Development and application of a denitrification test based on gas production

Abstract

In order to assess the toxicity of compounds in wastewater and activities in reactors a precise, reproducible, fast and simple batch test is used. This research was focused on the development of such a test to determine denitrifying activity. The test is based on measuring the rate of gas production during denitrification, by tracking both the pressure and the gas composition in the headspace of a sealed bottle. The optimum pH for batch activity was found to equal the pH in the lab-scale reactor (9.5) from which the sludge originated. The minimum COD/N ratio required for linear gas production curves with acetate/nitrate was 3.5 g COD/g N. A significant increase in specific activity at low solids concentrations (<2 g VSS/l) was observed. No clear relation between activity, DNA and RNA content of the sludge after the test and initial substrate to biomass (S0/X0) ratio could be established, indicating that other factors play a role in determining the activity, possibly adsorption and substrate mass transfer. Standardization of batch tests should therefore include the solids concentration.

Microbial population response to changes of the operating conditions in a dynamic nutrient-removal sequencing batch reactor

“…3b), where the specific denitrification rate was 6.81 mg N-NO x /(g-MLVSS h) ( Table 2). This value is in accordance with the literature values: 1.30-12.30 mg N-NO x /(g-MLVSS h) [28][29][30][31]. In reactor Ax, acetate and nitrate were rapidly consumed and there was some transient nitrite accumulation (Fig.…”

Effects of the cycle distribution on the performance of SBRs with aerobic granular biomass

“…The denitrification activity of the biomass was determined by means of batch experiments according to the methodology proposed by Buys et al [25] in order to know the biomass denitrifying capacity on PHA as organic matter substrate.…”

Monitoring the stability of an Anammox reactor under high salinity conditions

“…The maximum Specific Anammox Activity (SAA) of the biomass from the reactor was measured by means of batch assays described in detail by Buys et al [12] and modified by Dapena-Mora et al [8]. Maximum SAA was estimated from the maximum slope of the curve described by the cumulative N 2 production along the time and related to the biomass concentration in the vials.…”