title: Effect of initial pH and pH-adjusted acid on nutrient recovery from hydrolysis urine by combining acidification with evaporation-crystallization.
abstract: Nutrient recovery from human urine is a promising pretreatment of domestic wastewater and provides a sustainable recyclability of nitrogen (N), phosphorus (P), and potassium (K). In this study, we present a method to recover all nutrients from hydrolysis urine (HU) in the form of solid products by combining acidification with evaporation-crystallization. The effect of initial pH (pHinit.) on N retention was investigated, and the optimal pHinit.was further determined by analysis of N retention efficiency. Additionally, crystallization process and product composition based on different pH-adjusted acids were also compared. The results revealed that pHinit.of HU was the key factor for N retention, and the optimal pHinit.was 4. In addition, compared with HCl and H2SO4, acidification by H3PO4could effectively reduce energy consumption and improve nutrient content in urine-derived solid products (UDSPs) but increase the acid consumption. The major compositions (mass percentage, %) in UDSPs-Cl, UDSPs-S, and UDSPs-P were salammoniac (80%), lecontite (41%) and ammonium nitrate sulfate (30%), and biphosphammite (84%), respectively. The results also demonstrated that the method of mixing of UDSPs-Cl/UDSPs-S and UDSPs-P and addition of fillers such as calcite, ground limestone, or ground dolomite into them is suitable for improving nutrient balance and fertilizer efficiency.
authors.affiliation: International Science & Technology Cooperation Center for Urban Alternative Water Resources Development, Key Lab of Northwest Water Resource, Environment and Ecology, MOE, Engineering Technology Research Center for Wastewater Treatment and Reuse, Xi'an, Shaanxi Province, China.|Key Lab of Environmental Engineering, Xi'an, Shaanxi Province, China.|Xi'an University of Architecture and Technology, No. 13, Yanta Road, Xi'an, 710055, China.
authors.forename: Shanqing
authors.initials: S
authors.lastname: Jiang
authors.affiliation: International Science & Technology Cooperation Center for Urban Alternative Water Resources Development, Key Lab of Northwest Water Resource, Environment and Ecology, MOE, Engineering Technology Research Center for Wastewater Treatment and Reuse, Xi'an, Shaanxi Province, China. xcwang@xauat.edu.cn.|Key Lab of Environmental Engineering, Xi'an, Shaanxi Province, China. xcwang@xauat.edu.cn.|Xi'an University of Architecture and Technology, No. 13, Yanta Road, Xi'an, 710055, China. xcwang@xauat.edu.cn.
authors.forename: Xiaochang
authors.initials: X
authors.lastname: Wang
authors.affiliation: International Science & Technology Cooperation Center for Urban Alternative Water Resources Development, Key Lab of Northwest Water Resource, Environment and Ecology, MOE, Engineering Technology Research Center for Wastewater Treatment and Reuse, Xi'an, Shaanxi Province, China.|Key Lab of Environmental Engineering, Xi'an, Shaanxi Province, China.|Xi'an University of Architecture and Technology, No. 13, Yanta Road, Xi'an, 710055, China.
authors.forename: Shengjiong
authors.initials: S
authors.lastname: Yang
authors.affiliation: International Science & Technology Cooperation Center for Urban Alternative Water Resources Development, Key Lab of Northwest Water Resource, Environment and Ecology, MOE, Engineering Technology Research Center for Wastewater Treatment and Reuse, Xi'an, Shaanxi Province, China.|Key Lab of Environmental Engineering, Xi'an, Shaanxi Province, China.|Xi'an University of Architecture and Technology, No. 13, Yanta Road, Xi'an, 710055, China.
authors.forename: Honglei
authors.initials: H
authors.lastname: Shi
mesh_terms: D003460:Crystallization; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D009584:Nitrogen / Q000032:analysis; D014556:Urine / Q000737:chemistry*; D014835:Volatilization
chemical_list: D009584:Nitrogen
keywords: Acid consumption; Crystallization; Fertilizer; Human urine; Nitrogen retention efficiency; Volume reduction factor