A hybrid process of Fe-based catalytic ozonation and biodegradation for the treatment of industrial wastewater reverse osmosis concentrate

Abstract This work investigated the feasibility of a hybrid process consisting of catalytic ozonation and biodegradation (i.e., sequencing batch reactor, SBR) for the treatment of the industrial-based reverse osmosis concentrate (ROC) with specific characteristics of high levels of total dissolved solids (TDS) and refractory pollutants. The Fe-based homogeneous and heterogeneous catalytic ozonation was in parallel investigated and compared in terms of contaminant removal efficiency and biodegradability variation. The Fe-based heterogeneous catalyst carried the higher potential to improve the biodegradability of ROC (i.e., 0.32 v. s. 0.27 for B/C, the ratio between BOD5 and COD) although its direct COD removal efficiency was inferior to the homogeneous one (i.e., 49% v. s. 59% after 25 min' reaction). The ROC pretreated by the Fe-based heterogeneous catalytic ozonation for 5 min was further treated by biodegradation. After the hybrid treatment, the COD concentration reached ∼40 mg/L meeting with the discharge standard (GB, 18918-2002), under the optimal reaction conditions of 2.0 L/min ozone flow rate for catalytic ozonation and 120 min’ aeration for biodegradation. The solution pH should not be adjusted by taking both the treatment efficiency and operating cost into consideration. The treatment cost of the hybrid process was estimated to be 0.15 USD/m3. This work could provide a feasible and economic option for the proper management of the industrial-based ROC and should be of interest to the application fields.