Sound technical content, curated with aloha by
Ted Mooney, P.E. RET
Pine Beach, NJ
The authoritative public forum
for Metal Finishing 1989-2024
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High TDS and NaCl problem in effluent treatment
Q. I am facing problem of high TDS in effluent due to the water used in regeneration of DM plant?
Can you suggest the way out?
- Chandigarh, India
2006
A. Hi Gaurav,
The high TDS is due to usage of hydrochloric acid. It produces sodium chloride which is highly soluble in water.
If you use dilute sulfuric acid in its place and neutralise the combined effluent with calcium hydroxide ( (not carbonate), it will precipitate calcium sulphate. Its solubility in water is only 2000 ppm, i.e. 2 grams per litre.
Of course it is a lot of work to prepare and stock dilute( 5%) sulfuric acid on the previous day for use to allow time to cool it as it produces tremendous heat during preparation.
The trouble is worth taking for achieving a low TDS in the effluent and also added bonuses of avoiding chloride slip in the DM water produced and also doubling the capacity between two regenerations.
Best of luck,
- Mumbai, Maharashtra, India
Q. Hi I am a ETP in charge of Electroplating plant having two different streams in waste water treatment plant separately we treat it by two different methods 1.Biological for sewage and 2.Chemical precipitation for electroplating.
My question is can we reduce the high TDS by using constructed wetland as a biofilters?
As mentioned by Dr.Hammer
Constructed wet lands:-
Constructed wet land is a artificial mangrove like situation having water weeds in it, and it will absorb the salts from the waste water.
Can we do it like this?
- Aaaurangabad, Maharashtra, India
2006
A. Artificial wetland works fine for:
- extra treatment after biological treatment (to remove some of the dissolved salts e.g. nitrate, ammonia, ...)
- removing the last fraction of the suspended solids (e.g. reducing the suspended solids from 50-100 mg/l after biological treatment down to ~10 mg/l after artificial wetland. In that case you must design the artificial wetland in such a way that the water stream percolates through a sand bed (either vertical percolation : distribution of the water streams on the surface, drainage pipes some 1 - 1,5 m below the surface) of horizontal (infiltration on one side of a strictly rectangular wetland, drainage pipes on the opposite side).
Artificial wetland does NOT remove chloride, sulphate, ... and similar inorganic salts from a waste water stream.
The only reasonable way to reduce the salt load in the waste water is to make changes in the production plant itself (less drag out, reuse of static rinse water, increase life time of plating baths, electrowinning of spent etching fluid instead of chemical treatment, etc.)
Artificial wetlands can support quite some suspended solids from the biological treatment. Artificial wetlands will fail quickly (by plugging, by intoxication of the water plants) if waste water from the chemical precipitation step containing more than say 20 mg/l suspended solids is fed to it.
- Gent, Belgium
A. Hello Gangadhar,
I agree with Mr. Bert on the ways to reduce the TDS. The method of measuring TDS is a point to be considered. If it is by Conductivity Meter, what is the factor you have used to convert conductivity to TDS? This factor also affects TDS measurements.
Subramanian Ramajayam
consultant - Bangalore, India
Q. Sir, I ask you one question is how to reduce the TDS of effluent in galvanised industry. TDS is 50,000 ppm so which treatment to give for the reduction of TDS and also COD, BOD, cloride, sulphate, metals. Please guide me which treatment useful for reduction of these parameters.
Dharmadhikari Santosh- PUNE, India
June 24, 2008
Q. Hello, I am a student of Chemical Engineering, and I'm doing an internship on the biological treatment of waste-water by activated sludge (anaerobic, aerobic, aeration and clarifier). We worked with a "problem" in the clarifier. When it reaches a very large load of sulphate (more than 4 g/L), the mud does not seem to settle and the clarifier overflows, compromising the quality of treated water. Does anyone have any ideas on what can influence the sulphate? Or any bibliography?
Thank you.
- France
April 11, 2012
A. Where does all the sulphate come from? Are you adding aluminum sulphate as a coagulant? If so, reduce the dosage. Add a polymeric coagulant if necessary.
Jeffrey Holmes, CEF
Spartanburg, South Carolina
Q. We have difficulty to maintain the TDS below 1500 ppm. Because treated water ppm is 8000-9000 ppm. We add more raw water for reducing the ppm. How to solve the TDS problem? We can maintain easily 2200-2600 ppm.
Anil Kumar singh- Gurgaon, India
April 18, 2012
Q. Sir,
We treat effluent water that has 300 ppm of chloride content, while we add poly aluminum chloride for a coagulate agent. We want to reduce chloride content to less then 50 ppm, kindly tell me the method.
Thank you
- Chennai, tamil nadu, ndia
July 26, 2012
A. Hi Raja. The first thing to do may be to switch to poly aluminum sulphate, and not use chloride because there is no answer except to reduce the use of chloride at the source.
Were you to invest a fortune in RO or DI equipment, and waste incalculable energy and chemicals doing this, you will still have the salt on your hands, to be disposed of in a landfill ... until such time as the liner leaks or wears out and the salt poisons the earth and kills the aquifer.
opinion! The traditional & proper thing to do with saltwater, of course, was to discharge it to the sea. But as you probably realize, in the world's effort to stop irresponsible ocean dumping, we've collectively decided to salt our earth instead of the ocean :-(
If I'm wrong, I welcome enlightenment.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. Sir,
I am working in distillery condensate policing unit, there is very high TDS and high conductivity in the final water. My aim is to reduce the TDS and conductivity of the water, so that we can reuse the water to distillery process.
The responsible thing for TDS is the aerobic culture carry over as per my observation.
Please give me the suggestion to solve it
- Manoli, Belgaum, Karnataka, India
July 3, 2013
A. Dir Sirs,
Good afternoon. Great day!
Perhaps a technology to view concerning your questions:
www.FloatingIslandInternational.com
- Floating artificial wetlands. Look for the article and paper on landfill leachate treatment with floating wetlands.
The technology was sufficient to render landfill leachate from BLACK/high TDS/inorganics/organics/color to almost clear effluent. Using plants.
See also research with German University: Max Plank Institute - formative basis for wetlands and use of plants for Plant Phytokinetics/phytoremediation.
The complexity of the natural world is designed to handle most anything we can generate and break it down when properly understood and applied (most of these systems requre more room). However, a biological process then must be operated as such -- either aerobic/anaerobic/anoxic -- but again, may have the capacity to handle your questions.
See formative work with plant systems to clean up almost anything in wastewater:
Ocean Arks International is another web site.
Stewardship is a basic understanding that we should employ in all of our endeavors including each other.
Thank you kindly. Have a great day!
engineering - Harrisburg, Pennsylvania, USA
Effluent treatment for biscuit plant
Q. I am working on an ETP in a biscuit manufacturing unit. The electrical conductivity, residual sodium carbonate, and percent sodium is more than the standard values.
Please suggest methods to reduce them separately. The chemicals we are using in ETP are: Lime, caustic soda ⇦liquid caustic soda in bulk on Amazon [affil link] , alum & polymer.
Himanshu Jadonbiscuit manufacturing unit - bangaluru,Karnataka, India
August 25, 2015
Q. Can anyone give me solution for removal of high TDS from effluent? Which treatment technology is suitable to reduce high TDS from effluent?
Parameters are as follows:
TDS = 83819 PPM
Sulphate = 70324 ppm
Phosphate = 8223 ppm
Chloride = 2184 ppm
TSS= 89 PPM
pH = 1.25
BOD= <10 mg/lit
COD= 16 mg/lit
sulfuric acid = 7%
type of industry - pharma.
Please reply.
- Pune, Maharashtra, and India
September 3, 2015
A. You could try adding calcium hydroxide to about a neutral pH. That will precipitate almost all of the P and most of the S. Then, filter. The solid, I would guess, would be nonhazardous. Might even make a decent fertilizer.
Dave Wichern
Consultant - The Bronx, New York
A. I suggest that you try lime precipitation to precipitate calcium phosphate and calcium sulphate. The quantity of sludge will be very large.
Lyle Kirmanconsultant - Cleveland Heights, Ohio
A. Mr. Kirman is entirely right. Also, I know from experience that such sludges don't dewater well. You might expect 150 - 200 gallons of solids after filter pressing from a 1000 gallon batch.
What I once did to evaluate dewatered solids volume I called "bench scale pressing." Put a wad of cotton, then a little bed of sand in the bottom of a 5 cc syringe. Cover this with a little circle of filter paper. Now, fill the syringe with wet sludge. Now, insert the plunger and start pushing it down. Gradual pressure is best. Press it out until you can't get anymore fluid out. Since the cross sectional area of the syringe is about 0.2 - 0.25 sq. in., it's not hard to exert 80 - 100 psi with your thumb.
Now, evaluate. It may be that you would be better off neutralizing with NaOH, evaporating, then disposing of the residue as a solid waste.
Dave Wichern
Consultant - The Bronx, New York
Q. Hi, I am a chemical engineer and I am working in a High TDS effluent treatment Plant. We are facing with a problem in reducing COD. We can't reduce COD below 100. Biological treatment does not work. How we can reduce COD below 100?
sanaz azimiPetrochemical Effluent Treatment Plant - bandare mahshahr , Iran
October 12, 2015
Q. I am Process safety manager and I have given a task to reduce TDS of my ETP from 90000 to 2000 it mostly contains:
|
Appearance 2 pH 3 COD mg/lit. 4 NH3-N mg/lit. 5 TDS mg/lit. 6 Chloride mg/lit. 7 SO4 mg/lit. 8 Calcium by AAS mg/lit. 9 Calcium by Titration 10 Magnesium by AAS 11 Magnesium by Titration 12 Sodium mg/lit. |
Stream 1 Slight Yellow 7.66 1448 292 80895 45670 721 93 375 165 2249 5949 |
Stream 2 Slight Yellow 8.66 2736 450 136448 64604 850 1599 3672 506 11015 7380 |
Please suggest as we are mixing both the streams and just removing COD and NH3-N currently.
Regards,
Viral
Fertilizer,Nutrient - Surat,Gujarat, India
January 20, 2016
Q. I am dealing with a project to reduce the TDS from specific value given in table, can any one give me a solution for this issue apart from Multi effect evaporator.
1) pH - 7.40
2) COD - 738 ppm
3) TDS - 93324 ppm
4) Cl2 - 53361 ppm ( outlet result )
5) SO4 - 2200 ppm ( outlet result )
6) NH3N - 18 ppm
7) TSS - 82 ppm ( outlet )
8) Hardness - 13900 ppm
- mumbai Maharashtra India
March 25, 2016
Q. I have a FireTube Boiler , and the ground water has a hardness of 490 and the TDS is 2250, For feed water to the above boiler what do I need to do with the above Raw water? Can you please suggest me the process for the above raw water, so as to allow me to safe run of the boiler at 8KG/Cm2
Srinivas Rao- VIJAYAWADA, AndhraPradesh, India
February 4, 2016
Q. I am an intern under environmental science. In my company we are experiencing a challenge of high TDS. The chemicals we are using to treat the effluents are HCl, Aluetch (caustic soda ⇦liquid caustic soda in bulk on
Amazon [affil link]
), and polymer.
Please advise
- Nairobi, Kenya
May 26, 2016
A. Hi Dickson. To get substantive help you probably need to detail what you are treating, in what volume, etc. But I'm sure you realize that the NaCl which results from your treatment regimen is extremely soluble (hundreds of thousands of ppm), so you're not going to be able to be able to chemically treat the wastewater to reduce the TDS. Switching from caustic soda ⇦liquid caustic soda in bulk on Amazon [affil link] to lime would help somewhat. What is the source of the wastewater?
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
A. Your problem with high TDS is not unusual. Usually, the solution involves going back to the process lines and minimizing dragout and dumps of concentrated solutions. This may involve recovery and similar systems to purify rather than dump concentrates. This requires a detailed audit of your lines that will quantify the sources of the TDS. But, if you already know the main contributors, then focus on them.
After that, look at your treatment practices, since they also add TDS, sometimes very significantly.
consultant - Cleveland, Ohio USA
Q. Sir, I am working in ETP plant. We use HCl to neutralize pH. My question is how can we reduce 4500 TDS to 2500 TDS? Is there any solution? Please suggest. Thank you
Lakshmikanth yadav- Tumkur, Karnataka, India
June 2, 2016
Q. Hi, our company is currently treating deep well water. Water analysis shows high TDS and chlorides. What is the best solution to reduce them aside from using a reverse osmosis equipment? Thank you.
Angela Si- San Juan City, Metro Manila, Philippines
June 13, 2016
Q. We have difficulty to maintain the TDS below 2000 ppm. Because treated water ppm is 4000-5000 ppm. Hence we add more raw water for reducing the TDS. How to solve the TDS problem?
R.Mailerum perumallatex industries - nagercoil, tamilnadu, India
July 1, 2016
A. Hi. I'll agree that diluting your effluent with raw water -- pouring precious fresh water down the drain -- is an unacceptable solution. In the finishing industry in the USA, that approach would be illegal. However, unless you describe your treatment regimen and what the TDS is comprised of, I don't expect that anybody will be able to help. Good luck.
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. Dear all,
We use PAC (Poly Aluminum Chloride)for effluent flocculation & it is working very well but chloride contains are increasing due to PAC.
I have tested many more flocculants for the same but for our effluent quality PAC gives the best results except Chloride.
Please suggest any options to reduce chloride.
Thanks
- Mahad, Maharashtra, India
October 7, 2016
Q. Sir, My TDs in clarifier inlet is 8000..where as outlet is 13000...but my hardness in inlet is 2000 ..outlet hardness is 50...I am using lime and soda ash ....
Bhagavan KumarWater treatment - vishakapatnam, andhra Pradesh, India
December 15, 2016
Q. In a sugar production industry I am working as ETP in charge. I am facing high TDS and frequently facing Aseptic condition in Aeration tank; so any one help me to resolve the issue?.
Pancheshwara BhoviMylar sugars Ltd. - Bellary Dist, Karnataka State India
January 4, 2017
Q. Hi,
This is Badal, Working in a accessories company as ETP Manager. Capacity is 12 m3/H, but our waste generation is around 4m3/H. Inlet Parameter is;
PH = 10
TDS = 1300
DO = 1
BOD = 50
COD = 300
as I have more capacity in the tank, can I use more fresh water into the tank and will it help us to improve the inlet waste water quality?
- DHAKA, NARSINGDI, BANGLADESH
February 16, 2017
A. Hi MD. In the USA it is strictly forbidden to dilute in that fashion. I don't know the rules in Bangladesh, but it is certainly poor practice.
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. Hello,
I am working in an acid zinc plating of cast iron (caliper and carrier).
For acid pickling, we use HCl
Out trouble is Cl Ion in waste water. We must discharge the pickling acid into another tank and it must be exit from the company, which costs much money.
I have 2 questions:
1- what is the system of waste water treatment in presence of Cl Ion.
2- can I have a formulation from H2SO4 pickling for cast iron parts?
Thanks a lot,
- tehran, iran
July 4, 2017
A. Hi Asghar...
1. I do not believe that there is any practical way to treat chlorides because they are so soluble, but using inhibitors (so acid is not wasted dissolving iron), and an acid extender (to precipitate the iron) should help you secure significantly more life from the acid.
2. Cast iron is more prone to smutting in sulfuric acid than in hydrochloric acid because ferric carbide is not soluble in sulfuric acid. If you seek only acid activation of the surface, a dip in a few percent of sulfuric acid may suffice, but serious pickling will probably not work.
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
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Ed. note: Only our regular helpers Lyle & David have contributed answers in 3+ years now. Please offer some answers rather than just your questions, folk! Trying to teach is a wonderful way to learn; and being told by other readers why your suggestion is questionable is intensive training!
If you really can't help with even one of the many open questions here, please surrender your 'ETP-in-charge' title because you're hopelessly unqualified :-)
LAKH = 100,000
Q. Dear Friends,
I have an effluent with TDS=>3 lakhs ppm, BOD> 1 lakhs ppm, pH>11.5.
I came to a result having COD<600 ppm, pH~6.8, but TDS of the treated solution is still 54,000 ppm and that is due to NaCl only. Can anybody help me out how to reduce it in sustainable way.
Thank you in Advance
Researcher - Gandhinagar, Gujarat INDIA
October 21, 2017
A. Hi Dr. Chaudhary. I don't think you'll find any practical way of removing NaCl from any reasonable volume of wastewater. I think you'll need to find out exactly where the Na and Cl are coming from and reduce or replace. Good luck.
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. Dear Sir,
I want to treat a effluent with neutral pH, Chlorides - 120000 ppm, COD - 150000 ppm, BOD - 20000 ppm TDS - 280000 ppm. Flow - 25000 Liters / day. Kindly suggest suitable treatment process
- Pune, Maharashtra, India
December 11, 2017
A. You can use AOP (Advanced Oxidation Process), this can reduce the COD & the TDS will go ahead but won't affect the process, later you can use MVR (Mechanical Vapor Recompression) to remove it.
Pradeep Joshi- Vadodara & Mumbai, India
October 9, 2022
Q. Hi All,
This is Swati, I am a design engineer in Water & Waste Water Treatment company. I have an inquiry for the food industry wastewater. The wastewater parameters are as:
TSS: 59160 ppm
TDS: 204357 ppm
COD: 16000 ppm
BOD: 4000 ppm
pH: 4.11
The product will be used for irrigation. Please suggest me how to reduce the above parameters.
- Sharjah, UAE
December 5, 2017
A. You can use AOP process.
Pradeep Joshi- Vadodara & Mumbai, India
October 9, 2022
Q. Hello everyone! I have a process of industry scale which involves use of water soluble polysaccharide, acrylamide, alkali to hydrolyze and acetic acid ⇦ this on eBay or Amazon [affil links] to neutralize. The effluent water has high TDS of 10000. How can this be reduced? How much is acceptable for discharge in sea water?
Anu Singh- New Delhi
January 17, 2019
Ed. note: Sorry, this RFQ is old & outdated, so contact info is no longer available. However, if you feel that something technical should be said in reply, please post it; no public commercial suggestions please ( huh? why?)
A. Since sea water has a TDS of approximately 35,000, TDS should not be a problem, but other parameters, like BOD, may be a problem.
Lyle Kirmanconsultant - Cleveland Heights, Ohio
Q. I have an effluent with TDS of the following values:
Sodium ion - 19552 mg/lit
Sulphate ions - 24845 mg/lit
carbonate ions - 9087 mg/lit
I need to get down the TDS values to 2000 - 2500
I have tried to precipitate sulphate and the carbonate using calcium hydroxide, which does not work very well. Probably it requires some sort of catalyst for forward reaction. So is there any way I can do this? Apart from this is there any way by which I can reduce sodium?
- Mumbai, India
May 10, 2019
A. Hi Sachin. Except for expressing your exact concentrations to five significant digits, your question doesn't really seem substantively different than several previous ones, so please review the suggestions already offered. You are using extremely soluble salts like sodium & sulphates and asking for a practical removal method when there probably isn't one :-(
Unfortunately, if your TDS limit is 2000-2500 mg/lit, and this is a high volume application where special, energy intensive techniques like evaporation are impractical, and you can't dispose of a brine (it is a truism that "all desalination processes produce a concentrated brine"), you'll probably have to limit and recycle your use of these highly soluble salts. I don't think there is any 'silver bullet' chemical you can add to precipitate sodium sulphate to anything approaching the solubility limit you are seeking. Good luck.
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Q. Hello everyone! I am a student of Chemical Engineering and I am doing a project in a toilet cleaner producing factory where the effluent TDS is around 30000-40000 ppm when it comes from the toilet cleaner plant which has to be brought down below 1200. I am looking for an alternative to a RO plant or a evaporator plant. Is there any possible method to do so like electrolysis or something? I can include the chemical composition of the effluent stream if someone can propose a method or needs to know of it. Waiting for a positive reply.
Siddharth Singh- Sitharganj, Uttarakhand, India
May 31, 2019
A. Hi Siddharth. Most metals (not sodium) can be chemically precipitated, so on the off-chance that you have very large amounts of metal, you can consider that. I doubt that electrodeposition offers much potential.
Not long ago we didn't have practical RO ... it could be that the thing to do is to be grateful that we have it, and to use it as productively as possible, rather than trying to eliminate it :-)
Luck & Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
Continuously recycling high calcium sulphate effluent
Q. Hi Myself Akshay,
In our company we have ETP, the wastewater is spent acid (H2SO4) which comes out of mixing clay and H2SO4 acid and nothing else.
So spent acid is neutralized with lime and the by-product is gypsum and neutralized water of 7 pH.
Water is high in TDS, same neutralized water is re-used in making lime solution of 10 pH which is then used for neutralizing next batch of spent acid.
So my question is how many times can we use the neutralized water again as each time the TDS level will get higher and also not to mention that gypsum takes 50% moisture with it.
The main objective of using neutralized water is that it saves us RO and also we cannot mix lime directly with spent acid as it doesn't dissolve with it.
So is it okay to use again and again the neutralized water for making lime solution?
- SURAT, GUJARAT, INDIA
March 5, 2020
A. Hi Akshay
Although I have no experience with clay-acid effluent or making gypsum, this does not sound like a problem to me. Unlike many chloride chemicals, calcium sulphate has quite limited solubility (about 1/4 g per 100 ml), so it sounds like it will just keep precipitating as gypsum indefinitely.
Regards,
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
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