DEVELOPMENT OF INTEGRATED MEMBRANE BIOREACTOR AND CHEMICAL PROCESSES FOR ADVANCED WASTEWATER TREATMENT

Abstract

The global rise in population and rapid industrialization and urbanization have resulted in a significant increase in wastewater production, putting a strain on existing treatment facilities. This has led to the release of certain pollutants into the aquatic environment, including emerging contaminants such as pharmaceuticals, pesticides, hygiene products, endocrine-disrupting agents, surfactants, and industrial chemicals. These pollutants are found in wastewater, groundwater, rivers and lakes and pose a potential threat to human health and cause various illnesses such as reproductive disorders, cardiovascular disorders, cancer, immune deficiency, nervous system syndrome, brain development delay, and memory disruption. The secondary treatment (biological processes) in a typical treatment plant is the most crucial step as it removes approximately 80-90% of pollutants. However, conventional treatment methods are not effective in completely removing emerging contaminants, and advanced treatment techniques must be utilized. In this work, different types of wastewaters containing emerging pollutants were treated using conventional activated sludge process, membrane filtration, and advanced oxidation processes. The following emerging pollutants were used as targets: caffeine, ibuprofen, metronidazole, naproxen, sulfamethoxazole, bisphenol A, and carbamazepine. The implementation of a sequencing batch reactor (SBR) led to the elimination of a significant amount (78-86%) of total organic carbon (TOC), with only small reductions (11%, 45%, and 6%) observed for naproxen, bisphenol A, and sulfamethoxazole, respectively. The SBR effluents then were treated with membrane filtration and chemical oxidation processes. Track-etch membranes (TEMs) and phase inversion membrane (PIM) were employed. It should be emphasized that TEMs were employed in wastewater treatment for the first time. TOC removal efficiency ranged from 1% to 6% for each of the four membranes evaluated. 10 nm TEM demonstrated almost complete removal of bisphenol A (93%) and insignificant removals for naproxen (11%) and sulfamethoxazole (14%). The elimination mechanism of bisphenol A employing membranes was probably connected to size exclusion and sorption. Ultimately, the effluents from SBR and membrane filtration were treated with sulfate-radical-based advanced oxidation processes (AOPs). Remarkably, full removal of emerging contaminants and TOC were obtained after 30 minutes for the effluents after membrane filtration using 10 mM of K2S2O8 and 25 mg/L of zero-valent iron (ZVI) under UV, demonstrating the great potential of combining membrane filtration and AOPs.