Abstract:Abstract}This paper compares the operation of a traditional single-stage system with a two-stage, reversible flow biodenitrification system for removing nitrates from drinking water. The purpose of this study was to investigate the ability of these two-stage systems to remove nitrate and residual organics from treated water as compared to single-stage units. In the reversible flow system, the second-stage (i.e. follow) reactor is operated in series with the first-stage (i.e. lead) reactor. After a given period… Show more
“…The accurate supply of the electron donor depends on the reaction stoichiometry, but the reported stoichiometric coefficients have not been consistent. For example, the reported carbon in the ethanol‐to‐nitrate (CH 3 CH 2 OH‐C:NO 3 − )‐N ratio (w/w) varied from 0.9 to 1.6 g C/g N (Woodbury & Dahab, 2001; Kapoor & Viraraghavan, 1997; Dahab & Kalagiri, 1996; Matějů et al, 1992). One reason for the variability is that these studies did not consider that ethanol was consumed for reduction of dissolved oxygen (DO).…”
mentioning
confidence: 99%
“…Phosphate (P) as a nutrient is sometimes required. In most studies, phosphate was supplied at a concentration greater than that required by stoichiometry to ensure it was not a limiting factor (Woodbury & Dahab, 2001; Dahab & Kalagiri, 1996). However, oversupply of phosphate is a poor practice because it wastes chemicals, increases the risk of calcium phosphate precipitation (Lee & Rittmann, 2003), and may spur biofilm growth in the distribution system (Sathasivan et al, 1997).…”
This article tests the theory of using nitrate carrier surface loading (SL) as the primary design criterion for heterotrophic denitrification of drinking water. Two load‐increase tests (flow rate and nitrate concentration) with a pilot‐scale heterotrophic biofilm reactor identified that the maximum SL was approximately 6 g nitrogen/m2/d and was controlled by the effluent nitrite concentration. A comparison of SL values obtained from the literature also showed that the maximum SLs were similar for a wide range of heterotrophic denitrification processes. All of the SL values are consistent, even though the empty bed contact time and the nitrate volumetric loading varied widely. The experimental results confirm that the electron donor should be supplied at the stoichiometric requirement to achieve simultaneously low concentrations of nitrate, nitrite, and organic carbon.
“…The accurate supply of the electron donor depends on the reaction stoichiometry, but the reported stoichiometric coefficients have not been consistent. For example, the reported carbon in the ethanol‐to‐nitrate (CH 3 CH 2 OH‐C:NO 3 − )‐N ratio (w/w) varied from 0.9 to 1.6 g C/g N (Woodbury & Dahab, 2001; Kapoor & Viraraghavan, 1997; Dahab & Kalagiri, 1996; Matějů et al, 1992). One reason for the variability is that these studies did not consider that ethanol was consumed for reduction of dissolved oxygen (DO).…”
mentioning
confidence: 99%
“…Phosphate (P) as a nutrient is sometimes required. In most studies, phosphate was supplied at a concentration greater than that required by stoichiometry to ensure it was not a limiting factor (Woodbury & Dahab, 2001; Dahab & Kalagiri, 1996). However, oversupply of phosphate is a poor practice because it wastes chemicals, increases the risk of calcium phosphate precipitation (Lee & Rittmann, 2003), and may spur biofilm growth in the distribution system (Sathasivan et al, 1997).…”
This article tests the theory of using nitrate carrier surface loading (SL) as the primary design criterion for heterotrophic denitrification of drinking water. Two load‐increase tests (flow rate and nitrate concentration) with a pilot‐scale heterotrophic biofilm reactor identified that the maximum SL was approximately 6 g nitrogen/m2/d and was controlled by the effluent nitrite concentration. A comparison of SL values obtained from the literature also showed that the maximum SLs were similar for a wide range of heterotrophic denitrification processes. All of the SL values are consistent, even though the empty bed contact time and the nitrate volumetric loading varied widely. The experimental results confirm that the electron donor should be supplied at the stoichiometric requirement to achieve simultaneously low concentrations of nitrate, nitrite, and organic carbon.
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