Wastewater treatment after processing of duck slaughter line - Anaerobic biological treatment

According to the water quality characteristics of slaughter wastewater, it has good biodegradability. It is more suitable for aerobic biological treatment in terms of organic matter content, organic element type and pH value, so it is currently in the selection of slaughter wastewater treatment technology. The aerobic biological method is a cost-effective treatment.

Anaerobic biological treatment:

Anaerobic fermentation technology mainly uses anaerobic microorganisms to grow and reproduce raw sugar and Amino Acids in the feces, and carry out biogas fermentation. The hydration of the faeces with low water content (60-70%) is mainly lactic acid fermentation, while the high moisture content of the faeces is mainly biogas fermentation. The advantage is that there is no need for ventilation, no need to turn over, energy saving, and low cost. Anaerobic biological treatment can remove a large amount of soluble organic matter, the removal rate can reach 70-80%, and can kill infectious bacteria. The anaerobic fermentation technology can reduce COD and BOD5 in wastewater. Because anaerobic microbial biodegradation produces less sludge than aerobic microbial biodegradation, it does not need to consume oxygen, and does not consume electricity, and it can produce biogas, a clean energy source. Therefore, more and more internationally The country has begun to pay attention to the research and application of anaerobic fermentation technology. At present, anaerobic fermentation technology has many applications in the biological treatment of wastewater and solid waste, and various types of fermentation processes and equipment with excellent performance have been developed. Anaerobic biological treatment is mainly used to treat high concentration organic wastewater. A variety of improved anaerobic processes are used in the treatment of slaughter wastewater. The main processes are:

1 anaerobic adhesive film expansion bed process

The treatment process of the process is: waste water → grid → primary sedimentation tank → anaerobic adhesive membrane expanded bed → secondary sedimentation tank → effluent.

The process has a water volume of 500m3/d, a hydraulic retention time of 2.7h, a COD removal rate of 75-80%, and good effluent quality, which is reused in the slaughtering workshop.

2 anaerobic filter process

The treatment process of the process is: wastewater → pretreatment → anaerobic filter → secondary sedimentation tank → effluent.

The removal rates of COD and SS in this process are 89% and 62%, respectively, and the grease removal rate is 50%. The trial operation experience in this process shows that the pretreatment of slaughter wastewater is very important, mainly to remove suspended solids and oil, and create for subsequent biological treatment. condition.

3 anaerobic-filtration process

The process flow is: wastewater → conditioning tank → anaerobic digestion tank → sedimentation → filtration → effluent.

The process was completed and put into operation at the Zhejiang Meat Food Station. Since it was put into operation, the performance was stable and the effect was good. Anaerobic digestion and recovery of biogas 2 × l02m3 / a, annual operating costs of only 0.05 yuan / m3 (1988 price), the process of treatment water volume of 60m3 / d, CODCr and SS removal rate of 91.7% and 94.4%, respectively, color and bacteria The total removal rates were 78.9% and 99.7%, respectively.

Compared with the aerobic method, the anaerobic method has the advantages of low cost, low sludge generation, stable and easy dehydration under the condition of obtaining the same high BOD5 removal rate, small occupied area, convenient operation, and methane generated as fuel for reuse. The advantages. However, the commonly used UASB, AF, ASBR and other high-efficiency anaerobic reactors are greatly affected by the suspended solids in the wastewater and their oil and fat concentrations. If the concentration of ammonia nitrogen contained in the wastewater is high, or the ammonia nitrogen produced by the process of anaerobic decomposition of organic matter is high, so that the water quality does not meet the discharge standard, the combined process described below must be adopted.