Potential of anaerobic co-digestion for treating organic wastewaters from semiconductor and electronics industries: Effects of mixing ratio and magnetite supplementation

Abstract

In the past decade, wastewater volumes from the semiconductor and electronics industries in Korea have increased by over 50 %, necessitating efficient and sustainable methods to minimize environmental impacts. This study investigated the anaerobic co-digestion of three prevalent organic chemicals found in semiconductor and electronics wastewater, tetramethylammonium hydroxide (TMAH), ethyl lactate (EL), and dimethyl sulfoxide (DMSO), to assess the potential for simultaneous treatment and valorization of the wastewater. While TMAH and EL degraded effectively and produced biogas under mono-digestion conditions, methanogenic degradation of DMSO was not observed. However, robust DMSO conversion to methane was achieved in co-digestion with TMAH and EL at appropriate mixing ratios (<= 33.3 % DMSO, total organic carbon basis). The DMSO-to-EL ratio was critical for effective co-digestion treatment, with EL serving as a readily utilizable electron donor for DMSO reduction, initiating its methanogenic degradation. TMAH could have enhanced DMSO degradation by promoting methylotrophic methanogenesis, which contributes to the intermediates from DMSO degradation. Meanwhile, DMSO&apos;s toxicity and low biodegradability reduced the methane production rate in co-digestion runs compared to TMAH or EL mono-digestion, along with substantial H2S production. Adding magnetite counteracted this inhibition and accelerated methanogenesis, possibly by supporting the activity of electroactive DMSO reducers. The findings suggest that anaerobic co-digestion of TMAH, EL, and DMSO wastewaters can offer a viable solution for sustainable wastewater management in the semiconductor and electronics industries, reducing these industries&apos; energy and environmental footprints.