Study On The Combined Process Of Biological And Advanced Treatment Of Phenol/Acetone Production Wastewater

Phenol/acetone production wastewater is a typical high-concentration organic wastewater, containing complex toxic components and high salt content. As s result, the wastewater is difficult to treat. In this study, an integrated activated sludge reactor was used to treat phenol/acetone wastewater, Then, two advanced treatment process, Fenton process and coagulation-sedimentaion-catylytic-ozone-oxidation（CSCOO） process, were used to treat the reactor effluent. The efficiency of the two process was investigated, and the optimal parameters were obtained.In phenol/acetone production wastewater, organics below 1kDa contributed 94.2% of TOC, which are mainly biodegradable. The integrated activated sludge reactor could remove effectively most organics and semivolatile orgnics detected by dichlorine-extraction-GC-MS. The average COD removal efficiency was 81.1%. The effluent of the reactor contained high concentration of bacterial cells, which contribute COD by 7¹60mg/L. The effluent also contained some refractory organics.Both Fenton process and CSCOO process could remove effectively aromatics, large moleculars and semivolatile orgnics detected by dichlorine-extraction-GC-MS. Dosage of Fe2+ before H2O2 could obtain higher organic removal rate for the Fenton process. Optimal wastewater pH for organic removal was 3-5. Lack or excess of Fe2+ and H2O2 resulted poorer removal efficiency. Under optimized conditions（pH5, FeSO4·7H2O of 1g/L first, H2O2（30%） of 1m L/L later, reaction 30min）, the effluent COD of Fenton process could reach the special emission limit（50mg/L） of Emission standard of pollutants for petroleum（GB 31571-2015）. The COD removal efficiency was 76.7%.The wastewater pH of 8-10 could facilate organic removal by CSCOO process. Under optimized conditions（pH=8, total O₃ dosage of 200mg/L in two series with EBRT of 30 min for each one）, the effluent COD of CSCOO process could reach the emission limit（60mg/L） of Emission standard of pollutants for petroleum（GB 31571-2015）. The COD removal efficiency was 57.9%.