AHP-Based Decision\nfor the Selection of a Draw Solution\nfor Anaerobic Osmotic Membrane Bioreactors

The selection of a suitable draw solution (DS) is critically\nimportant\nfor the forward osmosis (FO)-based processes since membrane fouling\nand inhibition caused by DS are the key problems in anaerobic osmotic\nmembrane bioreactor (AnOMBR) systems. This study aims to select a\nsuitable DS for the AnOMBR system treating slaughterhouse wastewater,\nconsidering the results of FO performance and the biochemical methane\npotential (BMP) test. In the first step of the study, the DSs obtained\nfrom the literature review were subjected to prescreening, and 18\nDSs were evaluated. Eight out of 18 DSs (4 organics and 4 inorganics)\nwere selected using the first analytical hierarchical process (AHP).\nIn the second stage, reverse salt flux selectivity (RSFS), water flux\n(<i>J</i><sub>w</sub>), and reverse salt flux (<i>J</i><sub>s</sub>) values were determined to evaluate the FO performance\nof the 8 selected DSs by batch FO experiments. A BMP test was performed\nto investigate the inhibition effect of each DS on the anaerobic performance.\nThe experimental results of batch FO and BMP studies were subjected\nto a second AHP analysis. The second AHP analysis showed that MgCl<sub>2</sub> was the most suitable DS. The autopsy analysis demonstrated\nthat the primary source of fouling on the FO membrane was the accumulation\nof MgCl<sub>2</sub> on the membrane’s surface. Although the\nfouling on the FO membrane did not seriously damage the membrane structure,\nit caused the membrane surface to become rougher and more hydrophobic.