A hybrid anaerobic osmotic membrane bioreactor - membrane distillation for water reclamation: aquatic toxicity, membrane fouling characterization, and economic assessment

Abstract

The incomplete removal of pharmaceutically active compounds (PhACs) by conventional wastewater treatment has been challenging due to their ecological implications. Therefore, advanced technologies are necessary to remove PhACs efficiently. In the present study, an anaerobic osmotic membrane bioreactor - membrane distillation (AnOMBR-MD), aiming to remove seven PhACs, was evaluated by an integrated approach, considering the environmental toxicity, fouling characterization, and economic assessment. PhACs removal was evaluated using liquid chromatography coupled with mass spectrometry. Besides, organic matter and nutrient removal were evaluated. The FO and MD membrane fouling was characterized with scanning electron microscopy and energy dispersive spectroscopy. Toxic effects were analyzed for Aliivibrio fischeri, Daphnia similis, and Raphidocelis subcapitata. Furthermore, a preliminary economic assessment was carried out using capital and operating expenditures. The results showed a DOC, N-NH4+, and P-PO43- removal of 92%, 97%, and 99.9%, respectively, while removal of PhACs was >96%. However, the distillate was classified as very toxic forR. subcapitata, and a strong correlation was found between toxicity and the Mg2+ originating from the draw solution (DS). This result showed the importance of including toxicity tests in the selection of DS. The economic evaluation indicated that the higher cost is related to the membrane replacement due to the decrease in the permeate flux, pointing out the need for future studies that address cleaning strategies to solve the organic and inorganic fouling on the membrane's surface. In this sense, this study promoted an improvement in understanding the AnOMBR-MD technical-economic viability aiming at full-scale application.