Open AccessSynchronously recovering different nutrient ions from wastewater by using selective electrodialysis
Author(s) -
Yenan Li,
Zhi-Long Ye,
Ruili Yang,
Shaohua Chen
Publication year - 2022
Publication title -
water science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.406
H-Index - 137
eISSN - 1996-9732
pISSN - 0273-1223
DOI - 10.2166/wst.2022.352
Subject(s) - electrodialysis , chemistry , inorganic chemistry , potassium , electrolyte , cationic polymerization , chloride , struvite , magnesium , membrane , biochemistry , organic chemistry , electrode
Digestive slurry normally contains various nutrient ions with high concentrations, including NH 4 + , PO 4 3- , K + , Mg 2+ , Ca 2+ and SO 4 2- , which is a resource pool for nutrient recovery. In this study, a synchronously cationic and anionic selective electrodialysis (SCAE) was developed to recover anionic and cationic nutrient ions. Results showed that SCAE could synchronously recover more than 85.0%, 90.2% and 97.8% of PO 4 3- , SO 4 2- and other cations (including NH 4 + , K + , Ca 2+ , Mg 2+ ) from the simulated digestive slurry, respectively. The ionic permeation sequence, NH 4 + > K + > Ca 2+ > Mg 2+ for cations, and SO 4 2- > PO 4 3- for anions, was affected by hydrated radius and hydration numbers, and did not alter despite the variation in electric field. High electrolyte concentration in the product streams would promote the recovery efficiency of both divalent cations and anions due to the ionic replacement effect and the demand for charge neutrality. Under continuous operation, the maximum concentrations of PO 4 3- , SO 4 2- , Mg 2+ , Ca 2+ , NH 4 + and K + in product streams reached 231.9, 496.6, 180.7, 604.3, 9,648.4 and 4,571.4 mg·L -1 , respectively. By directly mixing different streams, the feasibility of producing mineral fertilizers without dosing externally precipitating chemicals was proved. Struvite, NH 4 HSO 4 and potassium chloride minerals were produced successfully. The outcome provided an optional method for nutrient recovery from wastewater.