Phosphorus recycling from sewage sludge: more fertilizer, fewer heavy metals: Phosphorus is essential as an agricultural fertilizer. Globally, this indispensable element is becoming increasingly scarce, putting an increasing focus on recovery where natural phosphate deposits are rare. Glatt Ingenieurtechnik GmbH has further developed its patented PHOS4green fertilizer production process so that sewage sludge ash from conurbations with high heavy metal contents can be used. Their removal means that fewer pollutants are released into the environment. Glatt has expanded its PHOS4green process to facilitate the legally compliant recovery of valuable materials from sewage sludge ash contaminated with heavy metals