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

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 NO3- removal, while there was no significant influence on POI43- removal. Lowering down HRT from 10 h to 5 h did not significantly influence NO3- and PO43- removal The NO3- removal performance and microbial community structure in the biofilters indicated that NO3- 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 PO43- removal was improved by the bio-oxidatiOn of Fe(II) in siderite to Fe(III) via the strain PXLI. The coexistence of the strain PXLI and natural siderite in nitrate contaminated aquifers provides a practical technology for in situ remediation of nutrient contaminated waterbodies. (C) 2018 Published by Elsevier Ltd.