Greener approach for microplastics detection in wastewater sludge using multimodal spectroscopic techniques

Area of Science:

• Environmental Science
• Analytical Chemistry
• Materials Science

Background:

• Wastewater sludge analysis is crucial for environmental monitoring.
• Conventional methods are time-consuming and reagent-intensive.
• Developing eco-efficient analytical workflows is a priority.

Purpose of the Study:

• To develop and validate an environmentally friendly analytical workflow for primary wastewater sludge.
• To integrate Ferro-sonication (Fe-UlS), density separation, and multimodal spectroscopy.
• To assess the workflow's efficiency, eco-friendliness, and analytical robustness.

Main Methods:

• Integrated Ferro-sonication (Fe-UlS) for solids reduction.
• Recyclable Zinc Chloride (ZnCl2) density separation (1.90 g/mL).
• Multimodal Laser Direct Infrared (LDIR) and Optical Photothermal Infrared (O-PTIR) spectroscopy for particle identification.

Main Results:

• Fe-UlS reduced total suspended solids by up to 98% in 30 minutes.
• LDIR detected 316 particles (10-500 μm), mainly polyurethane (56%).
• O-PTIR identified PTFE and Polycarbonate (PC) down to 6.4 μm, with a limit of detection of 60 particles/L.

Conclusions:

• The integrated workflow offers enhanced eco-efficiency by reducing reagent use and processing time.
• This method provides robust particle identification and quantification in wastewater sludge.
• The workflow presents a sustainable alternative to conventional sludge analysis protocols.