Presence of Microplastics and Mineral Matter in Biomass used for Anaerobic Digestion of Food and Kitchen Waste as Evidenced by FTIR ATR Spectroscopy

Anaerobic digestion of food and kitchen waste is becoming key source of renewable energy, green chemicals and organic fertilizers. However, contamination of the organic fraction with microplastics, usually originating from packaging, requires frequent recognition of the biomass feedstock quality. In our investigation, material identification of biowaste containing polymers and biopolymers was performed using Fourier Transform Infrared (FTIR) spectroscopy. Analysis of selectively collected municipal bio-waste revealed contamination with conventional plastics, while biodegradable plastics were less frequent. FTIR spectra indicated the plant-based nature of the biomass feedstock and, despite spectral complexity, provided satisfactory insights into the organic-to-mineral compounds quantitative ratio, which has practical value in biomass characterization.