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High TDS problem at effluent treatment plant

A discussion started in 2006 and continuing through 2017 . . .


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?

Gaurav Jain
- Chandigarh, India


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 sulphuric 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%) sulphuric 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,

Parameswaran Iyer
- 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?

Kiran Gangadhar Malbhage
- Aaaurangabad, Maharashtra, India


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

February 13, 2012

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
Bangalore, Karnataka, India

June 24, 2008

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,chloride, sulphate, metals. Please guide me which treatment useful for reduction of these parameters.

Dharmadhikari Santosh
- PUNE, India

April 11, 2012

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 sulfate (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 sulfate? Or any bibliography?
Thank you.

Ana Kaucz
- France

April 24, 2012

A. Where does all the sulfate come from? Are you adding aluminum sulfate as a coagulant? If so, reduce the dosage. Add a polymeric coagulant if necessary.

jeffrey holmes
Jeffrey Holmes, CEF
      South Carolina

April 18, 2012

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

July 26, 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,India

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.

opinion! Were you to invest a fortune in RO or DI equipment, and waste incalculable energy and chemicals doing this, you will still have the chloride on your hands, to be disposed of in a landfill ... until such time as the liner leaks and the salt poisons the earth and kills the aquifer.

The traditional & proper thing to do with saltwater is, of course, to discharge it to the sea. But as you probably know, in our effort to stop irresponsible ocean dumping, we've collectively decided to poison the land with salt rather than to return the sodium chloride to the sea from which it came :-(

If I'm wrong, I welcome enlightenment.


Ted Mooney,
Teds signature
Ted Mooney, P.E. RET
Pine Beach, New Jersey

July 3, 2013

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

Mantesh Magadum
- Manoli, Belgaum, Karnataka, India

November 4, 2013

A. Dir Sirs,

Good afternoon. Great day!

Perhaps a technology to view concerning your questions:

- 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!

Steve Zeller
engineering - Harrisburg, Pennsylvania, USA

Effluent treatment for biscuit plant

August 25, 2015

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, alum & polymer.

Himanshu Jadon
biscuit manufacturing unit - bangaluru,karnataka,india

September 3, 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
pH = 1.25
BOD= <10 mg/lit
COD= 16 mg/lit
sulphuric acid = 7%

type of industry - pharma.
Please reply.

Ganesh patil
- Pune, Maharashtra, and India

September 26, 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
Dave Wichern
Consultant - The Bronx, New York

September 28, 2015

A. I suggest that you try lime precipitation to precipitate calcium phosphate and calcium sulfate. The quantity of sludge will be very large.

Lyle Kirman
consultant - Cleveland, Ohio

October 2, 2015

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
Dave Wichern
Consultant - The Bronx, New York

October 12, 2015

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 cant reduce COD below 100. Biological treatment does not work. How we can reduce COD below 100?

sanaz azimi
Petrochemical Effluent Treatment Plant - bandare mahshahr , Iran

January 20, 2016

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:

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
Stream 2
Slight Yellow

Please suggest as we are mixing both the streams and just removing COD and NH3-N currently.

Viral Soni
Fertilizer,Nutrient - Surat,Gujarat,India

February 4, 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

Prashant Katke
- 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

May 26, 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), and polymer.
Please advise

Dickson Mulewa
- Nairobi, Kenya

May 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 to lime would help somewhat. What is the source of the wastewater?


pic of Ted Mooney
Teds signature
Ted Mooney, P.E. RET
Pine Beach, New Jersey
Striving to live "Aloha"

June 1, 2016

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.

Lyle Kirman
consultant - Cleveland, Ohio USA

June 2, 2016

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 13, 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

July 1, 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 perumal
latex industries - nagercoil, tamilnadu, india

July 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.


pic of Ted Mooney
Ted Mooney, P.E. RET
Pine Beach, New Jersey
Striving to live "Aloha"

October 7, 2016

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.


Amey Kale
- Mahad, Maharashtra, India

December 15, 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 Kumar
Water treatment - vishakapatnam,andhra Pradesh,india

January 4, 2017

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 Bhovi
Mylar sugars Ltd. - Bellary Dist, Karnataka State India

February 16, 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?


February 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.


pic of Ted Mooney
Ted Mooney, P.E. RET
Pine Beach, New Jersey
Striving to live "Aloha"

July 4, 2017

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,

asghar norouzi
- tehran, iran

July 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 sulphuric acid than in hydrochloric acid because ferric carbide is not soluble in sulphuric acid. If you seek only acid activation of the surface, a dip in a few percent of sulphuric acid may suffice, but serious pickling will probably not work.


pic of Ted Mooney
Ted Mooney, P.E. RET
Pine Beach, New Jersey
Striving to live "Aloha"

Ed. note: Nobody but our regular helpers Lyle and David has offered an answer in over 3 years now. Please contribute some answers, folks -- trying to teach is a wonderful and fulfilling way to learn!
And if you honestly can't answer even one of the open questions on this page, please surrender your 'ETP-in-charge' title because you are not qualified :-)

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