Integrative membrane coagulation adsorption bioreactor (MCABR) for enhanced organic matter removal in drinking water treatment

An integrative membrane coagulation adsorption bioreactor (MCABR) with simultaneous dosing of polyaluminium chloride (PACl, 10 mg/L) as the coagulant and powdered activated carbon (PAC, 8 mg/L) as the adsorbent into the bioreactor was put forward and investigated for the drinking water treatment from slightly polluted surface water. The MCABR exhibited excellent capacity for the removal of organic matter even at a low hydraulic retention time of 0.5 h. As for DOC, UV254, TOC, CODMn, THMFP, HAAFP, BDOC and AOC, the removal efficiencies by the MCABR reached to 63.2, 75.6, 68.3, 72.7, 55.3, 56.2, 67.4 and 75.5%, respectively. In the MCABR, four kinds of mechanisms, i.e. separation by the membrane, biodegradation by micro-organisms, coagulation by PACl, and adsorption by PAC jointly contributed to the removal of dissolved organic matter (DOM), with their respective contributions of 11.1, 8.3, 24.6 and 19.2% in DOC removal, and 11.4, 5.0, 38.1 and 21.1% in UV254 removal. Furthermore, scanning electronic microscopy (SEM) and confocal laser scanning microscopy (CLSM) observations showed that a sludge layer was formed on the membrane surface in the MCABR, which was demonstrated to provide additional rejection for DOM in the mixed liquor, especially for the organic molecules of 3000–300 Da.