Biology Forums - Study Force

I'm doing an independent project that involves building an anaerobic digester.  My goal is to ultimately take the methane produced by the bacteria and burn it in a diesel engine.  The digester will take the form of a large tank, however in my preliminary experiments I plan to use Erlenmeyer flasks.

I have multiple questions:

1. In my preliminary research I read that many methanogens are stimulated by vitamins, however, I could not find out which specific vitamins are beneficial to growth. What are these vitamins and in what ratios should I add them?

2. I also read that many methanogens are stimulated by acetate and formate.  I was thinking that if I added a small amount of acetic and formic acid to the digester, the need for both hydrogen (for autotrophs) and acetate/formate would be met.  Is this a good idea?  Why/why not?

3. I would like to, if possible, minimize the number of sulphate-producing bacteria.  This is because hydrogen sulphate (H2S) is often an unwanted byproduct of anaerobic digestion.  Is there any way to do this?

4. Are there any species of bacterium that produce methane more than others?  How would I nourish the growth of these species?

Hey, to answer your first question, I found an article that will answer this question to the bone :). I highlighted the important parts. See attachment. Also, check out the methodology of that paper I attached, it talks about acetate being added and why it is good!

A high level of acetate (30 mM) was required by Methanomicrobium mobile for growth. Methanobrevibacter ruminantium, another rumen methanogen, requires a similar level of acetate (8 ). Acetate is required at lower concentrations by several other methanogens, including Methanobrevibacter smithii, Methanococcus voltae, Methanomicrobium paynteri, Methanogenium cariaci, Methanogenium olentangyi, Methanogenium tatii, and Methanoplanus limicola (22, 26). It has been shown in Methanobrevibacter ruminantium (8 ) and Methanococcus voltae (23) that acetate is incorporated into cellular carbon. Acetate is found in many anaerobic environments, including the rumen, from which Methanomicrobium mobile was isolated. Acetate has also been found to be important for the growth of many other ruminal bacteria (7).

According to the following link, membrane filtration should remove sulphate- and nitrate-reducing organisms: http://tinyurl.com/2fpfgae. (http://tinyurl.com/2fpfgae.) There are also anaerobic ways to remove the sulfate. See next attachment.

I could not have asked for a better response.  Many thanks!

You're welcome!

Good luck.