Abstract In the context of sustainable agriculture and circular resource management, the use of wastewater treatment plant secondary sludge in agriculture represents an interesting opportunity. Its use is strictly regulated to guarantee environmental and food safety through analysis of both sludge and soils on which it was spread. The present article reports on 14 years of seven heavy metal analyses in the Walloon Brabant region (Belgium) from 2008 to 2022. A total of 6687 soil samples and 1578 sludge samples were analyzed in atomic absorption spectroscopy. The concentrations of heavy metals in both sludge and soils were below the regulatory limits (respectively for 98.1% and 97.7% of samples) and remained stable during the study period. The current management of sludge and its implementation at each stage of the chain (administration, sewage treatment plant operators, laboratories, and farmers) is successfully achieving its objectives regarding heavy metals.
Maesen et al. (Tue,) studied this question.