AWWA WQTC58912

The main objective of this study was to characterize the effects of water quality parameters on the inactivation kinetics of A.hydrophila (ATCC 7966) with monochloramine. An additional objective was to characterize the effect of dynamic disinfection on the inactivation kinetics of A. hydrophila with monochloramine. Variability in the inactivation kinetics of A. hydrophila observed in this study is also addressed. Preparation of bacterial suspension. A. hydrophila (ATCC 7966) in freezed-dried form was obtained from ATCC (American Type Culture Collection, Manassas, Virginia). Experimental procedures to recover the bacterial pellet and to prepare the bacterial suspension for disinfection experiments were described previously (Sirikanchana et al., 2002) with some exceptions. Bacterial suspension in the total volume of 25 ml, rather than 49 ml, was incubated in a 50-mL centrifuge tube at 30C and placed in a shaking incubator for 25 hours instead of 41.5 hours. Sterile glycerol was mixed with the bacterial suspension to obtain a final concentration of 25% (v/v) rather than 10% (v/v). The effect of water temperature on the inactivation kinetics of A. hydrophila with monochloramine was characterized by performing disinfection experiments at 5-30C. The experiments were performed with batch reactors immersed in a recirculating water bath. Synthetic solutions were used in this study. The pH was maintained constantly at pH 6 or 8 using 0.01 M phosphate buffer, or pH 10 using 0.01 M borate buffer. Monochloramine concentrations investigated ranged from 0.5 to 5 mg/L as Cl2. Experimental procedures for monochloramine disinfection and viability assessment followed the instruction as described by Sirikanchana et al. (2002). Includes 5 references, figure.