Currently, new processes for recycling P from wastewater streams were developed during the last years. In one incubation experiment, two pot experiments and one two-year field experiment the P fertilizing effect of struvite, one solar dried sewage sludge, one untreated (ut) sewage sludge ash (SSA) and five different treated SSAs were analyzed in comparison to a commercial P fertilizer. The results illustrated that these recycled products are promising renewable P fertilizers, whereby struvite is suited best due to its low contamination level and its high P bioavailability.<eng>
