Amid the ongoing energy transition and the growing imperative for sustainable access to sanitation, solar technologies are emerging as a key component in wastewater treatment across Africa. A growing body of research underscores the increasing interest in these solutions, particularly in rural and peri-urban areas where access to conventional electricity infrastructure remains limited or absent (Organization, W. H., and Fund, U. N. C., 2021). Despite the continent’s substantial solar potential exceeding 2,000 kWh/m²/year in many regions (Taylor et al., 2022) the adoption and implementation of solar-powered treatment systems remain uneven and fragmented. Table 1 aims to shed light on current trends and to explore opportunities for scaling up the integration of solar energy in wastewater management throughout the African continent.

While solar-based technologies such as SODIS and AOPs offer promising pathogen removal and are well suited for decentralized contexts, they often lack robustness under fluctuating weather conditions (Sansaniwal, 2022). Additionally, despite high treatment performance in lab-scale studies, few long-term or large-scale deployments have been documented in Africa (Elmolla and Chaudhuri, 2010). There is also a lack of comparative life cycle assessments to evaluate environmental impact relative to conventional systems (Pichat, 2016).

Membrane processes have proven their effectiveness in treating both domestic and industrial wastewater around the world (Wintgens et al., 2005; Ulanicki et al., 2007; Al Aukidy et al., 2017; Frascari et al., 2018; Nqombolo et al., 2018; Wouter et al., 2019; Issaoui et al., 2022; Othman et al., 2022; Mzahma et al., 2023; Shehata et al., 2023). In Africa, the use of membrane technologies for wastewater treatment has also been documented (Obotey Ezugbe and Rathilal, 2020; Yusuf et al., 2020; Nasir et al., 2022; Phungela et al., 2024). Membrane bioreactors have been used not only for wastewater treatment, but also in combination with post-treatment processes such as microfiltration, ultrafiltration, nanofiltration, reverse osmosis, or electrodialysis, to improve the quality of treated water and thus enable its reuse (Al-Sayed et al., 2018; Tabraiz et al., 2023; Hoinkis et al., 2022). In a context of increasing pressure on water resources, these studies open up promising prospects for more sustainable water management on a continent where water stress affects large portions of the population (Lema, 2025).

South Africa stands out as one of the African countries where the use of membrane processes for wastewater treatment has been adopted by municipalities and industries, with several municipal and industrial wastewater treatment plants using membrane technologies currently in operation (Phungela et al., 2024; Richards et al., 2025). Studies on the application of membrane processes for wastewater treatment have also been reported. For example, Aziz and Kasongo (2021), Aziz and Kasongo (2021) achieved selective reuse levels of municipal wastewater treated by an MBR depending on the type of membrane used for post-treatment (ultrafiltration, nanofiltration, or reverse osmosis). Richards et al. (2025) evaluated the feasibility of reusing effluents from three decentralized membrane bioreactor (MBR) wastewater treatment facilities located in the Western Cape province of South Africa. The results showed that effluents from all facilities generally meet national irrigation standards, with only one facility requiring pH correction. The study emphasizes the importance of exploring alternative low-cost technologies for MBR effluent treatment, as well as the need for integrated managed aquifer recharge models to assess different groundwater replenishment scenarios. Meyo et al. (2021), for their part, investigated the use of an MBR as a post-treatment for poultry slaughterhouse wastewater in the city of Cape Town. Following treatment with an Expanded Granular Sludge Bed (EGSB) reactor, the MBR provided additional contaminant reduction, achieving peak removal efficiencies greater than 95% for TSS and COD, and up to 80% for fats, oils, and grease.

In North Africa, several studies on the use of membrane processes for wastewater treatment have been reported in Egypt, Morocco, Tunisia, and Algeria (Al Aukidy et al., 2017; Kitanou et al., 2018; Al-Sayed et al., 2023; Mzahma et al., 2023). In Tunisia, for example, the work of Jallouli et al. (2023) highlighted promising results in the treatment of textile industry wastewater using an immersed membrane bioreactor. A laboratory-scale pilot was used, consisting of a bioreactor (BR) equipped with a filtration unit containing polyester mesh with 30 µm pore diameter, operating at an influent flux of 30 LMH. The results showed a significant reduction in COD and DOC concentrations, reaching average values of 34 ± 10 mg/L and 32 ± 7 mg/L, respectively, corresponding to removal efficiencies of 96.0% ± 1.1% and 94% ± 1.05%. Removal rates of 96% for COD and 85% for color were also achieved. Ammonia (NH₃) was removed at a rate exceeding 97%, sulfates at 41%, and phosphates at 37%. The final pollutant concentrations were well below regulatory limits, demonstrating the effectiveness and viability of this technology for treating textile wastewater. In addition, Recent studies highlight the potential of waste-derived membranes for sustainable oily wastewater treatment. Research demonstrates that geopolymer membranes fabricated from waste bricks achieve >90% oil rejection when cured at 60 °C–80 °C, with an optimal liquid-to-solid (L/S) ratio of 0.30–0.35 enhancing cross-linking density and mechanical strength (Boushila et al., 2025). Similarly, work shows that membranes produced via phase inversion using discarded plastics and oasis fibers exhibit >90% separation efficiency, with polymer composition and pore structure governing permeability and fouling resistance (Zrelli et al., 2023). Additionally, ceramic membranes derived from oasis waste remove >85% of oils and suspended solids from car wash wastewater, outperforming conventional polymeric membranes in chemical stability and fouling resistance (Zrelli et al., 2022). Collectively, these studies underscore the viability of repurposing industrial and agricultural waste into high-performance membranes, offering cost-effective, eco-friendly alternatives for wastewater remediation while addressing waste valorization challenges. In Egypt, Abdel-Shafy and Abdel-Shafy (2017) also reported studies on the combined use of MF, UF, and NF for the extraction of valuable compounds from urine, as well as the use of MBRs for the treatment of blackwater and municipal wastewater. The organic loads in the MBR effluent consistently met the required standards. The results demonstrated high efficiency of the membrane bioreactor (MBR) for wastewater treatment. Applications of membrane technologies have also been reported in Burkina Faso, West Africa Sawadogo et al. (2018a), Nouhou Moussa et al. (2023), Nouhou Moussa et al. (2023) used a membrane bioreactor (MBR) for the treatment of brewery and sugar industry wastewater. These studies demonstrated chemical oxygen demand (COD) removal rates of up to 95%. The use of nanofiltration and reverse osmosis following the MBR led to organic matter and mineral removal rates reaching 99%, resulting in effluents suitable for reuse. Taking advantage of the favorable climatic conditions of the Sudano-Sahelian zone, anaerobic operation led to biogas production volumes of 0.21 L biogas/g COD removed for brewery wastewater (Sawadogo et al., 2018a; Sawadogo et al., 2018b; Sawadogo et al., 2022) and 0.32 L CH₄/g COD removed for sugar industry wastewater (Nouhou Moussa et al., 2023; Sawadogo et al., 2024). The high temperatures typical of the Sahelian climate are therefore favorable for anaerobic operation of the membrane bioreactor.

In East Africa Gukelberger et al. (2020), studied the use of a membrane bioreactor (MBR) for the treatment of domestic wastewater as part of a sustainable water management approach in the Lake Victoria region. The MBR was used to treat domestic wastewater to provide make-up water for a recirculating aquaculture system (RAS). They reported that the application of MBRs in wastewater treatment holds promising potential, not only for recirculating aquaculture systems, but also for the treatment of wastewater from fish processing in the Lake Victoria region.

While the performance of these waste-derived membranes is promising with oil rejection rates above 90% and strong chemical stability scalability remains a challenge. Most results stem from laboratory or pilot-scale studies. Furthermore, membrane fouling, mechanical durability, and variable composition of source waste materials could affect long-term reliability (Noureddine, 2021; Zrelli et al., 2023). There is a need for further field validation in diverse African conditions to assess lifecycle costs and maintenance requirements.

Membrane systems deliver excellent contaminant removal, especially in industrial settings; however, high energy requirements, membrane fouling, and costs of maintenance limit their accessibility in off-grid or rural areas. Moreover, although waste-derived membranes are an exciting innovation, their long-term durability and performance in real-world settings remain insufficiently explored (Obotey Ezugbe and Rathilal, 2020; Nasir et al., 2022).

Combined solar-membrane systems function as sustainable water treatment solutions in African areas because they address both the water scarcity problem and energy access issue. Membrane systems utilizing solar power combine RO with MBR and the joint UF-NF system to supply water throughout various parts of Africa.

The countries of Kenya Uganda and Tanzania together lead the way for decentralized solar-powered water treatment in East African regions. The Membrane Bioreactor (MBR) serving Kisumu Kenya’s tilapia farming receives daily 3–4 cubic meters of wastewater using a 14.3 kWp solar-powered system. A novel combination design obtains 40% self-power along with exceptional ammonium extraction capacities that guard fish health from toxicity and support thriving aquatic farming operations. The design’s ability to scale up leads to both environmentally sustainable fish farming alongside employment generation in the region thereby strengthening the area’s economic and environmental resistance (De et al., 2023). In Kampala Uganda they operate an MBR-GAC system powered by 7 kWp solar energy which processes 7–8 cubic meters of wastewater daily for irrigation needs coupled with toilet flushing. An aquaculture wastewater treatment system combined filtration tanks with denitrification and nitrification tanks, yet it retrieved most materials from local suppliers except for the monitoring unit and membrane module. The PES membrane module operating at 125 mbar pressure had a 25 m² flat surface area that delivered permeate flux between 10 and 15 L/m²/h while being measured periodically. The plant accomplished COD and TOC decreases of 50% while the nitrification reached an 80% level. The measured average rate of denitrification equaled 20%. Water quality significantly improved when the modified GAC installation managed to eliminate 90% of pharmaceutical residues. The acclimation of sludge in the system led to a remarkable 75% improvement in diclofenac removal efficiency because of increased hydraulic retention time and sludge retention time. The integration of supercapacitors with the system provides backup power for continued operation during blackouts and delivers 43% autonomous clean energy capabilities thus offering a sustainable and durable solution for hospital wastewater treatment (De et al., 2024).

A team evaluated solar-powered membrane filtration for treating contaminated water in Tanzanian rural areas having limited access to electricity along with clean water. The system applies an ultrafiltration step followed by nanofiltration to reach World Health Organization drinking water requirements (fluoride <1.5 mg/L) when treating water with 50–60 mg/L fluoride and 255 mg/L TOC organic matter in the natural water sources.

Solar photovoltaic panels directly wired to the system make the system independent from both power grid connections and power storage systems while solar irradiance varies. The clean water production rate reached 1,200 L per day while the energy consumption rate amounted to 1.5 kWh for every cubic meter of water. The system faced both organic matter buildup in the membrane and user acceptance towards the final product since it was deemed contamination-free (Shen et al., 2016; Schäfer et al., 2018).

North Africa leverages solar-membrane systems for industrial and municipal wastewater treatment. Researchers in Tunisia operated two membrane bioreactors at pilot scale next to a typical activated sludge treatment system in order to analyze water quality standards and energy consumption. The evaluation of MBR system energy usage indicated results matching or outperforming conventional system efficiency levels which stood at 3 kWh/m³. A solar integration system maintains diesel generator independence and demonstrates equivalent specific energy requirements to conventional systems to generate high-quality treated water. Integrated solar-MBR technology presents a sustainable method for decentralized domestic water treatment throughout North African regions as it provides effective irrigation solutions (Skouteris et al., 2014). In addition, the integration of green-synthesized TiO₂/MnO₂ nanoparticles into solar-powered membrane systems for the treatment of pulp and paper industry wastewater, with a particular focus on applications in Africa, especially Egypt. The solar-membrane system delivered outstanding performance since it eliminated chemicals present in wastewater by 85%–90% of COD and color together with suspended solids (Abed et al., 2024; Mousa et al., 2025). The introduction of TiO₂/MnO₂ nanoparticles into the system enhanced both photocatalytic under solar conditions and membrane flux and reduced fouling which increased membrane longevity. Operation of solar systems dramatically decreased running expenses making it an eco-friendly affordable method appropriate for Egypt’s water-scarce industrial regions.

Solar desalination combined with modular treatment has become a large-scale technology leader across Southern Africa. South African specialists have implemented solar energy into modular drinking water systems while integrating Combined Solar-Membrane Systems to solve water scarcity problems. The implemented systems demonstrated exceptional performance by reducing pathogens by 95% and attaining turbidity levels lower than 1 NTU while maintaining substantial total dissolved solids (TDS) elimination. The modular units leveraged solar energy while exploiting abundant sunlight for delivering sustainable and decentralized water solutions with energy efficiency. The results confirm that Combined Solar-Membrane Systems exhibit great potential for improving water access in distant South African areas which lack proper water services (Kumar et al., 2022). The Witsand facility in South Africa demonstrates an outstanding model of battery-independent solar desalination systems. The plant relies on Osmosun^® specialized technology to support reverse osmosis performance by automatically integrating grid power when solar input decreases especially during nighttime (Richards and Lipnizki, 2023).

Namibia opened its initial solar-powered desalination plant at the University of Namibia’s Henties Bay campus after partnering with Finnish companies. Solar PV reverse-osmosis technology operates at the Henties Bay plant to generate 3,500 L/h of clean water with an energy requirement of 2.five to three kWh/m³ that outmatches diesel-based systems by 40%. This desalination system effectively gets rid of 99.7% salts as well as 99.9% bacteria and 99.5% viruses while meeting WHO requirements and lowering the TDS from 35,000 ppm to less than 500 ppm. This plant reduces annual CO₂ emissions by 12 tons in addition to minimizing operational expenses through fossil fuel system reduction of 50–60 percent. This system combines modular convenience through which users can begin operations at 5 m³ per day for villages but can expand to 1,000 m³ per day for cities and features hybrid power backup that maintains system reliability beyond 95% standards. Treated water obtained through the filtration process helps increase crop production in experimental farms by 20%–30% as demonstrated through pilot projects. This model demonstrates solar desalination’s viability for arid regions, combining zero-emission operation, cost savings, and scalable water security—a blueprint for sustainable development in water-scarce areas (Hoffmann and Dall, 2018; Antti, 2019) (Table 3).

A successful implementation of large-scale solar-membrane wastewater treatment systems in Africa needs an organized multistakeholder collaboration. Key actions should include: creating enabling policy environments with targeted financial incentives to accelerate technology adoption; prioritizing context-specific research to adapt systems to local hydrological and climatic conditions; strengthening cross-sector collaboration through public-private partnerships to mobilize technical and financial resources; mainstreaming these solutions into national water security and climate resilience frameworks; and building local capacity through vocational training and community engagement programs to ensure sustainable operation and maintenance. A comprehensive approach tackles both technological implementation alongside sustainable operation to consolidate the technology’s potential benefits for enhancing water security throughout various African regions.

Despite their innovative design, some modular hybrid systems face limitations. For example, while energy autonomy is improved through PV integration and supercapacitors, performance can be inconsistent under fluctuating solar irradiance. Additionally, reliance on imported membrane modules or electronic monitoring systems may increase costs and reduce local ownership (Schäfer et al., 2018; Richards and Lipnizki, 2023). These factors should be carefully considered when scaling up in remote or resource-constrained areas.

A comparative Assessment of Technologies Based on Cost-Effectiveness, Environmental Sustainability, and Deployment Feasibility in Diverse African Contexts is given in table 2.

To facilitate cross-country analysis, the Table 3 summarizes the distribution, effectiveness, and contextual challenges of each technology.

Hybrid systems represent a promising integration of solar energy and membrane performance, especially for remote or semi-urban areas. However, their technical complexity, dependence on imported components (De et al., 2024), and lack of skilled local operators (Richards and Lipnizki, 2023) present real deployment barriers. There is also a gap in standardized methodologies for evaluating cost-benefit and resilience under climate variability (Zrelli et al., 2023). Research should focus on optimizing designs for modularity and local manufacturing potential.