Enhanced biodegradability and ammonia nitrogen removal of high-salinity pharmaceutical wastewater by ozonation with iron-based monolithic catalyst packing

Abstract

High-salinity pharmaceutical wastewater has gained much attention due to its refractory organic contaminants which are difficult to be effectively removed by traditional treatment methods, catalytic ozonation as an effective method for advanced treatment is expected to solve this problem. In this research, the treatment efficiency of ozonation with iron (Fe)-based monolithic catalyst packing for high-salinity pharmaceutical wastewater advanced treatment was evaluated, and a combination of catalytic ozonation-anoxic oxic (CO-AO) process has been applied to improve the existing wastewater treatment system. The influence of the ratio of O3 dose to influent COD (O/C) on COD, BOD5/COD, NH4+-N and NO3−-N was systematically investigated by regression analysis. Results showed that Fe-based monolithic catalyst packing could effectively remove COD (163.5 mg/L to 118.2 mg/L on average) and NH4+-N (70.3 % on average) from wastewater and improve the biodegradability of wastewater (the average BOD5/COD increased from 0.065 to 0.165). Regression analysis showed that the biodegradability of high-salinity pharmaceutical wastewater improved with the increase of O/C in the range of 0.1–1.3. The operation data of 588 days showed that the catalytic ozonation-anoxic oxic process could greatly reduce the effluent COD and NH4+-N concentration. The Cl− was the key factor associated with a large amount of NO3−-N in effluent. The long-term deposition of CaCO3 has a negative effect on the treatment effect, but it can improve the corrosion resistance of the catalyst. The findings of this study clearly demonstrate the significant potential and feasibility of Fe-based monolithic catalyst packing, also promote the application of the catalytic ozonation-anoxic oxic in high-salinity actual wastewater treatment.