Removal of trace organic contaminants by an MBR comprising a mixed culture of bacteria and white-rot fungi

Abstract

The degradation of 30 trace organic contaminants (TrOC) by a white-rot fungus-augmented membrane bioreactor (MBR) was investigated. The results show that white-rot fungal enzyme (laccase), coupled with a redox mediator (1-hydroxy benzotriazole, HBT), could degrade TrOC that are resistant to bacterial degradation (e.g. diclofenac, triclosan, naproxen and atrazine) but achieved low removal of compounds (e.g. ibuprofen, gemfibrozil and amitriptyline) that are well removed by conventional activated sludge treatment. Overall, the fungus-augmented MBR showed better TrOC removal compared to a system containing conventional activated sludge. The major role of biodegradation in removal by the MBR was noted. Continuous mediator dosing to MBR may potentially enhance its performance, although not as effectively as for mediator-enhanced batch laccase systems. A ToxScreen3 assay revealed no significant increase in the toxicity of the effluent during MBR treatment of the synthetic wastewater comprising TrOC, confirming that no toxic by-products were produced.

Keywords: 1-hydroxy benzotriazole; 2,6-dimethoxy phenol; Biosorption and biodegradation; CAS; CFU; DMP; EDG; EMR; EWG; HBT; HRT; LiP; MBR; MEB; MLSS; MLVSS; Mediator-enhanced laccase system; Membrane bioreactor (MBR); MnP; PhACs; TMP; TN; TOC; TrOC; Trace organic contaminants (TrOC); White-rot fungi; colony forming unit; conventional activated sludge; electron donating functional groups; electron withdrawing functional groups; enzymatic membrane reactor; hydraulic retention time; lignin peroxidase; logD; logarithm of the distribution coefficient which is the ratio of the sum of concentrations of all forms of the compound (ionized and unionized) in octanol and water at a given pH; malt extract broth; manganese peroxidase; membrane bioreactor; mixed liquor suspended solids; mixed liquor volatile suspended solids; pharmaceutically active compounds; total nitrogen; total organic carbon; trace organic contaminants; transmembrane pressure.