With the rapid development of urban construction and the growth of urban population, urban garbage has become one of the main factors of global environmental pollution. At present, there are four kinds of disposal methods widely used at home and abroad: comprehensive utilization, incineration, composting and sanitary landfill. Sanitary landfill is the main way of waste treatment in the world. In the process of landfill, due to waste fermentation and precipitation, groundwater and surface water soaking, a large number of landfill leachate will be produced. Landfill leachate treatment equipment is always a very difficult problem in the design, operation and management of landfill.
Technology of landfill leachate treatment equipment
In the treatment of leachate, if it is combined with urban sewage, it is easy to destroy the activity of microorganisms. In addition, the landfill is usually far away from the town, so its leachate often has to be treated separately. At present, the mature and applicable technology of landfill leachate treatment equipment is: biochemical method + membrane separation method. This process not only has low production cost, but also has good effluent quality, which conforms to the new level I discharge standard issued by the state.
There are many factors that may affect the properties of leachate in the process of liquid flow, including physical factors, chemical factors and biological factors, so the properties of leachate change in a considerable range. Generally speaking, its pH value is in the range of 4-9, cod is in the range of 2000-62000mg / L, BOD5 is in the range of 60-45000mg / L, NH4-N is in the range of 50-1000mg / L, SS is in the range of 30-2000mg / L, TN is in the range of 100-2000mg / L. The concentration of heavy metals in municipal sewage is basically the same. Landfill leachate is a kind of high concentration organic wastewater with complex components. If it is discharged, it will seriously pollute the surrounding farmland and water system, especially the groundwater or the surrounding environment, with more serious consequences. In order to protect the environment, it is necessary to treat the leachate. Landfill leachate has the characteristics different from the general urban sewage: high concentration of BOD5 and COD, high metal content, large change of water quality and quantity, high content of ammonia nitrogen, imbalance of microbial nutrient elements, etc.
Advantages of landfill leachate treatment equipment
1. High quality and stable effluent quality
Due to the high efficiency of membrane separation, the separation effect is far better than that of the traditional sedimentation tank, the treated water is extremely clear, the suspended solids and turbidity are close to zero, bacteria and viruses are largely removed, and the water quality of the treated water is better than that of the domestic miscellaneous water quality standard (cj25.1-89) issued by the Ministry of construction, which can be directly used as non drinking municipal miscellaneous water for reuse.
At the same time, membrane separation also enables The microorganism is completely intercepted in the bioreactor, so that the system can maintain a high concentration of microorganisms, not only improve the overall removal efficiency of pollutants in the reactor, ensure a good quality of effluent water, but also the reactor has a good adaptability to various changes of the influent load (water quality and quantity), which is resistant to impact load, and can stably obtain high quality of effluent water quality.
2. Less excess sludge production
The process can operate under high volume load and low sludge load, and the output of excess sludge is low (theoretically, zero sludge discharge can be realized), which reduces the cost of sludge treatment.
3. Small floor area, not limited by setting occasions
The bioreactor can maintain a high concentration of microorganisms, with a high volume load of the treatment device and a large area saving; the process flow is simple, compact, and covers a small area, which is not limited by the location, suitable for any occasion, and can be made into ground, semi underground and underground.
4. Removal of ammonia nitrogen and refractory organics
Due to the complete interception of microorganisms in the bioreactor, it is conducive to the interception and growth of slow-growing microorganisms such as nitrifying bacteria, and the nitrification efficiency of the system can be improved. At the same time, the HRT of some refractory organics in the system can be increased, which is conducive to the improvement of the degradation efficiency of refractory organics.
5. Convenient operation and management, easy to realize automatic control
The process realizes the complete separation of HRT and SRT, and the operation control is more flexible and stable. It is a new technology easy to realize the equipment in sewage treatment, and it can realize the automatic control of microcomputer, so that the operation management is more convenient.
6. Easy to transform from traditional process
The process of landfill leachate treatment equipment can be used as the advanced treatment unit of traditional sewage treatment process, which has a broad application prospect in the field of advanced treatment of effluent from secondary sewage treatment plant.
