A Review of Sulfate Removal Technologies in Wastewater: A Perspective on Simultaneous Removal of Sulfate and Co-Existing Contaminants

The high concentrations of sulfate and other pollutants in various contaminated waters awaiting treatment have emerged as a global environmental challenge, frequently exceeding the discharge limits for pollutants in wastewater worldwide. Simultaneous removal processes for sulfate and other pollutants offer not only effective treatment but also potential significant economic benefits. Previous reviews have primarily focused on the sulfate removal efficiency and the associated economic and environmental benefits of single or combined technologies, with limited discussion on the simultaneous removal of sulfate and other aquatic pollutants. To address this gap, this review proposes an innovative perspective focusing on the co-removal performance and technical pathways of sulfate and other pollutants via various removal technologies, alongside an evaluation of their effectiveness. First, this paper summarizes the myriad pollutants potentially present in contaminated waters across various global scenarios and reviews existing fundamental sulfate removal processes, including chemical precipitation, ion exchange, and reverse osmosis. The advantages and limitations of these technologies in wastewater treatment are analyzed, with particular emphasis on their performance in the simultaneous removal of sulfate and other pollutants. Subsequently, the application of achieving simultaneous removal of sulfate and metal ions through the combination of multiple removal processes and the dynamic regulation of the crystallization process is analyzed. Finally, the review evaluates the economic and environmental viability of combined processes and dynamic regulation technologies, discusses the challenges encountered in practical applications, and outlines directions for future research. This review innovatively shifts the focus of sulfate removal technologies toward the simultaneous removal of sulfate and other pollutants, thereby promoting the development of sulfate removal technologies in a more efficient and sustainable direction.