Control of MIB, Geosmin and TON by membrane systems

Abstract

Control of taste and odour compounds in drinking water supplies represents a key treatment objective for many municipalities. Geosmin and 2-methylisoborneol (MIB) represent the primary compounds responsible for taste and odour present in surface waters throughout the world. This research evaluated the ability of membrane systems to control taste and odour when treating a highly organic surface water source and also when challenge tested with MIB and geosmin stock solutions. Reduction of taste and odour compounds by conventional coagulation-sedimentation-filtration treatment, microfiltration (MF), or ultrafiltration (UF) was only significant when oxidation and coagulation were employed. Solely using porous filtration in the form of MF or UF membrane systems resulted in variable removal between 5 and 40%. None of the three treatment technologies could consistently meet the USEPA threshold odour number (TON) secondary standard of 3 units. The cellulose acetate nanofilter consistently removed 35–50% of TON, MIB and geosmin; however, this would still not provide assurance of compliance with the TON standard of 3 units. A polyamide nanofilter provided over 99% removal of MIB and geosmin, representing the most capable system evaluated. Application of the homogeneous solution diffusion equation indicated that size exclusion drives removal of taste and odour compounds.