Dear Deeksha,

Since source of effluent is not clear in your question, exact nature of effluent can not to be ascertain . Please do the analysis of various chemical components of effluent, then use chelating compounds to react and removed.

Till you get the analysis done, you may explore following option also:

use Electrocoagulation with different types of electrodes (MOC) i,e, Iron/ composite metal/ Aluminum). You may need to add Oxidation chemicals for complete oxidation & coagulation.

regards

dinkar

@dinkar Saxena

Sir the effluent is from a dye Industry. It is having high Phenols.

Deeksha Chaturvedi, There is a problem with the biological treatment then the BOD of the effluent is 500-700 ppm. A god treatment should achieve BOD less than 100 ppm. Likely the problem with the biological treatment is too little biomass or contact time and perhaps the phenols inhibit the bacteria.

Knowing the origin of the untreated waste (domestic or industrial sewage, industrial waste etc.) will help to further optimise the treatment/pre-treatment regime. Also, I agree with Henrik in that biomass quality and contact time are critical and there is possibly an inhibitory substance(s) that affect(s) its performance.

Deeksha Chaturvedi

We assessed in-depth and the wastewater treatment of over 20 large textile industries in Bangladesh and concluded a.o. that a well designed and operated activated sludge (AS) biological treatment would achieve effluent BOD < 30 ppm. For wastewaters containing high levels of toxic/inhibiting compounds such as phenols we recommended a tailored retrofit upgrade of the AS system. If interested I could email you an extract of our summary report.

@Bruno Peeters will the pH be affected via the treatment process (AS) u recommended?

@bruno peeters It would be great if you could email me the summary report.

Prosper Ovuoraye

In all biological treatment systems incl. AS the pH will rise slightly due to increased alkalinity (HCO3-) especially in aerobic systems such as AS where CO2 gets stripped out by aeration.

Bruno Peeters The pH of our biological treatment is going down. There is pH drop in the bioreactor but no significant Ammonia reduction is observed.

Reduction of ammonia may not be significant then depending on the water chemistry. But pH drop might be significant regarding discharge. If the effluent is acidic may not be environmental friendly. I did love to be involved in a research to modify a reactor design with little or no significant drop in pH. With Ammonium reduction guarantee decrease in odour of the effluent.

Prosper Ovuoraye

If the influent wastewater has low alkalinity and high TKN (ammonia + organic nitrogen) with respect to COD and BOD, then the pH could drop in aerobic biological treatment (such as AS) because of nitrification producing acid nitrates NO3-. However to prevent this (and save aeration energy) we apply partial nitritation (NO2-) and direct ammonia oxidation using this nitrite: NH4+ + NO2- > N2 + 2. H2O

Dear Deeksha,

I have designed one ETP for dying wastewater for Client at Sonepat cap 50 KLD in Sonepat, Haryana.

The scheme selected is bar screen >>Equlisation tank>>EC having electrode of Composite Iron (from Hognus), >>Tube Settler>> MBR>> RO for recycling the recovered water. The system is working for last 2 yrs.

You may also use the same scheme...

..even can enhance oxidation of phenol by adding H2O2 in EC ... so that inhibiting compounds are removed.

thanks & regards

dinkar

After the biological treatment, you could pass the solution through activated carbon columns to lower the BOD or some other organic waste adsorbent from the area.

It depends on the coagulant used here to achieve the biodegradability you seek. Bet one of the most effective approach to this is the integration of Adsorption process. Adsorption using activated carbons should follow immediately after AOP or Coagulation process. This will drive the COD/BOD down. Change the coagulant used.

Some clarifications are needed, as follows:

1. What type of waste are you treating (domestic sewage, industrial, etc)?

2. What is the actual BOD5 value measured and by what methodology?

Aristos Loucaides The information you ask for is in the question text and first answers in the beginning of the thread.

long HRT Electro coagulation + MBR?

If one third of the COD is still residual BOD, it probably means that you interrupted the biological treatment too early. You can either increase the retention time, or intensify the biodegradation process.

Reducing the Biochemical Oxygen Demand (BOD) of an effluent with high Chemical Oxygen Demand (COD) and low Total Suspended Solids (TSS) requires a combination of physical, chemical, and biological treatment methods. Here are some common approaches to achieve BOD reduction:

It's essential to conduct a thorough characterization of the effluent to determine the most suitable treatment approach based on its specific characteristics. Treating high-COD effluents can be challenging, and a combination of treatment methods often yields the best results. Consulting with wastewater treatment experts and conducting pilot-scale studies can help identify the most effective treatment strategy for a given effluent.