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Laccase-catalysed degradation of 30 trace organic contaminants (TrOCs) with diverse chemical structure was investigated in an enzymatic membrane reactor (EMR) equipped with an ultrafiltration membrane. Compared to the results from batch incubation tests, the EMR could facilitate degradation of some phenolic and a number of non-phenolic TrOCs. Laccase, which was completely retained by the membrane, formed a dynamic gel layer on the membrane surface onto which TrOCs were adsorbed. EMR investigations with active and heat-inactivated laccase confirmed that the TrOCs retained by the active laccase gel layer were eventually degraded. Redox-mediator addition to the EMR significantly extended the spectrum of efficiently degraded TrOCs, but a limited improvement was observed in batch tests. The results demonstrate the important role of TrOC retention by the enzyme gel layer dynamically formed on the membrane in achieving improved degradation of TrOCs by the mediator-assisted laccase system. Despite following the same hydrogen atom transfer pathway, the mediators tested (syringaldehyde and 1-hydroxybenzotriazole) exhibited TrOC-specific degradation improvement capacity.

Laccase-catalysed degradation of 30 trace organic contaminants (TrOCs) with diverse chemical structure was investigated in an enzymatic membrane reactor (EMR) equipped with an ultrafiltration membrane. Compared to the results from batch incubation tests, the EMR could facilitate degradation of some phenolic and a number of non-phenolic TrOCs. Laccase, which was completely retained by the membrane, formed a dynamic gel layer on the membrane surface onto which TrOCs were adsorbed. EMR investigations with active and heat-inactivated laccase confirmed that the TrOCs retained by the active laccase gel layer were eventually degraded. Redox-mediator addition to the EMR significantly extended the spectrum of efficiently degraded TrOCs, but a limited improvement was observed in batch tests. The results demonstrate the important role of TrOC retention by the enzyme gel layer dynamically formed on the membrane in achieving improved degradation of TrOCs by the mediator-assisted laccase system. Despite following the same hydrogen atom transfer pathway, the mediators tested (syringaldehyde and 1-hydroxybenzotriazole) exhibited TrOC-specific degradation improvement capacity.

Laccase-catalysed degradation of 30 trace organic contaminants (TrOCs) with diverse chemical structure was investigated in an enzymatic membrane reactor (EMR) equipped with an ultrafiltration membrane. Compared to the results from batch incubation tests, the EMR could facilitate degradation of some phenolic and a number of non-phenolic TrOCs. Laccase, which was completely retained by the membrane, formed a dynamic gel layer on the membrane surface onto which TrOCs were adsorbed. EMR investigations with active and heat-inactivated laccase confirmed that the TrOCs retained by the active laccase gel layer were eventually degraded. Redox-mediator addition to the EMR significantly extended the spectrum of efficiently degraded TrOCs, but a limited improvement was observed in batch tests. The results demonstrate the important role of TrOC retention by the enzyme gel layer dynamically formed on the membrane in achieving improved degradation of TrOCs by the mediator-assisted laccase system. Despite following the same hydrogen atom transfer pathway, the mediators tested (syringaldehyde and 1-hydroxybenzotriazole) exhibited TrOC-specific degradation improvement capacity.

Laccase-catalysed degradation of 30 trace organic contaminants (TrOCs) with diverse chemical structure was investigated in an enzymatic membrane reactor (EMR) equipped with an ultrafiltration membrane. Compared to the results from batch incubation tests, the EMR could facilitate degradation of some phenolic and a number of non-phenolic TrOCs. Laccase, which was completely retained by the membrane, formed a dynamic gel layer on the membrane surface onto which TrOCs were adsorbed. EMR investigations with active and heat-inactivated laccase confirmed that the TrOCs retained by the active laccase gel layer were eventually degraded. Redox-mediator addition to the EMR significantly extended the spectrum of efficiently degraded TrOCs, but a limited improvement was observed in batch tests. The results demonstrate the important role of TrOC retention by the enzyme gel layer dynamically formed on the membrane in achieving improved degradation of TrOCs by the mediator-assisted laccase system. Despite following the same hydrogen atom transfer pathway, the mediators tested (syringaldehyde and 1-hydroxybenzotriazole) exhibited TrOC-specific degradation improvement capacity.

The removal of four recalcitrant trace organic contaminants (TrOCs), namely carbamazepine, diclofenac, sulfamethoxazole and atrazine by laccase in an enzymatic membrane reactor (EMR) was studied. Laccases are not effective for degrading non-phenolic compounds; nevertheless, 22-55% removal of these four TrOCs was achieved by the laccase EMR. Addition of the redox-mediator syringaldehyde (SA) to the EMR resulted in a notable dose-dependent improvement (15-45%) of TrOC removal affected by inherent TrOC properties and loading rates. However, SA addition resulted in a concomitant increase in the toxicity of the treated effluent. A further 14-25% improvement in aqueous phase removal of the TrOCs was consistently observed following a one-off dosing of 3 g/L granular activated carbon (GAC). Mass balance analysis reveals that this improvement was not due solely to adsorption but also enhanced biodegradation. GAC addition also reduced membrane fouling and the SA-induced toxicity of the effluent.

Previous studies have confirmed significant removal of various trace organic contaminants (TrOCs) by white-rot fungal cultures under sterile batch test conditions. However, little is known about TrOC removal in continuous flow fungal reactors in a non-sterile environment. This study reports the removal of two TrOCs, namely, bisphenol A and diclofenac, by a fungal membrane bioreactor (MBR).

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. 2013 Elsevier Ltd.

This study investigated the removal of trace organic contaminants by a combined membrane bioreactor - granular activated carbon (MBR-GAC) system over a period of 196 days. Of the 22 compounds investigated here, all six hydrophilic compounds with electron-withdrawing functional groups (i.e., metronidazole, carbamazepine, ketoprofen, naproxen, fenoprop and diclofenac) exhibited very low removal efficiency by MBR-only treatment. GAC post-treatment initially complemented MBR treatment very well; however, a compound-specific gradual deterioration of the removal of the above-mentioned problematic compounds was noted. While a 20% breakthrough of all four negatively charged compounds namely ketoprofen, naproxen, fenoprop and diclofenac occurred within 1000-3000 bed volumes (BV), the same level of breakthrough of the two neutral compounds metronidazole and carbamazepine did not occur until 11,000 BV. Single-solute isotherm parameters did not demonstrate any discernible correlation individually with any of the parameters that may govern adsorption onto GAC, such as log D, number of hydrogen-bond donor/acceptor groups, dipole moment or aromaticity ratio of the compounds. The isotherm data, however, could differentiate the breakthrough behaviour between negatively charged and neutral trace organic contaminants. © 2013 Elsevier Ltd.

The removal efficiency of 22 selected trace organic contaminants by sequential application of granular activated carbon (GAC) and simultaneous application of powdered activated carbon (PAC) with membrane bioreactor (MBR) was compared in this study. Both sequential application of GAC following MBR treatment (MBR–GAC) and simultaneous application of PAC within MBR (PAC–MBR) achieved improved removal (over 95%) of seven hydrophilic and biologically persistent compounds, which were less efficiently removed by MBR-only treatment (negligible to 70%). However, gradual breakthrough of these compounds occurred over an extended operation period. Charged compounds, particularly, fenoprop and diclofenac, demonstrated the fastest breakthrough (complete and 50–70%, in MBR–GAC and PAC–MBR, respectively). Based on a simple comparison from the long-term performance stability and activated carbon usage points of view, PAC–MBR appears to be a better option than MBR–GAC treatment.

The removal efficiency of 22 selected trace organic contaminants by sequential application of granular activated carbon (GAC) and simultaneous application of powdered activated carbon (PAC) with membrane bioreactor (MBR) was compared in this study. Both sequential application of GAC following MBR treatment (MBR–GAC) and simultaneous application of PAC within MBR (PAC–MBR) achieved improved removal (over 95%) of seven hydrophilic and biologically persistent compounds, which were less efficiently removed by MBR-only treatment (negligible to 70%). However, gradual breakthrough of these compounds occurred over an extended operation period. Charged compounds, particularly, fenoprop and diclofenac, demonstrated the fastest breakthrough (complete and 50–70%, in MBR–GAC and PAC–MBR, respectively). Based on a simple comparison from the long-term performance stability and activated carbon usage points of view, PAC–MBR appears to be a better option than MBR–GAC treatment.

The removal efficiency of 22 selected trace organic contaminants by sequential application of granular activated carbon (GAC) and simultaneous application of powdered activated carbon (PAC) with membrane bioreactor (MBR) was compared in this study. Both sequential application of GAC following MBR treatment (MBR–GAC) and simultaneous application of PAC within MBR (PAC–MBR) achieved improved removal (over 95%) of seven hydrophilic and biologically persistent compounds, which were less efficiently removed by MBR-only treatment (negligible to 70%). However, gradual breakthrough of these compounds occurred over an extended operation period. Charged compounds, particularly, fenoprop and diclofenac, demonstrated the fastest breakthrough (complete and 50–70%, in MBR–GAC and PAC–MBR, respectively). Based on a simple comparison from the long-term performance stability and activated carbon usage points of view, PAC–MBR appears to be a better option than MBR–GAC treatment.

Previous studies have confirmed significant removal of various trace organic contaminants (TrOCs) by white-rot fungal cultures under sterile batch test conditions. However, little is known about TrOC removal in continuous flow fungal reactors in a non-sterile environment. This study reports the removal of two TrOCs, namely, bisphenol A and diclofenac, by a fungal membrane bioreactor (MBR).

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. 2013 Elsevier Ltd.

The removal efficiency of 22 selected trace organic contaminants by sequential application of granular activated carbon (GAC) and simultaneous application of powdered activated carbon (PAC) with membrane bioreactor (MBR) was compared in this study. Both sequential application of GAC following MBR treatment (MBR–GAC) and simultaneous application of PAC within MBR (PAC–MBR) achieved improved removal (over 95%) of seven hydrophilic and biologically persistent compounds, which were less efficiently removed by MBR-only treatment (negligible to 70%). However, gradual breakthrough of these compounds occurred over an extended operation period. Charged compounds, particularly, fenoprop and diclofenac, demonstrated the fastest breakthrough (complete and 50–70%, in MBR–GAC and PAC–MBR, respectively). Based on a simple comparison from the long-term performance stability and activated carbon usage points of view, PAC–MBR appears to be a better option than MBR–GAC treatment.

This study investigated the removal of trace organic contaminants by a combined membrane bioreactor - granular activated carbon (MBR-GAC) system over a period of 196 days. Of the 22 compounds investigated here, all six hydrophilic compounds with electron-withdrawing functional groups (i.e., metronidazole, carbamazepine, ketoprofen, naproxen, fenoprop and diclofenac) exhibited very low removal efficiency by MBR-only treatment. GAC post-treatment initially complemented MBR treatment very well; however, a compound-specific gradual deterioration of the removal of the above-mentioned problematic compounds was noted. While a 20% breakthrough of all four negatively charged compounds namely ketoprofen, naproxen, fenoprop and diclofenac occurred within 1000-3000 bed volumes (BV), the same level of breakthrough of the two neutral compounds metronidazole and carbamazepine did not occur until 11,000 BV. Single-solute isotherm parameters did not demonstrate any discernible correlation individually with any of the parameters that may govern adsorption onto GAC, such as log D, number of hydrogen-bond donor/acceptor groups, dipole moment or aromaticity ratio of the compounds. The isotherm data, however, could differentiate the breakthrough behaviour between negatively charged and neutral trace organic contaminants. © 2013 Elsevier Ltd.

The removal of trace organics by a membrane bioreactor–granular activated carbon (MBR–GAC) integrated system were investigated. The results confirmed that MBR treatment can be effective for the removal of hydrophobic (logD > 3.2) and readily biodegradable trace organics. The data also highlighted the limitation of MBR in removing hydrophilic and persistent compounds (e.g. carbamazepine, diclofenac, and fenoprop) and that GAC could complement MBR very well as a post-treatment process. The MBR– GAC system showed high removal of all selected trace organics including those that are hydrophilic and persistent to biological degradation at up to 406 bed volumes (BV). However, over an extended period, breakthrough of diclofenac was observed after 7320 BV. This suggests that strict monitoring should be applied over the lifetime of the GAC column to detect the breakthrough of hydrophilic and persistent compounds which have low removal by MBR treatment.

The removal of trace organics by a membrane bioreactor–granular activated carbon (MBR–GAC) integrated system were investigated. The results confirmed that MBR treatment can be effective for the removal of hydrophobic (logD > 3.2) and readily biodegradable trace organics. The data also highlighted the limitation of MBR in removing hydrophilic and persistent compounds (e.g. carbamazepine, diclofenac, and fenoprop) and that GAC could complement MBR very well as a post-treatment process. The MBR– GAC system showed high removal of all selected trace organics including those that are hydrophilic and persistent to biological degradation at up to 406 bed volumes (BV). However, over an extended period, breakthrough of diclofenac was observed after 7320 BV. This suggests that strict monitoring should be applied over the lifetime of the GAC column to detect the breakthrough of hydrophilic and persistent compounds which have low removal by MBR treatment.

The removal of trace organics by a membrane bioreactor–granular activated carbon (MBR–GAC) integrated system were investigated. The results confirmed that MBR treatment can be effective for the removal of hydrophobic (logD > 3.2) and readily biodegradable trace organics. The data also highlighted the limitation of MBR in removing hydrophilic and persistent compounds (e.g. carbamazepine, diclofenac, and fenoprop) and that GAC could complement MBR very well as a post-treatment process. The MBR– GAC system showed high removal of all selected trace organics including those that are hydrophilic and persistent to biological degradation at up to 406 bed volumes (BV). However, over an extended period, breakthrough of diclofenac was observed after 7320 BV. This suggests that strict monitoring should be applied over the lifetime of the GAC column to detect the breakthrough of hydrophilic and persistent compounds which have low removal by MBR treatment.

The removal of trace organics by a membrane bioreactor–granular activated carbon (MBR–GAC) integrated system were investigated. The results confirmed that MBR treatment can be effective for the removal of hydrophobic (logD > 3.2) and readily biodegradable trace organics. The data also highlighted the limitation of MBR in removing hydrophilic and persistent compounds (e.g. carbamazepine, diclofenac, and fenoprop) and that GAC could complement MBR very well as a post-treatment process. The MBR– GAC system showed high removal of all selected trace organics including those that are hydrophilic and persistent to biological degradation at up to 406 bed volumes (BV). However, over an extended period, breakthrough of diclofenac was observed after 7320 BV. This suggests that strict monitoring should be applied over the lifetime of the GAC column to detect the breakthrough of hydrophilic and persistent compounds which have low removal by MBR treatment.

The removal of trace organics by a membrane bioreactor–granular activated carbon (MBR–GAC) integrated system were investigated. The results confirmed that MBR treatment can be effective for the removal of hydrophobic (logD > 3.2) and readily biodegradable trace organics. The data also highlighted the limitation of MBR in removing hydrophilic and persistent compounds (e.g. carbamazepine, diclofenac, and fenoprop) and that GAC could complement MBR very well as a post-treatment process. The MBR– GAC system showed high removal of all selected trace organics including those that are hydrophilic and persistent to biological degradation at up to 406 bed volumes (BV). However, over an extended period, breakthrough of diclofenac was observed after 7320 BV. This suggests that strict monitoring should be applied over the lifetime of the GAC column to detect the breakthrough of hydrophilic and persistent compounds which have low removal by MBR treatment.

The removal of trace organics by a membrane bioreactor–granular activated carbon (MBR–GAC) integrated system were investigated. The results confirmed that MBR treatment can be effective for the removal of hydrophobic (logD > 3.2) and readily biodegradable trace organics. The data also highlighted the limitation of MBR in removing hydrophilic and persistent compounds (e.g. carbamazepine, diclofenac, and fenoprop) and that GAC could complement MBR very well as a post-treatment process. The MBR– GAC system showed high removal of all selected trace organics including those that are hydrophilic and persistent to biological degradation at up to 406 bed volumes (BV). However, over an extended period, breakthrough of diclofenac was observed after 7320 BV. This suggests that strict monitoring should be applied over the lifetime of the GAC column to detect the breakthrough of hydrophilic and persistent compounds which have low removal by MBR treatment.

The effects of controlled temperature variation in the range of 10–45 °C were assessed in a lab-scale MBR that treated synthetic municipal wastewater spiked with selected micropollutants. The effects were evaluated with respect to total organic carbon (TOC) and total nitrogen (TN) removal, micropollutant removal, sludge growth, level of soluble microbial products (SMPs) in the mixed liquor and membrane fouling. Overall, the temperature shifts caused high variation in the TOC and TN levels in the reactor supernatant, however that in membrane-permeate was relatively more stable, substantiating the robustness of the MBR process. Results regarding the removal of micropollutants at ambient temperature (20 °C) demonstrate an apparent correlation between hydrophobicity, chemical structures and the removal of micropollutants. Temperature variation below and above 20 °C, especially the operation under 45 °C appeared to significantly influence the removal of certain less hydrophobic (log D < 3.2) micropollutants possessing strong electron withdrawing functional groups. The removal of most hydrophobic compounds (log D > 3.2) was stable under the temperature range of 10–35 °C, however, deteriorated at 45 °C. The temperature shifts were also associated with higher levels of SMP in the mixed liquor which appeared to trigger membrane fouling as evidenced by a rapid increase in transmembrane pressure.

The effects of controlled temperature variation in the range of 10–45 °C were assessed in a lab-scale MBR that treated synthetic municipal wastewater spiked with selected micropollutants. The effects were evaluated with respect to total organic carbon (TOC) and total nitrogen (TN) removal, micropollutant removal, sludge growth, level of soluble microbial products (SMPs) in the mixed liquor and membrane fouling. Overall, the temperature shifts caused high variation in the TOC and TN levels in the reactor supernatant, however that in membrane-permeate was relatively more stable, substantiating the robustness of the MBR process. Results regarding the removal of micropollutants at ambient temperature (20 °C) demonstrate an apparent correlation between hydrophobicity, chemical structures and the removal of micropollutants. Temperature variation below and above 20 °C, especially the operation under 45 °C appeared to significantly influence the removal of certain less hydrophobic (log D < 3.2) micropollutants possessing strong electron withdrawing functional groups. The removal of most hydrophobic compounds (log D > 3.2) was stable under the temperature range of 10–35 °C, however, deteriorated at 45 °C. The temperature shifts were also associated with higher levels of SMP in the mixed liquor which appeared to trigger membrane fouling as evidenced by a rapid increase in transmembrane pressure.

The effects of controlled temperature variation in the range of 10–45 °C were assessed in a lab-scale MBR that treated synthetic municipal wastewater spiked with selected micropollutants. The effects were evaluated with respect to total organic carbon (TOC) and total nitrogen (TN) removal, micropollutant removal, sludge growth, level of soluble microbial products (SMPs) in the mixed liquor and membrane fouling. Overall, the temperature shifts caused high variation in the TOC and TN levels in the reactor supernatant, however that in membrane-permeate was relatively more stable, substantiating the robustness of the MBR process. Results regarding the removal of micropollutants at ambient temperature (20 °C) demonstrate an apparent correlation between hydrophobicity, chemical structures and the removal of micropollutants. Temperature variation below and above 20 °C, especially the operation under 45 °C appeared to significantly influence the removal of certain less hydrophobic (log D < 3.2) micropollutants possessing strong electron withdrawing functional groups. The removal of most hydrophobic compounds (log D > 3.2) was stable under the temperature range of 10–35 °C, however, deteriorated at 45 °C. The temperature shifts were also associated with higher levels of SMP in the mixed liquor which appeared to trigger membrane fouling as evidenced by a rapid increase in transmembrane pressure.

The effects of controlled temperature variation in the range of 10–45 °C were assessed in a lab-scale MBR that treated synthetic municipal wastewater spiked with selected micropollutants. The effects were evaluated with respect to total organic carbon (TOC) and total nitrogen (TN) removal, micropollutant removal, sludge growth, level of soluble microbial products (SMPs) in the mixed liquor and membrane fouling. Overall, the temperature shifts caused high variation in the TOC and TN levels in the reactor supernatant, however that in membrane-permeate was relatively more stable, substantiating the robustness of the MBR process. Results regarding the removal of micropollutants at ambient temperature (20 °C) demonstrate an apparent correlation between hydrophobicity, chemical structures and the removal of micropollutants. Temperature variation below and above 20 °C, especially the operation under 45 °C appeared to significantly influence the removal of certain less hydrophobic (log D < 3.2) micropollutants possessing strong electron withdrawing functional groups. The removal of most hydrophobic compounds (log D > 3.2) was stable under the temperature range of 10–35 °C, however, deteriorated at 45 °C. The temperature shifts were also associated with higher levels of SMP in the mixed liquor which appeared to trigger membrane fouling as evidenced by a rapid increase in transmembrane pressure.