Related Experiment Video
Updated: Nov 28, 2025
05:05
Quantification of Polybutylene Adipate Terephthalate-based Micro- and Nano-plastics from Soil Using Proton Nuclear Magnetic Resonance Spectroscopy
Published on: June 6, 2025
578
A highly efficient multi-step methodology for the quantification of micro-(bio)plastics in sludge
Federica Ruggero1, Alexandra E Porter2, Nikolaos Voulvoulis3
1Department of Civil and Environmental Engineering, University of Firenze, Firenze, Italy.
Summary
A new method efficiently identifies and quantifies microplastics and micro-bioplastics in sludge. This research is crucial for understanding plastic contamination in agricultural end-products from waste treatments.
Area of Science:
- Environmental Science
- Analytical Chemistry
- Materials Science
Background:
- Microplastics and micro-bioplastics pose environmental risks, particularly in agricultural applications derived from waste treatment.
- Current quantification methods are insufficient for micro-(bio)plastics, especially in complex matrices like sludge.
- Incomplete degradation of compostable bioplastics under suboptimal conditions can lead to their accumulation in final products.
Purpose of the Study:
- To develop and validate a multi-step methodology for the identification and quantification of micro-(bio)plastics in sludge.
- To assess the efficacy of the developed method for various sizes of plastic fragments.
- To apply the methodology to real-world samples from an anaerobic digestion plant and evaluate current legislative thresholds.
Main Methods:
- A multi-step approach involving initial oxidation with 35% hydrogen peroxide to remove organic matter.
- Subsequent flotation using sodium chloride solution to separate micro-(bio)plastics.
- Microscopic analysis of residues using a fluorescence microscope with a green filter for identification and quantification.
Main Results:
- The methodology demonstrated high removal efficacy: 94-100% for 0.5-2 mm fragments and 92-96% for 0.1-0.5 mm fragments.
- Polyethylene, starch-based Mater-Bi®, and cellophane microplastics were successfully recovered from food waste pulp samples.
- Significant amounts of microplastics (<2 mm and ⩾2 mm) were quantified, indicating potential contamination of organic fertilizers.
Conclusions:
- The developed methodology is effective for identifying and quantifying micro-(bio)plastics in sludge.
- Current legislative limits for plastic quantification in organic fertilizers (2 mm) may be inadequate due to the presence of smaller microplastic particles.
- Further research is needed to understand the fate of micro-(bio)plastics during biological waste treatment processes.
