Reynaert Eva, Greenwood Esther E, Ndwandwe Bonginkosi, Riechmann Michel E, Sindall Rebecca C, Udert Kai M, Morgenroth Eberhard
Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600, Dübendorf, Switzerland.
University of KwaZulu Natal, Pollution Research Group, 4041, Durban, South Africa.
Water Res X. 2020 Apr 8;7:100051. doi: 10.1016/j.wroa.2020.100051. eCollection 2020 May 1.
On-site wastewater reuse can improve global access to clean water, sanitation and hygiene. We developed a treatment system (aerated bioreactor, ultrafiltration membrane, granular activated carbon and electrolysis for chlorine disinfection) that recycles hand washing and toilet flush water. Three prototypes were field-tested in non-sewered areas, one in Switzerland (hand washing) and two in South Africa (hand washing, toilet flushing), over periods of 63, 74 and 94 days, respectively. We demonstrated that the system is able to recycle sufficient quantities of safe and appealing hand washing and toilet flush water for domestic or public use in real-life applications. Chemical contaminants were effectively removed from the used water in all prototypes. Removal efficiencies were 99.7% for the chemical oxygen demand (COD), 98.5% for total nitrogen (TN) and 99.9% for phosphate in a prototype treating hand washing water, and 99.8% for COD, 95.7% for TN and 89.6% for phosphate in a prototype treating toilet flush water. While this system allowed for true recycling for the same application, most on-site wastewater reuse systems downcycle the treated water, i.e., reuse it for an application requiring lower water quality. An analysis of 18 selected wastewater reuse specifications revealed that at best these guidelines are only partially applicable to innovative recycling systems as they are focused on the downcycling of water to the environment (e.g., use for irrigation). We believe that a paradigm shift is necessary and advocate for the implementation of risk-based (and thus end-use dependent) system performance targets to evaluate water treatment systems, which recycle and not only downcycle water.
现场废水回用可以改善全球获得清洁水、卫生设施和个人卫生的状况。我们开发了一种处理系统（曝气生物反应器、超滤膜、颗粒活性炭和用于氯消毒的电解装置），该系统可回收洗手和冲厕用水。三个原型在无下水道地区进行了实地测试，一个在瑞士（用于洗手），两个在南非（分别用于洗手和冲厕），测试周期分别为63天、74天和94天。我们证明了该系统能够在实际应用中回收足够数量的安全且适宜的洗手和冲厕用水，供家庭或公共使用。所有原型中的废水均有效去除了化学污染物。在一个处理洗手水的原型中，化学需氧量（COD）的去除效率为99.7%，总氮（TN）为98.5%，磷酸盐为99.9%；在一个处理冲厕水的原型中，COD的去除效率为99.8%，TN为95.7%，磷酸盐为89.6%。虽然该系统实现了同一用途的真正回用，但大多数现场废水回用系统将处理后的水降级使用，即将其用于水质要求较低的用途。对18项选定的废水回用规范进行分析后发现，这些指南充其量仅部分适用于创新回用系统，因为它们侧重于将水降级排放到环境中（例如用于灌溉）。我们认为有必要进行范式转变，并提倡实施基于风险（因此取决于最终用途）的系统性能目标，以评估不仅是将水降级使用而且还进行回用的水处理系统。
