Abstract
The effective use of non-oxidizing biocides is critical for maintaining microbial control in water treatment applications. A variety of methods and approaches may be used to improve and optimize biocide efficacy in these systems. Results of efficacy testing have shown improved killing of bacteria by biocides with the addition of selected surfactants and adjuvants. Enhanced microbial control may also be achieved by combinations of certain biocides which display a synergistic effect on mixed populations of organisms. Studies have also shown the benefit of rotating or alternating biocides to control resistant organisms which may develop following use of low doses of a single biocide. Collectively, these approaches may enhance the degree of control achieved in a given water system. Other ways to provide additional knowledge on biocide dosing and microbial control may be achieved through the use of model biofilm systems. Many variations of biofouling models have been used to evaluate biocide dosing strategies under simulated dynamic conditions; however, these systems were complicated and time-consuming to operate. Newer methods are available using microtiter plates for evaluating biocide efficacy against biofilm populations on surfaces. Other factors which contribute to effective use of biocide include the ability to monitor the biocide concentration to achieve more accurate dosing and using rapid microbiological methods for assessing microbial contamination.
