When producing biogas from a semi-solid or liquid substrate, water is added to dilute it. The slurry dilution factor actively affect the biogas production, as higher water content may dilute the decomposer cells and enzymes per unit substrate, which is bad for the process .
So, my question is that what is the best slurry dilution factor for biogas production anaerobically using cattle manure, where I can achieve maximum biogas yield?
Normally 1:1 water is added in cow dung on volume basis
or Best is you add water such quantity that with total solids of sllury becomes 8%
Dear Pankaj,
Indeed, if use only cow dung (TS is ca. 15-16%), the ratio dung : dilution water is ca. 1:1 so as get a slurry humidity of ca. 90-92%. If use co-digestion with other organic materials, the water to be added should be calculated considering the TS of each material, then determine the average TS of the organic substrate to get a diluted mixture of ca. 8% TS. For example, if use a mixture of 8 parts cow dung (TS 15%) and 2 parts grains straw (TS ca.86%), the average TS of the mixture will be (8*15 + 2*86)/10 = 29.2%. For bringing the mixture to 8% TS, the water to be added is determined as: 10 parts organic substrate (dung + straw) * 29.2/8 = 36.5 parts diluted material. This means that you should mix 10 parts organic substrate and 26.5 parts water. And so on for any other mixture...
Respected Carmen Mateescu,
Thank you very much for your reply with valuable help.
Hi, there is no strict rule for dilution to make a slurry, just make a slurry starting with 1:1, or even less if you can get a slurry, and as it is an anaerobic culture. Then try to establish your best under your available working conditions. Good luck.
I agree with all answers above, especially with explanation of Dr. Mateescu. It is very important to think about solid content in the basic raw material (cow manure). As Dr. Mateescu mentions, the cow dung solid content is 15 % to 16 %. It is the case whem straw is used as a bedding. When the cows are breeded withou beding, the solid content in manure is much lower, between 5 % and 8 %. In the latter case no dilution is needed.
It is clear that more detailed should be mentioned in put questions.
Best regards
Vit
Vikram Rathod how would you know that the TS has reached 8% from say 20%. is there a calculation for this?
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