Increased phosphorus recovery from sewage sludge through an innovative one-step combustion process
To reach a resource efficient society, material loops have to be developed. The phosphorus is particularly urgent in order to ensure a sustainable food production. More than 90% of the phosphorus (P) fertilizers used for food production in the world comes from P-mines. According to expertize these mines will be depleted in 50 to 100 years. The P from the food production is transported in the food chain, through humans, to the sewage and collected in the sludge. The sludge is thus rich on P and some is used as fertilizer back on farmland. However, the sludge is not only rich on P; it contains medicines, resistant bacteria, micro plastics, dioxins and heavy metals also ending up on the farmland. If the sludge instead is combusted, a P-rich ash is produced, while organic pollutants are destroyed. By the proposed innovative combustion process the remaining heavy metals will be volatilized and a pure P-rich ash fertilizer will remain. The heavy metals i.e. Cd is removed from the eco-system.
