Boosting dark fermentation with co-cultures of extreme thermophiles for biohythane production from garden waste

Abstract

Proof of principle of biohythane and potential energy production from garden waste (GW) is demonstrated in this study in a two-step process coupling dark fermentation and anaerobic digestion. The synergistic effect of using co-cultures of extreme thermophiles to intensify biohydrogen dark fermentation is demonstrated using xylose, cellobiose and GW. Co-culture of Caldicellulosiruptor saccharolyticus and Thermotoga maritima showed higher hydrogen production yields from xylose (2.7±0.1molmol(-1) total sugar) and cellobiose (4.8±0.3molmol(-1) total sugar) compared to individual cultures. Co-culture of extreme thermophiles C. saccharolyticus and Caldicellulosiruptor bescii increased synergistically the hydrogen production yield from GW (98.3±6.9Lkg(-1) (VS)) compared to individual cultures and co-culture of T. maritima and C. saccharolyticus. The biochemical methane potential of the fermentation end-products was 322±10Lkg(-1) (CODt). Biohythane, a biogas enriched with 15% hydrogen could be obtained from GW, yielding a potential energy generation of 22.2MJkg(-1) (VS).

Anaerobic Process

“…Biochar addition also affected the volatile fatty acid generation in hydrogen production and methane production. Tabassum et al (2016) Multiple-stage co-digestion Abreu et al (2016) investigated biohythane production through co-cultures anaerobic digestion using garden waste as feedstock. The digestion process was divided into two phases: dark fermentation for hydrogen production followed by anaerobic methane production.…”

Garden and food waste co-fermentation for biohydrogen and biomethane production in a two-step hyperthermophilic-mesophilic process

“…oat straw hydrolysate (Arriaga et al, 2011) and mushroom farm waste hydrolysate (Li et al, 2011). Among agricultural wastes, garden waste (GW) appears as a very attractive raw material for biohydrogen production (Boldrin, 2009;Shi et al, 2013;Abreu et al, 2016), and its production has been increasing considerably with rapid urbanization worldwide.…”

“…https://doi.org/10.1016/j.biortech.2019.01.085 Received 9 November 2018; Received in revised form 15 January 2019; Accepted 19 January 2019 GW typically includes different fractions such as grass clippings, hedge cuttings, small branches, leaves and wood debris, and consists primarily of renewable polysaccharides and lignin (Shi et al, 2013;Abreu et al, 2016).…”

“…In the last years, several studies using FW or GW for biohydrogen production were performed (Cheng et al, 2011;Pan et al, 2013;Yasin et al, 2013;Nissilä et al, 2014;Abreu et al, 2016;Algapani et al, 2018;Ghimire et al, 2018), but the potential utilization of both wastes simultaneously by co-fermentation was not evaluated. In GW the fermentable sugars are present in complex and hardly digestible forms, while FW is an easier biodegradable substrate which is also a source of nitrogen (that is lacking in GW).…”

“…After upgrading, the generated biomethane can be used directly as renewable fuel or fed into the established natural gas grid, thus replacing fossil fuels and contributing for reducing the greenhouse gas emissions. The two-step approach for hydrogen and methane production has been tested with different substrates, from pure sugars to diverse feedstocks such as municipal, agricultural and food industry wastes (Wang and Zhao, 2009;Liu et al, 2013;Costa et al, 2015;Abreu et al, 2016). However, only few studies were reported on hydrogen and methane production from more than one residue in co-fermentation, e.g.…”