District Heat-driven Membrane Distillation for Drinking Water Purification

Abstract: The demand for clean and accessible water is growing worldwide due to population growth and still millions are without this necessity. Urban areas are developing rapidly but adequate water is frequently a deficiency in these areas. Bottled water is often the solution to this problem but a more thoughtful alternative in terms of cost and environmental impact would be preferable. Membrane distillation presents as an alternative for this problem. Membrane distillation is a thermally driven water purification process which requires heat as an energy source. A source of heat which have become more widespread in urban areas today is district heating. The integration of membrane distillation with district heating could therefore provide an environmentally and economically sustainable solution for clean and accessible water. This thesis presents a techno-economic and environmental analysis of a potential integration of a membrane distillation unit with district heating network. The focus of the study has been on finding and evaluating costs for a membrane distillation system integrated with district heating as well as examining the environmental impact from the purification process. The study use Germany as a case example for the integration and commercialization of membrane distillation technology as the country have a developed district heating network in urban areas and a high consumption of bottled water. The findings from the study is that, for the system design employed, the cost for water purified with membrane distillation is $0.0111/litre, which is cheaper than the average price of bottled water in Germany ($0.3/litre). The environmental impact for water purified with membrane distillation is 0.024 kg CO2e/litre, which is significantly lower than the environmental impact from bottled water (0.225 kg CO2e/litre).