The Lab-Scale Test On Pharmaceutical Wastewater Treatment Using Advanced Oxidation-UASB-MBBR Process

Wastewater produced by chemically synthetic pharmaceutical processes has been widely regarded as one kind of industrial wastewater difficult to treat due to its characteristics of complex components, high COD, ammonia and salt concentration, and most importantly, the containing of biologically inhibiting wastes. According to the treatment process plan including pretreatment, anaerobic treatment and aerobic treatment in series, the labarotary scale test on the treatment of SIMA wastewater has been divided into three parts and conducted respectively to study the feasibility and efficiency of each unit.The pretreatment is carried out through comparison of the COD removal among flocculation, advanced oxidation and adsorption. Advanced oxidation is chosen as the pretreament process because data show that the removal of advanced oxdiation is superior to that of the other two. The dosage of reagents and operational conditions are obtained as following: add FeSO₄·7H₂O (8 g) to one liter wastewater, agitate sufficiently and adjust pH to 8 using Ca(0H)2 solution of 5%. Then add 20 ml H₂O₂ solution of 30% and decrease agitation rate gradually as floe grows after 2 ml PAM (negative ion) added.The anaerobic treatment is performed using a laboratory-scale upflow anaerobic sludge blanket (UASB) reactor. The experiment is mainly concerned with start-up process of UASB reactor seeded with the mixture of granule and aerobic active sludge. COD removal reaches 70% with VSS concentration of 6.7 g/L, which initially is 6.1 g/L, when applied volumetric load and sludge load increase to 2.5 kgCOD/(m3 ? d) and 0.26 kgCOD/(kgVSS ? d), respectively. During day 87 to 108, methane production varies between 0.75-0.91 L/d. The most significant factor that influences sludge granulation is found to be the concentration of toxic wastes in the water, which shows two different effects—acute and chronic effects. The former prevents load from increasing, while the latter prolongs the start-up phase and inhibites the activity of the bacteria.The aerobic treatment is conducted using two moving bed biofilm reactors (MBBR) connected in series. The influent of aerobic experiment is prepared by diluting SMIA wastewater to simulate UASB effluent. Total COD removal reaches 88.6% when the applied load of Reactor 1 varies from 1.2 to 1.6 kgCOD/(m³ ? d). The aerobic system has a certain capacity of both nitrification and nitrogen removal. When total HRT remains 32 h, the removal of TN is 25.5% and 56.2% of ammonia in Reactor 2 has been converted into nitrate. Meanwhile, it has been found that the sludge load of Reactor 1 is lower than that of a MBBR treating municipal wastewater, which is possibly because of the inbihition of the microbes bythe toxic wastes. Furthermore, the key factor influencing the activity of the sludge is found to be temperature when nutritions available are sufficient.Helpful results such as the removal of the contaminants, the treating capacity of the processes mentioned above, some operational conditions and dosage of the chemicals have been obtained from the experiments, which can be refered to in polit test and field application.