Combining H2 Generation and Grey Water Recycling at Household Scale

Worldwide there is a rising demand for water and/or diminishing water resources, which is increasing the pressure on public water supplies. To contribute to this challenge, interest in domestic wastewater recycling systems is increasing. Concurrently there is also considerable interest in renewable energy sources such as generating H2 for small scale, decentralized systems. Associated with the H2 generated from the solar-powered electrolysis of water is the production of O2 which can be used to support the biological treatment of domestic wastewater, thereby enabling its partial re-use. As a preliminary evaluation of the feasibility of combining H2 generation and wastewater reuse/recycling at household scale, this project has considered the use of O2 for supporting a biological grey water treatment system. Based on assumed UK conditions, significant amounts of H2 and O2 can be generated via a matched photo-voltaic - PEM electrolysis system. The estimated H2 generated would be capable of satisfying 44% of energy needs for cooking, while the estimated O2 generated is sufficient in principle to satisfy the treatment of typical grey water flows via a membrane bioreactor process, in terms of BOD. The figures of merit of the proposed system are summarized and its potential impact on sustainability is described.