Effect of activated carbon, oxidation and UV treatment on 2-methylisoborneol and geosmin removal from treated water

摘要

Geosmin and 2-methylisoborneol (MIB) are two contributors to taste and odour in water, and originate from cyanobacteria and other microorganisms in surface water. This thesis examined the use of activated carbon, hydrogen peroxide and UV treatment on removal of these two compounds from water.Geosmin and MIB were analysed using headspace solid phase micro-extraction (SPME) and gas chromatography coupled with mass spectrometry and flame ionization detection. Method development examined the effect of salt addition, sample heating time, and extraction time on GC peak area. Salt addition gave up to 40% lower GC peak areas for MIB and geosmin compared to samples without salt, while increasing sample heating time and extraction time increased GC peak area, increasing the lower detection limits. Two minutes extraction time gave peak areas 75% of that for 10 minutes extraction time. Both GC-MS and GC-FID were reliable methods for analysis with standard deviations being less than 5% of the average peak area obtained from the GC.Activated carbon was effective at removing geosmin and MIB, with 500 mg GAC per L removing 90% of the geosmin and MIB. Geosmin absorption showed a type II isotherm suggesting monolayer followed by multilayer absorption, while MIB absorption was almost linear. Langmuir-Freundlich and Freundlich isotherms fitted the MIB data well but not as well for geosmin. Oxidative treatment using H2O2 removed 84 % of geosmin and 49 % of MIB. UV degradation of geosmin and MIB using the Steriflo system removed up to 31 % of MIB and 76 % of geosmin after 4 hours. After 18 hours, geosmin had 84 % removal while MIB was only 66 %. Addition of H2O2 increased removal for MIB and geosmin up to 89 and 90 % respectively after 18 hours. Experimental results were simulated using a model that accounted for UV and hydrogen peroxide degradation, using one set of parameters over a range of conditions for each of MIB and geosmin.