1, rural sewage source
Since the reform and opening up, especially since the 17th National Congress of the Communist Party of China, China has obviously accelerated the pace of building a new countryside, and vigorously developing the construction of new countryside or small towns is a major strategy to promote the development of rural economy or small towns. However, while developing rural economy or small town economy, it also brings environmental pollution problems. Controlling pollution and protecting the environment is another important measure for sustainable development.
The construction of new countryside and small towns in China involves environmental protection issues, mainly including rural sewage pollution and rural garbage pollution. In rural sewage pollution, mainly domestic sewage pollution, livestock and poultry breeding sewage pollution, pesticide and fertilizer pollution, but also some industrial pollution and other pollution. These pollutants are mixed with domestic sewage, so rural sewage is actually the general name of the above sewage.
2. Characteristics of rural sewage
(1) The sewage receiving area is small, the sewage quantity is small, the coefficient of variation is large, and the water quality and quantity fluctuate greatly.
(2) The mixed discharge of industrial wastewater and domestic sewage in some rural areas has a certain impact on water quality.
(3) The management can't keep up with the reason why the rainwater is not diverted, and some of them have groundwater infiltration.
(4) There may be a leap-forward development in rural areas, with less sewage in the near future and more sewage in the long term.
5. Due to the problem of funds, imperfect infrastructure and weak technical force, even if the sewage treatment station is built, it may be difficult for the community to maintain a treatment system with high energy consumption, large maintenance and complex management. Therefore, new sewage treatment processes and technologies that are economical, efficient, energy-saving, simple, effective, strong in impact resistance and stable in operation should be selected for new rural sewage treatment in China.
The new countryside is generally divided into three types: 1000 community, 2,000 community and 3,000 community, and the average drainage of each community is 0. 15m? /d, pollutant concentration CODcr < 900 ㎎/L, PH 6.5 ~ 7.5, BOD5 < 350 mg/L, SS < 700 mg/L, chroma (dilution multiple method) < 200, containing a certain amount of nitrogen and phosphorus, which has good biodegradability, but the water quality and quantity fluctuate greatly. It can be seen that the water quality index of rural sewage is obviously higher than that of urban domestic sewage, and the low-load technology occupies a large area, has a large investment and high operating cost. Therefore, the high-load sewage treatment process "diversion biological aerated filter" is especially suitable for the needs of rural sewage treatment and sewage treatment construction in small towns in China.
3, sewage treatment method
China's sewage treatment started late and developed rapidly. The main technology used in sewage treatment is biochemical treatment. Commonly used technologies include contact oxidation method, AB method, A/O method, oxidation ditch, SBR, biological aerated filter and directed biological aerated filter.
Diversion biological aerated filter is a new sewage treatment process with independent intellectual property rights in China. According to the different subsequent treatment processes, it can be divided into hydrolysis-diversion biological aerated filter, anaerobic-diversion biological aerated filter, air flotation-diversion biological aerated filter, rapid sedimentation-diversion biological aerated filter, ultrasonic-diversion biological aerated filter, microwave-diversion biological aerated filter, ozone-diversion biological aerated filter and so on.
Combined with other processes in upgrading, nitrogen and phosphorus removal and reclaimed water reuse, the AB method-the guided biological aerated filter was developed. A/O process-shunt biological aerated filter; A2/O method-diversion biological aerated filter; Oxidation ditch-diversion biological aerated filter; SBR guided biological aerated filter; Advanced treatment processes such as biological contact oxidation-split aeration biological filter.
Second, the introduction of the process technology of the diversion biological aerated filter
1, technical source
On the basis of traditional biological aerated filter, diversion biological aerated filter is a sewage treatment process and new technology developed by fully drawing lessons from eight design methods, such as downward flow biological aerated filter method, upward flow biological aerated filter method, contact oxidation method, biofilm method, manual rapid filtration method, precipitation separation method, pumpless sludge reflux method and water supply rapid filtration method, and secondary or tertiary sewage treatment process. In 2005, it obtained the national patent with the patent number ZL200420033672.4.
Diversion biological aerated filter has been used in Beijing, Shandong, Hebei, Guizhou, Shanxi, Sichuan, Inner Mongolia, Heilongjiang, Jiangsu, Jilin, Henan, Hubei, Tianjin and other places in China, and has set up cases for the treatment of wastewater from hospitals, life, chemical industry, slaughter, food, flax, alcohol and pharmaceuticals. A large number of applications have proved that the CODcr of effluent quality is generally below 20 mg/L, BOD5 is generally below 10 mg/L, and the lowest is 3.50 mg/L; SS is generally below 20 mg/l, and the lowest is 6.55 mg/l.
2. Table of technical characteristics
Diversion biological aerated filter (CCB) makes sewage complete the process of aeration → sedimentation → secondary aeration → secondary sedimentation in the same treatment tank, which solves the technological process that other sewage treatment needs four tanks. Especially in the case of continuous water inflow, intermittent aeration of water inflow → aeration → sedimentation → effluent is realized, and sludge backflow is realized at the same time, and the whole operation is not idling. Its advantages are more outstanding than other sewage treatment methods, and the treatment effect is excellent. Directed biological aerated filter (BAF) is the replacement product of sewage treatment such as AB method, SBR method, A2O method, contact oxidation method, secondary aeration method and intermittent aeration method. In August 2009, it was listed as an "innovative project" by the Ministry of Science and Technology with the project code of 09C26215205564; ; From June 5438 to February 2009, the Ministry of Environmental Protection listed this product in the Catalogue of Environmental Protection Technologies Encouraged by the State (UNCED 2009)No. 146; 20 10 In May, the Ministry of Science and Technology, the Ministry of Environmental Protection, the Ministry of Commerce and the General Administration of Quality Supervision, Inspection and Quarantine identified the diversion biological aerated filter as a "national key new product" with the number of 2065438+00GR467010; 20 12 July, the Ministry of Environmental Protection listed the guided biological aerated filter as the national environmental protection technology catalogue (Ministry of Environmental Protection 2065438+02) No.39 during the Twelfth Five-Year Plan period. ..
Diversion biological aerated filter (CCB) makes sewage complete the process of aeration → sedimentation → secondary aeration → secondary sedimentation in the same treatment tank, which solves the technological process that other sewage treatment needs four tanks. Especially in the case of continuous water inflow, intermittent aeration of water inflow → aeration → sedimentation → effluent is realized, and sludge backflow is realized at the same time, and the whole operation is not idling. Its advantages are more outstanding than other sewage treatment methods, and the treatment effect is excellent. Directed biological aerated filter (BAF) is the replacement product of sewage treatment such as AB method, SBR method, A2O method, contact oxidation method, secondary aeration method and intermittent aeration method. In August 2009, it was listed as an "innovative project" by the Ministry of Science and Technology with the project code of 09C26215205564; ; From June 5438 to February 2009, the Ministry of Environmental Protection listed this product in the Catalogue of Environmental Protection Technologies Encouraged by the State (UNCED 2009)No. 146; 20 10 In May, the Ministry of Science and Technology, the Ministry of Environmental Protection, the Ministry of Commerce and the General Administration of Quality Supervision, Inspection and Quarantine identified the diversion biological aerated filter as a "national key new product" with the number of 2065438+00GR467010; 20 12 July, the Ministry of Environmental Protection listed the guided biological aerated filter as the national environmental protection technology catalogue (Ministry of Environmental Protection 2065438+02) No.39 during the Twelfth Five-Year Plan period. ..
Third, the technical performance of the diversion biological aerated filter
1), technology foresight
The diversion biological aerated filter (BAF) is a typical three-phase diversion, nitrogen and phosphorus removal reactor with high load, submerged and fixed biological bed, which fully draws lessons from eight sewage treatment design methods. The treated sewage is superior to the discharge standard, reaching the quality of reclaimed water reuse, and the technology is forward-looking
2), process innovation
The diversion biological aerated filter makes the sewage in the same treatment tank, which solves the technological process that other sewage treatment needs four tanks to complete. The whole operation is not idle. Therefore, the process is innovative.
3) Economy of project investment
The BOD5 volume load of the diversion biological aerated filter is 5 ~ 10 times that of the conventional secondary biological treatment, and the microbial biomass is as high as 10 ~ 15g/L, so there is no need to set up a secondary sedimentation tank, and the project investment is economical.
4) Stability of treatment effect
There are aerobic and anoxic environments in the plant, which can realize nitrification and denitrification without worrying about sludge bulking and microbial loss caused by hydraulic load impact. Even if the sewage is reduced by less than half, or restarted after stopping water supply, it only takes a short time for normal operation, so the treatment effect is stable.
5) simplify the processing flow.
Because the diversion aeration biological filtration method integrates two aeration tanks, two sedimentation tanks and two filtration tanks, the treatment process is simplified, so the treatment process is simplified.
6) Economy of investment and operating expenses
Due to the short process flow, small tank capacity and less land occupation, the project cost is greatly reduced. In addition, the device uses filter material to cut, block and finely break bubbles, which enhances the gas-liquid mass transfer effect, increases the contact area and time between microorganisms and air, greatly improves the oxygen-increasing efficiency of the filter, and is economical in investment and operation cost.
7) Simple operation and management.
Through liquid level sensing, dissolved oxygen tester, timer, frequency converter and PLC program control system, the full automation of diversion biological aerated filter is realized, and the operation and management are simple.
8) Typical nitrogen and phosphorus removal
(1), the basic principle of nitrogen and phosphorus removal by guided aeration biological filtration.
The principle of nitrogen removal by directed biological aerated filter is to transform organic nitrogen into ammonia nitrogen, and then transform ammonia nitrogen into nitrite nitrogen and nitrate nitrogen through nitrification and denitrification bacteria, and then transform nitrate nitrogen into ammonia gas through denitrification, so as to achieve the purpose of nitrogen removal from wastewater.
The principle of phosphorus removal by directed aeration biological filtration is that under anaerobic conditions, phosphorus accumulating bacteria convert the organic phosphorus in their own cells into inorganic phosphorus and release it, and use the energy generated in this process to absorb the dissolved organic matter in wastewater to synthesize PHB, so that under aerobic conditions, phosphorus accumulating bacteria degrade PHB and provide the energy needed to absorb phosphorus in wastewater, thus completing the role of phosphorus accumulation.
), temperature and operation mode adaptability
Because a large number of microorganisms will not be lost, the activity of their strains can be maintained even if they are not operated for a long time, and the special high microbial biomass of the diversion aerated biological filter makes it very adaptable to temperature changes.
10), which is convenient for maintenance and replacement.
The main rotating equipment of the diversion biological aerated filter is placed on the ground, and the main equipment and materials are made in China, which is convenient for maintenance and replacement.
1 1), flexibility of engineering construction.
The system unit of the diversion aeration biological filtration method is modular structure, which can be designed centrally or independently, and is beneficial to expansion, which can better adapt to the topography of various regions and upgrade the old sewage treatment project.