Advanced treatment of biochemical tail water of pig wastewater by magnetic BAF process

In order to realize the biochemical tail water of pig wastewater resource utilization, this study took the A2O process effluent from the sewage treatment station of a pig enterprise in Jingzhou City as the sample. After coagulation pretreatment, the effluent entered the biofilter aerated with magnetic ceramics and ordinary ceramics as the fillers, respectively, to explore the pollutant removal effect of the device under the action of magnetic field, as well as the influence of magnetic field on the specific aerobic rate and nitrification rate of microorganisms. The experimental results showed that the mechanical properties of magnetic ceramic particles prepared under the conditions of m (sludge): m (kaolin): m (magnetic powder)=3∶1∶4, preheating temperature of 300 ℃, and calcination temperature of 1 000 ℃ were the best. Under the same conditions, the magnetic field could shorten the start-up time of biofilter by increasing the specific oxygen consumption rate and nitrification rate of microorganisms, and the removal effect of pollutants in the stable stage was better than that of ordinary biofilter. When the magnetization of the ceramides was 2.8 mT, HRT was 8 h, and DO was 4-5 mg/L, the system worked best. The removal rates of COD and NH4+-N were 76.1% and 93.8%, respectively. The dissolved microbial by-products and the ferritic acid-like substances in the effluent almost disappeared, and only a small amount of humic acids with complex molecular structure and stable chemical properties remained, which met the class Ⅰ standard in Integrated Wastewater Discharge Standard (GB 8978-1996).