Chlorine Treatment of STP effluent For Reuse : Disadvantages? Appropriate Alternate Options?
Submitted by iwp on July 7, 2009 - 19:47
We are a leading group in water and waste water treatment plant construction in India. We are using chlorination as a disinfection process till date. I want to know is there any disadvantages of using chlorine if the treated water is reused for toilet flushing and horticulture, or is it better to use UV disinfection for the same .
We are in process of constructing a STP and the treated water will be supplied to nearby airport .As the water has to be supplied to airport authority there should be minimal faecal coliform level which can be achieved by using UV system. However its a costly affair hence I want to collect some information regarding the advantage of UV system before implementing it in the project instead of chlorination.
I request the co-operation of the users of the forum in this regard.
Neha
Comments
1.
Dear Member,
It is pleasing to note that you are planning to use STP-Effluent for re-use for lower-end uses i.e flushing etc.
This will definitely result in considerable savings in water-resources and also energy which would have been used to source new-water from bore-wells,
If the intention is to use the water for horticulture in air-port, we suggest apply phyto-remediation i.e use of plants to remedy sightly polluted water, the outlet from these plantation-beds will be coliform/ pathogen free and also the plant beds can be made aesthetically good. Also these plants are not dependent on electrical-power, and works 24X7,
Some practices are required, and this will take up space to grow-foster-nurture these plants which will remedy the water to a good standard.
We will be able to give you some data on the areas, technology, type of plants Etc,
Pl do refer to old queries answered in this section to get more clear idea about- DEWATS- Decentralized Waste water Treatment Systems.
with well wishes from VigyanVijay,
AjitSeshadri
http://www.vigyanvijay.org
ajit.seshadri@vigyanvijay.org
Er. Ajit Seshadri,Head- Environment, The Vigyan Vijay Foundation
2.
Dear Neha,
The organo chlorine compounds do form during chlorination.
However if STP and Tertiary treatment plant are properly designed then chlorination will be the best option. Around 2 PPM chlorine can drastically reduce the bacterial count.
For effective disinfection by UV the water must have the excellent clarity.
Please visit our web site to have more details and call us if need any further help.
With regards,
Prof. R. V Saraf
Director
Viraj Envirozing India Pvt. Ltd.
Pune, Maharashtra
http://www.virajenvirozing.com
3.
Dear Neha,
This issue was earlier discussed in this forum. Kindly go through the links here: Document by US EPA. that clearly states the merits and demerits of UV disinfection. The possibility of reactivation cannot be eliminated by UV disinfection. Also its efficiency is highly affected by the TSS content of the wastewater.
that clearly states the merits and demerits of UV disinfection. The possibility of reactivation cannot be eliminated by UV disinfection. Also its efficiency is highly affected by the TSS content of the wastewater.
Chlorine residual is desirable to prevent any possibility of recontamination or reactivation of the wastewater, particularly when it is reused. In fact the reuse guideline for wastewater by USEPA, Guidelines for Water Reuse (EPA/625/R-04/108) U.S. EPA, September, 2004, has specified residual chlorine content for certain reuse purpose where human contact is likely.
In this context it is preferable to do some chlorine dosing even after UV disinfection.
Regards
Sandeepan Chowdhury
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