Struvite production from food processing wastewater and incinerated sewage sludge ash as an alternative N and P source: Optimization of multiple resources recovery by response surface methodology

Abstract

Nitrogen (N) and phosphorus (P) cause eutrophication in water body, but they also act as an essential and limiting nutrient in agriculture. In this study food wastewater (FW) and incinerated sewage sludge ash (ISSA) were combined together as the alternative NH4+-N and PO43−-P sources to produce struvite. PO43−-P (67.0 g/kg SSA) was leached from the ISSA by acid and alkali treatment of ISSA. Multi-response surface methodology (RSM) has been applied to find the optimal condition for the maximal NH4+-N and PO43−-P recovery of 79.6% and 99.9%, respectively, from the mixed solution of ISSA leachate and centrifuged FW at pH 9.28, Mg/P 2, and N/P 0.6. Overall yields were 64.9% NH4+-N (27.1 g NH4+-N /L FW) and 72.7% PO43−-P (72.8 g T-P/kg ISSA) from the FW and ISSA, respectively. XRD, ICP-OES, and P-bioavailability analysis confirmed that the recovered precipitate had high struvite content (77.5%) and P-bioavailability (98.4%) with negligible heavy metals content. FW and ISSA were successfully combined together to produce struvite and it can be utilized as an effective fertilizer.