Performance, water quality and enviro-economic investigations on solar distillation treatment of reverse osmosis reject and sewage water

Abstract

In this work, effective treatment of RO reject and domestic sewage water in a single step using indigenously developed tilted solar distillation unit has been proposed. Behavior of the unit along with its characteristics, treated water quality, environmental benefits and economics has been reported based on experimental observations. Around, 4.79 and 4.48 L/d of treated water are produced by the unit at a thermal efficiency of 48.5% and 45.3% during RO reject and sewage water distillation, respectively. Suspended particles of re-circulated sewage water caused clogging of wick and affected tilted solar distillation unit’s performance and efficiency. Smooth operation of the unit is noticed during RO reject distillation. The proposed unit could prevent at least 23.73 tons of CO2, 158.54 kg of SO2 and 64.75 kg of NO emissions during its 20 Yr life span. Wick replacement frequency and interest rate have a signification impact on distillation unit’s treated water production cost. The proposed distillation unit’s treated water production cost is lower than basin solar stills reported in literatures. Treated water is clear, odor free and bacterial free. Physical properties and heavy metal concentrations of treated water are well within the standards for safe drinking water except BOD (Biological Oxygen Demand) and COD (Chemical Oxygen Demand) such that the treated water can be used for other domestic and irrigation purposes. The results obtained from this study confirm solar distillation as an effective and sustainable option for wastewater treatment.