Treatment of pharmaceutical wastewater by combined process of micro- electrolysis-UASB-improved two-stage A/O-sequence batch precipitation

The comprehensive wastewater from a pharmaceutical chemical plant in Shandong Province consists of concentrated wastewater，clean wastewater and domestic wastewater. The concentrated wastewater has the characteristics of high COD and high NH3-N，and therefore requires pretreatment after quality separation to meet the water quality standards for the receiving body of the wastewater treatment plant. Firstly，the concentrated wastewater was pretreated with micro-electrolysis. The pretreated concentrated wastewater was mixed with the clean and domestic wastewaters after removing the suspended solids before undergoing subsequent treatment through an UASB-improved two stage A/O-sequence batch precipitation combination process. Engineering practice showed that this process had a good treatment effect on the comprehensive wastewater，resulting in stable operation and a high capacity to handle impact loads. After treatment，the COD，NH3-N and TN of the effluent were reduced to below 200，3 and 20 mg/L，respectively，meeting the secondary standards in Table 4 of the Comprehensive Sewage Discharge Standard （GB 8978-1996） and meeting the water quality requirements of the receiving water body of the sewage treatment plant.