Persistent Organic Pollutants in Bio-Based Fertilizers from Waste Sources

This study evaluates the presence of persistent organic pollutants—including PFAS, PCBs, PCDD/Fs, and PAHs—in bio-based fertilizers (BBFs) derived from agricultural, food industry, and sewage sludge waste. Most BBFs met national EU threshold limits, except for pyrolyzed sewage sludge, which showed elevated PAH levels. High extractable organic fluorine (EOF) in some BBFs indicates significant PFAS content, particularly in sewage sludge- and chicken manure-based products. Thermal treatments like pyrolysis and incineration at high temperatures reduced POP concentrations, though PAHs were sometimes formed as by-products. Biowaste and hygienized agricultural waste BBFs showed lower contaminant levels. Temporal trends show declining concentrations of legacy pollutants in sewage sludge, attributed to regulation and process improvements. Predictive modeling suggests BBF application results in low soil contamination risk, with minimal plant uptake and negligible contribution to human tolerable daily intake. However, PFAS bioavailability in vegetables remains a concern, warranting further monitoring and treatment optimization. The findings support the safe use of certain BBFs in circular agriculture but highlight the need for targeted controls on sewage sludge-derived products.