Chien Shih-Hsiang, Dzombak David A, Vidic Radisav D
Department of Civil and Environmental Engineering, University of Pittsburgh , Pittsburgh, Pennsylvania.
Environ Eng Sci. 2013 Jun;30(6):324-332. doi: 10.1089/ees.2012.0502.
Recent studies have shown that treated municipal wastewater can be a reliable cooling water alternative to fresh water. However, elevated nutrient concentration and microbial population in wastewater lead to aggressive biological proliferation in the cooling system. Three chlorine-based biocides were evaluated for the control of biological growth in cooling systems using tertiary treated wastewater as makeup, based on their biocidal efficiency and cost-effectiveness. Optimal chemical regimens for achieving successful biological growth control were elucidated based on batch-, bench-, and pilot-scale experiments. Biocide usage and biological activity in planktonic and sessile phases were carefully monitored to understand biological growth potential and biocidal efficiency of the three disinfectants in this particular environment. Water parameters, such as temperature, cycles of concentration, and ammonia concentration in recirculating water, critically affected the biocide performance in recirculating cooling systems. Bench-scale recirculating tests were shown to adequately predict the biocide residual required for a pilot-scale cooling system. Optimal residuals needed for proper biological growth control were 1, 2-3, and 0.5-1 mg/L as Cl for NaOCl, preformed NHCl, and ClO, respectively. Pilot-scale tests also revealed that was absent from these cooling systems when using the disinfectants evaluated in this study. Cost analysis showed that NaOCl is the most cost-effective for controlling biological growth in power plant recirculating cooling systems using tertiary-treated wastewater as makeup.
近期研究表明，经过处理的城市污水可成为可靠的替代淡水的冷却水。然而，污水中营养物浓度和微生物数量的升高会导致冷却系统中生物大量繁殖。基于三种氯基杀生剂的杀生效率和成本效益，对其在以三级处理污水作为补充水的冷却系统中控制生物生长的效果进行了评估。基于批次、实验室规模和中试规模实验，阐明了实现成功生物生长控制的最佳化学方案。仔细监测了浮游和固着阶段杀生剂的使用情况及生物活性，以了解这三种消毒剂在该特定环境中的生物生长潜力和杀生效率。诸如温度、浓缩倍数和循环水中氨浓度等水质参数，严重影响了循环冷却系统中杀生剂的性能。实验室规模的循环测试表明，其能够充分预测中试规模冷却系统所需的杀生剂残留量。适当控制生物生长所需的最佳残留量，以氯计，次氯酸钠、预制氯化铵和二氧化氯分别为1、2 - 3和0.5 - 1mg/L。中试规模测试还表明，使用本研究中评估的消毒剂时，这些冷却系统中不存在（此处原文缺失相关内容）。成本分析表明，在以三级处理污水作为补充水的发电厂循环冷却系统中，次氯酸钠在控制生物生长方面最具成本效益。
