Environmental Engineering and Management Program, School of Environment, Resources and Development, Asian Institute of Technology, P.O. Box 4, Khlong Luang, Pathumthani, 12120, Thailand.
Environmental Engineering and Management Program, School of Environment, Resources and Development, Asian Institute of Technology, P.O. Box 4, Khlong Luang, Pathumthani, 12120, Thailand; Department of Environmental Microbiology, Eawag: Swiss Federal Institute of Aquatic Science and Technology, 8600, Dubendorf, Switzerland.
Water Res. 2019 Apr 15;153:53-62. doi: 10.1016/j.watres.2019.01.006. Epub 2019 Jan 16.
In many low-income countries, the poor conditions of sanitation systems have been a significant cause of mortality since they accelerate waterborne disease transmission. Developing sanitation systems in these countries is a pressing concern in both the public and private sectors. This research investigated a decentralized domestic wastewater treatment system using ultraviolet light-emitting diodes (UV-LEDs). Although UV-LED disinfection has become more widespread in recent years, it is a novel approach for domestic wastewater treatment. Domestic wastewater was pretreated by a low-cost pretreatment system with an inclined settler and a sand filter prior to feeding a novel flow-through UV LED reactor. At an inlet flow rate of 30 L/h, the COD, TSS, and turbidity of the effluent were 17.7 mg/L, 3.0 mg/L, and 3.9 NTU, respectively. UV transmittance at 285 nm was enhanced from 29.1% to 70.4%, improving the influent quality for UV LED disinfection. The flow-through UV LED reactor was operated at various flow rates from 10 to 50 mL/min, resulting in applied UV doses of 69.4 to 47.8 mJ/cm respectively. These doses are sufficient for inactivating total coliforms in the wastewater to meet the water reuse guidelines for agriculture for both processed food crops and non-food crops. Fouling, which was observed starting at 2 d of operation, decreased the disinfection efficacy to 27% after 25 days of continuous operation. Of the fouling layer, 67% was attributed to organic matter, in contrast to previous fouling studies with mercury UV lamps in which the fouling layer consisted primarily of inorganic compounds. The fouling was reversed by off-line citric acid cleaning for 4 h after every 400 h of continuous operation.
在许多低收入国家，卫生系统条件恶劣是导致死亡率上升的一个重要原因，因为这会加速水传播疾病的传播。在这些国家发展卫生系统是公共和私营部门的当务之急。本研究调查了一种使用紫外线发光二极管（UV-LED）的分散式家庭废水处理系统。尽管近年来 UV-LED 消毒变得更加普遍，但它是一种处理家庭废水的新方法。家庭废水在进入新型流通式 UV-LED 反应器之前，先经过低成本预处理系统，包括斜沉池和砂滤器进行预处理。在入口流速为 30 L/h 的情况下，出水的 COD、TSS 和浊度分别为 17.7 mg/L、3.0 mg/L 和 3.9 NTU。在 285nm 处的 UV 透射率从 29.1%提高到 70.4%，改善了 UV-LED 消毒的进水质量。流通式 UV-LED 反应器在 10 至 50 mL/min 的不同流速下运行，分别产生 69.4 至 47.8 mJ/cm 的应用 UV 剂量。这些剂量足以使废水中的总大肠菌群失活，符合农业用水再利用指南中对加工食品作物和非食用作物的要求。从运行第 2 天开始观察到的结垢现象，在连续运行 25 天后，使消毒效果降低至 27%。在结垢层中，有 67%是有机物，而之前使用汞 UV 灯进行的结垢研究中，结垢层主要由无机物组成。在连续运行 400 小时后，每 400 小时离线进行 4 小时柠檬酸清洗，可以逆转结垢。
