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Water Quality (Constituent) Analysis for a proposed water distribution network

Greetings,

I am looking for a standard procedure for determining the bulk reaction rate to undertake a water quality (constituent) analysis.  I understand from the AWDM book and other literature that the procedure entails sampling water from the source through bottle tests and making chlorine tests every day and plotting the results on a semi-log chart to get the bulk reaction rate value.  However, I need a detailed standard procedure with step-by-step instructions to send to the lab so that they make the tests accordingly and come up with the results.  I have made my research online and could not get hold of such a document.  I would highly appreciate your help in that regard.

I would also appreciate any help regarding any empirical equation to determine the wall reaction rate, as I understand that it depends on specific factors such as pipe material, age, and other such considerations.

Thanks and best regards,

Amine Salameh

Parents
  • Hello Amine,

    You can find some additional literature in the WaterGEMS Help section. You can navigate to File > Help to access the Help section. Here in the index, if you go to Technical Reference > Water Quality Theory you will find the formulae used for water quality analysis done in WaterGEMS and the theory behind the modeling aspects of it. Additionally you can go through the ADWM book or other reference articles.

    We have another article which can guide WaterGEMS users an insight into how they can obtain water quality data for constituent analysis. See the article below;

    Getting data and setting up for a Constituent Analysis in WaterGEMS and WaterCAD

    Let me know if this helps.


    Regards,

    Yashodhan Joshi

  • Thanks Yashodhan for your response.

    I have already reviewed the article that you had mentioned above, and my post was based on it.  I made further research online to get further papers and similar information but I am still underway and I am under a tight deadline.  My main aim is to feed a lab with a detailed procedure for them to follow in undertaking these bottle tests.  Something like an AWWA procedure or similar.  I thought that the author of the article above would know such references.

    I have also found some research papers that talk about wall reaction rates but I also need an empirical equation to account for the different parameters that enter into the reaction between chlorine and material such as biomass and others that could be found on internal pipe walls.  Otherwise, the determination of the wall reaction rate would be very hard to justify in front of the client and I want to avoid such a situation. 

    Thanks and best regards,

    Amine

  • Amine,

    As I'm sure you realize, there is no such thing as a typical bulk or wall reaction rate. Those values vary widely from system to system.

    A reference I use is Rosman, Clark and Grayman, 1994, "Modeling Chlorine Residuals in Drinking Water Systems," Journal of Environmental Engineering, 120(4), 803-820.

    In their study, they found a bulk reaction rate of 0.55/day and a wall reaction rate between 0.15 to 0.45 m/day. Of course, your system will be different.

    There was another good paper by Vasconcelos, et al, 1997, "Kinetics of Chlorine Decay,: J AWWA, 89(7) 54-65 July.

    What I would do in your situation is perform a sensitivity analysis varying the reaction rates for multiple scenarios and plotting all the results on a single graph for multiple junctions.

    Tom

  • I contacted Walter Grayman who is probably teh most knowledgeable person on this topic. Here is his reply.

    "I am not going to be much help.  As far as bulk decay, I have been adamant with all of my clients that the first step in any chlorine study is a bottle test.  Easy and cheap.  There are no typical values and I have personally seen values ranging from less than 0.1 to 15 per day. There are numbers in the Vasconcelos paper but more definitive is the underlying AWwaRF report. Unfortunately I do not have it in electronic form.

     For wall demand, all that exists are anecdotal values.  Use of the relationship between wall decay and roughness is suspect - sounds reasonable but no definitive data.  Again my advice has been to do a field study and collect chlorine residuals, run the model assuming zero wall demand and compare modeled vs. measured chlorine. Based in that adjust wall demands somewhat guided by the fact that wall demand is higher in unlined cast iron pipes and smaller pipes.  The science and body of knowledge on this has not really expanded in the past two decades."

  • You also asked about the steps for running a bulk reaction test. I can't find a standard procedure but here is the way I see it.

     

    1. Take a sample of treated water leaving plant.
    2. Place water in a series of clean bottles.
    3. Seal full bottles tightly and place in the dark in a constant temperature location similar to the typical temperature of the water.
    4. At designated time steps, take one bottle and conduct a chlorine test. Initially plan on 1, 2, 6, 12, 18, 24 hours until you see a trend. You need to increase or decrease the frequency accordingly.
    5. Continue until you reach the max water age across the system or chlorine goes to near zero.
    6. Plot and analyze the data.

     

    It’s important to use very clean bottles. Any impurity can mess up results.

  • Tom - I like this thought process.  I would add an incubator and put it at 20 deg C especially if the lab is running BODs.  Still might be a little too warm depending on the situation but 20C is a pretty typical temperature study point and easy to maintain.  I'd also suggest glass not plastic.  What would be ideal is if you had several Hach pocket colorimeter optical glass containers that way you could minimize off gassing while cooking in the incubator and test right in the vial. In fact I might try this on some of my facilities!

  • Good thought. And BOD bottles would be easy t work with. But they need to be very clean. Possibly if you had some brand new bottles would be best. I agree that 20 deg C would be an ideal temperature. You can correct the rate constant with equations from physically chemistry.

Reply
  • Good thought. And BOD bottles would be easy t work with. But they need to be very clean. Possibly if you had some brand new bottles would be best. I agree that 20 deg C would be an ideal temperature. You can correct the rate constant with equations from physically chemistry.

Children
  • Amine,

    I dug up a paper by Vasconcelos et al, 1997, "Kinetics of Chlorine Decay," JAWWA, 89(7), p. 54.

    They gave first order reaction rates as:

    Bellingham 0.83/day

    Fairfield     1.16

    Harrisburg 0.23

    North Marin - Russian 1.32

    North Marin - Stafford 17.7  

    North Penn - Keystone 0.082

    North Penn - Forest Park 0.767

    North Penn - Well 17 0.355

    North Penn - Well 12 0.102

    The values range over almost 3 orders of magnitude. You tell me which one is right for you.

    First order wall reaction rates ranged from 0 to 0.27 to 1.52 m/day.

    Good luck.

    Tom