scholarly journals Experimental Investigation of Substrate Shock and Environmental Ammonium Concentration on the Stability of Ammonia-Oxidizing Bacteria (AOB)

Water ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 223
Author(s):  
Hareef Ahmed Keerio ◽  
Wookeun Bae
Keyword(s):  
Steady State ◽  
Oxygen Uptake ◽  
Uptake Rate ◽  
Oxygen Uptake Rate ◽  
Operating Conditions ◽  
Ammonium Concentration ◽  
Ammonia Oxidizing Bacteria ◽  
Batch Reaction ◽  
Specific Oxygen Uptake Rate ◽  
The Stability

A wastewater treatment plant (WWTP) frequently encounters fluctuation in ammonium concentration or flow rate (Q), which may affect the stability of ammonium oxidizing bacteria (AOB). In this study, two continuous stirred tank reactors (CSTRs) were operated for 588 days and ammonium concentration was varied at various steady-state conditions. There was no inhibition observed in CSTR operation and AOB acclimated once at a certain ammonium concentration. Cells at an acclimated steady-state concentration (200 mgTAN/L from R(A) and 1000 mgTAN/L from R(B)) were extracted to perform a batch test at operating conditions, and self-inhibition behavior was observed in the batch reaction. In CSTR operation, the environmental ammonium concentration was varied and the specific oxygen uptake rate (SOUR) value was estimated from daily profile data and compared with batch reaction. In the CSTR operation as a substitute for self-inhibition, the SOUR was shifted towards the maximum specific oxygen uptake rate (SOURmax) and no self-inhibition was observed. For further justification of the CSTR’s stability, several total ammonium nitrogen (TAN) concentrations (range from ~−106 to ~+2550 mgTAN/L) were directly added to interrupt the stability of the process. As a substitute for any effect on the SOUR, the CSTRs were recovered back to the original stable steady-state conditions without varying the operational conditions.

Study on Evaluation Methods for Biodegradability and Biotoxicity of Industrial Effluents

2012 ◽  
Vol 518-523 ◽  
pp. 516-519 ◽  
Author(s):  
De Gang Xu ◽  
Ju Feng Li ◽  
Yu Zhong Li
Keyword(s):  
Oxygen Uptake ◽  
Dehydrogenase Activity ◽  
Uptake Rate ◽  
Oxygen Uptake Rate ◽  
Phenol Formaldehyde ◽  
Industrial Effluents ◽  
Assessment Method ◽  
Sewage Plant ◽  
Extreme Sensitivity ◽  
Specific Oxygen Uptake Rate

The industrial effluents produced in petrochemical production contain kinds of pollutants and fluctuate wildly, also lead sewage plant to be impacted frequently. It is significant to develop a method that warms the effluents quality early, efficiently and accurately. As a result, it can make the biochemical devices run and manage smoothly. Based on the extreme sensitivity of Oxygen Uptake Rate (OUR) and Dehydrogenase Activity (DHA) to the abnormal effluents and toxicants, this study proposed a comprehensive assessment method of biodegradability and biotoxicity with Specific Oxygen Uptake Rate (SOUR) and Specific Dehydrogenase Activity (SDHA). And it also discussed the biodegradability and biotoxicity of the industrial effluents with different pH and toxicant by detecting OUR, SOUR and DHA. The results showed that, these three indexes were extremely sensitive and accurate to the effluents quality change. And the maximum concentrations of phenol, formaldehyde and carbinol that the microorganisms can allow in the industrial effluents were 350mg/L, 70mg/L and 170 mg/L. When the sewage plant was functioning normally, SOUR and SDHA fluctuations were 3.0~7.0 and 1.0~4.0 respectively. Therefore, they have important application value and prospect to early warming in the effluents quality.

scholarly journals Specific Oxygen Uptake Rate and Mass Transfer Coefficient in Activated Sludge System

2019 ◽  
Vol 4 (2) ◽  
pp. 24-32
Author(s):  
S.H. Tan ◽  
◽  
Jamaiatul Lailah M.J. ◽  
Aida Isma M.I. ◽  
◽  
...  
Keyword(s):  
Mass Transfer ◽  
Oxygen Uptake ◽  
Dissolved Oxygen ◽  
Activated Sludge ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Uptake Rate ◽  
Oxygen Transfer ◽  
Oxygen Uptake Rate ◽  
Specific Oxygen Uptake Rate

Activated sludge process is one of the effective methods in biological wastewater treatment and the impact of oxygen transfer through aeration process has the most important breakthroughs as it served as the largest consumer in the treatment. Aeration is an energy demanding process. Oxygen transfer into an activated sludge is a very challenging issue in the field of multiphase flows. Apart from the physical mass transfer phenomena between gas, liquid and solids phases, the transport mechanisms are also overlapped by time and temperature, varying microbial activity, impurity loads, adsorption and desorption processes. Oxygen uptake rate (OUR) for microbial population in the activated sludge system is important parameter to determine the amount of oxygen consumed during aerobic heterotropic biodegradation in the system. Evaluation of specific oxygen uptake rate (SOUR) and the volumetric mass transfer coefficient (KLA) of oxygen for three different wastewater treatment processes, namely conventional activated sludge (CAS), oxidation ditch (OD) and sequencing batch reactor (SBR) treating municipal wastewater in Kuala Lumpur have been carried out. In-situ and ex-situ measurement of pH, dissolved oxygen (DO), temperature, MLSS and MLVSS were carried out. In the activated sludge treatment, very low concentration of dissolved oxygen may cause the wastewater to turn septic resulting in death of bacteria or in active due to unstable anaerobic conditions. Conversely, an excessive dissolved oxygen may result to high energy and high 25 operating cost. Higher flowrate may also cause dissolved oxygen to rise, reducing the quality of sludge and slowing the denitrification process in the system. Results revealed that the OUR for SBR, OD and CAS were 9.582 mg O2 /L/hr, 10.074 mg O2 /L/hr and 13.764 mg O2 /L/hr, respectively. Low oxygen uptake rate indicates a low rate of microbial respiration. By computing the OUR, the mass transfer coefficient could be evaluated. It should be noted that among the treatment system in this study, the conventional activated sludge shows the highest mass transfer coefficient and specific oxygen uptake rate of 2.038 hr-1 and 15.605 mg O2 /g MLVSS/hr, respectively. Improving the oxygen transfer rate and reducing aeration in the system could achieve a cost-effective aeration system.

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