scholarly journals Enhancing Nitrate Removal from Waters with Low Organic Carbon Concentration Using a Bioelectrochemical System—A Pilot-Scale Study

Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 516 ◽  
Author(s):  
Rauno Lust ◽  
Jaak Nerut ◽  
Kuno Kasak ◽  
Ülo Mander
Keyword(s):  
Organic Carbon ◽  
Dissolved Oxygen ◽  
Oxygen Concentration ◽  
Power Efficiency ◽  
Municipal Wastewater ◽  
Nitrate Removal ◽  
Treatment Plant ◽  
Municipal Wastewater Treatment ◽  
Dissolved Oxygen Concentration ◽  
Organic Carbon Concentration

Assessments of groundwater aquifers made around the world show that in many cases, nitrate concentrations exceed the safe drinking water threshold. This study assessed how bioelectrochemical systems could be used to enhance nitrate removal from waters with low organic carbon concentrations. A two-chamber microbial electrosynthesis cell (MES) was constructed and operated for 45 days with inoculum that was taken from a municipal wastewater treatment plant. A study showed that MES can be used to enhance nitrate removal efficiency from 3.66% day−1 in a control reactor to 8.54% day−1 in the MES reactor, if a cathode is able to act as an electron donor for autotrophic denitrifying bacteria or there is reducing oxygen in a cathodic chamber to favor denitrification. In the MES, greenhouse gas emissions were also lower compared to the control. Nitrous oxide average fluxes were −639.59 and −9.15 µg N m−2 h−1 for the MES and control, respectively, and the average carbon dioxide fluxes were −5.28 and 43.80 mg C m−2 h−1, respectively. The current density correlated significantly with the dissolved oxygen concentration, indicating that it is essential to keep the dissolved oxygen concentration in the cathode chamber as low as possible, not only to suppress oxygen’s inhibiting effect on denitrification but also to achieve better power efficiency.

scholarly journals Study of the Effect of Fossil Organic Carbon on 14C in Groundwater from Hvinningdal, Denmark

Radiocarbon ◽  
1997 ◽  
Vol 40 (2) ◽  
pp. 915-920 ◽  
Author(s):  
E. Boaretto ◽  
L. Thorling ◽  
Á. E. Sveinbjörnsdóttir ◽  
Y. Yechieli ◽  
J. Heinemeier
Keyword(s):  
Mass Spectrometry ◽  
Organic Carbon ◽  
Dissolved Oxygen ◽  
Oxygen Concentration ◽  
Accelerator Mass Spectrometry ◽  
Combined Effect ◽  
Dissolved Oxygen Concentration ◽  
Apparent Contradiction ◽  
Preliminary Step ◽  
Groundwater Dating

The carbonate hydrochemistry of groundwater from the Hvinningdal aquifer (Denmark) was studied by radiocarbon (accelerator mass spectrometry (AMS)) and δ13C measurements as a preliminary step towards 14C groundwater dating. The 14C concentrations varied between 30 and 100 percent modern carbon (pMC) in apparent contradiction with tritium (3H) data, which in most cases indicate a post-bomb date. The dilution of 14C can be explained as being due to the combined effect of dissolution of old soil carbonate and oxidation of old organic carbon. The last effect proved to be essential. To calculate this correction the dissolved oxygen concentration was used together with the δ13C values. The combined corrections bring the 14C concentrations up to post-bomb levels in better agreement with the 3H data.

Analysis of Oxygen Transfer and Dissolved Oxygen Concentration Measurement Tests in a Wastewater Treatment Plant

2014 ◽  
Vol 656 ◽  
pp. 486-494
Author(s):  
Marius Daniel Roman ◽  
Raluca Andreea Felseghi
Keyword(s):  
Dissolved Oxygen ◽  
Oxygen Concentration ◽  
Oxygen Transfer ◽  
Treatment Plant ◽  
Dissolved Oxygen Concentration ◽  
Coverage Area ◽  
Type Size ◽  
Oxygen Efficiency ◽  
Oxygen Transfer Capacity ◽  
Tank Geometry

The efficiency of oxygen transfer depends on many factors including the type, size and shape of diffusers and the tank geometry. In this paper, the effect of the depth of water in the tank and the extension of coverage area of diffusers on each of oxygen transfer capacity, efficiency and dissolved oxygen concentration is tested. Experimental procedure is adopted to evaluate the effect of dissolved oxygen concentration. The results of the case study showed that, both the depth of water and the extent of coverage area of diffuser had a significant effect on the tested parameters. The values of oxygen transfer capacity was 76,7 kg O2/h and oxygen efficiency (without agitation): 5,3 kg O2/h, oxygen efficiency (with agitation): 4,2 kg O2/h.

Effect of Physicochemical Variables on Algal Autoflotation

1992 ◽  
Vol 26 (7-8) ◽  
pp. 1769-1778 ◽  
Author(s):  
S.-I. Lee ◽  
B. Koopman ◽  
E. P. Lincoln
Keyword(s):  
Dissolved Oxygen ◽  
Oxygen Concentration ◽  
Retention Time ◽  
Contact Time ◽  
Pilot Scale ◽  
Dissolved Oxygen Concentration ◽  
Physicochemical Variables ◽  
Rise Rate ◽  
Mixing Intensity ◽  
Maximum Rise

Combined chemical flocculation and autoflotation were examined using pilot scale process with chitosan and alum as flocculants. Positive correlation was observed between dissolved oxygen concentration and rise rate. Rise rate depended entirely on the autoflotation parameters: mixing intensity, retention time, and flocculant contact time. Also, rise rate was influenced by the type of flocculant used. The maximum rise rate with alum was observed to be 70 m/h, whereas that with chitosan was approximately 420 m/h. The efficiency of the flocculation-autoflotation process was superior to that of the flocculation-sedimentation process.

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