Simultaneous removal of nitrate and phosphate from wastewater by siderite based autotrophic denitrification

Abstract The potential of simultaneous removal of nitrate and phosphate from wastewater by a single anaerobic Fe(II) oxidizing denitrifiers (the strain PXL1) was assessed using siderite biofilters under different influent TOC concentrations and hydraulic retention times (HRTs) over a 160-day trial. Higher TOC concentrations promoted NO 3 − removal, while there was no significant influence on PO 4 3− removal. Lowering down HRT from 10 h to 5 h did not significantly influence NO 3 − and PO 4 3− removal. The NO 3 − removal performance and microbial community structure in the biofilters indicated that NO 3 − was reduced to N 2 by both strain PXL1 and heterotrophic Acidovorax delafieldii . Iron content analysis of the used siderite along the biofilters showed that PO 4 3− removal was improved by the bio-oxidation of Fe(II) in siderite to Fe(III) via the strain PXL1. The coexistence of the strain PXL1 and natural siderite in nitrate-contaminated aquifers provides a practical technology for in situ remediation of nutrient contaminated waterbodies.