I am currently formulating a farm model for AD of a highly biodegradable substrate of maximum biogas yield of about 485 mL biogas/gVS. I want to include a percentage to account for the headspace and would appreciate any suggested literature for the ideal headspace.
Dear Arinze Ezieke I suggest you to read follow book which has focused specifically on biogas and its technologies;
Biogas: Fundamentals, Process, and Operation; written by Meisam Tabatabaei
It depends on digester kind you expected to use. If you mean the substrate volume in the digester, it is in general term between 75 to 90% of digester volume
I think 20-25% headspace seems to be enough. However, when the lipid and protein content of the waste to be digested is high, scum and foam formation take place. Hence, it may need to increase the headspace of the digester further.
Continuous or semi-continuous digester systems need to have enough headspace to prevent foaming or accumulation of scums clogging up the inlet and outlet connections of the digester. The formation of foams or scums in the head spaced depends on the characteristics of the feed substrate, and mixing speed and rate of the sludge in the reactor. Appropriate mixing is the best method to overcome the accumulation of foams and scums in the digester.
Hi Arinze Ezieke, I think it depends on the measure you used to test biogas volume. If it is pressure mehtod. When the TS of digestion system is below 10%, and very day you test volume and withdraw the biogas. Under this condition, you need more than 30% of the reactor volume.
I suppose that head-space volume depends substantially on the substrate used for anaerobic digestion. For example substrates rich in protein tend to produce a lot of foam and head-space would be up to 40 % of the bioreactor total volume.
Regards
Vit
For this answer, I suggest reading this article:
Article Optimization of methane production parameters during anaerob...
Optimization of methane production parameters during anaerobic co-digestion of food waste and garden waste.
DOI: 10.1016/j.jclepro.2020.123130.
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