Effect of sucrose on denitrification through simulation, lab-scaled batch tests and pilot plants

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.