I am trying to build a two (or more) stage AD reactor and thus we need to inhibit the methanogens in the 1st reactor. The classical approach is to lower the pH with acid solution but it turns impracticable for medium to high sized reactors. Does anybody any idea how to achieve this objective? Thanks in advance for your collaboration input.
Servio Tulio Cassini Brazil
Oxygenate your reactor by air sparging. If you just want to use the first reactor for the hydrolysis step this seems the easiest way to me. Methanogens are obligate anaerobic microorganisms effectively suppressed in the presence of oxygen.
You can try 2-bromoethanesulfonate and maybe chloroform -pl see Chidthaisong & Conrad (2000) Soil Biol and Biochem 7 ,977-988.
I realise that you have a 2-stage process so you can't add inhibitors.
I found that in the first tank the pH will be slightly acidic as acetate is produced (pH 5.5 to 6) whereas in the methane generation tank the pH is higher (closer to 7). The First tank can be stirred well and can have higher hydraulic flow rates but to promote methanogenesis in the second tank the mixing is kept to a minimum and retain as much biomass as possible as methanogens have a slower growth rate. I expect that aeration will affect the strict anaerobic conditions required for the methogenesis step.
Hello...I don't have much experience with anaerobic digestion but may be you can add to your reactor a carbon source which can be easily converted to carboxylic acids then you will be able to manage a low pH without using acid. I am thinking in something like crude glycerol (biodiesel by-product) or some other feedstock available in your region.
Dear Cassinni,
You can inhibit the methanogens simply by heat treatment, alkali, acid and chemical tretaments
amongst them heat is the best one to inhibit the methanogens
also maintain the ph below 7. since Neutral pH is favourable for methanogens..
by maintaining these two conditions u can inhibit methanogens.
Dear Servios,
My thesis was with acid fermentation, pH 4.8 and 7.0 at the exit at the entrance. All colleagues offered effective contributions 2 bromoethanesulfonate, perhaps glycero (?), Heating 80 degrees inoculum, lower pH with substrate, oxygenate the medium. In my day was even told that the common detergent (appropriate dilution) eliminates the methanogenic.
However in my work, I made a "natural inoculation." Glucose solution (2g / l) at pH 7.0. Entered the reactor effluent and I returned for food (for input). So to get too impregnated support, the flow must be very low.
See details at:
Milk, JAC, Fernandes BS, Pozzi And Barboza M, Zaiat M. 2008.Application of anaerobic packed-bed bioreactor for the production of hydrogen and organic acids. International Journal ...
International Journal of Hydrogen Energy 01/2008; 33: 579-586.
At your disposal.
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