Alternatives to Chlorine Dioxide

Chlorine and sodium hypochlorite are two alternatives, but typically chloring dioxide is used instead of these because it forms less harmful compounds when reacting with hydrocarbons. The worst of these is dioxin when can form when chlorinating with straight chlorine gas.

Ammonia can also be used in water treatment, which forms less corrosive compounds in solution.

You can also use UV and ozone. These, however, have no residual protection, so chlorination is still a necessary follow-up if the water is to be stored for some time. They do however provide the advantage of greatly reducing chlorine dosage and thus reduce the the formation of potentially carcinogenic THMs.

Processes should be designed as inherently safe as possible. In this case opt to use bleach (sodium hypochlorite) because it is in the liquid state.

Calcium hypochlorite is often preferred, as it loses strength less rapidly during storage.

According to the EPA document, "Alternative Disinfectants and Oxidants Guidance Manual", ozone is the most effective oxidant available, but, as noted by others, it has no residual effect. It produces no known harmful byproducts, and is effective against a number of organisms that are resistant to other treatments. The real issue is what is the destination of the treated effluent? One needs to know this to properly select the appropriate treatment...

Thanks for your reply

We are using treated effluent for make up water of cooling tower.

Watch for diseases of all kinds not to be spread. You live in an incubation chamber were you are! If only tertiary treated you will have problems. Sooner than later.

Good luck would be an irresponsible greeting! Ky.

SEE MY COMMENTS ON ANOTHER CURRENT DISCUSSION UNDER THE HEADING :

"Ozone as a disinfectant in water filtration"...... I think you will have answers to your questions under my two replys.

Depending on flow rate, ionization is an alternative, and it leaves residual ions to maintain purity. I have a system on my swimming pool, and maintenance is very stable. Actually, liquid bleach does the hard work, then the ions maintain.

The guy at http://www.carefreeclearwater.com/request.aspx is very knowledgeable and helpful. (I don't represent them; in fact I bought a competitor's system. Don't tell him!)

Hydrogen peroxide at 6-8% might be a suitable alternative?

Water treatment with ozone is also the advantage of eliminating most of the pharmaceutical products that can be found in the water. While the other disinfection technique usually do a good job at eliminating bacterial and viral contamination, ozone treatment seems to be the only one that can be used to eliminate the traces of hormones and medication found in surface water sources.

The main problem with ozone technology, is the high cost of the equipment needed to produce it. Once this hurdle is overcome, operating costs are usually lower than with other technologies. With ozone, there's no need to handle and store dangerous chemicals.

You can find small ozone generators that can handle the production needed for a swimming pool, all the way to the ones consuming megawatts of power and suppling enough ozone to treat the water of cities the size of Los Angeles.

The use of chlorine dioxide as well as some of the alternate compunds such as sodium chloride or calcium chloride will provide a residual protection as stated above. These are a chemical kill and require time to accomplish the destruction of the bacteria. For this reason, these are introduced into the effluent in combination with a detention tank. They also provide, as others have stated, a measure of residual protection after the initial bacteria kill. Other alternatives such as ultraviolet or or ozonation have no such retentive protection.

If, however, you are discharging this effluent (as the term "effluent" implies) retentive protection is probably not a concern. In that case, you can use ultraviolet disinfention or ozonation as others have noted. Each of these would provide adequate kill, but with no residual protection. However, there is an added advantage to the ultraviolet inasmuch as it provides a bacteria kill that is not chemical in nature and thus does not alter the chemical propertise of the effluent. It kills the bacteria by virtue of the lethal nature of the ultraviolet light.

Some locations, such as where I am now, require the removal of residual chlorine in the ffluent stream before it is discharge to the receiving waters. This is accomplished via yet another chemical reation to reduce the chlorine residual. But the result is still a chemical being discharged. Also, ultraviolet kill is nearly immediate. This eliminates the need for a retention tank (normally called a "chlorine contact tank") to allow the chlorine to be in contact with the bacteria for a period of 15 to 30 minutes to effect the kill.

These are some considerations that you must review when designing your disinfection system. They all have merit and must be considered to provide the best treatment for your particular situation.

Experiments done in Montreal, showed that ozone is far superion to UV in waste water application. Ozone returns to oxygen which is good for the water anyway. Ozone destroys the hormonal compounds (not UV) that are turning the fish from male to female. This is a worst problem than a few bacterial or viruses that are destroyed by ozone anyway. Ozone works in dirty water where UV doesn't work that well.

This is why, based on scientific research soon to be published, Montreal will build the largest ozone waste water treatment in the world within two-three years.

Google anodic oxidation water purification. Back in the eighties I had developed a system which did just that. There are so many entries that it is hard to give you the links you could be looking for. Have a look around maybe you can find some thing there.

It is a very complex (if you want to understand all the processes involved), although simple way of treating water. Very cost effective too.

Good Luck, Ky.