A comprehensive analysis of hydrogen production through electrolysis of industrial wastewater: Prospects and challenges

Sustainable hydrogen production is central to achieving global decarbonization and water stewardship goals. This review is the first to present an integrated techno-economic and environmental feasibility assessment of producing hydrogen from industrial wastewater in Bangladesh, directly linking high-strength effluent management with clean energy generation. Industrial wastewater, often untreated and rich in biodegradable organics, presents an underexploited feedstock that can simultaneously mitigate pollution, reduce freshwater consumption, and generate clean energy. However, such integrated analyses remain scarce, particularly in developing economies where industrial effluent discharge is a major sustainability challenge. This review assesses the feasibility of hydrogen generation from industrial effluents via dark fermentation (DF) and proton exchange membrane electrolysis (PEME), supported by advanced pretreatment strategies. DF achieves yields up to ∼3.5 ​L H2 L−1 effluent (∼3 ​mol ​mol−1 glucose) with strong cost advantages for high-COD (>1.5 ​g ​L−1) streams, while PEME offers >75 ​% electrical efficiency and offsets 9–12 ​L ​kg−1 H2 in freshwater demand when treated wastewater is used. Pretreatment methods physical, chemical, biological, and nanomaterial-ekgsnabled remove >90 ​% of inhibitory contaminants, enhancing system longevity. A Bangladesh case study illustrates the technology, cost, water-energy nexus, identifying DF as optimal for high-strength effluents and PEME as viable where low-cost renewable electricity and grid-service flexibility are prioritized. Addressing research gaps in pilot-scale validation, impurity-tolerant materials, and enabling policy frameworks can position wastewater valorization as a dual-benefit solution for SDGs 6 and 7, advancing both clean water and clean energy transitions.