Ammonia Nitrogen Removing In Piggery Wastewater By Chemical Precipitation

It is studied in this paper how to remove ammonia nitrogen from piggery wastewater by chemical precipitation. And the controlled condition is determined by orthogonal experiment which is Mg : N ratio of 1.2, P : N ratio of 1.05, pH- about 10.0, stirred time about 15 minutes, stirred velocity about lOOr/min after placing twenty minutes. Then high strength ammonia nitrogen wastewater from piggery is treated by chemical precipitation. The result is that the removal rate of high strength ammonia nitrogen from piggery wastewater is 90%, that is, ammonia nitrogen concentration from 960mg/L to 100mg/L, but the best stirred time is 20 minutes.Base on them, a method to treat piggery wastewater was proposed, that is Screening-UASB-Chemical precipitation-SBR. The result from experiments indicates that, after the process, the indices of COD_cr, NH3-N in effluent are up to the discharge standards, which is better than the method without chemical precipitation. So the chemical precipitation is effectual to remove ammonia nitrogen from piggery wastewater. It conduces to improve the general effect of the method and the precipitate is a composite fertilizer.