The 1,2-Dichloropropane in the return water of the cooling tower

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Dear all,

The return water of the cooling tower we analytics contain 1,2-Dichloropropane, the concentration is  0.00093/ 0.00090 mg/L, while the 1,2-Dichloropropane of the supply water is not detector (N.D.), the concentration of the method detection limit (MDL) is 0.00041mg/L. Could someone tell us kindly : the formation mechanism of 1,2-Dichloropropane , and how to prevent the trace value detected ?

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6 Answers

  1. Here is what CHAT GPT has to say:

    1,2-Dichloropropane (1,2-DCP) is a colorless liquid with a chlorinated hydrocarbon structure, and it is primarily used as an industrial solvent and chemical intermediate. It is also found as a contaminant in some groundwater and soil due to its past use as a soil fumigant.

    The formation mechanism of 1,2-DCP is not entirely clear, but it is believed to be formed from the reaction between chlorine and other organic compounds present in the water or soil. The use of certain chemicals and industrial processes may also contribute to the formation of 1,2-DCP.

    To prevent the trace value of 1,2-DCP from being detected in the return water of the cooling tower, several measures can be taken, including:

    1. Source control: Identify and eliminate the sources of 1,2-DCP in the cooling tower system. This may include replacing or modifying equipment or processes that may be contributing to the contamination.

    2. Treatment: Implement appropriate treatment technologies to remove 1,2-DCP from the cooling tower water. This may include activated carbon adsorption, reverse osmosis, or other advanced oxidation processes.

    3. Monitoring: Regularly monitor the cooling tower water to detect any trace amounts of 1,2-DCP and take appropriate corrective action as needed.

    It is important to note that even trace amounts of 1,2-DCP can pose health risks, as it is a potential carcinogen and has been linked to other health effects. Therefore, it is important to take appropriate measures to prevent its presence in the cooling tower water.

  2. 1,2-Dichloropropane is an organic compound classified as a chlorocarbon. It is a colorless, flammable liquid with a sweet odor. it is obtained as a byproduct of the production of epichlorohydrin, which is produced on a large scale.1,2-Dichloropropane is an intermediate in the production of perchloroethylene and other chlorinated chemicals. It was once used as a soil fumigant, chemical intermediate, as well as an industrial solvent and was found in paint strippers, varnishes, and furniture finish removers but some of these uses have been discontinued.  Thus, there is reasonable evidence that 1,2-dichloropropane may be a carcinogen

    1,2-Dichloropropane is a waste chemical stream constituent which may be subjected to ultimate disposal by controlled incineration. Incineration, preferably after mixing with another combustible fuel, care must be exercised to assure complete combustion to prevent the formation of phosgene.

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  4. Thanks Muthu.  I could not find any resources suggesting that 1,2-DCP is a disinfection byproduct. Until fairly recently (1980s) it was used as an agricultural insecticide in the USA. Groundwater contamination can be found in agricultural areas.

    It also used to be used in paint strippers.

    Lin, where is this site? What are surrounding industries?

    2 Comments

  5. Pat gave a really good answer.

    But, I think 1,2 DCP may be forming as a disinfectant byproduct if you're using a chlorine-based disinfectant.

    Also, can't you let the trace levels be, i don't think that's going to affect your processes.

    2 Comments

  6. The Dichlorpropane is probably not being formed in your system. More likely it is just being concentrated to above the detection limit.  

    1,2-DCP has a vapor pressure much lower (40 mm Hg) than water (760 mm Hg). This means that less of it is going to evaporate into the air in the cooling tower relative to the evaporating water.

    How many cycles of concentration are you running?  If you are running 6 cycles and assuming that none of the 1,2-DCP is transferring to the air, then the incoming source water may have up to 0.000016 mg/L. If some is transferring to the air, then the source water could be even higher.

    I would start and try and find a lab that can give you a lower detection limit on the source water. I would look for something in the range of .000001 mg/L as if the 1,2-DCP is not transferring to the air it may be at much higher cycles of concentration.

    For the short term, I would drain and refill the cooling tower and/or decrease your cycles of concentration by about 66% to reduce the expected value to less than the detection limit.

    Long term after you determine if you actually have 1,2-DCP in your source water and at what concentration, I would look at the feasibility of using activated carbon or another adsorbent to remove it before feeding to the tower.

    5 Comments

    1. Could you run a small tower beside the big one using the same feed water and see if the DCP is concentrated there also? Otherwise, Activated Carbon or other adsorbent to remove it is your best bet. I would look at renting a relatively large carbon bed and running is directly off the basin to pull the main concentrations down. Then a smaller bed run on a side stream should be adequate.  You currently have about 37 grams of DCP dissolved in the water. At 7 cycles you will have less than 100 mg/day of incoming DCP.

       

      From Henry's Law, the very low mole fraction of the DCP and the low vapor pressure mean that relative to the evaporating water far less of the DCP is evaporating. That means that your 7-10 cycles for the water could be 100-1000 cycles of DCP.  Since you are only at about two times the detection limit, you could increase your blowdown rate and you should see a reduction. But adsorbent is probably the better solution.