Study On The Pretreatment Of Azithromycin Wastewater By Combined Coagulation-Fenton-like Oxidation Process

Azithromycin wastewater has the characteristics of high COD, low BOD and containing inhibiting material which has biological toxicity. It is organic wastewater which is hard to deal with. When using normal biological or chemical and physical methods, it is difficult to meet process technology and economy requirements. It has become a difficult problem urgently to be solved to deal with this kind of wastewater efficiently in the field of environment protection technology at home and aboard.In this paper, the joint-process of coagulation and Fenton-like oxidation used in Azithromycin wastewater pretreatment was studied. In the study, the COD removal rate of wastewater was used as an important index in the treatment efficiency evaluation. In the phase of coagulation process, some important operational factors, such as coagulant, dosage of the coagulation, pH value, sedimentation time as well stirring time, were studied. In the second phase of Fenton-like catalytic oxidation, the effects of five main factors such as H2O2 dosage, the ratio of the catalyst to H2O2, pH value, reaction temperature and reaction time,on the Azithromycin waste water treatment at atmospheric pressure were discussed in detail.In coagulation process, Poly Aluminum chloride (PAC) was selected as the coagulant. The optimum experimental conditions of the treatment of azithromycin wastewater were obtained by Orthogonal test methods, which as follows:pH was 3, PAC dosage was 0.45 mL per 200 mL wastewater, stirring time 20min, settling time 30min. Removal percent of COD could reach up to 46.48% at above optimum experimental conditions.After the wastewater was treated by coagulation, and then Fenton-like oxidation was used to pretreat the above wastewater. Through orthogonal experiments, the conclusion was obtained as follows:1) At room temperature and atmospheric pressure, according to the effect on the treatment efficiency, the order of the factors was:H2O2 dosage was the first, the second was pH value, and then the dosage ratio of activated carbon loading iron to H2O2, reaction time and temperature were at last.2) The optimum process conditions in Fenton-like oxidation were as follows:the ratio of the mass of the catalyst(activated carbon loading 2% iron) to the volume of 30% H2O2 -6:1(g:L); pH value -2, dosage of 30% H2O2-2.5 mL, reaction time-60 min. 3) Under the above optimum conditions, the average COD removal in Fenton-like oxidation was 71.90%.4) After the two-step coagulation- oxidation process, the total COD removal rate could reach 84.82%.Through the comparison and analysis of experimental data, the conclusion in this article can provide reference for Azithromycin wastewater treatment in further study.