Solar Powered Distillation System in Dairy Effluent Treatment

Water is one of the key resources in the world, which is slowly becoming scarce due to the daily increase in demand. To fulfil the rising demand for water within the dairy processing industry, this paper aims to provide clean water by treating dairy effluent. If the effluent from the processing facility is directly discharged into water bodies, it poses significant dangers to aquatic animals and plants, as it contains several chemicals and impurities. Treating dairy effluent not only prevents water pollution but also generates high-quality fresh drinking water. In this work, it is proposed to integrate a concentrating photovoltaic thermal (CPVT) system with a dairy effluent treatment process, which generates both electricity and thermal output (hot water). The dairy effluent treatment process includes the following stages: screening, chemical coagulation, dissolved air flotation, sequential batch reactor (SBR), multi-effect distillation (MED), reverse osmosis (RO), and disinfection. After SBR, 40% of the effluent stream is directed to MED, while the remaining 60% is treated through RO, followed by disinfection. The final output of the plant is fresh drinking water. A plate heat exchanger is used to preheat the effluent, increasing its temperature from 25°C to 75°C before entering the MED. The hot fluid in the exchanger is sourced from the CPVT system. The plate and frame heat exchanger is designed using HTRI Xchanger software, while the CPVT system is modelled using TRNSYS software to simulate the electrical and thermal outputs. The treatment plant is designed to handle a capacity of 121.64 cubic metres per day, estimated to be generated by a medium-scale dairy manufacturing company producing various dairy products. The electrical load from the CPVT system powers different treatment stages involved in treating the dairy effluent.