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Biogas from sweet sorghum

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Hello friends,

I am working on a theoretical report of designing a 700 cubic meter capacity of biogas plant with sweet sorghum as a substrate in mesophilic temperature.

I am having some questions
1. Sweet sorghum as a feeding material, i am bit confused in determining the organic loading rate per day. With the capacity of the fermenter and the hydraulic retention time, we can calculate the feeding rate.

Sweet sorghum harvested and utilize for biogas production directly, not used for sugar and ethanol extraction, will be it efficient?

Any suggestion regarding, what would be the hydraulic retention time of the plant with sweet sorghum as a feeding material?

What has to be the size of the sweet sorghum to be cut for optimum degradability?

What would be the specific gas production?

2. Is it possible to produce efficient biogas using only sweet sorghum as a feeding material and just use the manure for initial start up?

3. What would be the efficient ratio of mixing sweet sorghum with the water?

4. In order to have a better degradability and optimum pH, for example added lime or NaoH would improve the condition of the degradation.
Can the lime or NaoH added directly to the fermenter? or how it has to be done?

Any suggestions would be appreciated.

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1. Use C6H12O6 -----> 3CO2 +3CH4 as an approximate chemical reaction in the biodigester. From this you can figure out how much biomass it takes to make a certain amount of biogas.

Throwing away all that tasty sorghum syrup?! Usually biodigesters are a last step for biomass, after all the other valuables have been extracted. But if that is what you want to do......

The smaller you cut the biomass, the more surface area it will have and the faster the bacteria will be able to process it. How much effort do you want to put into chopping it up?

2. Probably will work. But then you are relying on the bacteria self-regenerating, rather than new manure refreshing the microbes in the tank.

3. Water is just the medium that the bacteria live in. As long as the material in the biodigester doesn't go dry, there will be bacterial decomposition.

4. Why do you think the pH needs to be raised? Are you concerned that you are getting a lactic fermentation that is hung up at a low pH?
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