Journal of Cleaner Production 340 (2022) 130809 Available online 3 February 2022 0959-6526/© 2022 Elsevier Ltd. All rights reserved. Harvesting biohydrogen from industrial wastewater: Production potential, pilot-scale bioreactors, commercialization status, techno-economics, and policy analysis Muhammad Abdul Qyyum a, 1 , Sherif Ismail b, c, 1 , Shou-Qing Ni b , Ihsanullah Ihsanullah d, *** , Rizwan Ahmad e , Amin Khan f , Ahmed Tawfk g, * , Abdul-Sattar Nizami h, i , Moonyong Lee j, ** a Department of Petroleum & Chemical Engineering, Sultan Qaboos University, Muscat, Oman b Shandong Provincial Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao, Shandong, 266237, China c Environmental Engineering Department, Zagazig University, Zagazig City, 44519, Egypt d Center for Environment and Water, Research Institute, King Fahd University of Petroleum and Minerals, Dhahran, 31261, Saudi Arabia e Department of Chemical and Energy Engineering, Pak-Austria Fachhochschule, Institute of Applied Sciences & Technology (PAF-IAST), Haripur, Pakistan f State Key Laboratory of Silicon Materials, School of Materials Science and Engineering, Zhejiang University, Hangzhou, 310027, China g National Research Centre, Water Pollution Research Department, 12622, Dokki, Cairo, Egypt h Sustainable Development Study Center, Government College University Lahore, Lahore, 54000, Pakistan i Centre of Excellence in Environmental Studies (CEES), King Abdulaziz University, Jeddah, Saudi Arabia j School of Chemical Engineering, Yeungnam University, Gyeongsan, 712–749, South Korea A R T I C L E INFO Handling editor: Cecilia Maria Villas Bˆ oas de Almeida Keywords: Biohydrogen production Industrial wastewater treatment Hydrogen economy Clean energy Fermentation ABSTRACT Herein, recent reports on hydrogen production from wastewater were comprehensively evaluated. There are numerous methods of biohydrogen production from various types of wastewater. Fermentation is one of the most promising methods of biohydrogen production from industrial wastewater owing to its ease of operation and rapid hydrogen production. The sequential dark/photo fermentation approach generated a maximum hydrogen yield (HY) of 7.1 mol H 2 /mol glucose with an estimated hydrogen production cost of 2.57 US $/kg and 2.83 US $/kg for dark and photo-fermentation, respectively. Pre-existing studies demonstrated that the successful implementation of pilot-scale fermentation bioreactors with a maximum hydrogen production rate (HPR) of 17 m 3 /m 3 ⋅d, but HPR is negatively correlated with reactor volume; more pilot-scale studies using high-strength wastewater for optimum performance are needed. The current implementation and commercialization chal- lenges during hydrogen production were also highlighted in this review. Furthermore, a literature survey revealed research gaps associated with optimum conditions for maximized biohydrogen yield. Numerous review studies in literature focus on biohydrogen potential from solid biowaste; nevertheless, a comprehensive review on biohydrogen from wastewater is still needed. The recommendations of this review are designed to facilitate researchers and policymakers in achieving sustainable development goals (SDGs), including clean water and sanitation (SDG 6), renewable energy (SDG 7), sustainable communities (SDG 11), and climate action (SDG 13). 1. Introduction Fossil fuels are the primary source of energy consumed worldwide (i. e., 87% of the total energy used) and are facing accelerated depletion as well as critical sustainability concerns (Martinez-Burgos et al., 2020). In addition, fossil fuel combustion foments global warming with its sig- nifcant greenhouse gas (GHG) emissions. Hydrogen, on the other hand, is a clean fuel and is considered an alternative biofuel that can be easily * Corresponding author. ** Corresponding author. *** Corresponding author. E-mail addresses: maqyyum@gmail.com, m.qyyum@squ.edu.om (M.A. Qyyum), engr.ihsan.dir@gmail.com, ihsankhan@kfupm.edu.sa (I. Ihsanullah), at. elmetwaly@nrc.sci.eg (A. Tawfk), mynlee@yu.ac.kr (M. Lee). 1 These authors contributed equally. Contents lists available at ScienceDirect Journal of Cleaner Production journal homepage: www.elsevier.com/locate/jclepro https://doi.org/10.1016/j.jclepro.2022.130809 Received 21 August 2021; Received in revised form 28 January 2022; Accepted 31 January 2022