In the heart of South Africa, where water scarcity is a pressing concern, a groundbreaking study led by Rhulani Shingwenyana from the Council for Scientific and Industrial Research (CSIR) is paving the way for innovative water reclamation techniques. The research, published in the journal ‘Desalination and Water Treatment’ (which translates to ‘Water Purification and Treatment’), explores the viability of using membrane distillation (MD) to reclaim clean water from municipal wastewater, integrating nutrient recovery in the process.
The study focuses on the use of two hydrophobic membranes, polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF), to treat wastewater that has undergone advanced nutrient removal processes. Shingwenyana and his team found that PTFE membranes outperformed PVDF, offering more favorable results for water reclamation. “PTFE was more favorable, while the effect of lower permeate/distillate temperature was found marginal,” Shingwenyana noted, highlighting the efficiency of PTFE membranes in this application.
A crucial aspect of the research was the pre-treatment of the wastewater before membrane distillation. Techniques such as sand filtration, activated carbon adsorption, and acidification/neutralization significantly enhanced the membrane flux and minimized the permeation of ammonia. This pre-treatment not only prevented scaling but also aided in increasing the pH of the solution, making the process more efficient and durable. “Pre-treating the struvite synthesis supernatant before membrane distillation grossly enhanced the flux of the membrane and minimized the permeation of ammonia,” Shingwenyana explained.
The results were promising, with PTFE membranes achieving an average mass flux of 1.4 g/cm²/h over an extended period, demonstrating their durability and effectiveness. The high-quality product water reclaimed through this process can be used in various applications, including agriculture, industry, or even as drinking water, albeit with the need for remineralization.
The implications of this research are far-reaching, particularly for the energy sector. As water scarcity becomes an increasingly critical issue, the ability to reclaim and reuse water efficiently can significantly impact industrial operations. The integration of nutrient recovery with clean water reclamation using membrane distillation presents a feasible option that not only valorizes municipal wastewater but also addresses water scarcity concerns.
“This study goes a long way in validating the applicability of this technology in clean water reclamation, thus demonstrating the feasibility of bridging the gap between brine-rich technologies and the zero-liquid discharge (ZLD) systems,” Shingwenyana stated. The research aligns with Sustainable Development Goal (SDG) 6: Clean Water and Sanitation, emphasizing the importance of sustainable water management practices.
As the world grapples with water scarcity and the need for sustainable water management, this research offers a glimmer of hope. The integration of nutrient recovery with clean water reclamation using membrane distillation could revolutionize the way we treat and reuse wastewater, paving the way for a more sustainable future. The study’s findings, published in ‘Desalination and Water Treatment’, provide a solid foundation for further exploration and implementation of this technology in various sectors, ultimately contributing to the global effort to achieve SDG 6 and ensure clean water and sanitation for all.