Development of a novel phosphorus recovery system using incinerated sewage sludge ash (ISSA) and phosphorus-selective adsorbent

Abstract

Phosphorus is an essential nutrient but faces foreseeable resource depletion. The incinerated sewage sludge ash (ISSA) is a promising source for recovering phosphorus. In this study, we proposed a new system for recovering phosphorus from ISSA. This innovative system uses phosphorus-selective adsorbent to purify phosphorus from the ISSA acid leachate. Laboratory scale batch and column tests were performed to demonstrate the feasibility of the system. Note that >70% of phosphorus in ISSA can be recovered as a high-purity recovery product. The product showed a structure similar to hydroxyapatite (Ca₅(PO₄)₃OH). The total amount of Ca, P, and O in the product was above 90 wt%. The content of trace elements (As, Cd, Cr, and Pb) in the product was below the fertilizer limits, suggesting that the health and environmental risks of using fertilizer in agriculture are negligible. The expected costs of the system were estimated. The reusability of the adsorbent can reduce the operational costs to a satisfactory level. This study provides a practical alternative for recovering phosphorus from ISSA.

Keywords: Adsorbent; Fertilizer; Phosphorus recovery; Sewage sludge ash; Trace elements.