Anaerobic biodegradation and decolorization of a refractory acid dye by a forward osmosis membrane bioreactor†
In this study, the feasibility of utilizing an anaerobic osmotic membrane bioreactor (OMBR) for the treatment of a refractory acid dye, Lanaset red G.GR, is demonstrated. The experimental results show that an increased sludge concentration and reversed salt accumulation exacerbate membrane fouling, which leads to flux decline. The excellent rejection performance of the forward osmosis (FO) membrane and salt accumulation could lead to a reduction of microbial activity and an increase in soluble microbial product (SMP) and extracellular polymeric substance (EPS) contents. These consequences will affect the OMBR performance. Moreover, the FO membrane demonstrated a limited rejection of aniline-type intermediates. These overall findings suggest that the OMBR process is a good option for the treatment of dyeing wastewater. Further improvements on the membrane materials and membrane surface properties to alleviate fouling, salt reverse osmosis as well as the remaining color issues are still necessary before practical application becomes possible.