ACTINOMYCETES AS A FACTOR IN ODOR PROBLEMS AFFECTING DRINKING-WATER FROM THE NORTH SASKATCHEWAN RIVER

In 1991 the numbers of actinomycetes in the water from the North Saska tchewan River, the colour of the water and the flow rate of the river were all found to increase coincidentally at the onset of spring runof f. These same conditions had previously been associated with odours in the treated water. When more than one hundred actinomycete isolates f rom water samples were tested for their ability to produce geosmin and 2-methylisoborneol, the majority were able to produce one or both of these odorous compounds. When representative actinomycete isolates wer e tested for their susceptibility to disinfection with chloramine unde r conditions commonly encountered in water treatment processes, they g ave CT99 values varying from a low of 3.6 to a high of 92 (mg/l min). This wide range of sensitivities seen in the small numbers of isolates tested suggests that chloramine-resistant odour-causing organisms cou ld escape the water treatment processes during the spring runoff perio d. Odour problems could result from having these organisms become esta blished in the distribution system. In addition to their ability to pr oduce geosmin or 2-methylisoborneol, we found that two of three actino mycete isolates tested were able to transform the common pollutant and disinfection by-product 2,4,6-trichlorophenol into the extremely odor ous compound 2,4,6-trichloroanisole.