Biosolids, land, agriculture, health
Landspreading of sewage sludge remains the most economical and practical means for its disposal, with some countries, such as Ireland, disposing up to 90% to land. Its nitrogen, phosphorus and metal content make it an effective fertiliser replacement. However, there are potentially serious issues associated with its use in agriculture. These range from impacts on the environment through surface losses of nutrients, metals, pharmaceuticals and personal care products (PPCPs), and emerging contaminants, as well as build-up of contaminants in the soil and transfer to the human food chain. This paper details the main findings of an Irish Environmental Protection Agency (EPA)-funded study which investigated these issues. This study characterised treated sewage sludge (‘biosolids’) from wastewater treatment plants employing different means of sludge treatment, examined surface losses of various physico-chemical parameters following land application, measured metal uptake by ryegrass, and modelled the potential impacts on human health.