Application of Integrated Technologies for the Treatment of High-Strength Industrial Wastewater in Vietnam

Abstract

In this study, an integrated process is employed in a wastewater treatment plant (WWTP) with a capacity of 200 m3/day for treatment of highly toxic wastewater from different industrial effluents, including electronic manufacturing, metal electroplating, painting process, waste gasoline. The wastewater was characterized by the chemical oxygen demand (COD) of about 30,000 mg/L and various heavy metals with a wide range of concentration, which makes the wastewater complicated and recalcitrant as compared to domestic and municipal wastewater. The study was divided into 2 phases (i.e., lab-based experiments and on-site operation) with three treatment steps including Fenton-related advanced oxidation process (AOP), coagulation, and spiral wound reverse osmosis (SPRO) filtration. For the Fenton process, the effective conditions were determined experimentally as reaction time of 60 minutes with pH of 3.0, H2O2 600 mg/L, and Fe2+ of 200 mg/L. For the coagulation, following parameters are effective values: pH of 7.5, coagulant as poly aluminum chloride (PAC) of 700 mg/L, and polymer of 15 mg/L. During 5 months of operation at WWTP under defined effective conditions, high COD removal efficiency of >99% was obtained. The concentration of heavy metals in the effluent satisfied the allowable discharge levels. In addition, a high recovery rate of water permeates (i.e., 80%–90%) can be obtained from the SPRO system. The treated water meets the national discharge standard indicating the potential for wastewater reuse. This study successfully demonstrates the practicability of the integrated process as Fenton—coagulation and reverse osmosis (RO) membrane to treat wastewater containing recalcitrant pollutants with high concentrations, which promotes the applicability of advanced technologies for WWTP in Vietnam. It also provides useful information and valuable data for the WWTP owner during the actual operation to obtain a stable performance and economic efficiency. The study determined effective conditions for operation of a highly toxic wastewater treatment plant with capacity of 200 m3/day located in Bac Ninh province, Vietnam. The treatment process integrated advanced oxidation as Fenton and coagulation followed by RO membrane filtration to remove recalcitrant pollutants from different industrial effluents including electronic manufacturing, metal electroplating, painting process, waste gasoline. This integrated and advanced technology has not been examined much in Vietnam and the practical applicability is thus limited. The investigation employed real wastewater collected at the treatment plant to find out the actual treatment efficiency. The results and findings obtained in this study demonstrated the excellent performance of treatment process, which encourage the replication of the technology. The wastewater after treatment satisfied the current national discharged standards and was proposed for reuse due to high-quality water output. The study also helps the investor to reduce the operational cost which mainly relied on the chemicals and energy consumption.