Abstract
The aim of this study was to assess the impact of sucrose as external carbon source on denitrification. The specific denitrification rate (SDNR) determined using batch tests showed that acclimation to sucrose can increase SDNR in post and pre-anoxic denitrification zones by 47% and 116%, respectively. The use of sucrose in pre-anoxic zone led to an SDNR of 2.72±0.15 mg NO3- N/g MLVSS/h. This is 2.1 times higher than in the absence of external carbon and 1.7 times higher than the SDNR when sucrose was added into post-anoxic zone. The experiment has also tested the effect of sucrose on a pre-anoxic denitrification system with low carbon-to-nitrogen ratio (C/N) influent of 7.2 by adding roughly 150mgCOD/L of sucrose into the pre-anoxic zone. This was done through two simulation modellings before the results were verified with a pilot plant trial run. The two simulation models (a basic conceptual model and Biowin) showed a drop of effluent TN from 31.8±8 mg/L to 17.7±2.2 mg/L and 23.7±10.3 mg/L respectively. While the pilot plant test showed a clear drop from 32.7±4.7 mg/L down to 17.7±5.5 mg/L after adding sucrose. The result showed that the conceptual model was providing a more accurate simulation run than the Biowin model in this case.
Highlights
The availability of organic carbon is one of the key elements for complete denitrification as it is often the limiting substrate for this process [1,2,3]
Adding an external carbon source into post- or pre-anoxic zone allows for increased denitrification, while requires little modifications of an existing WWTP
Finding an alternative cost-effective external carbon substance is amongst the priorities of the wastewater treatment industry for the past two decades [1]
Summary
The availability of organic carbon is one of the key elements for complete denitrification as it is often the limiting substrate for this process [1,2,3]. Adding an external carbon source into post- or pre-anoxic zone allows for increased denitrification, while requires little modifications of an existing WWTP. Methanol is the most used and documented carbon source [4], and was recommended by the US EPA as the most appropriate choice for additional substrate because of their availability, low production of sludge, and no additional nitrogen would be introduced into the system. Finding an alternative cost-effective external carbon substance is amongst the priorities of the wastewater treatment industry for the past two decades [1]
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