Evaluation of refractory organic removal in combined biological powdered activated carbon - microfiltration for advanced wastewater treatment

Biological powdered activated carbon (BPAC) was incorporated with a microfi ltration (MF, 0.2 mum pore size) system to remove the refractory organic ma tter contained in secondary sewage effluent. A synthetic secondary sewage e ffluent was used as influent in this study, containing both non-biodegradab le organic substances (such as humic acid, lignin sulfonate, tannic acid an d arabic gum powder) and biodegradable ones. These refractory organic mater ials were possibly degraded in contact with microorganisms for 20 similar t o 27 days. Although humic acid and arabic gum were weakly adsorbed on the a ctivated carbon, they could be effectively removed in the BPAC reactor. The TOC removal at a powdered activated carbon (PAC) concentration of 20 g/L w as higher than at 0.5 similar to2 g PAC/L (83% and 66-68%, respectively). T he higher removal efficiency was due to the increased rejection at the memb rane module in which most of the PAC was accumulated. More than 90% of non- biodegradable compounds removal (detected as E-280, UV absorption at 280 nm ) occurred in the BPAC reactor. The biological growth parameter b/Y, used i n system design, was estimated to be 0.017 d(-1). Relatively high permeate flux of 1.88 m/d could be obtained even at higher PAC concentration of 20 g /L.