title: Simultaneous nitrate and phosphate removal from wastewater lacking organic matter through microbial oxidation of pyrrhotite coupled to nitrate reduction.
abstract: This study investigated the efficiency of a pyrrhotite autotrophic denitrification biofilter (PADB) technology for simultaneous N and P removal from wastewater lacking organic matter. A PADB was constructed with natural pyrrhotite as the biofilter medium and inoculated with autotrophic denitrifies enriched from anaerobic sludge. Over an operating period of 247 days, PADB efficiently removed NO3(-) and PO4(3-) simultaneously from wastewater that lacked organic matter. The hydraulic retention time (HRT), and influent NO3(-) and PO4(3-) concentrations affected the removal of NO3(-) and PO4(3-). A longer HRT led to lower concentrations of NO3(-) and PO4(3-) in the effluent. The PO4(3-) removal was influenced by NO3(-) removed; the more NO3(-) removed, the more PO4(3-) removed. As the synthetic wastewater containing NO3(-)-N of 28 mg L(-1) and PO4(3-)-P of 6 mg L(-1) in the absence of organic matter was treated by PADB at HRT of 24 h, total oxidized nitrogen (TON; NO2(-)-N + NO3(-)-N) and PO4(3-)-P concentrations of effluent were as low as 1.13 and 0.28 mg L(-1), respectively. When treatment of municipal wastewater treatment plant (WWTP) secondary effluent with TON of 21.11 mg L(-1) and PO4(3-)-P of 2.62 mg L(-1) at HRT of 24 h, the effluent TON was 1.89 mg L(-1) and PO4(3-)-P was 0.34 mg L(-1). PO4(3-) was removed through the formation of secondary minerals with Fe and Ca. These secondary minerals contained elevated phosphorus, which presents a potential for P recovery from wastewater.
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, 22 Hankou Road, Nanjing 210093, China. Electronic address: liruihua@nju.edu.cn.
authors.forename: Ruihua
authors.initials: R
authors.lastname: Li
authors.affiliation: Earth and Ocean Sciences, School of Natural Sciences and Ryan Institute, National University of Ireland, Galway, Ireland.
authors.forename: Liam
authors.initials: L
authors.lastname: Morrison
authors.affiliation: Microbiology, School of Natural Sciences, National University of Ireland, Galway, Ireland.
authors.forename: Gavin
authors.initials: G
authors.lastname: Collins
authors.affiliation: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, 22 Hankou Road, Nanjing 210093, China.
authors.forename: Aimin
authors.initials: A
authors.lastname: Li
authors.affiliation: Civil Engineering, College of Engineering and Informatics and Ryan Institute, National University of Ireland, Galway, Ireland. Electronic address: xinmin.zhan@nuigalway.ie.
authors.forename: Xinmin
authors.initials: X
authors.lastname: Zhan
mesh_terms: D058440:Denitrification; D009566:Nitrates; D009584:Nitrogen; D010710:Phosphates; D010758:Phosphorus; D014865:Waste Disposal, Fluid; D062065:Wastewater
chemical_list: D009566:Nitrates; D009584:Nitrogen; D010710:Phosphates; D010758:Phosphorus; D062065:Wastewater
keywords: Autotrophic denitrification; Biofilter; Pyrrhotite; Simultaneous nutrient removal; Wastewater lacking organic matter