The most accurate way of assessing the waste is by using a laboratory digester. Feed the waste to the digester and measure the biogas quality and quantity; attribute the biogas to the waste fed to the unit - job done in two months or so. The time constraint may not be acceptable and desktop calculations supported by simple laboratory tests are possible but provide less accurate results. For first order approximations of methane production: 1. dry the waste to obtain the % Total solids at 105 deg C. 2. ash the dried component at 550 deg. C. to and weigh to provide the fraction of dried waste which is volatile. From these figures derive the number of Kg of VS in each cubic meter of waste. 3. In the digester you will normally recover about half of the VS as biogas by mass. 4. Biogas has a mass of about 1.2 kg/ cubic meter 5. Biogas has 55% Methane and more than 5kwh thermal of energy. 6. Put into an engine you will recover 25% as electricity and 50% as hot water at 85 deg. C 7. Half of the energy is required for digester heating. Caveats - does not work for oils and greases - you get more gas, does not work for lignin (woody materials) - you get no gas. toxicity is a problem with some wastes (ammonia inhibition) etc. The largest controlling factor in any biogas system is the amount of solids fed to the digester. If the first order calculations plus caveats work economically, then get into the design by first doing more detailed investigation and testing of the waste, feeding this into the digester model and deriving results for all the outputs of the system. We use such calculations in the first assessment of digesters up to 1 MW in output as well as for digesters at farm scale. The most important rule is this - it is the waste that produces the biogas not the digester. I hope this is useful. Dr. Les. Gornall Practically Green Environmental Services. www.practicallygreen.com > > Is anyone aware of a "standard" test to measure the methane generating > > potential of wastewater. We are working on a project that is evaluating > the > > anaerobic process for several industrial wastewater streams and are > looking > > for a way to evaluate both the degradibility of the wastewater and the > > resultant amount of methane generated (would also give an idea of > anaerobic > > toxicity). Maybe something similar to a BOD test - except measure methane > > generated not oxygen used? > > Thanks for any help. > > JEFF > > > > > > Digestion List Archives: > > http://www.crest.org/discussion/digestion/200202/ > > > > Digestion List Moderator: > > Paul Harris, paul.harris@adelaide.edu.au > > http://www.roseworthy.adelaide.edu.au/~pharris > > List-Post: <mailto:digestion@crest.org> > > List-Help: <mailto:digestion-help@crest.org> > > List-Unsubscribe: <mailto:digestion-unsubscribe@crest.org> > > List-Subscribe: <mailto:digestion-subscribe@crest.org> > > > > Other Digestion Events and Information: > > http://www.bioenergy2002.org > > http://crest.org/discussiongroups/resources/biomass/biogas/BIOGASMK.pdf > > http://www.crest.org/articles/static/1/1010424940_7.html > > > > Beginners Tour of Biogas > > http://WWW.roseworthy.adelaide.edu.au/~pharris/biogas/beginners > > > > > > > > Digestion List Archives: > http://www.crest.org/discussion/digestion/200202/ > > Digestion List Moderator: > Paul Harris, paul.harris@adelaide.edu.au > http://www.roseworthy.adelaide.edu.au/~pharris > List-Post: <mailto:digestion@crest.org> > List-Help: <mailto:digestion-help@crest.org> > List-Unsubscribe: <mailto:digestion-unsubscribe@crest.org> > List-Subscribe: <mailto:digestion-subscribe@crest.org> > > Other Digestion Events and Information: > http://www.bioenergy2002.org > http://crest.org/discussiongroups/resources/biomass/biogas/BIOGASMK.pdf > http://www.crest.org/articles/static/1/1010424940_7.html > > Beginners Tour of Biogas > http://WWW.roseworthy.adelaide.edu.au/~pharris/biogas/beginners > Digestion List Archives: http://www.crest.org/discussion/digestion/200202/ Digestion List Moderator: Paul Harris, paul.harris@adelaide.edu.au http://www.roseworthy.adelaide.edu.au/~pharris List-Post: <mailto:digestion@crest.org> List-Help: <mailto:digestion-help@crest.org> List-Unsubscribe: <mailto:digestion-unsubscribe@crest.org> List-Subscribe: <mailto:digestion-subscribe@crest.org> Other Digestion Events and Information: http://www.bioenergy2002.org http://crest.org/discussiongroups/resources/biomass/biogas/BIOGASMK.pdf http://www.crest.org/articles/static/1/1010424940_7.html Beginners Tour of Biogas http://WWW.roseworthy.adelaide.edu.au/~pharris/biogas/beginners
