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topic 41896p2

High TDS and NaCl problem in effluent treatment

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A discussion started in 2006 but continuing through 2020

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 can't 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?


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Ted Mooney, P.E. RET
finishing.com - Pine Beach, New Jersey
Aloha -- an idea worth spreading

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.


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Ted Mooney, P.E. RET
finishing.com - Pine Beach, New Jersey
Aloha -- an idea worth spreading

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.


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Ted Mooney, P.E. RET
finishing.com - Pine Beach, New Jersey
Aloha -- an idea worth spreading

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.


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Ted Mooney, P.E. RET
finishing.com - Pine Beach, New Jersey
Aloha -- an idea worth spreading

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 truly can't help with even one of the many open questions here, please surrender your 'ETP-in-charge' title because you're unqualified :-)

October 21, 2017 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

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

Dr. Jai Prakash Chaudhary
Researcher - Gandhinagar, Gujarat INDIA

October 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.


pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com - Pine Beach, New Jersey
Aloha -- an idea worth spreading

December 11, 2017

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

Suryakant Samant
- Pune, Maharashtra, India

December 5, 2017

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

January 17, 2019

Q. Hello everyone! I have a process of industry scale which involves use of water soluble polysaccharide, acrylamide, alkali to hydrolyze and acetic acid 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
  ^- Privately contact this inquirer -^

February 1, 2019

A. Since sea water has a TDS of approximately 35,000, TDS should not be a problem, but other parameter, like BOD, may be a problem.

Lyle Kirman
consultant - Cleveland Heights, Ohio

May 10, 2019

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?

Sachin Kumar
- Mumbai, India

May 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 sulfate to anything approaching the solubility limit you are seeking. Good luck.


pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com - Pine Beach, New Jersey
Aloha -- an idea worth spreading

May 31, 2019

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 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,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com - Pine Beach, New Jersey
Aloha -- an idea worth spreading

Continuously recycling high calcium sulphate effluent

March 5, 2020

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 gyspsum 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?

Akshay B

March 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.


pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com - Pine Beach, New Jersey
Aloha -- an idea worth spreading

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