Enhanced co-generation of cellulosic ethanol and methane with the starch/sugar-rich waste mixtures and Tween 80 in fed-batch mode

Abstract

Background The mixed-feedstock fermentation is a promising approach to enhancing the co-generation of cellulosic ethanol and methane from sugarcane bagasse (SCB) and molasses. However, the unmatched supply of the SCB and molasses remains a main obstacle built upon binary feedstock. Here, we propose a cellulose–starch–sugar ternary waste combinatory approach to overcome this bottleneck by integrating the starch-rich waste of Dioscorea composita Hemls. extracted residue (DER) in mixed fermentation. Results The substrates of the pretreated SCB, DER and molasses with varying ratios were conducted at a relatively low solids loading of 12%, and the optimal mixture ratio of 1:0.5:0.5 for the pretreated SCB/DER/molasses was determined by evaluating the ethanol concentration and yield. Nevertheless, it was found that the ethanol yield decreased from 79.19 ± 0.20 to 62.31 ± 0.61% when the solids loading increased from 12 to 44% in batch modes, regardless of the fact that the co-fermentation of three-component feedstock was performed under the optimal condition defined above. Hence, different fermentation processes such as fed-batch and fed-batch + Tween 80 were implemented to further improve the ethanol concentration and yield at higher solids loading ranging between 36 and 44%. The highest ethanol concentration of 91.82 ± 0.86 g/L (69.33 ± 0.46% of theoretical yield) was obtained with fed-batch + Tween 80 mode during the simultaneous saccharification and fermentation at a high solids loading of 44%. Moreover, after the ethanol recovery, the remaining stillage was digested for biomethane production and finally yielded 320.72 ± 6.98 mL/g of volatile solids. Conclusions Integrated DER into the combination of SCB and molasses would be beneficial for ethanol production. The co-generation of bioethanol and biomethane by mixed cellulose–starch–sugar waste turns out to be a sustainable solution to improve the overall efficacy in biorefinery.

Low-cost biofuel-powered autoclaving machine for use in rural health care centres

“…Hence, the total energy required for a complete sterilisation cycle is 2.804 KWH which is equivalent to 10.094 MJ of heat. The cellulosic ethanol biofuel has energy content of 30 kJ/g [25]. An aliquot of 1 L of the biofuel is 2.23 kg which makes 66.9 MJ/L.…”

Optimization of food‐to‐microorganism ratio and addition of Tween 80 to enhance biohythane production via two‐stage anaerobic digestion of food waste

“…In addition, Tween can be broken down and utilized by microorganisms and has little negative impact on the environment. Previous studies on Tween include the treatment of water pollutants, 20,21 the degradation characteristics of non‐ionic surfactants represented by Tween, 22 and the effect of addition of Tween on the production of hydrogen, 23 methane, 18 ethanol and other fuels by AD 24 . Some studies on Tween mainly focused on the SSAD system.…”

“…Previous studies on Tween include the treatment of water pollutants, 20,21 the degradation characteristics of non-ionic surfactants represented by Tween, 22 and the effect of addition of Tween on the production of hydrogen, 23 methane, 18 ethanol and other fuels by AD. 24 Some studies on Tween mainly focused on the SSAD system. Only the promotion effect of Tween on the hydrolysis process is known.…”