In addition to high concentration of grease, grease sewage also contains phospholipids, soaps and other organic substances as well as acid, alkali, salt and solid suspended substances. COD and BOD are very high. At the same time, grease sewage is mostly intermittent discharge, with complex composition and unstable pH value.

Grease sewage from the grid into the grease trap, after acidification grease isolation treatment can recover a large number of grease, not only can reduce the organic load of subsequent treatment process, but also can recover valuable grease. The sewage goes through the oil separation tank to remove the surface oil slick and then enters the neutralization regulating tank. The sewage in the regulating tank is pumped into the air floating tank to remove the floating oil, phospholipid, soap foot and COD in the sewage. Water enters the YanYangChi, using acidification hydrolysis of anaerobic bacteria, will be broken into organic macromolecular organic matter in wastewater such as small molecule organic compound, ensure follow-up aerobic biochemical degradation, YanYangChi water into the SBR biological contact oxidation pool, all kinds of organic pollutants in water by aerobic biological oxidation decomposition is converted to CO2, HO2 harmless substance, such as to achieve the goal of removing pollutants. The water is discharged into the intermediate tank, after adding coagulant, it enters the reaction tank for full mixing, and then enters the biological carbon filter after the natural separation of sludge and water through the sedimentation tank. Part of the residual organic matter is absorbed and trapped by activated carbon and biodegraded at the same time. At this time, the effluent completely meets the requirements of reuse, which can be re-used as circulating cooling water and miscellaneous water, or discharged directly to the standard.

The sludge from the air floating tank and sedimentation tank is discharged into the sludge drying tank regularly. After drying, the sludge cake is transported out to landfill, and the filtrate is returned to the regulating tank for re-treatment.

Anaerobic biological treatment: its advantage is that it can treat higher concentrations of organic sewage without diluting the water concentration. At present, the anaerobic treatment process mainly adopts the up-flow anaerobic sludge bed (UASB), anaerobic biological filter bed (AF), anaerobic compound bed (AFB) and common anaerobic digester, etc., and generally adopts the medium temperature digestion mode. The COD value of the sewage after anaerobic treatment is still relatively high, and the aerobic treatment process is generally required to make the sewage quality meet the standard. Although a number of projects have been put into operation in sewage treatment of domestic plant oil plants, most of the existing domestic biological treatment processes are aerobic treatment processes. The first reason is that anaerobic treatment has disadvantages such as long start-up time and complex operation management and treatment.

Aerobic biological treatment: aerobic biological treatment process is currently the most important process in the biological treatment of plant oil plant sewage, among which the commonly used are:

Activated sludge process: activated sludge process for oil wastewater treatment is to take continuous cycle of microbial growth under aerobic conditions, take organic matter (oil) as the only carbon source, and transform and combine it into organic components in the body of microorganisms to achieve the purpose of degrading oil. This process is a widely used aerobic process, but it has the disadvantages of poor impact load resistance, low volume load, large volume and easy to cause sludge swelling.

SBR process: SBR process is a variation of activated sludge process, which has the advantages of high automation, strong impact resistance and no sludge swelling. The SBR method can reduce the investment and operation cost of the one-time project because it eliminates the sedimentation and sludge backflow. Although the SBR method has the above advantages, it also has some disadvantages, such as not suitable for high concentration sewage and continuous flow sewage treatment, high requirement for automatic control system, and complicated operation.

Biofilm: biofilm is an aerobic process based on activated sludge process. And went into a state of suspended microbes in activated sludge process, biological membrane method is the microorganisms in the attached growth on the membrane surface, is located in the packing, due to the aeration equipment aeration can stir effect, makes the biofilm renewal speed up, increased activity, and the effect of biofilm process sewage and volume load is higher than that of activated sludge process have larger, the current domestic oil wastewater aerobic biological treatment system with biofilm process. The biofilm process is mainly applied to the case of small amount of oil and sewage and small site.

It is necessary to systematize and synthesize the treatment of oily wastewater to have significant purification effect. Microorganisms used alone is mainly on the often blocked by grease, with the traditional method and is not easy to clean up the place such as pipeline, microbes as long as part of the decomposition of fat, the fat viscosity can be down to clear the purpose of, at the same time, the microorganism and the pipeline middle odor organic matter decomposition, in the form of no odor deodorization.