If doing this was so easy than there would not be need of any research or analysis in the field of anaerobic digestion. Please read some basics of anaerobic digestion.

You might be unaware but there are also reactors which has retention time of around 15 days.

Your question is little bit confusing, because you do not have good information on the process. I agree with @Abhijeet Singh that HRT is lower than 30 days in many cases. So the best way would be to learn some basics of an anaerobic digestion at first.

Best regards

Vit

Dear Kelechi Ukaegbu-Obi

One can reduce the HRT by retaining the microbial consortium within the reactor either through immobilisation or formation of microbial granules / aggregates. A sufficiently high amount of microbial biomass within the reactor ensures that the nutrients get metabolised quickly.

Here are some literatures to get you going:

Chapter Production of Methane Biogas as Fuel Through Anaerobic Digestion

Chapter Biogas production from cheese whey: past, present and future

All the best, Rob.

Good discussion.

Thank you all for your answers and @ Robert Thomas Bachmann for the literatures.

Certainly, by utilizing microbial immobilization systems, like fluidized bed or steady bed anaerobic reactors...

Thank you very much @ Dimitri Georgiou

You can use DIET to increase the methane production rate by adding conductive material or high efficient electrogenesis flora. In this case, a relatatively low HRT and high methane yield wolud be achieved.

Dear Kelechi Ukaegbu-Obi ,

the degradation of organic compound in anaerobic conditions is dependent on degree of polymerization, thus its time may very e.g. cellulose is polymer of sugars ( polysaccharides ) takes a longer path to be degarde or breakdown needs higher HRT. where as simple sugar would take shorter path to decompose in to CO2, H2O.needs shorter HRT.

yes you can reduce the HRT if some enzyme like Cellulase (for above mentioned case) is added to the system in hydrolysing stage

I would recommend that please get the analysis & identification of compounds present in wastewater, then find decomposing accelerator (enzyme etc) for the same to reduce the HRT.

regards

Dinkar Saxena

Nice summary dear Dr. Saxena

Thank you so much @ Dinkar Saxena

Hi Kelechi Ukaegbu-Obi

If you want to increase the gas production, you may need to: 1). increase the amount of loading; 2). biodegradability of the substrate (e.g. through mechanical, thermal, chemical, or other pre-treatments); 3). use balanced nutrient.

If you want to get the same gas production faster, you may need to increase the process, such as by: 1). increasing the amount of microbes (e.g. using immobilization, increasing SRT, solid recirculation); 2). increasing the process temperature (e.g. using thermophilic process); 3). ensuring microbial contact with substrate (e.g. using motor stirrer, circulation)

Regards,

Alam

Nice topic....interesting discussion.

Thank you so much @ Alam Surya Wijaya

Hi Kelechi Ukaegbu-Obi , you can decouple the SRT from the HRT by using a 2-phase anaerobic digestion approach. Depending on what your substrate is (if its a rapidly fermented substrate like fruit waste or waste with a high content of organics) you can run your operation in two reactors, i.e., hydrolysis/acidegonesis in one and acetogenesis and methanogenesis in the other. These systems have been reported to be efficient in terms of CH4 yield. Another option could be designing your system with a low HRT and higher SRT (say 15 - 20 days), this will allow time for reproduction of slow growing anaerobes (methanogenes), increase the contact time between your substrate and the microbes, thus, more organics will be converted, more energy recovery and in turn reduced reactor volume.