In-situ synthesis/purification integration strategy for simultaneous capture of ammonium and phosphorus from digested piggery wastewater using magnesium-doped tricalcium aluminate

• In-situ synthesis/purification integration (ISSPI) strategy was adopted for NH 4 + and PO 4 3- removal. • The strategy was achieved based on constructing Mg-doped tricalcium aluminate (Mg-C 3 A). • Mg-C 3 A exhibited excellent capacities for NH 4 + (43.0 mg·g −1 ) and PO 4 3- (20.2 mg·g −1 ). • The hydration properties of Mg-C 3 A played vital roles in the ions removal/recovery. • ISSPI strategy using Mg-C 3 A was compelling for authentic wastewater treatment. Simultaneous capture of ammonium (NH 4 + -N) and phosphate (PO 4 3− -P) in digested piggery wastewater is of great urgency yet remains a challenge. Recently, the in-situ synthesis/purification integration (ISSPI) strategy, with the essence of converting contaminations to high value-added products, has aroused great enthusiasm in the environmental remediation realm. In the present work, we employed ISSPI method for simultaneous elimination and recovery of NH 4 + and PO 4 3- from digested piggery wastewater based on the construction of a novel material system, i.e. , Mg-doped tricalcium aluminate (Mg-C 3 A), which coupled the features of cement-based material tricalcium aluminate (Ca 3 Al 2 O 6 , C 3 A) and Mg dopants. The released metal cations (Ca 2+ , Mg 2+ , and Al(OH) 4 − ) of Mg-C 3 A were expected to act as precipitation agents to capture NH 4 + and PO 4 3− via the formation of Ca(NH 4 ) 2 (HPO 4 ) 2, MgHPO 4 ·3H 2 O or AlPO 4 ; OH − established an alkaline environment for the enhancement of NH 4 + removal via neutralization; Mg 2+ played a major role in the recovery of NH 4 + and PO 4 3− , with the formation of valuable struvite as fertilizer. Benefited by these functions, Mg-C 3 A exhibited superior removal capacity for NH 4 + (43.0 mg·g −1 ) and PO 4 3− (20.2 mg·g −1 ). More importantly, the ISSPI method using Mg-C 3 A was prospective to be applied for authentic effluent treatment as demonstrated by response surface methodology (RSM), with the concentration of both ions down to the discharge standard of livestock and poultry breeding, China (80 mg·L −1 for NH 4 + ; 8 mg·L −1 for PO 4 3− ). This research provided an alternative and promising approach for the simultaneous removal and recovery of NH 4 + and PO 4 3− from digested piggery effluent, shedding light on environmental remediation.