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Microplastics in wastewater treatment plants and sewage sludge: Occurrence, fate under treatment, impacts, and mitigation

Year: 2026

Type: article

Abstract: Earlier sludge-focused reviews mapped the occurrence and detection of microplastics (MPs) in sewage sludge. This mini-review addresses a subsequent gap: the 2025–2026 evidence on dual particle- versus mass-based inventories, the interaction of MPs with antibiotic resistance genes (ARGs) under aging and polymer type, thermal hydrolysis process (THP) control of those markers, and laboratory- to pilot-scale adsorbents and process trains. Sewage sludge is a major sink for MPs that enter wastewater treatment plants (WWTPs). Conventional wastewater treatment moves a large share of MPs to the solid residuals, while specialized industrial streams can bring higher loads. Risk is thereby redistributed toward sludge rather than eliminated. National assessments confirm that sludge is essential for the terrestrial spread of MPs. Sludge processing stimulates interactions between MPs and the biological and thermal steps: composting or digestion can enrich or shift ARGs and mobile genetic elements; THP suppresses these markers. Sequential thermal–biological trains achieve the lowest final MP abundances reported among the compared configurations. Aged MPs enhance conjugative gene transfer. MP-derived dissolved organic matter (DOM) adds to the soluble carbon pool. Certain polyethylene particles affect methane generation in size-dependent ways. MPs also raise ARG abundance in sludge, intestinal, and plant settings. Biodegradable polymers may cause more severe adverse effects on resistance and virulence profiles than conventional plastics. Biochar amendments either accelerate MP degradation or provide high adsorption capacity for MPs. Advanced mass-based methods improve quantification accuracy. Integrated thermal–biological trains and engineered adsorbents currently offer the most promising control routes, although full-scale validation remains limited. The challenges and research and development needs for handling MPs in wastewater sludge are outlined at the end of this mini-review.

Source: Desalination and Water Treatment

DOI: 10.1016/j.dwt.2026.101994

Authors: Mini Ho, Jo-Shu Chang, Duu-Jong Lee

Institutions: National Taiwan University, Tunghai University, Yuan Ze University

Language: English

Topic: Microplastics and Plastic Pollution

Subfield: Pollution

Field: Environmental Science

Domain: Physical Sciences

SDGs: Responsible consumption and production, Clean water and sanitation, Good health and well-being

Open Access status: gold

Estimated APC paid: $1,000