Residential sewage treatment equipment
A community is a relatively independent area with one or more functions, including residential communities in the usual sense, hospitals, parks, tourist resorts, new university towns, and highway life service areas. The drainage system is usually not Within the coverage of the urban municipal pipe network, independent sewage treatment facilities must be set up. There is no uniform limit on the capacity of the sewage system in the community. The United States proposes to limit the processing capacity of a single structure to a range of 3 785 m3/d. According to my country’s situation, it is recommended to define a treatment plant with a sewage volume below 4 000 m3/d as a residential sewage treatment plant. Residential sewage in the community is different from urban sewage including some industrial wastewater. Its water quality and quantity characteristics are: water quality and water quantity change coefficients in hours, pollutant concentrations are usually lower than urban sewage, sewage biodegradability is good, and treatment is less difficult; and because The source of pollution is relatively simple, considering the treatment technology and cost, it has considerable technical feasibility and high reuse value. The data shows that taking domestic water as an example, the water used for cooking and drinking accounts for about 5%, and the domestic miscellaneous water that does not come into direct contact with the human body, such as toilet flushing water, accounts for 20% to 30%. , Air conditioning cooling water, ground flushing water and vehicle cleaning water can also be classified as domestic miscellaneous water, and there is no high water quality requirement. This distribution of water provides the possibility for the reuse of residential sewage. According to the functional characteristics of the community, the direction of the domestic sewage reuse in the community should mainly be toilet flushing water, green irrigation water, ground flushing water, vehicle flushing water, and non-contact landscape water. According to China’s water quality standards for domestic miscellaneous water (toilet flushing, urban greening, car wash flushing, etc.), and referring to the “Water Reuse Recommendation Guidelines”, “Municipal Miscellaneous Water Quality Standards” and Japan’s “Urban Domestic Water Regarding the water quality requirements of this type of recycled water in the “Reclaimed Water Quality Standard”, it is generally required that the domestic sewage of the community is subjected to secondary intensive treatment and disinfection, so that the quality of the reused water can meet the standard, which can meet the general requirements for the general reuse of community domestic sewage.
Residential sewage reuse in the community can not only provide a new “water source” for water-deficient areas, it can also play a role in preventing pollution even in areas with abundant water sources, and alleviate the pressure on urban sewage pipe networks and sewage treatment.
1. Typical treatment process of residential sewage
The residential sewage treatment process is developed on the basis of the traditional urban sewage treatment process. Conventional municipal wastewater secondary biological treatment processes mainly include: oxidation ditch technology, SBR process (series), BAF process, A2/O process, biological treatment + constructed wetland process, etc. According to the characteristics of the community and its sewage, the general residential sewage treatment facilities should have a reasonable process flow, stable treatment effect, and use integrated facilities, and try to use buried treatment, and the ground should be greened; if above-ground treatment is used, it needs to be in line with the surrounding environment. Coordinate and minimize secondary pollution such as odor, noise, and sludge.
2. Reuse technology of residential sewage
In recent years, through the use of foreign mature technology for reference and domestic research and practice, community reuse technology has been rapidly developed. The purpose of advanced treatment of domestic sewage is to further remove suspended solids (SS), organic matter, nutrients such as nitrogen and phosphorus, and soluble inorganic salts in the sewage. According to the different uses of wastewater reuse and geographical conditions, the treatment process and flow are also very different. The advanced treatment process of sewage usually has the following categories: (1) Coagulation, clarification, and filtration methods; (2) Direct filtration method; (3) Micro-flocculation filtration method; (4) Contact oxidation method; (5) Biological fast filtration Pool method; (6) fluidized bed biological oxidation method; (7) activated carbon adsorption method; (8) membrane filtration technology (ultrafiltration, nanofiltration, etc.); (9) biological membrane technology. For the reuse of residential sewage, according to the destination of sewage reuse, my country generally adopts the following process.
Common residential sewage reuse process
1 Greening, flushing and other secondary effluent → disinfection → reuse
2 Secondary effluent such as air conditioning cooling water → filtration → disinfection → reuse
3 Secondary effluent of car washing, fire fighting, air conditioning cooling water, etc.→coagulation and sedimentation→sand filtration→disinfection→reuse
With the development of residential sewage treatment technology, the difference between secondary treatment and advanced treatment is no longer as obvious as in the past.Such as biofilm technology, biological activated carbon technology, BAF process, etc. are used as secondary enhanced treatments. Generally, the secondary biochemical treatment effluent is mixed. Advanced treatment such as coagulation and filtration can meet the requirements of reuse after disinfection. With the increasing requirements for reuse, advanced treatment technologies such as biological activated carbon technology, membrane bioreactor and membrane technology are gradually being valued.
1. Biological activated carbon technology
Biological activated carbon is an effective method to remove trace organic matter. Its essence is the coordination of biodegradation and physical adsorption of carbon. Based on the theory of biological activated carbon, Wang Zhansheng and others selected cheap porous materials or inert materials (such as ceramsite or slag, etc.) to replace activated carbon, a new type of process-particle filler biological contact oxidation method, in the advanced treatment of urban sewage Has been successfully applied. The application of biological activated carbon process to treat the secondary effluent of community domestic sewage can reduce the final COD of the effluent to about 30 mg/L, and the BOD, SS, chroma, etc. can also meet the requirements for reuse. Compared with the traditional coagulation, clarification, and filtration process, the process engineering investment is slightly higher, but the operating cost is lower.
2. Membrane technology
Membrane technology mainly refers to membrane separation technologies such as nanofiltration, ultrafiltration, permeation and reverse osmosis. Residential sewage in the community is effluent after secondary treatment and advanced treatment by membrane technology such as reverse osmosis (RO). The effluent can be used as industrial water or domestic water. However, due to the high cost of membrane technology and the troublesome operation and management, it is not widely used in China.
3. Membrane Bioreactor (MBR)
As a new type of sewage treatment and water reuse technology, MBR has a good application prospect in the reuse of residential sewage. MBR integrates the biodegradation effect of the bioreactor and the high-efficiency separation effect of the membrane. It has the advantages of good effluent water quality, high processing load, small footprint of the device, less mud production, and easy automatic control. The effluent can be directly reused after disinfection, and even can be reused as a drinking water source. MBR has been well applied in the wastewater reuse industry in developed countries, but the high cost of the membrane itself, complex operating system and high operating cost hinder its application in the treatment of residential wastewater reuse.
3. Considerations on the reuse technology of residential sewage
As a relatively independent living area, the community not only puts forward requirements for the reuse of community sewage, but also makes the community sewage reuse technology face a series of problems that need to be considered in the promotion and operation.
1. Reliability of reuse technology
Through years of research and development, the domestic sewage reuse technology in the community has gradually been completed. The main purpose of domestic sewage reuse in the community is domestic miscellaneous water. The water quality and stability requirements are high. Therefore, in the actual engineering design, it is necessary to choose a reasonable and reliable one based on the quality and quantity of the domestic sewage in the community, as well as the function and environmental requirements of the community. Processing technology; and consider the long-term safe and reliable operation.
2. Intelligent management of reuse facilities
Residential sewage reuse facilities in the community have a small treatment scale and are generally part-time management. Therefore, intelligent management must be considered in the design, such as the use of PLC automatic control. The community reuse facilities adopt intelligent management such as PLC automatic control, which can not only ensure the stable and reliable operation of treatment facilities, and ensure the safety of effluent water quality, but also promote advanced sewage treatment processes such as SBR and A2/O that require relatively high control systems. Further promotion and application in the reuse of residential sewage.
3. Safety of reused water
Residential sewage reuse in the community is mainly for domestic miscellaneous water and non-contact ornamental landscape water. Therefore, it is necessary to minimize the possibility of toxic or harmful non-domestic sewage entering the residential sewage treatment station in the community to prevent damage to the normality of the residential sewage treatment station Operation may affect the quality of the effluent water; and from the perspective of sanitation and health, the reused water must be strictly disinfected. In addition, for the reuse of residential sewage, sprinkler irrigation should not be used as green water as much as possible; and when used as landscape water, it should not be used as landscape water that easily forms water mist such as waterfalls and fountains.
4. Environmental coordination of reuse facilities
The community is an independent area with relatively concentrated people. In the process selection and the design of the single structure of the domestic sewage reuse facilities in the residential area, the harmony and coordination of the surrounding residential environment must be considered. Therefore, the residential sewage reuse facilities not only require advanced technology, stable operation and intelligent management, but also need to have a good solution to noise and odor during operation, such as landscape bamboo forest and other artificial wetland technology; sludge digestion and treatment must be considered , Reduce the external discharge of sludge.