Dear Lalit,

I think that you should use both anerobic and aerobic conditions since some of the pollutants are resistant to anerobic treatment and others not, and vice versa.

The principle of the aerobic biodegradation is as follow: oxygen is needed by degradable organisms in their degradation at two metabolic sites, at the initial attack of the substrate and at the end of respiratory chain [9]. Bacteria and fungi could produce oxygenases and peroxidases they could help with the pollutant oxidization and get benefits from observing the energy, carbon and nutrient elements released during this process. A huge number of bacterial and fungal general possess the capability to release non-special oxidase and degrade organic pollutants. There are generally two types of relationships between the microorganism and organic pollutants: one is that the microorganisms use organic pollutant as sole source of carbon and energy; the other is that the microorganisms use a growth substrate as carbon and energy source, while another organic compound in the organic substrate which could not provide carbon and energy resource is also degraded, namely cometabolism. The classic aerobic biodegradation reactors include activated sludge reactor and membrane

bioreactor.

Anaerobic degradation processes have always been considered to be slow and inefficient, in comparison to aerobic degradation. However, the anaerobic degradation not only decreases the COD and BOD in the waste water, but also produces renewable energy. Moreover, the anaerobic bacteria could break down some persistent organic pollutants, such as lignin and high molecular weight PAH, which show little or no reaction to aerobic degradation. Besides, anaerobic processes could treat the wastewater with high loads of easy-to-degrade

organic materials (wastewaters of the sugar industry, slaughter houses, food industry, paper industry, etc.) efficiently and costly. These advantages make investigation and application of anaerobic microbial mineralization in organic polluted water important. Generally speaking, anaerobic reactor could be divided into anaerobic activated sludge process and anaerobic biological membrane process. The anaerobic activated sludge process includes conventional stirred anaerobic reactor, upflow anaerobic sludge blanket reactor, and anaerobic contact tank. The anaerobic biological membrane process includes fluidized bed reactor, anaerobic rotating biological contactor, anaerobic filter reactor. Upflow anaerobic sludge blanket reactor and anaerobic filter reactor are selected as the representative of the two kinds of reactors mentioned above.

For more information on this topic, please read the chapter contained in the following link:

http://outsidethesink.rtu.lv/documents/Water_Treatment.pdf

Hoping this will be helpful,

Rafik

Dear Rafik,

Thank you for sharing your valuable experience on the anaerobic process. I also agree with　you　that　both　anaerobic　and　aerobic　process　would　be　required　to　treat　this　kind　of　wastewater. I will laso read the rpert which you have sent me. 

I would like to request for your further point of view on the process scheme and retention time (HRT) in the anaerobic process.

--I feel at least one day HRT should be provided to the anaerobic process.

--I wonder which scheme would be preferable:

Anaerobic activated sludge tank followed by MBR (aerobic activated sludge process)

Or

 Aerobic activated sludge tank followed by anaerobic (activated sludge tank) with membrane (Anaerobic MBR)

In both the cases recirculation would be helpful for minimizing any inhibition and sufficient treatment of pollutants.

The influent has approximately following characteristics: temp. 50 degree Celsius (which will be brought down to say 35 degree Celsius); BOD 600-1000 mg/l, COD 1500-3000 mg/l (BOD/COD around 0.34), FA less than 150 mg/l; Acetaldehyde less than 450 mg/l and  Ethylene Oxide less than 200 mg/l. I understand this influent has to make up for deficiency in nutrients, buffer, etc. before biological treatment.  

As you also mentioned about different kind of anaerobic process, I wonder which kind of process will be more preferable for this kind of wastewater. The simplest could be anaerobic activated sludge kind process. UASB can also be one of the options. But I think developing granules in UASB under this kind of wastewater could be difficult. However, influent temperature of 35 degree Celsius which is available is good for UASB. 

 I would be thankful for your point of view on the above matter.

I would to request for suggestions. Under the above stated influent condition, in the anaerobic process followed by MBR, how much effluent COD (MBR effluent) is expected. Is there need of any pre-treatment of this effluent before feeding to RO?  

Dear Lalit,

If you are planning to use the upflow anaerobic sludge blanket reactor (UASB), it will be recommended that the scheme should consists of the aerobic treatment before the anaerobic one. From the numbers you have listed in your first message, I do not see any necessity to any pretreatment process before the RO since the COD and BOD values are relatively not high.

For, the aerobic and anaerobic schemes, I suggest that you read pages 254-265 of the book that I attached in my first answer.

Hoping this will be helpful,

Rafik

Thank you for your guidance. Will color also be removed after the UASB followed by MBR? Do we need any further step to remove the color from the effluent of MBR? Which will be the easer process for the removal of color?