Waste water treament - besides disposal 3

[cougarfan]

I work at a chemical plant which has to dispose of solvent laden waste water to a waste incineration place and I would like to find another was to handle this. Typically, we are getting rid of thousands of gallons of waste with about 5 % of it being solvents and a few other misc fluids... The problem is that we are also a batch chemical facility and as such, change processes regularly so the solvent that is in the tank today will probably be different that the solvent we use tommorrow.... any suggestions other that finding the cheapest price to dispose of waste

 

[rbcoulter]

Distill the solvents & re-use them.

 

[25362]

In addition to what rbcoulter advised, also reuse the water.

 

[StoneCold]

dideyjohn
We have the same problems. We truck out tanker loads of waste water and waste solvent to an incinerator. I have proposed a couple of ways of handling the wastes but no one is interested in changing. Some of the options for the water were filtration then organic adsorption on to carbon or macro-molecular polymer, then reverse osmosis. An alternative would be to burn the waste solvent in a boiler and then use the heat and a falling film evaporator to separtate the water and solvent from the salts/solids. Then use the macro-molecular polymer to separate off the solvents from the water. I don't know of anyone who is doing this but I would be interested to hear if anyone has been able to implement these types of processes or others to reduce their waste.

 

[saxon]

didyjon, Depending on the solvent species molecular size, you could run the waste water through ultra-filters, the water will come off as permeate wich can be recycled back into the plant water loop. The concentrate contanining the solvent can then be sent to a still where the solvents are split off for reuse. The bottoms from the still will still in all probability have to be sent off site as Haz.-waste. or if the BTU content is high enough, mixed with fuel, and sent to an onsite Boiler or Industrial Furnace.

This recycle approach may place your plant into the category of a Treatment Storage and Disposal Facility necessitating changes to your Environmental Permit Status. If this happens, you will be taking on a tremendous Administrative/Enginnering/Maintenance burden in order to comply with the new permit status. This approach will also kick in Federally mandated BIF regulations not too mention changes to the plants Air Permit. These are also very onerous to comply with.

Sometimes just shipping the waste off-site to an approved TSDF for destruction/recycle is the simplest and cheapest approach. When everything is taken into consideration.

Hope this helps.
saxon

 

[StoneCold]

saxton
We spend close to 200k USD on waste disposal. Do you think that at that level it is worth persuing? I have never had to deal with the permitting and regulations of a TSDF facility before so I am not sure how hard that is. We had TSDF status before but we "downgraded" in the past to get out from under the paperwork. Are most facilities shipping their material offsite?

 

[saxon]

Bradstone, Check with your Environmental Health and Safety Group. Since I'm unfamiliar with your plant, permitting requirements, and other intimate details, the EHS group is the first place to start. Then you will need to do a Projects Cost Analysis Comparison. Comparing all of the cost between installing, operating, maintaining a treatment facility. Don't forget to include emergency incurred costs if you violate any and all permit terms and conditions due to failure of or improper operation of the system. Then compare this to your anualized costs for shipping off site.

If there is a cost benefit to treating the waste stream yourself, then it may be of interest to build and operate the system. But check in with who ever is responsible for handling the environmental affairs at your facility and definitly get them involved upfront. This may also require including the Company Legal staff.

Hope this helps,
saxon

 

[oxilume]

Strip the solvents from the water with a radial entrained vapor extraction mass transfer unit.

The REVEX MTU can be operated in a closed loop using an inert gas such as N2.

http://www.revextechnologies.com

 

[jongwon03]

Why don't you think about Freeze Concentration process, If you are interested in, I can share the practice and please contact me at kdwon@skevt.com

Sincerely,
KD

 

[asesor]

If the solvent is hydrocarbon based you could just use a 2 or 3 phase centrifuge( used in the oil industry for muds) and separate the two components ( water and hydrocarbon) I dont know your discharge parameters but sometimes the addition of an oleophylic filter( depending on the solvent specs) may do the job

 

[tulane21]

Depending on the type of solvents in the waste water, there are several onsite treatment options that would work (e.g. carbon adsorption, chemical extraction (mpp), steam stripping, etc), since they can handle a wide variety of contaminants. My experience has been that shipping offsite can be very costly (as BradStone stated - $200K), especially if you have larger volumes of water. It may be worth the time and effort to look into these other options to see what fits best.
It is a good way to cut down on operational costs.

 

[4tuna]

From the EPA's Technology Innovation Office website (

http://www.clu-in.org)

comes the following news item you may be interested in:

PURE WATER, PURE AIR, PURE GENIUS

Success Stories: Canada’s Innovation Strategy. Government of Canada website, 18 Dec 2002

With very little knowledge of the environmental technology market, but certain that they had a dynamite idea, Brian Butters and Tony Powell of Purifics Environmental Technologies Inc., London, Ontario, developed a photo-catalytic treatment process to purify water and air of organic contaminants at the source with no generated waste. Their Photo-Cat® process accepts and treats water with suspended oil, turbidity, high levels of total dissolved solids, metals, and a wide range of organic contaminants at varying concentration ratios. The end result is that chemicals or toxins of concern are destroyed; the environmental hazards are eliminated at reduced cost with simplified operation. Photo-Cat® is a lower-cost alternative to treatment by other means, such as carbon treatment, reverse osmosis, and thermal catalytic air treatment. To date there is no other commercialized photo-catalytic system. Using $10,000 from Canada’s Industrial Research Assistance Program as seed money, the pair set to work, using parts they bought at Canadian Tire. In 1994, when Photo-Cat® was still in its developmental stage, Ontario Hydro heard about the product and asked for a demonstration. Once Ontario Hydro saw the process, it was convinced of the potential. And so was New Brunswick Power, which bought the first Photo-Cat® system, even though it was just a prototype. The technology can be applied to all kinds of contaminated waters, including landfill leachate: a 25 kW Photo-Cat® system has been installed at a U.S. Superfund Site for the destruction of 1,4-dioxane in landfill leachate. Contact: Purifics Environmental Technologies, Inc., 519-473-5788, info@purifics.com.

 

[phex]

to 4tuna:

i'd be very interested in getting some references besides those mentioned in the article. do you know of more plants/installations with their technology?

 

[4tuna]

Sorry phex I don't, I just happened across the article and thought I'd share it -- I don't have any first hand experience with this. You might want to contact purifics...

 

[moltenmetal]

Titanium dioxide photocatalytic systems (like Purifics), UV/peroxide, Fenton's reaction, ozone/peroxide and other chemical/advanced oxidation water treatment systems aren't new technologies- most of them have been around for at least 20-30 years and some of them have hundreds of installed systems worldwide. However, all of them are generally economically limited to a practical upper maximum level of 1000 mg/L of any particular organic species in water- unless your disposal costs are enormous and no other method of source contamination reduction will work. And there are lots of compounds which oxidize very poorly. A general rule of thumb: if the contaminant compound has at least one multiple bond or ring, or contains oxygen nitrogen or sulphur, it may be a good candidate for oxidation by one method or another (i.e. trichloroethylene, benzene, ethers etc. are usually easily oxidized by these methods). If it doesn't, chances are it isn't a good candidate- i.e. carbon tetrachloride is virtually impossible to treat by oxidation. See Calgon Carbon's oxidation technologies group or

http://www.hydroxyl.com,

both of whom compete with Purifics.

At 5% organics (i.e. ~ 50,000 mg/L), you'll have to do something else, including some physical means of separation if any of the solvents are less than miscible with water.

First things first: consider source reduction. Can you stop the solvents from entering the water in the first place?

Second: filter and do some good oil/water separation. This may reduce your problem considerably on a mass basis. Options to consider include oil/water separators with skimmers, centrifuges, dissolved air flotation, coalescing filters etc. All will return liquid product with less energy input than distillation.

Once you're sure that only dissolved or well-emulsified materials remain, your options include activated carbon treatment, air or steam stripping, pervaporation, distillation, and oxidation methods as mentioned before. If only a modest mass of relatively low-solubility compounds remain, then activated carbon is a good bet. If the compounds are volatile and non-miscible, consider air stripping with vapour phase carbon or a thermal or catalytic oxidizer on the offgas- i.e. burn the compounds, not the water!

If the compounds are water-miscible, they might be amenable to biodegradation- a good process for cheap removal of lots of mass, but only if it's degradable and not toxic enough to kill the bugs outright- provided you can wait that long and you have the labour to operate the plant.

Any of this will cost money. The best return on investment is usually at the entrance to the process (i.e. waste reduction), not at the end of the waste disposal pipe.

 

[thermicatech]

assuming large flow rates and if HHV of your liquid waste is less than 4500 BTU/lb, you can use a downfired incinerator, introducing the waste downstream of the burner.
If the HHV is larger than 4500 BTU/Lb and the waste does not contain salts, it can be used as burner fuel, introduced through a proper designed burner to handle waste liquid.
If you are interested in further info, please let me know.

 

[radwaste]

Which solvents are present in the waste water?

 

[chasewick]

Have you considered vacuum distillation with advanced oxidation final treatment? Our supplier Wastech Controls appears to have an answer that works.