Diatoms as ecological engineers in wastewater systems: a comprehensive review

Global wastewater generation continues to rise sharply, intensifying pressures on conventional treatment systems that are already constrained by high energy demand, sludge production, and poor removal of emerging contaminants. Diatoms have shown tremendous promise as natural bioremediation drivers capable of coupling pollutant removal with exceptional biomass valorization. However, the rapid expansion of research in this field has not been comprehensively synthesized. Unlike previous reviews that focus on isolated aspects of diatom-mediated wastewater remediation, provides a comparative and integrative synthesis of diatom-mediated wastewater remediation by linking frustule nanochemistry, extracellular polymeric substances (EPS), metabolic detoxification pathways, synthetic microbial ecology, and nanotechnology-enabled frustule functionalization within a single analytical framework We emphasize that frustule nanochemistry, extracellular polymeric substances, and engineered surface functionalization drive rapid adsorption of nutrients, metals, dyes, hydrocarbons, antibiotics, and pharmaceuticals, while metabolic assimilation pathways, biofilm physiology, and diatom–bacteria consortia regulate pollutant transformation, N and P cycling, and overall system stability. By organizing recent experimental findings into comparative multi-table frameworks, this review enables direct cross-evaluation of species-specific remediation efficiencies, heavy-metal uptake capacities, nutrient removal dynamics, engineered nanocomposites, and diatomaceous earth (DE) functionalization strategies. Emerging advances in nanotechnology, multi-omics, CRISPR-based engineering, microbial consortia design, and bioinspired materials are reshaping diatom-based remediation. Diatoms are increasingly viewed not only as biosorbents and biocatalysts but as integrated platforms combining adsorption, biodegradation, photocatalysis, and resource recovery. However, challenges remain in scalability, wastewater variability, biosafety, and regulatory approval. This review provides a forward-looking framework to advance diatoms as sustainable wastewater treatment agents within a circular bioeconomy.