Adsorptive removal of geosmin by ceramic membrane filtration with super-powdered activated carbon

Tap water free from unpleasant taste and odour is important for consumer satisfaction. We applied a super-powdered activated carbon (S-PAC) and microfiltration (MF) system to the removal of geosmin, a taste- and odour-causing compound. We used a specially pulverised PAC with a submicron particle size, much smaller than the normal PAC (N-PAC) particle size, as an adsorption pretreatment agent. MF and adsorption pretreatment with S-PAC removed geosmin with considerably greater efficiency and at a much lower dosage rate than with N-PAC. An S-PAC dosage of 2 mg/L was equivalent to an N-PAC dosage of more than 20 mg/L in the treatment of reagent-geosmin–spiked feed water – a dosage saving of 90%, with better removal. In experiments with feed water spiked with cultured Anabaena and geosmin, geosmin removal was attained with S-PAC at a dosage 10% of that of N-PAC. The superiority of S-PAC in removing naturally occurring geosmin from raw water was also confirmed. However, the dosage saving in this case was 75%. S-PAC also helped attenuate trans-membrane pressure increases in both physical backwash and chemical cleaning cycles. No significant trans-membrane pressure increase was observed during 4 months of MF operation with S-PAC addition, suggesting that S-PAC particles did not clog or foul the membrane.