THE EFFECTS OF EXPOSURE TIME, TEMPERATURE, PH, AND AMMONIA CONCENTRATION ON THE INACTIVATION RATE OF ASCARIS EGGS
Abstract:The threat of disease transmission necessitates the reduction of pathogens in land-applied biosolids. Thermal inactivation has proven an effective technique, but other mechanisms may contribute to the rate of inactivation, thereby decreasing treatment time. These experiments detail the effect of ammonia, temperature, pH, and exposure time on the inactivation of the egg of the wastewater pathogen, ASCARIS. ASCARIS eggs were heated for 24 hours in various concentrations of ammonia and at different pH levels, rinsed, incubated in optimum growing conditions, and viewed microscopically for development. While pH had no effect on inactivation, increasing temperature did with the inactivation occurring over a narrow threshold temperature range. Within this range, a supplementary inactivation was seen in eggs suspended in high ammonia, high pH solutions. This supplementary inactivation is directly related to the concentration of unionized NH3 present in the solution. These findings may help explain the wide range of times needed for ASCARIS inactivation in sludge. In addition, an understanding of ammonia inactivation could have implications for the design of sludge treatment systems.
Document Type: Research Article
Publication date: January 1, 2003
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