HIGH CHLORIDE WASTEWATER 1

[louvreChE]

I need a basic understanding of how easy or difficult it might be to treat some high chloride acidic wastewater.

We are regenerating water treatment resins using hydrochloric acid and the resulting 4-5 cu. m per day of wastewater has a chloride content of 7,000 - 8,000 mg/L.

The limit for discharge to the sewer is 1,000 mg/L for
chloride. Could you advise on the best treatment option available to reduce the chloride content to get the TDS below 3000mg/L prior to mixing with the other wastewater and
neutralisation.

 

[bimr]

There is no technology available to selectively remove chloride from wastewater without generating an additional waste stream containing chlorides.

Have you thought about adding water to dilute the wastewater? With the small volume of water that you are using, it may be practical.

Otherwise, your only option to reduce the chlorides is to evaporate the water leaving a concentrated brine waste. You then take the reduced brine offsite. Some vendors sell small evaporating units that would be appropriate for your application.

Since, it doesn't appear that you are a large di water user, a better solution is to go with a service di program. Vendors will supply service bottles with resin. The vendor periodically changes the bottles. The bottles are regenerated offsite so you do not have to bother with the regeneration or waste. A number of vendors are available to supply such a service.

It is like a bottled water delivery service except they are using portable ion exchange bottles.

 

[louvreChE]

Hi bimr,

That was a very useful information. Can you give me any company name where I could buy this evaporator? Also, would like to know what else H2O minerals will evaporate together with chloride? How can I size up this evaporator? What is the estimated power needed to use in the evaporator? Can it be treat TDS once chloride treated in the evaporator? Please help.

Will the chloride content reduce if I just collect the water with high chloride content in a storage tank and slowly feed it on the neutralization tank then discharge on the sea?

Appreciate your soonest possible reply.

thanks,
louvreche

 

[bimr]

Here is a company that makes small evaporators:

http://www.evaporator.com/evaporator.html

I have no experience with this company myself, and if you decide to pursue this, I would recommend that you get some references.

Basically, you will evaporate all of the water leaving the dissolved salts or TDS. The power needed is basically the energy to evaporate the water. I would expect the resulting brine constituents to be predominately sodium chloride.

You can probably discharge a chloride stream to the ocean, but not brine stream. You will have to permit the discharge with the local environmental permit agency wherever you are. If you are treating a wastewater, it is going to be more difficult to get a permit.

 

[jmj5152]

louvreChE. Why is the chloride limit so low when you are discharging to the sea?Presumably, you are also using NaOH for the anion regeneration, generating NaCl as your final waste? Sulfuric acid regeneration may be another option.

Evaporators for high chlorides will need Hastelloy parts, and be very expensive. I agree with bimr about the exchange tanks, however, that practice is not very common outside the US.
You can try contacting an electrodeionization equipment manufacturer. Such equipment uses electricity, and not chemicals for regeneration. Lots of suppliers, lowest cost is probably an OEM in your area associated with a company called Electropure, Inc. They are in Laguna Hills, California.