After decades of practice and exploration, some developed countries in foreign countries have accumulated a great deal of experience in the research and application of rural domestic sewage treatment technologies and have fostered many more successful technical models.
Stabilization pond - high efficiency algae pond system
Stabilization ponds mainly use the common action of bacteria and algae to remove the pollutants in sewage, which has the advantages of less capital investment, low operating cost, simple maintenance, effective removal of organic substances and pathogens in sewage and no sludge treatment. There are 3000 and 2000 stabilizing ponds in Germany and France respectively, while the United States already has some 10,000 stabilizing ponds. Based on the stable pond, Oswald of the University of California, Berkeley, pioneered and developed a highly efficient algae pond that maximizes the first-order kinetic degradation kinetics of algae by maximizing the oxygen produced by the algae. High efficiency algae ponds to COD, BOD5, ammonia nitrogen, total phosphorus and pathogens such as high removal rate, while harvesting higher aquatic plants is a good fertilizer. The advantages of high efficiency algae ponds are less construction work, less investment and operating costs, and ease of management and maintenance. The deficiencies are the impact of environmental factors such as light and temperature. At present, efficient algae ponds in Israel, Morocco, France, the United States, South Africa, Brazil, Belgium, Germany, New Zealand and other countries have research and application.
Biofilm treatment of domestic sewage
Biofilm is a widely used artificial sewage treatment technology, including anaerobic and aerobic biofilm two. Anaerobic or aerobic microorganisms attach to the surface of the carrier to form a biofilm to adsorb and degrade pollutants in the sewage so as to achieve the purpose of purification. The method has the advantages of simple equipment, lower running cost and high processing efficiency. The reactor is generally composed of packing (carrier), water distribution device and drainage system. The packing materials used are inorganic (ceramsite, slag, activated carbon, etc.) and organic (PVC, PP, plastic, fiber, etc.). Currently, new biofilm reactors and immobilized microbial technologies have also been extensively studied.
Japan Rural Sewage Association studied a lot of equipment suitable for the treatment of domestic sewage in villages and towns. The JARUS model of 15 different types of sewage treatment plants was designed. The treatment process mainly includes the biofilm method and plankton method, which has good sewage treatment effect, And small size, low cost, easy to operate.
Constructed wetland treatment system
The system is generally composed of artificial matrices (mostly gravel) and the marsh plants (reeds, cattails, ragweed and cannabis) growing on it and is a unique "soil-plant-microbe" ecosystem that uses A variety of plants, animals, microbes and soil together, step by step filtration and absorption of pollutants in sewage to achieve the purpose of purifying sewage. The technology has been widely used in countries such as Europe, North America, Australia and New Zealand. The disadvantage is that it requires a lot of land and addresses issues such as adequate supply of oxygen in soil and water, and the effects of temperature and plant growth season.
South Korea's rural residents scattered living, domestic sewage is not suitable for centralized treatment. Wetland wastewater treatment systems have been extensively studied in Korea due to their low energy consumption, low operating costs and low maintenance costs. Their decontamination mechanism is based on the ecological role of "land-plant systems." South Korea uses the treated wetlands to re-irrigate the rice so as to achieve a better purification effect. Commonly used wetland plants such as reed, cattail, kusnezoffii, etc., decontamination ability, good removal of pathogens. Wetlands have also started to be applied in our country. However, the problem of reuse of effluent in China's wetlands needs to be decided according to the specific circumstances and should not be blindly referred to for watering.
Earthworm ecological filter treatment system
Earthworm ecological filter is developed in recent years in France and Chile, is the use of earthworms devour organic matter, enhance soil permeability and earthworms and microorganisms synergies, and the design of sewage treatment technology, with high decontamination capability, but also Can reduce the amount of excess sludge. Earthworm ecological filter treatment system at the same time set the initial sedimentation tank, aeration tank, secondary settling tank, sludge return equipment and aeration equipment is equal to one, greatly simplifying the sewage treatment process. Its advantage is strong impact load, easy operation and management, easy to block and so on. The downside is that the environmental requirements of the high outside, vulnerable to temperature, will affect the system's processing efficiency. In our country has begun to have applications.
Soil capillary percolation system
Soil capillary percolation system, the sewage is dosed to the surface of the soil with a certain structure of the percolation ditch, pollutants by physical, chemical, microbial degradation and absorption and utilization of plants to be treated and purified. The United States, Japan, Australia, Israel, Russia and Western Europe have all along attached great importance to the research and application of this system. They have finalized and serialized the process flow, purification methods and construction facilities, and prepared relevant technical specifications. The technology of suspended solids, organic matter, ammonia nitrogen, total phosphorus and Escherichia coli removal rates are high, and less capital investment, low operating costs, easy maintenance, the entire system buried in the ground, will not smell, to ensure that the winter than Stable operation, easy to local sewage treatment and reuse.
In recent years, experts from the Australian Science and Industry Research Organization (CSIRO) have proposed a "FILTER" system, a wastewater recycling system that combines filtration, land treatment and concealed drainage. Based on land treatment, the wastewater is used to irrigate crops. Sewage is treated by crops and land before it is discharged through concealed pipes. The system can meet the crop's moisture and nutrient needs, while reducing the concentration of pollutants in sewage to meet emission standards.
Integrated integrated device processing technology
The development of integrated pre-treatment, secondary treatment and advanced treatment of small and medium-sized integrated wastewater treatment plant is a trend of domestic and international development of wastewater treatment. Japanese integrated research unit mainly uses anaerobic - aerobic - secondary sedimentation tank combination of both organic matter degradation and denitrification function, the effluent BOD5 <20 mg / l, TN <20 mg / l, developed in recent years Membrane processing technology enables deep processing of BOD and TN. Many European countries have developed small integrated wastewater treatment plants that combine SBR, moving bed biofilm reactors, biotopes and trickling filter technology with chemical phosphorus removal.
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