Abstract
Silica fouling reduces the effectiveness and durability of membrane-based treatment systems, and silicon contamination in industrial water streams poses ongoing operational issues. With an emphasis on their processes, drawbacks, and applicability for various silica species, this article provides a comparative examination of the main silica removal technologies: ion exchange, reverse osmosis (RO), ultrafiltration (UF), electrocoagulation (EC), adsorption, and lime softening. Although they need a significant amount of chemical input and pH control, lime softening and ion exchange are efficient for dissolved silica. RO requires thorough preparation and offers broad-spectrum separation, although it is susceptible to silica scaling. While UF works well with colloidal and particulate silica, it is unsuccessful with monomeric forms. EC achieves excellent removal rates with less sludge by combining electrochemical destabilisation and crystallisation. Adsorption provides variable selectivity, low energy consumption, and compatibility with membrane systems, especially when employing tailored materials like activated alumina, iron oxide-coated media, and functionalised hybrids. In addition to outlining important techno-economic considerations for scaling up silica extraction methods in intricate industrial water matrices, the paper highlights new developments in adsorbent design, such as surface modification, hierarchical porosity, and regeneration techniques.