Dissolved oxygen transfer from oscillatory flows to microbes in a permeable organic sediment bed

2020 ◽  
Vol 157 ◽  
pp. 119721
Author(s):  
Huijuan Tian ◽  
Qingxiang Li ◽  
Yuhong Dong
Keyword(s):  
Dissolved Oxygen ◽  
Oxygen Transfer ◽  
Oscillatory Flows ◽  
Sediment Bed ◽  
Organic Sediment

scholarly journals Oxygen transfer from flowing water to microbes in an organic sediment bed

Hydrobiologia ◽  
2008 ◽  
Vol 614 (1) ◽  
pp. 219-231 ◽  
Author(s):  
Makoto Higashino ◽  
Ben L. O’Connor ◽  
Miki Hondzo ◽  
Heinz G. Stefan
Keyword(s):  
Oxygen Transfer ◽  
Flowing Water ◽  
Sediment Bed ◽  
Organic Sediment

Estimation of oxygen transfer rate in sequencing batch reactor

1996 ◽  
Vol 34 (3-4) ◽  
pp. 413-420
Author(s):  
Y. C. Liao ◽  
D. J. Lee
Keyword(s):  
Dissolved Oxygen ◽  
Oxygen Transfer ◽  
Transfer Rate ◽  
Sequencing Batch Reactor ◽  
Batch Reactor ◽  
Oxygen Transfer Rate ◽  
Intermittent Aeration ◽  
Transient Effects ◽  
Operational Parameters ◽  
Transient Model

Transient model of oxygen transfer rate in a sequencing batch reactor is derived and solved numerically. The dissolved oxygen response under several conditions is analyzed. Effects of operational parameters and liquid bath height are studied. When with short, intermittent aeration periods, the transient effects on oxygen transfer rate may be substantial and should be taken into considerations. An example considering bioreaction is also given.

scholarly journals The Influence of Optic and Polarographic Dissolved Oxygen Sensors Estimating the Volumetric Oxygen Mass Transfer Coefficient (KLa)

2016 ◽  
Vol 10 (8) ◽  
pp. 142 ◽  
Author(s):  
Gustavo Andrés Baquero-Rodríguez ◽  
Jaime A. Lara-Borrero
Keyword(s):  
Mass Transfer ◽  
Wastewater Treatment ◽  
Dissolved Oxygen ◽  
Transfer Coefficient ◽  
Mass Transfer Coefficient ◽  
Oxygen Transfer ◽  
Airflow Rate ◽  
Oxygen Probe ◽  
Aeration System ◽  
Oxygen Measurement

Aeration is usually the most energy intensive part of the wastewater treatment process. Optimizing the aeration system is essential for reducing energy costs. Field tests oriented to estimate parameters related to oxygen transfer are a common approach to compare aeration systems. The aim of this research is to assess the effect of dissolved oxygen probe lag on oxygen transfer parameter estimation. Experimental procedures regarding to process automation and control were applied to quantify dissolved oxygen probe lag. We have measured oxygen transfer in clean water, under a wide range of conditions (airflow rate, diffuser characteristics and diffuser density), with optic and polarographic sensors for dissolved oxygen measurement. The oxygen transfer was measured as per ASCE Standard procedures. Nonparametric statistical tests were used to compare the estimated volumetric mass transfer coefficient KLa with different sensors. According to the results, there is not significant influence of the probe lag (also known as time constant) or probe characteristics on the parameters used to assess oxygen transfer efficiency. This fact has great relevance in common practice of aerobic process for wastewater treatment because dissolved oxygen monitoring is used as an input for decision making related to the energy optimization in the aeration system. Findings from these tests contradict previous studies which claim that lag time in polarographic sensors for the dissolved oxygen measurement can bias estimate KLa.

Prediction of dissolved oxygen concentration along sanitary sewers

1996 ◽  
Vol 34 (5-6) ◽  
pp. 525-532 ◽  
Author(s):  
J. Saldanha Matos ◽  
E. Ribeiro de Sousa
Keyword(s):  
Mathematical Model ◽  
Dissolved Oxygen ◽  
Oxygen Concentration ◽  
Oxygen Transfer ◽  
Oxygen Balance ◽  
Dissolved Oxygen Concentration ◽  
Empirical Expression ◽  
Slime Layer ◽  
Sanitary Sewers ◽  
The Mathematical Model

The oxygen balance in wastewater collection systems is important in respect to the degree of biological oxidation that occurs within the stream and in respect to the control of septicity and its effects. In this paper, a simple mathematical model is presented, in order to predict dissolved oxygen concentration profiles along sanitary sewers. The mathematical model was developed based on an analytical solution of the simple differential equation of dissolved oxygen balance in sewers, and includes an empirical expression for prediction of dissolved oxygen transfer to the slime layer on the pipe walls. Because the factors controlling dissolved oxygen balance in sewers are so complex, it would be unrealistic to expect, that with this rather simple model, dissolved oxygen concentrations can be accurately predicted. Nevertheless, it is reasonable to suppose that the predictions may be adequate for some design and operation purposes.

Oxygen transport rates through mats of Lemna minor and Wolffia sp. and oxygen tension within and below the mat

1977 ◽  
Vol 55 (14) ◽  
pp. 1926-1932 ◽  
Author(s):  
P. F. Morris ◽  
W. G. Barker
Keyword(s):  
Dissolved Oxygen ◽  
Oxygen Transfer ◽  
Lemna Minor ◽  
Close Packing ◽  
Early Summer ◽  
Gas Transfer ◽  
Layer Model ◽  
Air Water Interface ◽  
Oxygen Profile ◽  
Mat Thickness

A boundary-layer model has been used to describe the movement of dissolved oxygen through a vegetation mat of Wolffia sp. or Lemna minor. In an environment where light and temperature are held constant, the reaeration rate of the water below the mat is a linear function of mat thickness. In the light, the rate of oxygen transfer into water through a 10.5-mm mat is 4.4 times higher for Wolffia and 2.9 times higher for L. minor than in the dark. In the light the rate of oxygen transfer through Wolffia mats is significantly lower in August and September than in early summer. A seasonal shift in transport rates through L. minor mats has not been conclusively established. The efficiency of gas transfer through washed Wolffia and L. minor mats 8 to 16 mm in thickness varies from 4.0 to 47.0% of the estimated gas exchange rate for a small protected lake. The rate of gas transfer through the mat is higher than might be expected considering the close packing of the component fronds. The shape of the oxygen profile in the upper portion of a photosynthetically active mat indicates that much of the oxygen produced by photosynthesis of the submerged fronds may be lost to the atmosphere.When the light intensity falls below the level required to exceed the compensation point, dissolved oxygen levels in the water trapped between the fronds are quickly reduced to very low tensions despite the proximity of the entire mat to the oxygen-saturated air–water interface.

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.

Improvements to a stoat model of a full scale wastewater treatment works through the use of detailed mechanistic studies

1997 ◽  
Vol 36 (5) ◽  
pp. 277-284 ◽  
Author(s):  
A. J. Stokes ◽  
J. R. West ◽  
C. F. Forster ◽  
R. C. A. Kruger ◽  
M. de Bel ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Dissolved Oxygen ◽  
Activated Sludge ◽  
Oxygen Transfer ◽  
Dynamic Modelling ◽  
Accurate Information ◽  
Mechanistic Studies ◽  
Solids Retention ◽  
Reactor Mixing ◽  
Parameter Values

The performance of a wastewater treatment works has been simulated using a dynamic modelling package from WRc, STOAT. The estimation of appropriate parameter values has been performed both prior to and after detailed investigations of the mechanisms of oxygen transfer and mixing within the aeration lanes of the activated sludge plant. Interpretation of reactor mixing characteristics in the light of dissolved oxygen data is considered. The need for accurate information concerning solids retention times is exemplified by the model's sensitivity to sludge wastage rates.

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