Letter 20039

Ideas on how to cool wastewater and ways to reduce COD 

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I am researching ways to do a couple of things;

First- I need to reduce process water from about 110 degrees Fahrenheit(maximum temperature) to about 75 to 80 degrees Fahrenheit. The water line is pressurized and the flow is 500 gallons per minute(GPM) with a maximum of 700 GPM. We are in the process of reducing that flow to below 400 GPM. More information available upon request.

Second - I need a low cost way to reduce COD levels. currently we are running at about 4000-5000(mg/l) on the high end of production. And about 2500-3500(mg/l) on the low end. We are doing what we can in the processing plant. I am looking for suggestions/ideas for the treatment end.

Thanks!

Gregory J. Dayley
potato processing plant - Firth, Idaho

A cooling tower could easily cool this, but if you can't expose it to the atmosphere an evaporative condenser is very inexpensive to operate. The COD is a much bigger problem, probably requiring a trickling filter or activated sludge pond.

Ted Mooney, P.E.  finishing.com Brick, New Jersey

 

We have had excellent luck in plants of your type using microbial enzymes to eat the waste. It is a nice clean operation with the byproducts being carbon Dioxide, water and a little sludge.

Edward Petermann
- Kitchener, Ontario, Canada

This may become too complex to be practical, but is it possible to re-route the the water line through a cold water rinse tank (the cold water would act as the heat sink) or maybe a tank that needs a little heat, that could benefit from the hotter water passing through?

Dan Brewer
chemical process supplier - Gurnee, Illinois

I would like to follow-up the similar question on how to reduce the COD. Is there any practical ways ? What affects the COD ? Is temperature is a factor ? What about oil content (crude oil)? Thanks for the information

Johar
- Indonesia

++++ Please give us your full name and city on your followup, Johar. COD is Chemical Oxygen Demand. I don't remember the exact distinction between this and BOD (Biological Oxygen Demand) without going back and looking it up (my wastewater experience has been pretty much restricted to inorganic metal finishing wastes, which have little COD or BOD). But the principal is that you should not discharge waste water to the environment which would consume a great deal of oxygen to make itself right. Instead you should first subject it to a treatment which will oxidize such materials. A trickling filter, a highly oxygenated treatment pond, etc. Temperature could possibly distort a COD reading, but it is not part of what constitutes COD; but I think oil would be. Ted Mooney finishing.com Brick, New Jersey   August 12, 2008 How to reduce the cod from 4000 - 4500ppm to 100 - 150ppm. For reducing the cod what kind of chemicals to be used and the list of suppliers in India. Senthil kumar employee - tamilnadu, India