can be divided into natural wetlands and artificial wetlands. Natural wetlands are formed in a natural state, such as the wetlands mentioned above. Constructed wetland is a technology inspired by the purification function of natural wetland. Constructed wetland simulates and strengthens the function of natural wetland, and controls the sewage to the land where the soil (filler) is often saturated and aquatic plants such as reeds and cattails grow. In the process of sewage flowing in a certain direction, under the physical, chemical and biological synergistic effect of water-resistant plants and soil (filler), the organic matter in sewage promotes facultative microbial decomposition through filtration, root interception, adsorption, absorption, plant photosynthesis, oxygen transfer and so on. Constructed wetland has the advantages of good effect, low investment and low operating cost. However, there are also some problems, such as large area and winter will affect the treatment effect.
3 Conclusion
To sum up, the key to rural domestic sewage treatment is to choose the corresponding treatment technology according to the current situation of rural domestic sewage, rather than popularizing and copying the sewage treatment technology and design parameters in large and medium-sized cities to avoid high project investment and operating costs. At the same time, rural domestic sewage treatment should follow the principles of economy, high efficiency, energy saving and simplicity, strengthen the combination with local eco-agriculture, make sewage treatment a part of eco-agriculture, form an eco-agriculture model of sewage reuse, and realize the harmless and resource utilization of rural domestic sewage, thus further improving the reuse rate of rural water resources, alleviating the contradiction between supply and demand of water resources, and promoting the healthy development of rural economy and society.
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