Biodegradation of Drinking Water Taste and Odour Causing Compounds; Geosmin and 2-MIB Using Native Bacteria; Bioremediation Approach for Green Solution
Posted: 4 Dec 2019
Date Written: December 3, 2019
Formation of odorous and tasty compounds in drinking water, especially earthy and musty taste and odour (T&O) compounds have been a common and recurrent issue in the drinking water sector. Although the health aspects of water are the primary focus, consumers generally judge the quality of water by its aesthetic value. T&O compound episodes are the cause for most consumer complaints and rejections especially related to portable water where the flavour and smell of the water is the only measure of water quality for the end-user. Geosmin (trans-1, 10-dimethyl-trans-9-decalol) and 2-MIB (2-Methylisoborneol) are the responsible earthy and musty taints in drinking water. Hence removing these two odorants from drinking water is a necessity for worldwide water authorities and consumers. Although there are several other methods available to remove T&O compounds in drinking water, with the inherent drawbacks and higher costs in all other methods, biodegradation has been proved to be a better approach to provide a sustainable solution. Therefore, the current study was designed to determine biodegradation capability of Geosmin and 2-MIB using native bacteria. Raw water samples were collected from 18 reservoirs which are used as source water for drinking. Isolation of Geosmin and 2-MIB degrading bacteria in water were carried out using standard enrichment study and potential degraders were screened using the Biolog MT2 plate assay. The selected Geosmin and 2-MIB bacteria degraders were subjected to degradation kinetics study and identiﬁcation was carried out using 16S rRNA gene sequencing. Morphologically different 160 bacteria colonies from Geosmin treated samples and 100 colonies from 2-MIB treated water samples were isolated. Biolog MT2 plate assay was positive for 45 Geosmin and 28, 2-MIB degrading bacteria. Three-gram negative (Pseudomonas stutzeri MK968348), (Acinetobacter guillouisae MK968347), (Acinetobacter indicus MK972672), and one-gram positive (Bacillus cereus MK968363) bacteria showed complete degradation of Geosmin & 2-MIB (initial level 20 ppt) at 7 days of incubation. Interestingly Bacillus cereus isolated from Kanthale wewa water, showed 100% degradation of Geosmin (initial level 20 ppt) within 24 hours of incubation when compared to control set up and other bacteria isolates (R2=0.9876). Further, Acinetobacter guillouisae isolated from Jayanthi wewa water, showed 100% degradation of Geosmin (initial level 20 ppt) at 2 days of incubation when compared to control set up and other bacteria isolates (R2=0.9681). Moreover, Pseudomonas stutzeri isolated from Padawiya wewa water, showed 100% degradation of 2-MIB (initial level 20 ppt) at 3 days of incubation (R2=0.9572). The Degradation mechanism showed pseudo first-order degradation kinetics. Further research is carried out by inoculating above bacteria into a sand filter to remove Geosmin and 2-MIB.
Keywords: biodegradation, geosmin, 2-methylisoborneol, native, green
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