Grant: Discovery Grants Program - Individual

It is widely recognized that drinking water ought to be free from disease-causing organisms, objectionable odours, turbidity, and any colours resulting from the dissolved substances. Some of the major sources of drinking water, namely surface water and groundwater, contain substances that cause offensive odours. Some of these odours have been commonly associated with the presence of low-oxidation state sulphur compounds in water. Sulphides and polysulphides are examples of such low-oxidation state sulphur compounds. Organic sulphur compounds such as trimethylsulphide are known as significant contributors to the offensive odours in water. These sulphur species with low oxidation states are produced during a variety of biotic and abiotic processes including the oxidation of hydrogen sulphide and sulphide minerals, sulfate reduction, and the transformation of organic sulphur compounds. My short term-goals include the characterization of these compounds in drinking-water sources. In particular, part of the proposed study will be aimed at examining whether any of the low-oxidation state ionic compounds of sulphur are responsible for the formation of the organic sulphides found in water. One of my long-term goals is to perform a mechanistic-approach study aimed at an understanding of how these reduced sulphur compounds form. My other long-term goal is geared towards providing useful practical steps necessary in the removal of offensive odours from water sources having such problems. Currently this is in part carried out through chlorination, which is primarily intended for removal of harmful microbes from our drinking water. The down side of chlorination is that any residual chlorine has the potential of reacting with some dissolved organic matter to produce trihalomethanes which are carcinogen-suspects. I will investigate whether other oxidizing agents are suitable for removing the objectionable odours from our drinking waters. This study is expected to significantly contribute towards the understanding of the processes that cause offensive odours in water and to the development of effective and environmentally-friendly means of dealing with these odours.