Determination of Decay Coefficient of Biomass through Endogenous Respiration

Abstract

Endogenous respiration processes of nitrifying/denitrifying bacteria under aerobic and anoxic conditions were investigated in a batch study using three identical bioreactors of size 5 L. The rate of digestion of microbial protoplasm was determined through the oxidation of cell tissue and the formation of new cellular materials using the Volatile Suspended Solids (VSS) method. Chemical Oxygen Demand (COD), ammonia, nitrate and VSS were monitored simultaneously at different sludge age. Three exponential phases of metabolism, starvation and death were observed during VSS reduction in both the aerobic and anoxic digestion. In the aerobic digestion, the average endogenous decay coefficient of volatile suspended solids was 0.055 L dayG 1 with a 95% confidence limit of 0.017 whereas 0.053 L dayG 1 was observed for anoxic digestion with a 95% confidence limit of 0.038 at 25±1°C. Results show that anoxic digestion has a slightly reduced decay rate than aerobic digestion. Therefore, the characterization of biomass and determination of stoichiometry coefficients is essential for understanding the activities of microbes in treatment processes.

Cultivation of anaerobic ammonium oxidizing bacteria (AnAOB) using different sewage sludge inoculums: process performance and microbial community analysis

“…MLSS and MLVSS concentrations in reactor A1 gradually decreased over time. The gradual decrease in solids concentration in A1 reactor could be explained by endogenous respiration of heterotrophic denitrifiers 31 . Denitrification process was observed until the end of the experiments, however, at a very low rate.…”

Optimization of step-feed anoxic-oxic-membrane bioreactor (AO-MBR) with methanol addition for biological nitrogen removal in wastewater using BioWin and response surface methodology (RSM)

“…All batch experiment samples were taken over time. For the decay experiment, the sample was taken over days (lasting 15 -20 days) [16]. The samples for nitrification and carbon addition experiments were filtered through a 0.45 μm membrane filter and analyzed for NO2 --N and NO3 --N, and COD, respectively.…”

“…The YH was calculated as the ratio of the VSS produced over COD consumed. Finally, the bH was obtained following the Ezechi et al [16] study by the exponential decay method. The slope of the ln[VSS(t) -VSS(u)] over time is the bH value.…”

Nutrient Removal from Wastewater by Integrated Attached Growth Bioreactor

“…To this end, investigation into cheap, sustainable, yet effective water treatment methods have intensified. Such methods include Fenton oxidation process (Meric et al, 2004), coagulation and flocculation (Guida et al, 2007), membrane processes (Chianese et al, 1999), electrochemical processes (Ezechi et al, 2012b(Ezechi et al, , 2014b(Ezechi et al, , 2015cIsa et al, 2014), adsorption processes (Bansode et al, 2004;Ezechi et al, 2015d).…”