Salsali H R, Parker W J, Sattar S A
Department of Civil and Environmental Engineering, Carleton University, Ottawa, Canada.
Can J Microbiol. 2006 Apr;52(4):279-86. doi: 10.1139/w05-125.
It is known that the presence of volatile fatty acids may play a role in the inactivation of pathogens for systems that employ an acid phase reactor. This study was conducted to investigate the influence of volatile fatty acids on the inactivation of Salmonella spp. over a range of digestion temperatures. In this study, digesters that were treating municipal wastewater treatment plant sludges were operated at temperatures that ranged from 35 to 49 degrees C and had a solids residence time of 15 days. Samples collected from the effluent of the digesters were dosed with solutions containing acetic, propionic, and butyric acids alone and in mixtures, and the dosed effluents were analyzed for Salmonella spp. over time. In the first round of testing, the digester effluents were dosed with individual organic acids and also a mixture containing all three volatile fatty acids over a range of concentrations from 750 to 6000 mg/L, and the pH of the samples was fixed at a value of 5.5. In the second round of testing, the sample sludges were spiked with a fixed amount of organic acid mixture, and the pH was varied from 4.5 to 7.5. The reduction of Salmonella spp. in digester effluents, when dosed with volatile organic acids, was found to depend on pH, temperature, the chain length of the acids, and the concentration and composition of the acids present. Increases in temperature appeared to increase the inhibitory effects of the volatile organic acids. At mesophilic temperatures, acidic pHs resulted in a greater inhibition of Salmonella spp.; whereas at higher temperatures neutral pHs were found to be more inhibitory. The results suggest that acid phase digesters that operate at elevated temperatures and low pH can achieve substantial reduction of Salmonella spp.
众所周知，对于采用酸性阶段反应器的系统，挥发性脂肪酸的存在可能在病原体灭活中发挥作用。本研究旨在调查挥发性脂肪酸在一系列消化温度下对沙门氏菌灭活的影响。在本研究中，处理城市污水处理厂污泥的消化器在35至49摄氏度的温度范围内运行，固体停留时间为15天。从消化器流出物中采集的样品分别加入含有乙酸、丙酸和丁酸的溶液以及混合溶液，随时间对添加后的流出物进行沙门氏菌分析。在第一轮测试中，消化器流出物加入各种浓度范围为750至6000 mg/L的单一有机酸以及含有所有三种挥发性脂肪酸的混合物，样品的pH值固定为5.5。在第二轮测试中，样品污泥加入固定量的有机酸混合物，pH值在4.5至7.5之间变化。发现用挥发性有机酸处理时，消化器流出物中沙门氏菌的减少取决于pH值、温度、酸的链长以及存在的酸的浓度和组成。温度升高似乎会增加挥发性有机酸的抑制作用。在中温温度下，酸性pH值对沙门氏菌的抑制作用更大；而在较高温度下，发现中性pH值的抑制作用更强。结果表明，在高温和低pH值下运行的酸性阶段消化器可以实现沙门氏菌的大幅减少。
