List down the various factors responsible and how does this effect the overall biogas production when it is related to Hydraulic retention time of the digester based on the feedstock?
The factors that influence biogas production include C/N ratio, F/M ratio, pH, temperature, Organic Loading Rate, Hydraulic Loading Rate, and the presence of toxins. Factors influencing biogas production include feedstock type, pretreatment, substrate degradation, biogas properties, and pressure. Retention time in mesophilic anaerobic digester conditions normally is within 15–40 days. While for thermophilic anaerobic digester retention time is within 12–14 days Retention time are varies for different feed, and concentration Hydraulic retention time also affects the concentration of hydrogen in the biogas produced e.g. Poultry droppings have been found to produce biogas faster than cassava peels within a short period of retention time. Biogas production from cassava peels took longer retention time. Variation in the temperature of the digester affects the rate of biogas production from the two different substrates. Biogas is also generated from domestic solid wastes by anaerobic digestion over a retention time of 20 days at 40°C. The optimal retention time for cow dung in a biogas digester is 30 days, as indicated in the research using water hyacinth and cow dung for biogas production. It is concluded that when fresh pig manure is the substrate in polyethylene plug-flow bio digesters the optimum retention time is between 10 and 20 days with a solids concentration
The effect of hydraulic/solids retention times HRT/SRT on biomethane production can be seen in Biomethane Potential (BMP) batch tests of various substrates.
However in real world continuous flow AD plants also the Residence Time Distribution (RTD) related to the HRT/SRT is important. For a CSTR reactor this RTD is only 0,37 at the operating HRT/SRT. This implies that 63% of the feedstock remains less than the HRT/SRT in a mixed AD reactor. We overcome this challenge by installing CSTR in series and/or by increasing the SRT up to 100 times the HRT.
Prem Baboo THe retention time and the biogas effect explained in detail and looks perfect from the details and document point of view
Bruno Peeters I am of the same view when it comes to CSTR non mixing digesters vs mixing systems and this is the reason I support and suggest to have good mixing systems in place to start with. I agree with the HRT/SRT vs biogas production details you have shared.
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