TY - JOUR

T1 - Plastic input and dynamics in industrial composting

AU - Peneva, Stoyana

AU - Phan Le, Quynh Nhu

AU - Munhoz, Davi R

AU - Wrigley, Olivia

AU - Macan, Giovana P F

AU - Doose, Heidi

AU - Amelung, Wulf

AU - Braun, Melanie

PY - 2025/2/1

Y1 - 2025/2/1

N2 - Green and biowaste, processed within large facilities into compost, is a key fertilizer for agricultural and horticultural soils. However, due to improper waste disposal of plastic, its residues often remain or even lead to the formation ofmicroplastics (1 µm - 5 mm, MiPs) in the final compost product. To better understand the processes, we first quantified 'macroplastics' (> 20 mm, MaPs) input via biowaste collection into an industrial composting plant, and, then determined MiP concentrations at five stages during the composting process (before and after shredding and screening processes), and in the water used for irrigation. The total concentrations of MaPs in the biowaste collected from four different German districts ranged from 0.36 to 1.95 kg ton biowaste, with polyethylene (PE) and polypropylene (PP) representing the most abundant types. The "non-foil" and "foil" plastics occurred in similar amounts (0.51 ± 0.1 kg ton biowaste), with an average load of 0.08 ± 0.01 items kg and 0.05 ± 0.01 items kg , respectively. Only 0.3 ± 0.1 kg MaP t biowaste was biodegradable plastic. Compost treatment by shredding tripled the total number of MaPs and MiPs to 33 items kg , indicating an enrichment of particles during the process and potential fragmentation. Noticeably, a substantial amount of small MiPs (up to 22,714 ± 2,975 particles L ) were found in the rainwater used for compost moistening, being thus an additional, generally overlooked plastic source for compost. Our results highlight that reducing plastic input via biowaste is key for minimizing MiP contamination of compost. 

AB - Green and biowaste, processed within large facilities into compost, is a key fertilizer for agricultural and horticultural soils. However, due to improper waste disposal of plastic, its residues often remain or even lead to the formation ofmicroplastics (1 µm - 5 mm, MiPs) in the final compost product. To better understand the processes, we first quantified 'macroplastics' (> 20 mm, MaPs) input via biowaste collection into an industrial composting plant, and, then determined MiP concentrations at five stages during the composting process (before and after shredding and screening processes), and in the water used for irrigation. The total concentrations of MaPs in the biowaste collected from four different German districts ranged from 0.36 to 1.95 kg ton biowaste, with polyethylene (PE) and polypropylene (PP) representing the most abundant types. The "non-foil" and "foil" plastics occurred in similar amounts (0.51 ± 0.1 kg ton biowaste), with an average load of 0.08 ± 0.01 items kg and 0.05 ± 0.01 items kg , respectively. Only 0.3 ± 0.1 kg MaP t biowaste was biodegradable plastic. Compost treatment by shredding tripled the total number of MaPs and MiPs to 33 items kg , indicating an enrichment of particles during the process and potential fragmentation. Noticeably, a substantial amount of small MiPs (up to 22,714 ± 2,975 particles L ) were found in the rainwater used for compost moistening, being thus an additional, generally overlooked plastic source for compost. Our results highlight that reducing plastic input via biowaste is key for minimizing MiP contamination of compost. 

KW - Biowaste

KW - Microplastic pollution

KW - Composting

KW - Irrigation water

KW - Fragmentation

U2 - 10.1016/j.wasman.2024.11.043

DO - 10.1016/j.wasman.2024.11.043

M3 - Journal article

C2 - 39693994

VL - 193

SP - 283

EP - 292

JO - Waste Management

JF - Waste Management

SN - 0956-053X

ER -