Waste water reuse at factories

WWkayaker,

What percentage of uncontaminated water is normally reused without treatment?

What percentage of water used is uncontaminated and why should it be treated?

Why should water be treated as uncontaminated?

What form will the reuse take with the uncontaminated water to determine level of treatment required?

100% under optimal conditions.

However some equipment may benefit from a corrosion inhibiter, algecide, etc. (chemicals)

Weird Question without background

0-100% is a good range...

You define the water as "waste water".

If it is "uncontaminated" why call it wasterwater - it is still process water.

You indicate that it is heated...from / to what temperatures and use for what kind of cooling??

Also what is the source of the water and what are the characteristics of the incoming water???

Tom

What is process "at a factory?"

What is temperature BTU heat load in process waste water?

What is cost to remove heat "at a factory?" to get water back to useable temperature?

Difference in cost between 'Cost to remove heat in used process water' and 'cost of "new process water"' is the key determinant.

A linear program model can then be set up to determine lowest cost ratio/mix of new vs recycled process waste water.

milo

You can do whatever you pretty much want to do with it inside your plant, as long as safety and equipment operation is not affected. You don't need to worry about your DMR/NPDES requirements until you try to put it in my sewer system. :)

Waste or postprocess water should always be treated. It is contaminated.

The important things that you don't provide are:

What are the contaminents in the process water?

What is the intended "re-use" of the process water?

What level of "un-contamination" is allowed?

What is the temperature of the process water?

What is the allowable temperature?

Having answered these, then you can work on the questions you pose.

Be aware that although the water is "uncontaminated", bacteria/slime may grow in the recirculated water, especially if it is warm and exposed to ambient air, and even if the system is anaerobic. Cooling towers are classic examples.

Trace materials may build up upon recirculation and cause issues that are not seen otherwise.

Either way, some sort of treat/purge may be required.

Good luck, though..some industries can be essentially "closed loop" with nearly "zero discharge". But do it with your eyes open.

This is water from boilers, metal furnaces, and metal machining equipment. The heated water is well over 150 degrees F. I am trying to do this without using a "corrosion inhibiter, algecide, etc. (chemicals)". If the facility reuses 75% of the outflow to the sewer, will it require the use of "chemicals"?

From your description, the water is not only hot, it also has a fairly high mineral content. It may also contain bacteria. Check with your local environmental authorities first before doing anything with it. If the authorities say the water quality is okay, you can use it for non-potable purposes such as toilet flushing or mopping the floor.

You don/t say what the water is used for - what kind of process is the water exposed to.

Whether the water is reused or sent back into the world, should make no difference in the treatment. It should be released at least as pure as it is received!

At Hope Creek/Salem nuclear stations they use the water from the Delaware river for cooling/condensation, the water that is released back into the river must meet purity standards and must not raise the river temperature more than 1°F. The purity of the water released may be required to be better than the water that came from the river

The process water in itself is used over and over again. It is demineralized, de-aireaded, as it in most power plants.

The water is never exposed to any of the materials in the facility. It is ran through pipes for heating (boilers) and cooling (metal process equipment) purposes. It comes in as pure as it is received from the city water supply (although it is received with high enough levels of chlorine that the facility has to treat with a drip before discharging it to the creek). I am not sure what chemical is used in the drip to neutralize the chlorine.

Are you SURE there are no chemicals added?

Boiler chemicals are typical to prevent corrosion, and scale that would inhibit heat transfer.

According to the facility's enviornmental manager, there are no chemicals added.