Scrap Iron Filings assisted nitrate and phosphate removal in low C/N waters using mixed microbial culture |
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Authors: | Sanjena Narayanasamydamodaran Jian e Zuo Haiteng Ren Nawnit Kumar |
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Affiliation: | 1. State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, China2. State Key Laboratory of Hydroscience and Hydraulic Engineering, Tsinghua University, Beijing 100084, China |
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Abstract: | • Microbes enhance denitrification under varying DO concentrations and SIF dosages. • Abiotic nitrate reduction rates are proportional to SIF age and dosage. • Over 80% of the simultaneously loaded NO3−-N and PO43− is removed biologically. This study focuses on identifying the factors under which mixed microbial seeds assist bio-chemical denitrification when Scrap Iron Filings (SIF) are used as electron donors and adsorbents in low C/N ratio waters. Batch studies were conducted in abiotic and biotic reactors containing fresh and aged SIF under different dissolved oxygen concentrations with NO3−-N and/or PO43- influent(s) and their nitrate/phosphate removal and by-product formations were studied. Batch reactors were seeded with a homogenized mixed microbial inoculum procured from natural sludges which were enriched over 6 months under denitrifying conditions in the presence of SIF. Results indicated that when influent containing 40 mg/L of NO3−-N was treated with 5 g SIF, 79.9% nitrate reduction was observed in 8 days abiotically and 100% removal was accomplished in 20 days when the reactor was seeded. Both abiotic and seeded reactors removed more than 92% PO43− under high DO conditions in 12 days. Abiotic and biochemical removal of NO3−-N and abiotic removal of PO43− were higher under independent NO3−-N/PO43− loading, while 99% PO43- was removed biochemically under combined NO3−-N and PO43− loading. This study furthers the understandings of nitrate and phosphate removal in Zero Valent Iron (ZVI) assisted mixed microbial systems to encourage the application of SIF-supported bio-chemical processes in the simultaneous removals of these pollutants. |
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Keywords: | Scrap iron filing Nitrate removal Phosphate removal Mixed culture denitrification Zero valent iron |
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