Phosphorus recovery from fertilizer industrial wastewaters using bittern: Influence of wastewater composition and pH on struvite formation

Effluent from fertilizer-manufacturing facility contains a large amount of nutrients. In this study, wastewater was used to synthesize fertilizer-grade struvite through reaction with a bittern solution (denoted as R-B). The produced struvite was compared with different wastewater composition, including wastewater with added MgCl2.6H2O (R-Mg) and artificial wastewater with bittern solution (A-B). The results showed that the nutrient recovery of R-B was comparable to that of R-Mg sample, in which N and P were recovered by 64-68 % and 89-91 %, respectively. The nutrient recovery is feasible for crystallized struvite employing bittern. Energydispersive X-ray mapping profiles and X-ray diffraction revealed that the presence of impurities in real wastewater effect the crystal size and have attracted more mixed ions into struvite crystals. The solubility testing showed that N release in acidic and water was 23.3 wt% and 6.8 wt% after 60 days, indicating that the struvite was an extremely slow-soluble fertilizer for agricultural applications.