Study On Treatment Technology Of Organic Pharmaceutical Fermentation Wastewater With High Ammonia Nitrogen And Phosphate

The pharmaceutical fermentation wastewater with high COD, ammonia nitrogen and phosphate and poor biodegradability was treated by using the combined processes of "magnesium ammonium phosphate-coagulation and sedimentation-SBR" in this study. The performace of each process was investigated and the optimal operation parameters of were determined. The main achievements are as follows:The magnesium ammonium phosphate precipitation method(MAP) was used for wastewater pretreatment to removal nitrogen and phosphate. And then we conducted a test study on pretreatment of nitrogen and phosphorus removal. Mg Cl2· 6H2 O and Na H2PO4·12H2O were selected as precipitation agents for pretreatment. The optimal reaction conditions of MAP were determined as the initial p H of 9.0, the ratio of n(Mg2+) /n(PO43-) /n(NH4+) of 1.44:1.2:1 and the reaction time of 30 min. When the influent ammonia concentration was 1450~1600 mg/L, the treated effluent ammonia concentration was less than 90.0 mg/L, and the ammonia removal rate was above 90%. When the influent phosphorus concentration was 70~100mg/L, the treated effluent phosphorus content was less than 15.0 mg/L. In addition, COD was also removed by MAP treatment with an average removal rate of about 20%.The coagulation-sedimentation process was used to treat the effluent after MAP treatment.The polymerization aluminum chloride(PAC), poly ferric sulfate(PFS) and poly aluminum ferric chloride(PAFC) were compared as coagulation agents and PAC was determined to be better. The optimal coagulation conditions were determined as: PAC dosage of 10 m L, p H=8, and reaction time of 25 min. When the influent COD was 3200~3600 mg/L, the effluent COD was 2000~2200 mg/L after coagulation-sedimentation treatment and the removal rate was more than 30%. When the influent phosphorus concentration was 15~20 mg/L, the effluent phosphate concentration was less than 2 mg/L and the removal rate was more than 85%, which reached the discharge standard.A SBR reactor was used to treat the effluent of coagulation-sedimentation process. The successful start-up of the reactor was achived after 45 d since seeding aerobic sludge. The operation mode was "influent for 10min- aeration for 4h- anaerobic for 1.5h –sedimentation and effluent for 0.5 h". The efficient organics and nitrogen removal were obtained with this operation mode. Under the operation conditions of the influent COD of 2200 mg/L, the ammonia nitrogen of 80 mg/L, reaction temperature of 30 C, DO of 3.5 mg/L and p H of 7, the effluent COD was less than 30 mg/L and the removal rate of COD reached above 95%, while the effluent ammonia nitrogen was less than 5 mg/L and its removal rate reached more than 95%. After stable operation for nearly one month, the volumetric load reached 2.0kg COD/(m3·d), and the effluent quality could meet the "fermentation pharmaceutical industrial water pollutant discharge standards"(GB21908-2008).During operation process of SBR, the sludge settling ability was acceptable, and the sludge activity of nitrification and denitrification was strong. The FISH analysis was used to detect the nitrifying bacteria and denitrifying bacteria in the sludge, and their relative abundances reached to 18.21% and 21.94% finally, indicating that nitrifying and denitrifying bacteria became dominant in activated sludge.