Experimental research on piggry farm wastewater treatment by enhanced biological process

The novel technologies of anaerobic reactor and the enhanced biological nitrification and denitrification technologies were used to treat the intensive farm piggery wastewater. The results show that the new anaerobic reactor operates steadily，and its average COD_Cr removal is 75% under the 8 kg COD_Cr/(m³·d) of organic volume loading. The nitrification and denitrification are carried out through anoxic and aerobic process. With one hour's anoxic HRT and 3 days aeration HRT, the effluent NH₃-N is less than 10 mg/L; the average effluent COD_Cr, BOD₅ and NH₃-N are 550 mg/L, 53.0 mg/L, 8.8 mg/L, respectively, and the relevant removal rates are 87%, 96%, 98％, respectively. Enhancing the biological nitrogen removal by optimum carbon source distribution，the total nitrogen removal rate was 77.11%. The ratio of BOD₅/COD_Cr in the final effluent is about 0.10, the hard degradable pollutants are dominant, and it cannot reach the local discharge limitation standards of water pollutants, therefore, further physical-chemical treatment is indispensable.