Effect of methanogenic effluent recycling on continuous H₂ production from food waste

Abstract

The production of hydrogen from food wastes was studied in a two‐stage (dark fermentation‐digestion) process under mesophilic conditions. The effect of a recycling stream, from the methanogenic phase to the fermentation phase, over H2 production and alkali consumption was evaluated in a semicontinuous fermentation process. The cases of no‐recycling, direct recycling, and membrane permeate recycling of methanogenic supernatant (using an ultrafiltration and nanofiltration membrane) were evaluated. Adding a recycling stream from a methanogenic reactor to the hydrogen‐producing reactor significantly reduced the need of external alkali addition for pH control, up to 52%. The performance of the hydrogen‐producing reactors receiving the recycling stream was similar in all cases tested, with values of specific hydrogen production of about 30 mL g−1 VSadded. This value was also similar to that one obtained from the no‐recycling configuration. The use of a membrane pretreatment stage proved to be not necessary. Operating conditions established in the fermentation stage were enough to avoid any detrimental effect associated to methanogenic microflora predominance. © 2014 American Institute of Chemical Engineers Environ Prog, 34: 227–233, 2015

Anaerobic Digestion for Producing Renewable Energy—The Evolution of This Technology in a New Uncertain Scenario

“…The sequential production of H 2 and CH 4 has been proposed as a way to increase the economic feasibility and energy recovery of waste treatment plant [ 56 , 57 , 58 ]. This configuration is a logical approach since both processes have similar capabilities of treating the same type of substrates.…”

“…Cellulose is also a suitable substrate for biological hydrogen production, although the fermentative process still encounters several technical constraints. The coupling with anaerobic digestion has proven to be effective and the introduction of a recirculation stream from the methanogenic phase to the hydrogen-producing phase allows the recovery of alkalinity, needed for pH control, and also the recycling of microorganisms to keep the first hydrogen-producing stage active [ 57 , 76 ]. Qi et al [ 77 , 78 ] have proved the successful performance of the recirculating configuration and the feasibility of treating cellulose using this combined approach by evaluating food wastes and paper waste at different mixture ratios.…”

Biohydrogen Production via Dark Fermentation with Pig Manure and Glucose Using pH‐Dependent Feeding

“…To operate at higher organic loading rates (OLRs), a previous study focused on the feasibility of reactor systems using MO holdbacks [25]. Methods to hold back MOs include the use of granular sludge [26,27], fixed beds [28,29] or effluent recycle [30][31][32][33][34][35]. Higher MO concentrations allow higher substrate conversion rates but are more difficult to operate as HCB colonize more easily since there is less MO ejection.…”

An investigation of two‐stage thermophilic and mesophilic fermentation process for the production of hydrogen and methane from palm oil mill effluent

“…Recently, hydrogen is considered as a potential fuel for transport purposes and power generation. Hydrogen is a promising and sustainable energy carrier with a high energy content of 122 KJ/g that releases only water during combustion . Conventional methods of hydrogen production are found to be energy exhaustive, expensive, and non‐eco‐friendly .…”