Microbial community analysis is necessary to understand how different bacteria and archaea digest. However, during pretreatment, mostly of lignocellulosic biomass, the structure is broken, bypassing the need for hydrolytic bacteria (directly entering the subsequent stages of AD). It should be obvious that the microbial community of the subsequent stages of AD will be enriched after pretreatment since their desired feed has been made readily available. Microbial community analysis of such studies cannot help in identifying unique hydrolytic bacteria since their requirement has already been bypassed.
Only under specific conditions may it be necessary to conduct such analyses, such as when using bioaugmentation or investigating the effects of additives on the microbial community.
I hope that journals (editors/reviewers) understand this point and discourage researchers from wasting enormous findings on meaningless characterizations. Because some researchers carry out these characterizations, several journals now consider these analyses minimum requirements for publication.
Dear Jehangir Akram ,
It seems that you refer to the traditional mesophilic single stage AD of solid biomass using physical-chemical preprocessing.
Since 2013 we apply 2-stage thermophillic AD after physical preprocessing with the smaller 1st stage for bioenzymatic hydrolysis and pre-acidification using mainly facultative bacteria.
Exactly, I was referring to the traditional single-stage studies (such as BMP assays), which are being published in large numbers across journals. It's great to learn about your work, Bruno Peeters . Are you referring to lab-scale or pilot-scale work, or are these pre-treatments already being applied at full scale?
We apply 2-stage thermophilic AD since 2013 at full scale on organic solid waste and slurries from food and biofuel industries.
Bruno Peeters could you please tell what is the TS content you maintain inside the reactors and what is the SRT and HRT for your AD.
This case is a retrofit upgrade and extension of a failed AD plant on thick slops from biofuel production.
We maintain 45 - 50 gDS/L in the biomethane reactors (2nd stage) at 15 d SRT and 15 h HRT. In the 1st hydrolysis-acidification stage the SRT equals the HRT at 2-3 h.