Removal of trace organic contaminants by a membrane bioreactor–granular activated carbon (MBR–GAC) system

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 (log D > 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.

► Hydrophobic (log D > 3.2) and biodegradable trace organics were well removed by MBR.
► MBR treatment was less effective for hydrophilic and persistent trace organics.
► GAC post-treatment initially resulted in above 98% removal of all compounds.
► Breakthrough of the most hydrophilic and persistent compound occurred after 7320 BV.