Department of Microbiology, Faculty of Science, Stellenbosch University, Private Bag X1, Stellenbosch 7602, South Africa.
Ecosystem Environmental Services S.A., Sant Andreu de Llavaneres, Barcelona, Spain.
Sci Total Environ. 2020 May 15;717:137223. doi: 10.1016/j.scitotenv.2020.137223. Epub 2020 Feb 8.
The efficiency of two large-volume batch solar reactors [Prototype I (140 L) and II (88 L)] in treating rainwater on-site in a local informal settlement and farming community was assessed. Untreated [Tank 1 and Tank 2-(First-flush)] and treated (Prototype I and II) tank water samples were routinely collected from each site and all the measured physico-chemical parameters (e.g. pH and turbidity, amongst others), anions (e.g. sulphate and chloride, amongst others) and cations (e.g. iron and lead, amongst others) were within national and international drinking water guidelines limits. Culture-based analysis indicated that Escherichia coli, total and faecal coliforms, enterococci and heterotrophic bacteria counts exceeded drinking water guideline limits in 61%, 100%, 45%, 24% and 100% of the untreated tank water samples collected from both sites. However, an 8 hour solar exposure treatment for both solar reactors was sufficient to reduce these indicator organisms to within national and international drinking water standards, with the exception of the heterotrophic bacteria which exceeded the drinking water standard limit in 43% of the samples treated with the Prototype I reactor (1 log reduction). Molecular viability analysis subsequently indicated that mean overall reductions of 75% and 74% were obtained for the analysed indicator organisms (E. coli and enterococci spp.) and opportunistic pathogens (Klebsiella spp., Legionella spp., Pseudomonas spp., Salmonella spp. and Cryptosporidium spp. oocysts) in the Prototype I and II solar reactors, respectively. The large-volume batch solar reactor prototypes could thus effectively provide four (88 L Prototype II) to seven (144 L Prototype I) people on a daily basis with the basic water requirement for human activities (20 L). Additionally, a generic Water Safety Plan was developed to aid practitioners in identifying risks and implement remedial actions in this type of installation in order to ensure the safety of the treated water.
两个大型批量太阳能反应器（原型 I（140 L）和 II（88 L））现场处理当地非正规住区和农业社区雨水的效率进行了评估。未处理的[水箱 1 和 Tank 2-（初雨）]和处理过的（原型 I 和 II）水箱水样定期从每个地点采集，所有测量的理化参数（例如 pH 值和浊度等）、阴离子（例如硫酸盐和氯化物等）和阳离子（例如铁和铅等）均在国家和国际饮用水标准限值范围内。基于培养的分析表明，大肠杆菌、总大肠菌群、粪大肠菌群、肠球菌和异养细菌计数在两个地点采集的未处理水箱水样中分别有 61%、100%、45%、24%和 100%超过饮用水指南限值。然而，两个太阳能反应器的 8 小时太阳能暴露处理足以将这些指示生物降低到国家和国际饮用水标准范围内，原型 I 反应器处理的水样中有 43%的异养细菌仍超过饮用水标准限值（1 对数减少）。随后的分子生存能力分析表明，原型 I 和 II 太阳能反应器中分析的指示生物（大肠杆菌和肠球菌属）和机会性病原体（肺炎克雷伯菌属、军团菌属、假单胞菌属、沙门氏菌属和隐孢子虫属卵囊）的平均总体减少率分别为 75%和 74%。因此，大容量批量太阳能反应器原型每天可以为 4 人（88 L 型 II）至 7 人（144 L 型 I）提供基本的人类活动用水（20 L）。此外，制定了通用的水安全计划，以帮助从业人员识别此类装置中的风险并采取补救措施，以确保处理水的安全性。
