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Discussion papers
https://doi.org/10.5194/dwes-2018-29
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/dwes-2018-29
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Submitted as: research article 07 Jan 2019

Submitted as: research article | 07 Jan 2019

Review status
This discussion paper is a preprint. It has been under review for the journal Drinking Water Engineering and Science (DWES). A final paper in DWES is not foreseen.

De-chlorination of drinking water by forced aeration

Ghanim Hassan1 and Robert G. J. Edyvean2 Ghanim Hassan and Robert G. J. Edyvean
  • 1Department of Water Resources Techniques, Middle Technical University, Baghdad, Iraq
  • 2Department of Chemical and Biological Engineering, The University of Sheffield, Sheffield, UK

Abstract. Shock chlorination is a well-known practice in swimming pools and domestic wells. One of the limitations for using this technique in drinking water purification facilities is the difficulty of quickly removing high chlorine concentrations in water distribution systems or production facilities. In order to use this method in the drinking water industry a shock de-chlorination method should be introduced for producing microorganism and biocide free water. De-chlorination using natural stagnant aeration (leaving the water to lose the chlorine naturally) is the safest known method if compared with chemical and charcoaling methods. Unfortunately, stagnant aeration is a slow process. Therefore, developing a process for accelerating de-chlorination by aeration would pave the way for using shock de-chlorination in drinking water industry.

Forced air bubbling is a possible technique for de-chlorination but there is lack of data supporting such a process. The theory is that air bubbling has the advantages of higher mass transfer area, higher Reynolds number across the bubble water interface, and higher mass transfer concentration gradient as the bubbling presents a continuous stream of fresh bubbles. All of these factors accelerate aeration to various extents.

A 20 cm diameter, 1-meter height column provided with air sparger was designed to collect the desired data used in this study. Trichloroisocyanuric acid, sodium hypochlorite and chlorine gas were the three familiar sources of chlorine used to investigate their response to air bubbling.

Chlorine gas was the fastest and safest chlorine source to be dechlorinated. It dropped from 200 ppm to 0.02 ppm within 4 minutes or zero ppm within 6 minutes using an air flowrate of 9 l/min.

Sodium hypochlorite decreased from 200 ppm to 0.02 ppm within 6 minutes using air flowrate of 9 l/min. Trichloroisocyanuric acid found to be the chlorine source slowest to respond to de-chlorination. It decreased from 200 ppm to 0.02 ppm within 8 minutes using an air flowrate of 9 l/min.

Shock de-chlorination by aeration is found to be a promising method that opens up the drinking water industry and could produce microorganism and biocide free drinking water.

Ghanim Hassan and Robert G. J. Edyvean
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Interactive discussion
Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
Ghanim Hassan and Robert G. J. Edyvean
Ghanim Hassan and Robert G. J. Edyvean
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Short summary
Shock chlorination was not used in drinking water production process. This because the dechlorination process is a slow-motion technique. To overcome this difficulty, an aeration process was suggested. this work demonstrates how fast it is. It is concluded that shock chlorination followed by shock aerated dechlorination can produce high-quality water, zero bacterial content with zero Chlorine content.
Shock chlorination was not used in drinking water production process. This because the...
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