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Recycling water
Dear Sir/Madam,
How many method to recycle treated water from Electro Plating process. It is reliable to put back on production? Our plating process require De-Ionised Water.
What method is the most reliable in terms of initial installation cost and operation cost.
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Ali Mahyuddin Johor, Malaysia |
Your question is rather general, Mr. Mahyuddin. But recycling of end-of-pipe wastewater is generally impractical. Recycle the individual streams rather than mixing them together.
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 Ted Mooney, P.E. finishing.com Brick, New Jersey |
Dear Sir,
We have treatment plant system, and discharge of treated water from WWTP is about 12 gallons per minutes. Is it possible to re-use the discharged water for electroplating. We are using deionized water for the plating process.
How many method can be used for re-use that discharged water. What is most reliable method in terms of initial installation cost and operation cost.
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Ali Mahyuddin Johor, Malaysia |
This treated water is not going to be recyclable by any practical method. The right way to proceed is to deionize and recycle at each individual process step, not after treating with gallons of soluble salts like sulfuric acid and sodium hydroxide. If you de-ionize it, it will probably take as much water in regen and backwash as you will have saved.
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 Ted Mooney, P.E. finishing.com Brick, New Jersey |
First of two simultaneous responses --
Tsk, Tsk Ted!
It will not take anywhere near as much water as you say to regen and backwash! And it is not necessary to deionize water at every step! Most of their streams are probably compatible to be combined into a single feed stream to be fed to a common water recycling system. Unless they have cyanides, most acid and alkali streams can be combined with little or no issues, as "typically", the water still tends to be on the acidic side which keeps particulates and hydroxides, etc down. Equalization is a key here.
You can usually expect to have about a 94-98% reuse factor of the water. A counterflow packed bed design eliminates the backwash cycle, so there is a further savings in required water. We usually use 3.5 - 5 bed volumes or less in our systems per column (a bed volume is a comparative measure of the ion exchange resin used in the process - 1 cubic foot equals 7.43 gallons, so if you have 3.5 cubic feet of resin in each column, you have a total of 7 cubic feet for regen x 7.43 gallons, you get 52 gallons x 5 = 250 gallons total regen waste. Comparably, that would probably need regen on average every 3 days, so you generate 250 gallons of waste for every 17,280 gallons of water recycled on a 12 GPM/8 hr/day basis. That's 98.5% in my book.
End of pipe water can be recycled too using a well filtered RO system - usually a ultrafilter up front of the RO or even the replacement of a conventional treatment with a microfiltration system will make excellent pre-treated water for an RO, which can return 60-75% of the water back as low TDS recycle water. Feed that to a DI system and you can get extremely high quality water for a fraction of the cost of running city water through it.
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Tom Baker |
Ed. note: We have lost contact |
Second of two simultaneous responses --
Dilute rinses that are chemically compatible are easily recycled from a wide variety of plating processes. We've done hundreds of them. This is usually much more practical and economical than trying to recycle after conventional treatment. One of the best reasons to recycle before conventional treatment is that it saves more money.
Since it is fairly expensive to operate a conventional treatment system (chemicals, labor and sludge disposal), there can be a considerable savings in addition to the cost savings for water and DI system costs. Various sources estimate this cost to be $8-15 per thousand gallons treated. Typical operating costs for a recycling system are only $2-4 per thousand gallons.
In order to assess the potential for recycling at your facility, you need to do a little homework. A description of the process chemistries and rinse flows is needed as well as either a dragout estimate, or actual pH and conductivity measurements of each rinse. For flows that are less than 600 mg/l of TDS (total dissolved solids), a DI recycling system is usually the best choice. For higher TDS concentrations, an RO system (with pretreatment) may be a better choice, with the RO permeate feeding your existing DI equipment.
If you post more information about your plating processes, it will be easier to be more specific.
Lyle Kirmanwater treatment systems - Cleveland, Ohio
Tsk, tsk yourself, Tom. Part of the basis of my response, besides having been involved in wastewater treatment for 30 years, was YOUR lecture of last week :-)
The fellow has a treatment plant and he's talking about passing its thoroughly salty effluent through ion-exchange to re-use it. It is just silly to collect everything end-of-pipe, then treat it with caustic and acid to precipitate the metals, putting soluble Na and Cl ions in their place...then passing this effluent to ion exchange resin to remove the Na and Cl ions from the effluent so it can be recycled...then regenerating the cylinders, putting new Na and Cl in to drive out the old...then treating the regenerate with Na and Cl to neutralize it. And after adding Na and Cl four times in sequence to remove the previous Na and Cl, he hasn't recovered a gram of plating metal.
I don't take issue with the solutions you proposed, but they don't answer the question; I answered his question :-)
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Ted Mooney, P.E. finishing.com Brick, New Jersey |
Your right, Ted! I missed the text that stated "treated water".
Shame on me - and thanks for listening last week - nice to know someone wasn't asleep after that filling dinner! :-)
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Tom Baker wastewater treatment specialist Warminster, Pennsylvania |
Dear Sir,
Thank you for your support. I have an interest with Lyle Kirman advise. Our plating process have Nickel and Tn - Pb drag out which recycled back into plating tank. The WWTP only treating rinsing water. General info for Our Plating process sequence:
1)Acid wash, 2)Rinsing X 1, 3)Nickel Plating, 4)Nickel Drag out, 5)Rinsing X 3, 6)Acid wash, 7)Rinsing X 1, 8)Sn-Pb Plating, 9)Sn-Pb Drag out, 10)Rinsing X 2, 11)Neutralizer, 12)Rinsing X 2, 13)Hot Rinsing X 2, 14)Washing
Rinsing water discharge is approx. 2 gallons per minute for Nickel and Sn-Pb.
Final rinsing is manual wash, estimated discharge is 2 gallons per minute
Nickel rinsing water, pH = 2.5 and Nickel = 6.6 mg/ltr. and Solder rinsing water, pH = 2.6 and Tin = 4.21 mg/ltr, Pb = 9.2 mg/ltr.
Please tell me other required data. Thank you.
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Ali Mahyuddin Johor, Malaysia |
tq to all.. I very interested about water pollution..Personally I research about how to make a treatment of water and how to choose a best of product which give a more advantage, safe of cost and make a good to health... any body have a more information about this..please send me the information.. tq
Che Hasnida bt ab Hamid- Kuantan,Pahang,Malaysia
As you read above and was implied above, Che, many people have spent decades in the wastewater treatment of a single class of contaminants like electroplating wastes. Unfortunately you can't achieve a general education in water treatment via an internet posting. You'll need to start by reading a book or two on water treatment, then asking questions which are more specific. If your interest is in metal finishing waste water, Clarence Roy's "Operation and Maintenance of Surface Finishing Wastewater Treatment Systems" [link is to book info at Amazon] would be a good choice. Good luck.
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Ted Mooney, P.E. finishing.com Brick, New Jersey |