Low Cost Hypochlorite Generator Design Needed

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.

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.

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,

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