An overview of the application of renewable energy for wastewater treatment and energy recovery from wastewater in sub-Saharan Africa wastewater treatment plants

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• Renewable energy can lead to self-sufficient WWTP, reducing operating costs and grid use. • Study reviews biogas, solar, hydro, and heat pumps for sustainable wastewater treatment. • High costs, technical issues, and varied WW composition slow renewable energy adoption. • Renewable energy in WWTP reduces emissions and promotes a circular economy. • Research is required on low-cost renewable energy and storage for sub-Saharan Africa. The growing global demand for sustainable energy and water management solutions has driven the integration of renewable energy into wastewater treatment plants (WWTPs). This review critically analyses the application of renewable energy for wastewater treatment, energy recovery from wastewater, and challenges and opportunities of incorporating renewable energy technologies, i.e. biogas, solar energy, hydroelectric power, and thermal energy, into wastewater management system, with a focus on Sub-Saharan Africa (SSA). Technological advancements, including energy recovery from anaerobic digestion (AD), are discussed in highlighting the potential of renewable energy to transform WWTPs into energy-sufficient facilities. Then, it explores the region’s unique challenges: high capital and operational costs, complexity of the renewable technologies, and heterogenous wastewater composition, which hinder the widespread adoption of these technologies. Despite these challenges, renewable energy integration presents significant opportunities: offsetting the high energy cost, diversifying energy sources, lowering reliance on grid electricity and reducing carbon emissions. The review concludes with research trends and implications for SSA. Current research in SSA is focused on optimizing renewable energy systems for wastewater treatment, neglecting the development of low-cost renewable energy technologies suited for SSA’s specific conditions and improvement of energy storage solutions.