You may login with either your assigned username or your e-mail address.
The password field is case sensitive.

Troubleshooting ETP System

We have a Activated sludge extended aeration type ETP treating our effluent of foods, personal care products and printing and also sewage waste.  We have two aeration tanks (7.70*4*4.30)m , 120 kl each. Also ETP has a capacity of 350 KLD.

Inlet BOD IS AROUND 300-400 AND COD AROUND 1200-2000.

Now since sometime the outlet parameters are out of limit and the treated water is giving odour and has a black hazy colour. Also SV30 is more than 450. Please give us a solution and possible causes.





Dear Mr.Gautham,

Your question seeking help for your problems with your ETP has been forwarded to me for suggesting remedial measures.In order to diagnose your problem, I need the following information.

1.What are the main parts of your ETP(eg, balancing tank,aeration tank,clarifier,etc)?
2.What is the actual average flow through your ETP in KL/hr?
3.What is the size of your effluent collection/ balancing tank in terms of KL?
4.Do you have a water treatment plant? Is it an RO or DM or Softening plant?Does the waste from water treatment plant come into your ETP?If yes, approximately how much is it in KL/day?
5.Do you have a detailed analysis of raw effluent from your balancing/collection tank?

Where is your factory located? If necessary I will try and arrange for an engineer to visit for a detailed inspection.

Looking forward to your reply.


Water Management Consultant


Dear Gautam,

What we understand from your query is that either you seem to have some problem in your MLSS or you are having sludge removal problems. In ASP systems, the commonest problem is to restart the plant and get results. It may be that the plant was shut for a certain period of time leading to death of adult bacteria. The result is having low MLSS since the sludge age is insuffiocient to take care of the organic load. It may also be that the clarifier sludge is not being effectively removed which leads to anaerobic conditions in it. Black color denotes these two symptoms.

Kindly let me have the layout and hydraulic of your plant with tank sizing and i shall be able to tell you how to get rid of your problems.


Taral Kumar


Dear Mr.Gautam

The reason of your problem may be due to not having proper retantion time of each unit,it also happnes due to not feeding proper oxygen into areation you are suggested to use Effective microorganism (EM-culture) whic works in both condition Aerobic & anaerobic..yourETP parameter will 100% under control& also get rid of order my personal experince based on two trials in food industry industry(bevarage,milkproduct)..we got very good are fel free to contact on 09958096904 for more details.with regards
santosh yadav.

4. DO is less

Dear Mr.Gautham

Only two reasons

1. Dissolved oxygen is less

2. F/M ratio is imbalance



5. Troubleshooting ETP System

Dear sir,

I am Shantanu kumar shukla, B.Tech environmental engineering.

All the installations are right . After aeration we need only dosing system (feric chloride & lime),it will clear the water parameters.


Contact no.9935567373

6. ETP working

Dear Sir

I am working in ETP plant. It is a small scale pharmaceutical industry. We have problems in COD fluctuations.

Sometimes it is in under control less than 60ppm and sometime it increases to more than 1000 ppm. We have problem of black sludge floating in secondary sedimentation tank and now days aeration tank is also showing black water. We are using alum and lime,poly electrolytes for coagulation and flocculation in flux mixture flock form good but in few minutes it comes on to the upper surface of water.

Help me with the proper management of the ETP..

With regard,


7. Adjust flocculation according to the incoming characteristics

Dear Mr. Solanki,

It looks like you are not getting effluent of similar characteristics from the production at all times but your flocculation system is almost the same. You need to adjust flocculation according to the incoming characteristics. Flocs coming up in primary treatment is a result of improper flocculation/less flow to the settling tank/improper sludge wasting from primary clarifier.

Aeration tank turning black can be either from the overflow of the chemical sludge from primary clarifier or depleting/depleted microbial population in aeration basin. We have microbial products that can help maintain good health of bioreactor.

Please contact me at 9910170604 for further information/clarification.

Thanks and regards,
Chandan Mohanty
Technical Advisor
Amrit Clean Water Technologies Pvt. Ltd.

8. How to check MLSS & MLVSS and restore color of aeration tank?


We have an ETP with activated slude treatment. The entire aeration tank has gone black and COD has reduced.

I want to know the following:

1. How do I check the Mixed Liquor Suspended Solids (MLSS) & Mixed Liquor Volatile Suspended Solids (MLVSS) levels?

2. What immediate steps will restore the colour of aeration tank?

3. Is there any thumb rule to maintain the aeration in good shape?

Chetan Panchal

Post new comment

The content of this field is kept private and will not be shown publicly.
This question is for testing whether you are a human visitor and to prevent automated spam submissions.
13 + 3 =
Solve this simple math problem and enter the result. E.g. for 1+3, enter 4.
Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 2.5 India License.