Hydrogen production from wastewater: A comprehensive review of conventional and solar powered technologies

The need to reduce the carbon footprint of conventional energy sources has made green hydrogen a promising solution for the energy transition. The most environmentally friendly way to produce hydrogen is through water-based production using renewable energy. However, the availability of fresh water is limited, so switching to wastewater instead of fresh water is the key solution to this problem. In response to this issue, the present review reports the main findings of the research studies dealing with the feasibility of hydrogen production from wastewater using various technologies, including biological, electrochemical, and advanced oxidation routes. These methods have been studied in a large number of experiments with the aim of investigating and improving the potential of each method. On the other hand, the maturity of solar energy technologies has led researchers to focus on the possibility of harnessing this source and combining it with wastewater treatment techniques for the production of green hydrogen. Therefore, the present review pays special attention to solar driven hydrogen production from wastewater, by highlighting the potential of several technologies for simultaneous water treatment and green hydrogen production from wastewater. Recent results, limitations, challenges, possible improvements and techno-economic assessments reported by several authors, as well as future directions of research and industrial implementation in this field are reported.