Experimental Study On Pharmaceutical Wastewater Treated By Coagulation-Anaerobic Digestion

In this article, chemical synthesis pharmaceutical wastewater of Chengdu Pharmaceutical Co., Ltd. of Diao Group is taken as research object. The characteristics and treatment technologies status of pharmaceutical wastewater are briefly discussed through consulting lots of literatures at home and abroad. And theories of flocculation and anaerobic digestion are analyzed concisely.Treatment results of two kinds of coagulants used for pharmaceutical wastewater is compared in this paper. Then polyaluminium chloride (PAC) is determined as coagulant for this wastewater. After orthogonal test, the treatment initial conditions of PAC are determined as following:The initial PH value is 5, dosing quantity of PAC is 100mg/L,slowly stirring time is 20min, precipitation time is 30min. At the sme time, the order of single factor test is determined as dosing quantity, initial PH value, stirring time and precipitation time. Then the fluences of dosing quantity, initial PH value, stirring time and precipitation time in result of wastewater treatment are investigated through single factor test. The best process parameters of flocculation is listed as following:The initial PH value of wastewater is 8, best dosing quantity of PAC is 80mg/L, quickly stirring time is 1min (250r/min), slowly stirring time is 15min (50r/min), precipitation time is 50min.The anaerobic production treatment test of pharmaceutical wastewater mainly research the start-up process of bioreactor. The seed sludge of test is from anaerobic tank of Diao sewage treatment station. It is account for 40% effective volume of reaction vessel. The research of start-up test shows that:The volume load of normal temperature reactor is 2.24kgCOD/(m3·d), remove rate of COD is stable above 75%, effluent VFA is below 10.5 mmol/L. The volume load of medium temperature reactor is 3.36kgCOD/(m3·d), remove rate of COD is stable above 88%, effluent VFA is below 6mmol/L.Two different kinds of wastewater are chosen for reactor influent at operation phase. They are wastewater without coagulation pretreatment and effluent after coagulation. The relationship of COD remove rate change with hydraulic retention time of this two wastewater is investigate. The research results show that:Two different kinds of wastewater shows the same change law, COD remove rate in wastewater presents increasing tendency with the prolonging of reaction time in reactor. And COD remove rate increases slowly when the hydraulic retention time is between 0 and 6h. But it enters rapidly promote stage when the hydraulic retention time is between 6h and 24h. It is stable without significant increase when the hydraulic retention time exceed 30h. The COD remove rate of wastewater without coagulation pretreatment is about 90% after stability. The COD remove rate of effluent after coagulation is about 93%.This research complete or part-complete above two unites test of pharmaceutical wastewater according to technological process of physicochemical pretreatment-anaerobic biological treatment. We preliminarily understand and master the treatment capacity of whole process and fish out some process conditions. It can provide some references for treatment of such wastewater.