Process Simulation of Bio-hydrogen Production by Dark Fermentation

Masterarbeit (Fraunhofer IFF)


Dark fer­men­ta­ti­on is the most pro­mi­sing bio-hydro­gen pro­duc­tion tech­ni­que due to its high pro­duc­ti­vi­ty and pos­si­bi­li­ty of simul­ta­ne­ous was­te tre­at­ment through the use of orga­nic sub­stra­tes. Howe­ver, the low sub­stra­te con­ver­si­on in bio-hydro­gen, resul­ting in low unsta­ble bio-hydro­gen yiel­ds, is a major chal­len­ge in pro­cess com­mer­cia­liz­a­ti­on. This neces­si­ta­tes mathe­ma­ti­cal mode­ling and simu­la­ti­ons aimed at ana­ly­zing, opti­mi­zing and impro­ving bio-hydro­gen pro­duc­tion potential.

The mode­ling frame­work for metha­ne pro­duc­tion by anae­ro­bic diges­ti­on was modi­fied to descri­be bio-hydro­gen pro­duc­tion by dark fer­men­ta­ti­on. A pro­cess model for batch bio­re­ac­tors was deve­lo­ped based on the design princi­ples of Anae­ro­bic Diges­ti­on Model 1. Con­ti­nuous bio-hydro­gen pro­duc­tion was mode­led using a pseu­do-stoi­chio­metric non-line­ar approach. The kine­tic and stoi­chio­metric coef­fi­ci­ents app­lied for model simu­la­ti­ons in Mat­lab were retrie­ved from literature.

The batch model is reli­able and accu­rate­ly pre­dicts the pro­duct for­ma­ti­on and sub­stra­te degra­dati­on cha­rac­te­ris­tics. Howe­ver, it ent­ails rigo­rous simu­la­ti­ons and vali­da­ti­on for gene­ra­liz­a­ti­on. The con­ti­nuous model, on the other hand, yiel­ds hydro­gen evo­lu­ti­on and by-pro­ducts for­ma­ti­on in both steady and tran­si­ent sta­tes. The pre­fe­ren­ti­al bene­fit of this model lies in the fact that it incor­po­ra­tes fewer para­me­ters and can also be used for the simul­ta­ne­ous esti­ma­ti­on of dyna­mic inputs.