de Lima Isaac Ricardo, Dos Santos Luciana Urbano, Tosetto Mariana S, Franco Regina Maura Bueno, Guimarães José Roberto
Department of Sanitation and Environment, School of Civil Engineering, Architecture and Urban Design, University of Campinas, UNICAMP - P.O. Box 6021, ZIP Code 13083-852, Campinas, Sao Paulo State, Brazil E-mail:
Laboratory of Protozoology, Department of Animal Biology, Biology Institute, University of Campinas, UNICAMP - P.O. Box 6109, ZIP Code 13083-970, Campinas, Sao Paulo State, Brazil.
J Water Health. 2014 Sep;12(3):465-73. doi: 10.2166/wh.2014.221.
Physicochemical treatment efficiency for unrestricted urban water reuse was evaluated at a conventional activated-sludge wastewater treatment plant (WWTP). Pilot plant set-up consisted of an alum coagulation step, granular media upflow flocculation and direct downflow dual-media filtration followed by ultraviolet disinfection (dose of 95 mJ cm⁻²). Optimum aluminum sulfate dosage of 10 mg L⁻¹ and coagulation pH 7.0 were preset based on bench scale tests. Under WWTP stable operation, water quality met United States Environmental Protection Agency (USEPA) suggested guidelines for unrestricted urban reuse regarding turbidity (mean value 1.3 NTU) and suspended solids (mean value 2.1 mg L⁻¹). When WWTP overall plant performance dropped from 90 to 80% (although BOD value stayed below 6 mg O₂ L⁻¹, suggesting unrestricted reuse), solids breakthrough in filtrate was observed. Microorganism removal rates were: total coliforms 60.0%, Escherichia coli 63.0%, Giardia spp. 81.0%, and helminth eggs 62.5%; thus organisms still remained in filtrate. Ultraviolet (UV) disinfection efficiency was 4.1- and 3.8-log for total coliforms and E. coli, respectively. Considering low UV efficiency obtained for helminths and the survival of protozoa and helminths in the environment, effluent quality presents risk to public health if destined for unrestricted urban reuse.
在一座传统活性污泥污水处理厂对城市污水无限制回用的物理化学处理效率进行了评估。中试装置包括硫酸铝混凝步骤、颗粒介质上流絮凝和直接下流双介质过滤，随后进行紫外线消毒（剂量为95 mJ cm⁻²）。基于实验室规模试验预先设定了10 mg L⁻¹的最佳硫酸铝剂量和7.0的混凝pH值。在污水处理厂稳定运行期间，水质符合美国环境保护局（USEPA）提出的关于无限制城市回用的浊度（平均值1.3 NTU）和悬浮固体（平均值2.1 mg L⁻¹）的指导方针。当污水处理厂的整体运行性能从90%降至80%时（尽管生化需氧量值保持在6 mg O₂ L⁻¹以下，表明可无限制回用），观察到滤液中有固体穿透。微生物去除率分别为：总大肠菌群60.0%、大肠杆菌63.0%、贾第鞭毛虫属81.0%和蠕虫卵62.5%；因此滤液中仍有微生物残留。紫外线（UV）消毒对总大肠菌群和大肠杆菌的效率分别为4.1对数和3.8对数。考虑到对蠕虫的紫外线消毒效率较低以及原生动物和蠕虫在环境中的存活情况，如果将出水用于城市无限制回用，其水质会对公众健康构成风险。
