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:Wastewater
Denitrification system:Sulfur-driven denitrification
Denitrifying reactor:Packed-bed
Medium:Limestone and Sulfur granules
Culture taken from:Thiobacillus denitrificans
Organism (s) cultured:nan
Respiration:Anaerobic
Electron donor:Sulphur
Electron acceptor:Nitrate
Input NO3-N (mg/l):2.83
Nitrate removal rate (mg NO3-N/l/h):2.59
Denitrification rate (gNO3-N removed/m3/day):nan
Microorganisms identified:nan
Molecular tools:nan
Major findings:Study established chemical-biological interactive relationships using limestone as an alkalinity source to control the pH, in autotrophic denitrification of synthetic wastewater with varying alkalinity to NO3 /N ratios.
Authors:Koenig and Liu, 2002
Title:Use of Limestone for pH Control in Autotrophic Denitrification: Continuous Flow Experiments in Pilot-Scale Packed Bed Reactors
Pubmed link:Link
Full research link:Link
Abstract:The sulfur-utilizing autotrophic denitrification process consumes about 4 g alkalinity (as CaCO3) per g NO3–N reduced resulting in a decrease of pH. Using limestone as an alkalinity source to control the pH, autotrophic denitrification of synthetic wastewater with varying alkalinity to NO3–N ratios was evaluated in pilot-scale packed bed reactors operating in the upflow mode, which contained limestone and sulfur granules in different volumetric ratios. The results demonstrated that limestone supplies effective buffering capacity, if the initial alkalinity of the wastewater is insufficient for complete denitrification. The alkalinity supplied by limestone is a function of hydraulic retention time and the pH, which in turn depends on the extent of biological denitrification and the initial alkalinity to NO3–N ratio in the wastewater. The dissolution rate of limestone is inversely proportional to pH for pH values lower than 7.1. It was found that the ratio of influent alkalinity to theoretically required alkalinity in the wastewater should not be lower than 0.5 in order to prevent a decrease in nitrate removal performance. Based on the established chemical-biological interactive relationships, a multilayer approach was proposed to determine the optimum sulfur:limestone ratio for nitrate removal under steady state conditions, taking into account the characteristics of the influent wastewater.