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letter 6343

Low Cost Hypochlorite Generator Design Needed



A discussion started in 2000 & continuing through 2017 -- add your Q to bring it back to the Hot Topics page.

(2000)

Q. Hi,

I run a small NGO supplying drinkable water in Haiti via home-based purifiers. The purifiers use chlorination along with 2 stages of filtration. The project is tremendously successful with use compliance over 80% in extremely impoverished homes. As a result childhood diarrheal disease has dropped over 90% in homes with purifiers.

Haiti's recent economic problems (~90% inflation this year) is seriously threatening both the availability and affordability of commercial bleach. We need a LOW COST method of generating a hypochlorite solution. Sea Salt and soft water are readily available. Sodium hydroxide for stabilization is a bit more of a problem and will have to be shipped in.

We're ready to attempt a trial design but assistance and experience would be much appreciated. As an NPO/NGO, we also intend to keep all of our efforts in the public domain, as we have with the purifiers.

Sincerely,

Phillip Warwick
- Melbourne, Florida USA


(2000)

A. Phillip, I am very impressed with your program. I do not have much help to offer, however, except some suggestions.

Industrial forms of bleach are actually about 12% sodium hypochlorite solutions. This is therefore, at least 5 to 8 times stronger solution than household bleach, and also contains a slight residual of sodium hydroxide that makes it greater than pH 10, higher than household products. It is shipped in black poly drums and is stable for weeks in storage. I am not certain it would be safe to use for drinking water, but if that is what you are now using, there is probably no more economical form of hypochlorite available.

There are alternative devices in the market that generate a mixture of disinfecting agents, including hypochlorite, using DC electricity and a sodium chloride brine solution in a small cell. These use energy only as needed for a batch treatment. By metering it into the drinking water directly, as generated, hypochlorite storage is eliminated. I am not sure, however, if typical sea salt, with other chlorides present, would work, as salt similar to that used in water softeners in purity (sodium chloride only) is usually specified. These should not be terribly expensive devices to build or run, if a 12 v.DC source like a battery in an auto or truck was available, even in rural Haiti.

This technology may also be in the public domain, since it was developed for use by NASA, I believe.

W. Carl Erickson
- Rome, New York


(2000)

A. Phillip,

My company manufactures the electrochemical hypochlorite generators for another commercial concern here in the US. I essentially agree with the previous letter about the ability to build a small unit economically, however there are many safety concerns that you must look at in the design. The units generate hydrogen gas at the cathode, and this can be potentially explosive - lethally. Units must be well vented to prevent this. Additionally, the level of chlorine present in the solution is typically required to be less than 1% to reduce/eliminate chlorine gas formation - again a potentially lethal occurrence. Also, it is much more stable as a feed into potable water at lower concentrations and the risk of illness associated with the overdosing of hypochlorite is worse than that of diarrheal disease. For that reason, I would not ever recommend the use of industrial grades or concentrations of hypo being fed into water intended for ingestion.

There is not a significant amount of information available for very small units because the commercial production of both the generators as well as hypo solutions is typically supported by larger commercial interests. For instance, the smallest unit we manufacture is a 12 Kg/day unit. This has the capability to produce approx. 1300 liters of 0.8% hypochlorite from brine, which is enough to treat 45,000 - 75,000 Liters of water per day or more, dependent on the microbial dosage rates required.

tom baker
Tom Baker
   wastewater treatment specialist
Warminster, Pennsylvania



(2007)

Q. I am a process engineer working on hypochlorite generator unit.
I need to know how can I calculate the requirement for hypochlorite generator.

My source is sea water and I need to have unit hypochlorite generator to produce Calcium/sodium Hypochlorite from sea water.
My total water that needs to be chlorinated @ 3 ppm is 100 gallons/day.

I am looking forward to your comprehensive response.

Regards,

Khurram ur Rehman
process engineer - Lagos, Nigeria


November 27, 2010

Q. Dear Mr Tom Baker,
You said that your company built the smallest unit hypo generator of cap.12 kg/day.
I am planning to buy and install such hypo generator to disinfect drinking water of cap. (100 up to 1000 m3/hr) using salt or sea water as brine water (sea water will be used for the plants near sea side). Please help me to get more detail about the unit, pi diagram, energy cons. space req. and the estimate cost (CIF Jkt Indonesia )
Thank you

onma bana
- jakarta indonesia



September 12, 2017

Q. Dear Mr. Tom Baker,

We have a hypochlorite generator which produces 20 kg/h free chlorine by using sea water. Generator does not work efficiently nowadays so we want to buy a new hypo generator. We'll replace all the related equipment also.
Can I get your contact info somehow to get a quote from your company?
BR

timur arslan
- ankara, Turkye


September 2017

A. Sorry but we lost contact with Tom Baker years ago. If you have technical questions, however, perhaps our readers can assist. Good luck.

Regards,

pic of Ted Mooney
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"


September 13, 2017

You may want to contact Water Phoenix, www.waterphoenix.com.

Lyle Kirman
consultant - Cleveland, Ohio



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