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[Display omitted] • Surfactants aided microwave treatment was a promising pretreatment method. • The highest CHY of 367.87 ± 6.481 mL was obtained after SMIP. • The more energy saved by SMIP was confirmed by the energy assessment. • Significant structural damage of lignocellulose was observed after SMIP. The combination pretreatment strategy is an effective way to intensify photo-fermentative biohydrogen production (PFHP) process. In this study, the synergistic effects of microwave irradiation and surfactants on the hydrogen production performance, energy analysis and structural characteristics was evaluated. Results revealed that hydrogen production performance was improved after microwave irradiation pretreatment (MIP) and surfactants assisted microwave irradiation pretreatment (SMIP). SMIP group had a higher cumulative hydrogen yield (CHY) of 367.87 ± 6.481 mL compared with control group (223.26 ± 4.329 mL) and MIP group (303.66 ± 3.366 mL), which was an increase of 36.01% and 64.77%, respectively. Energy evaluation analysis showed that the energy ratio of SMIP (0.49) was higher than that of MIP (0.37) in the PFHP system, therefore, SMIP can save more energy. After SMIP, the corncob lignocellulose structure was greatly damaged, which was verified by SEM, FTIR, XRD and XPS analyses. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ultrafine grinding pretreatment has significant effect on the hydrolysis of corncob. • The GM(1,N) model has high predictability under the condition of scanty data. • The influence degree of each factor on reducing sugar yield can be identified. • The hydrogen yield from corncob was promoted after Ultrafine grinding pretreatment. Pretreatment of biomass helps to enhance reducing sugar yield from biomass during enzyme hydrolysis tests. Ultrafine grinding was applied to pretreat corncob. The effect of affecting factors including milling time, initial particle size and ball to power weight on the reducing sugar yield from corncob was investigated firstly. And then, an GM(1,N) model was constructed to model the ultrafine grinding pretreatment system predicting the reducing sugar yield from corncob based on experimental data, the results demonstrate GM(1,N) could predict the reducing sugar yield accurately and effectively without depending on the number of samples. The initial particle size was the most critical influential factor affecting reducing sugar yield according to the driving coefficient. The cumulative hydrogen yield was significantly affected by ultrafine grinding pretreatment, the hydrogen yield of pretreated corncob was 153.60 ± 5.8 mL/g total solids, which was higher than that of untreated corncob (113.20 ± 3.2 mL/g total solids). [ABSTRACT FROM AUTHOR]

[Display omitted] • Hydrogen production performance from corncob with surfactant addition was studied. • RLs and TSn addition promote significantly the hydrogen yield from corncob. • RLs had better performance on hydrogen production than TSn. • 0.08 g/L RLs addition achieved the maximum energy conversion efficiency of 5.47%. Surfactant addition can cause a significant change in the interface state of the solution system, which is helpful to avoid agglomeration and sedimentation of solid state, and improve the mass transfer capacity. Hence, the performance of high-solid photo-fermentative bio-hydrogen production system with bio-surfactant addition was evaluated in this work. Corncob was selected as raw material, and cumulative hydrogen yield (CHY) was taken as reference. The effect of Rhamnolipids (RLs) and Tea Saponin (TSn) addition on hydrogen yield capacity was investigated. The results showed that CHY was effectively increased by the addition of RLs and TSn, the highest CHY of 356.42 ± 16.5 mL and 265.38 ± 7.5 mL appeared when the concentrations of surfactant addition were 0.08 g/L RLs and 1.5 g/L TSn, which were 67.85% and 24.97% higher than control group, respectively. The maximum energy conversion efficiency reached 5.47% and 4.08% with an increase of 67.8% and 25.2%. [ABSTRACT FROM AUTHOR]

Enzymatic fermentation of lignocellulose biomass has shown great potential of hydrogen production but the yield is limited due to the complex structure of cellulose and hemi-celluloses. For the bio-hydrogen production from biomass, the pretreatment of biomass plays a vital role to increase the hydrogen yield. In the present work highly efficient pretreatment by mall milling of corncob biomass has been employed to optimize the thermo-physical and optical properties of corncob powder by employing state of art techniques including scanning electron microscope, x-rays diffractometer, thermogravimetric analysis, and Fourier transform infrared spectroscopy. The morphological observations from microscopic images are consisted with x-ray diffraction results where the broadening in the peaks suggests the smaller particle size (large surface area) after pretreatment. From the decomposition kinetic parameters and apparent activation energy calculation by FWO and DAEM methods, the sample S2 with lowest activation energy, can have highest hydrogen production yield which is consistent with our previous findings. The broadening in the absorption peak near 1046 cm−1 suggests that C O stretching vibration (cellulose and hemicellulose)mode has been changed after different ball milling. By tailoring their activation energies through ball milling one can optimize thermo-dynamic characteristics for enhancement of biohydrogen production. • Tailoring of complex structure can be effective to enhance biohydrogen production. • The SEM and XRD results confirm the smaller particle size after pretreatment. • Absorption peak near 1046 cm−1 suggests that C O stretching vibration. • Sample with lowest activation energy, can have highest hydrogen production yield. [ABSTRACT FROM AUTHOR]

[Display omitted] • Co-production of biohydrogen and biofertilizer is more profitable. • The CHY of 120 mesh corncob was the highest (71.16 mL/g TS). • The freeze-dried fertilizer had better slow-release effect. • Fertilizer of 120 mesh corncob had the best slow-release effect. In this study, corncob was taken as substrate, the co-production process of biohydrogen and biofertilizer by photo-fermentation was investigated and its carbon footprint analysis was conducted to evaluate the carbon transfer pathway. Biohydrogen was produced by photo-fermentation, and the hydrogen producing residues were immobilized by sodium alginate. Cumulative hydrogen yield (CHY) and nitrogen release ability (NRA) was taken as references, and the effect of substrate particle size on the co-production process was evaluated. Results showed that due to the porous adsorption properties, corncob size of 120 mesh was the optimal one. Under that condition, the highest CHY and NRA were 71.16 mL/g TS and 68.76%, respectively. The carbon footprint analysis indicted that 7.9% carbon element was released as carbon dioxide, 78.3% carbon element was immobilized in the biofertilizer, and 13.8% carbon element was lost. This work is significant of the biomass utilization and clean energy production. [ABSTRACT FROM AUTHOR]

[Display omitted] • Microwave irradiation showed significant effect on biohydrogen production process. • Highest CHY of 27.34 mL/g TS was obtained after microwave treated with surfactant. • An increase of 80.94% in CHY was achieved by treated corncob than untreated. • Substrate conversion efficiency of 90.44% indicated full substrate utilization. T he complex structure of corncob is the bottleneck that restricts its efficient biohydrogen production. Hence, effective treatment is an important exploration to break this limitation. The effect of microwave irradiation (MI) on photo-fermentative biohydrogen production (PFHP) process was evaluated in this paper. Diverse conditions (irradiation time, microwave power, and surfactant addition) were applied. Comparisons of cumulative hydrogen yield (CHY), microstructure, liquid products, and substrate conversion efficiency (S conv) were conducted. Results showed that the highest CHY of 27.34 ± 1.13 mL/g TS was achieved when the corncob was treated by MI assisted with surfactant addition. Optimal treatment conditions (5.51 min irradiation time, 772.03 W microwave power, and 0.08 g/L rhamnolipids addition) were obtained. MI assisted with surfactant addition helped with the structure destroys and content degradation, displaying a great improves on PFHP. Lower ethanol content and higher butyric acid content were obtained. An 80.94% increase in CHY and S conv of 90.44% were obtained than untreated corncob. [ABSTRACT FROM AUTHOR]

[Display omitted] • Tween-series surfactants greatly affected photo-fermentative bio-hydrogen production. • Highest CHY of 49.38 ± 1.90 mL/g TS was obtained with Tween 80 addition. • The addition of Tween 80 was beneficial to the growth and activity of PSB. • Inhibitory critical concentration of 0.42% was obtained by Han-Levenspiel model. Surfactants could improve the mass transfer capacity by avoiding agglomeration and sedimentation of substrate. This study evaluated the effects of diverse Tween series surfactants on hydrogen production performance of photo-fermentative biohydrogen production (PFHP) process. Tween 80 was found to be the most suitable surfactant. The maximum cumulative hydrogen yield (CHY) reached 49.38 ± 1.90 mL/g TS under 0.20% (v/v) Tween 80 addition. Highest energy recovery efficiency of 3.41 ± 0.13% and substrate conversion efficiency of 94.93 ± 0.44% were obtained, which was 50.37% and 1.7% higher than that of the control group, respectively. The effect of diverse Tween series surfactants on photosynthetic bacteria (PSB) was further studied. Results showed that Tween 80 significantly improved the growth and activity of PSB. The modified Han-Levenspiel model was adopted to analyze the effects of Tween 80 addition on PFHP. Results indicated that the reaction system was non-competitive inhibition, the predicted critical concentration of Tween 80 was 0.42% (v/v). This study provides a way to increase the CHY of corncob by the PFHP process. [ABSTRACT FROM AUTHOR]

• Cohesive strategy for two stage bio-hythane production process was investigated. • Suitable coupling time node realize the directional generation of bio-hythane. • Effluents with different components were adopted for bio-methane production. • Cogeneration of bio-H 2 and bio-CH 4 increases energy conversion efficiency. In order to maximize the substrate conversion, co-production of hydrogen and methane from two-stage anaerobic digestion has attracted wide attention. In two-stage fermentation process, the cohesive strategy is considered as a key indicator for bio-hythane yield. In this work, corncob powder was utilized as raw material. The pH of fermentative broth, bio-hythane yield, gas production rate and energy conversion efficiency were taken as indexes. Under the directional control of bio-chemical reaction process, the effects of diverse coupling time nodes on the fermentation process and the bio-hythane co-production potential were investigated. The results showed that when the coupling time node was 48 h, hydrogen production potential and methane production potential were 22.29 mL/g TS and 141.14 mL/g TS, respectively. The hydrogen content in the bio-hythane was 13.64% which satisfied the hydrogen concentration requirement, and the energy conversion efficiency was 27.6%. [ABSTRACT FROM AUTHOR]