Biological Nitrogen Removal Database
A manually curated data resource for microbial nitrogen removal
Biological Nitrogen Removal Database
A manually curated data resource for microbial nitrogen removal
Influent:Synthetic wastewater
Denitrification system:Sulfur-driven denitrification (SDN) system
Denitrifying reactor:PBR (Packed bed reactor)
Medium:Sulphur granules
Culture taken from:Thiobacillus denitrificans
Organism (s) cultured:nan
Respiration:Anaerobic
Electron donor:Sulfur-limestone
Electron acceptor:Nitrate
Input NO3-N (mg/l):nan
Nitrate removal rate (mg NO3-N/l/h):8.8~46.8
Denitrification rate (gNO3-N removed/m3/day):nan
Microorganisms identified:nan
Molecular tools:nan
Major findings:One of the problems associated with SDD systems is acidity which tends to inhibit denitrification, in this study limestone was added as an alkalinity source to control the pH. They found that the optimum volumetric ratio of limestone to sulphur for minimization of the reactor volume was 1:1.
Authors:Liu and Koenig., 2002
Title:Use of limestone for pH control in autotrophic denitrification: batch experiments.
Pubmed link:None
Full research link:Link
Abstract:The autotrophic denitrification process using elemental sulphur consumes about 4 g alkalinity (as CaCO3) per gram nitrate nitrogen reduced and is severely inhibited at pH lower than 5.5. Using limestone as an alkalinity source to control the pH, the autotrophic denitrification of synthetic wastewater with varying initial alkalinity to NO3–N ratios was evaluated in laboratory-scale batch reactors, which contained sulphur and limestone granules in different volumetric ratios. The results demonstrated that limestone supplies effective buffering capacity, if the initial alkalinity is insufficient for complete denitrification. The alkalinity supplied by limestone is a function of the pH, which in turn depends on the initial alkalinity of the wastewater and the extent of the biological denitrification. Given the specific denitrification rates, in mg NO3–N/g S h, and limestone dissolution rates, in mg CaCO3/g CaCO3 h, as a function of pH, the required volumetric ratio of limestone to sulphur for maintaining a given pH can be quantitatively established. It was found that the optimum volumetric ratio of limestone to sulphur for minimization of the reactor volume equals approximately 1:1.