Economic and energetic assessment of different phosphorus recovery options from aerobic sludge

Phosphorus removal from Wastewater Treatment Plant effluents is mandated by law under many circumstances, at the same time, the need for more efficient P recovery technologies in the form of valuable reusable products is also increasing, with the aim of conciliating environmental quality as well as the element's scarcity concerns. Several researchers have identified municipal wastewater as one of the most promising sources of phosphorus recovery, as other recovery pathways are often limited by leaks and short-circuits in the P anthropic cycle. Presently, phosphorus is traditionally removed from wastewater using chemical precipitation or biological methods, ending up in unusable products or excess sludge. Chemical (nonmetallic) precipitation, under controlled condition, could constitute a sustainable approach for achieving this goal, with the formation of struvite (magnesium ammonium phosphate hexahydrate) or other calcium phosphate compounds, which have great potential of being used as fertilizers. In this study, experimental and pilot-test conditions for recovery of P-based fertilizers from aerobically treated sludge are analyzed, estimating at the same time the economic and energy consequences of several process approaches on the treatment facility operation. (C) 2019 Elsevier Ltd. All rights reserved.