Hello Mustapha,

In fact it depends on your wastewater characteristics. You know varieties of wastewater characteristic are a lot. Some of them need mesophilic reactor however anothers need thermophilic. Oxygen has toxic effect to obligate anaerobic microorganisms such as methanojens. High sulphate concentrations have adverse effects to methanojens because of competition between sulphate reducing bacteria. If you want to get rid of this problem you should supply 1,7-2,7 value of COD/sulphate ratio in the influent wastewater. pH should be around neutral. We can do further contact if you would like.

Thank you very much Dr Olcayto Keskinkan for your answer.

In my study, we word with a synthetic wastewater ( C: N: P on ratio 100: 5: 1) : glycerol: Sodium nitrate: Potassium phosphate monobasic. with an initial COD of 900 mg/L and initial Dissolved oxyden (DO) of solution is 9 mg/L at Temperture of (16.5 +/- 3°C). My question is possible of anaerobic start up with these conditions in anaerobic biofilter? so I can input this solution in a reactor with DO of 9 mg/L or no?

Hi Mustapha, although your synthetic wastewater contain much dissolved oxygen, anaerobic degradation will be going on by activation of facultative anaerobic organism after oxygen consumed. So, aerobic-anaerobic conditions will be possible in your reactor. If biofilm thickness getting more milimeters anaerobic processes will be dominant. However if you block oxygen in your wastewater with various chemicals, anaerobic steady state conditions will become dominant quickly.

Regards,

Olcayto Keskinkan

if you want to start up your reactor quickly, the initial DO may be decreased by some physical methods. although the chemicals Dr Keskinkan said could do this, it will involved new environmental problems or disturbed your bioreaction in the reactor.

The composition of your medium is quite unusual for anaerobic digestion. The C:N:P ratio of 100:5:1 is adapted for aerobic treatment. In the case of anaerobic digestion. N should be organic nitrogen or ammonia and not nitrate because nitrate will favor denitrification which is hardly compatible with methanogenesis : it will consume COD and denitrification intermediates such as nitrite or N2O inhibit methanogens. Finally, the COD concentration is rather low for anaerobic digestion.

Thank you very much Professors Olcayto Keskinkan, Nuan Yang and Nicolas Bernet for your helps. So according to your answers, I will change the conditions of my study : ( SO3 to eliminate the DO (SO3 inhibitors of methanogens); increasing of COD (high COD) and N organic instead of nitrate). I can do this trial under temperature such 13°C to 25°C (less than mesophilic conditions)?

The lower the temperature, the lower the methanogenic activity... You cannot heat your reactor?

I can heat it, but if we can carry out trials by low temperature ( it's important for optimize energy!!!)

Sulfite could eliminate the DO, but it also could produce H2S in a anearobic condition. so be careful.

One of the important parameters to be monitored is the biomass concentration in the biorector. The product yeild coefficient should be evaluated in order to be sure that the carbon is converted to methane rather than biomass

Dear Mustapha!

Sorry to say this but I am a bit sceptic about your approach to anaerobic WW treatment. There is really a lot of literature to start with - even on i-net so you do not need to pay for books or journals … and I would really kindly advise you to start there and only after that consult colleagues with questions of relevance.

BTW: We are using artificial wastewater food for our experiments. Our own recipe, which works well after years of use, is here:

Table 1: Recipe for nutrients mixture added to the bioreactors .

NUTRIENT CONCENTRATION

Meat extract (Sigma-Aldrich) 0.108 g/L

Peptone(Sigma-Aldrich) 0.108 g/L

Yeast extract (Sigma-Aldrich) 0.108 g/L

NH4COOCH3(Merck) 0.264 g/L

NH4Cl (Carlo Erba) 0.033 g/L

K2HPO4(Carlo Erba) 0.019 g/L

KH2PO4(Sigma-Aldrich) 0.007 g/L

CaCO3(Sigma-Aldrich) 0.083 g/L

MgCO3(Sigma-Aldrich) 0.083 g/L

NaCl (Sigma-Aldrich) 0.033 g/L

FeSO4 x 7H2O (Sigma-Aldrich) 0.004 g/L

This mixture shall approach standard WW from a city in the range of 300 mg/l BOD5.

I do wish you a great research success! Please, keep me informed.

Regards, Boris

Dear Mustapha,

As Dr.Kompare mentioned before, use a typical synthetic wastewater recipe and go ahead. If possible you can supply anaerobic sludge from another local wastewater treatment plant to add and use in your reactor. However you should know that anaerobic microorganisms will not multiple quickly under lower temperature. You should be patient. Control the effluent by COD analyses. I think degradation rate and conditions in your reactor will be getting better in time (If you want accelarete the anaerobic metabolism you should heat the reactor. You can use water jacket for this). Don't forget to measure of COD change in time in your synthetic wastewater that have no microorganisms for comparison with your reactor and the synthetic ww data.

Regards,

Olcayto Keskinkan

There is no need to add any chemical that might affect the methanogens (like sulfite). Just bubble the feed solution with pure nitrogen gas...it will strip out the DO quite quickly. I have used this many times to ensure that feeds do not contain DO as well as to maintain anoxic/anaerobic environments in small lab reactors that have much higher surface to volume ratio than proptoype units and therefore are more prone to atmospheric oxygen transfer.

Beside of the mentioned parameters, Phases of SBR, biodegradable materials, pH etc. affects on ASBR performance