Technical NoteImpacts of powdered activated carbon addition on trihalomethane formation reactivity of dissolved organic matter in membrane bioreactor effluent

- PAC addition increased chlorine reactivity, but reduced bromine-containing THMs.
- PAC addition reduced effluent DOM, but increased the content of aromatic DOM.
- PAC addition enhanced removal of hydrophilic and <1 kDa DOM.
- PAC addition resulted in higher production of simple aromatic protein in effluent.
- PAC addition reduced fulvic acid-like and soluble microbial by-product-like.

Characteristics and trihalomethane (THM) formation reactivity of dissolved organic matter (DOM) in effluents from two membrane bioreactors (MBRs) with and without powdered activated carbon (PAC) addition (referred to as PAC/MBR and MBR, respectively) were examined to investigate the effects of PAC addition on THM formation of MBR effluent during chlorination. PAC addition increased the specific UV absorbance. Hydrophobic DOM especially hydrophobic acids in PAC/MBR effluent (50%) were more than MBR effluent (42%). DOM with molecular weight <1 kDa constituted 12% of PAC/MBR effluent DOM, which was less than that of MBR effluent (16%). Data obtained from excitation and emission matrix fluorescence spectroscopy revealed that PAC/MBR effluent DOM contained more simple aromatic protein, but had less fulvic acid-like and soluble microbial by-product-like. PAC addition reduced the formation of bromine-containing THMs during chlorination of effluents, but increased THM formation reactivity of effluent DOM.

121