Simultaneous nitrate and phosphate removal from wastewater lacking organic matter through microbial oxidation of pyrrhotite coupled to nitrate reduction

摘要

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 NOT and PO43- simultaneously from wastewater that lacked organic matter. The hydraulic retention time (HRT), and influent NOT and PO43- concentrations affected the removal of NO3- and PO43-. A longer HRT led to lower concentrations of NOT and PO in the effluent. The POT removal was influenced by NOT removed; the more NOT removed, the more PO43- removed. As the synthetic wastewater containing NOT -N of 28 mg L-1 and PO43- 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 PO43- -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 PO P of 2.62 mg L-1 at HRT of 24 h, the effluent TON was 1.89 mg L-1 and PO43- -P was 0.34 mg L-1. PO43- 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. (C) 2016 Elsevier Ltd. All rights reserved.