Wastewater treatment systems retain a significant proportion of microplastics (MPs) derived from domestic and industrial discharges; however, these emerging pollutants are not completely removed and tend to accumulate in the biological sludge generated during the treatment process. In this study, three biological-type wastewater treatment plants (WWTPs) located in Acapulco, Mexico, were analyzed. The concentrations of MPs in the biological sludge ranged from 830 to 9,300 items per liter. Using differential scanning calorimetry (DSC), the predominant polymers identified were high-density polyethylene (HDPE), polyethylene terephthalate (PET), and polypropylene (PP). It was estimated that the monthly concentrations of MPs in the sludge could reach up to 5.36 × 109 items/liter, while the annual concentrations could rise to 3.55 × 1010 items/liter. These findings highlight the urgent need to review and update the regulatory framework re-lated to the use of residual sludge for agricultural purposes since high loads of MPs and their transfer pose a potential risk to soil quality, ecosystem health, and long-term en-vironmental sustainability.

Wastewater treatment systems retain a significant proportion of microplastics (MPs) derived from domestic and industrial discharges; however, these emerging pollutants are not completely removed and tend to accumulate in the biological sludge generated during the treatment process. In this study, three biological-type wastewater treatment plants (WWTPs) located in Acapulco, Mexico, were analyzed. The concentrations of MPs in the biological sludge ranged from 830 to 9300 particles/L. Using differential scanning calorimetry (DSC), the predominant polymers identified were high-density polyethylene (HDPE), polyethylene terephthalate (PET), and polypropylene (PP). It was estimated that the monthly concentrations of MPs in the sludge could reach up to 5.36 × 10⁹ particles/L, while the annual concentrations could rise to 3.55 × 10¹⁰ particles/L. These findings highlight the urgent need to review and update the regulatory framework related to the use of residual sludge for agricultural purposes, since high loads of MPs and their transfer pose a potential risk to soil quality, ecosystem health, and long-term environmental sustainability.

The aim of this work was to carry out a microsynthesis of a graft copolymer from different starch sources with polycaprolactone (PCL) and to evaluate its effects on enthalpy during synthesis via differential scanning calorimetry (DSC). The copolymer was characterized via FTIR and pasting profile techniques. FTIR studies revealed that starch–PCL graft copolymerization was carried out on all starch sources. The pasting profile revealed that the copolymer presented low viscosity values (heating and cooling stages), compared with those of native starches. This finding indicates that copolymerization took place on the surface of the starch granules. Cassava starch presented the highest enthalpy values at synthesis temperatures of 150 °C and 160 °C.