title: Characteristics of simultaneous ammonium and phosphate adsorption from hydrolysis urine onto natural loess.
abstract: Nutrient recovery from human urine is a promising pretreatment of domestic wastewater and provides a sustainable recyclability of N and P. In this study, batch experiments were conducted to identify the characteristics of natural loess (NL) for the adsorption and recovery of ammonium and phosphate from hydrolysis urine (HU). The adsorption mechanisms, the adsorption kinetics and isotherms, as well as the major influencing factors, such as pH and temperature, were investigated. Results revealed that adsorption of ammonium occurred by means of ion exchange and molecule adsorption with the ≡ Si-OH groups, while phosphate adsorption was based on the calcium phosphate precipitation reaction and formation of inner-sphere complexes with ≡ M-OH groups. The adsorption processes of ammonium and phosphate were well described by the pseudo-second-order kinetic model and the Freundlich isotherm model. Adsorption of phosphate was endothermic, while ammonium adsorption was exothermic. Furthermore, the maximum ammonium and phosphate adsorption capacities of NL was 23.24 mg N g(-1) and 4.01 mg P g(-1) at an initial pH of 9 and 10, respectively. Results demonstrated that nutrient-adsorbed NL used as compound fertilizer or conventional fertilizer superaddition was feasible for its high contents of N and P as well as its environmental friendliness.
authors.affiliation: Key Lab of Northwest Water Resources, Environment and Ecology, Ministry of Education, Xi'an University of Architecture and Technology, Xi'an, 710055, China.
authors.forename: Shanqing
authors.initials: S
authors.lastname: Jiang
authors.affiliation: Key Lab of Northwest Water Resources, Environment and Ecology, Ministry of Education, Xi'an University of Architecture and Technology, Xi'an, 710055, China. xcwang@xauat.edu.cn.
authors.forename: Xiaochang
authors.initials: X
authors.lastname: Wang
authors.affiliation: Key Lab of Northwest Water Resources, Environment and Ecology, Ministry of Education, Xi'an University of Architecture and Technology, Xi'an, 710055, China.
authors.forename: Shengjiong
authors.initials: S
authors.lastname: Yang
authors.affiliation: Key Lab of Northwest Water Resources, Environment and Ecology, Ministry of Education, Xi'an University of Architecture and Technology, Xi'an, 710055, China.
authors.forename: Honglei
authors.initials: H
authors.lastname: Shi
mesh_terms: D000327:Adsorption; D064751:Ammonium Compounds / Q000737:chemistry / Q000302:isolation & purification*; D005308:Fertilizers; D006801:Humans; D006868:Hydrolysis; D007700:Kinetics; D010710:Phosphates / Q000737:chemistry / Q000302:isolation & purification*; D013696:Temperature; D014556:Urine / Q000737:chemistry*; D062065:Wastewater / Q000737:chemistry*; D018508:Water Purification
chemical_list: D064751:Ammonium Compounds; D005308:Fertilizers; D010710:Phosphates; D062065:Wastewater
keywords: Adsorption mechanisms; Fertilizer; Hydrolysis urine; Natural loess; Nitrogen recovery; Phosphorus recovery