Kong Xiaoying

Low-cost additive improved silage quality and anaerobic digestion performance of napiergrass

Effects of molasses-alcoholic wastewater on the ensiling quality of napiergrass were investigated at ambient temperature, and its anaerobic digestion performance was assessed at mesophilic temperature. Results showed that the molasses-alcoholic wastewater had positive effect on silage quality and anaerobic digestion performance. Lower pH values of 5.20-5.28, lower NH3-N contents of 32.65-36.60 g/kg and higher lactic acid contents of 56-61 mg/kg FM were obtained for the silage samples with molasses-alcoholic wastewater addition. Higher specific biogas yield of 273 mL/g VS was obtained for the sample with 11% molasses-alcoholic wastewater added. Therefore 11% molasses-alcoholic wastewater addition was recommended.

Improving methane production from anaerobic digestion of Pennisetum Hybrid by alkaline pretreatment

Alkaline pretreatment with NaOH was used to improve methane yield from Pennisetum Hybrid. The pretreatments were carried out with different NaOH solutions (2-8%u202fw/w) at three temperatures (35, 55 and 121u202f°C) for different periods of time (24, 24 and 1u202fh). All treated and untreated Pennisetum Hybrid were digested under mesophilic conditions (37u202f°C) to biogas, significant effects of the pretreatments on the yield of methane were observed. Results showed the modified Gompertz equation was reliable (determination coefficients (R2) greater than 0.96) to describe the kinetic behavior of anaerobic digestion of Pennisetum Hybrid. The best result, obtained by the treatment at 35u202f°C 2% NaOH for 24u202fh, resulted in the methane yield of 301.7u202fmL/g VS, corresponding to 21.0% improvement in the methane yield. Compositional, SEM, XRD and FTIR analysis confirmed that lignin removal, structural modification and cellulose crystalline variation were responsible for the improvement.

Performance of microbial fuel cell in different anode and cathode electrode sizes

Power generation in microbial fuel cell (MFC) at different cathode electrode surface area was examined in two-chambered system with sodium acetate as carbon sources. When the anode surface area of 66 cm² was used, the maximum power density increased by 44% when the cathode surface areas were increased from 66 cm² to 336 cm² and decreased by 21% when the cathode surface area was reduced to 14 cm², primarily as a result of the variation of cathode potential. The power increased from 2.56 W/m³ to 3.29 W/m³ with the cathode increasing from 14 cm² to 336 cm² when the anode surface area of 14 cm² was used. But a decreased power output of 2.40 W/m³ was observed when the relative electrode area of cathode and anode was 5AAn=Acat, the main reason may be the decreased in both anode and cathode potential. The low CE was in the range from 10 % to 15 % was obtained.

Comparison of dry and wet milling pre-treatment methods for improving the anaerobic digestion performance of the Pennisetum hybrid

Two types of milling pre-treatment methods were used to study their effects on the anaerobic digestion performance of the Pennisetum hybrid. The physical structure of the Pennisetum hybrid could be significantly damaged with both milling pre-treatment methods. With an increase in treatment time, the pore volume, surface area, average pore diameter, and the crystallization index of the Pennisetum hybrid increased gradually. The anaerobic fermentation test showed that, among the dry and wet milling pre-treatments, the highest specific methane yield was obtained at 3xa0h dry milling pre-treated (358.07 mL g−1 VS) and 6 h wet milling pre-treated grass (315.87 mL g−1), which was 41.04% and 24.42% higher than that of the untreated Pennisetum hybrid (253.88 mL g−1 VS). The median diameter (D50) of the Pennisetum hybrid was 25.28% and 22.36% lower than that of the untreated Pennisetum hybrid after 3 h dry and 6 h wet milling pre-treatment. After wet milling pre-treatment, the fluidity of the Pennisetum hybrid was much better than conventional “smashing” pre-treatment, which may make feeding easier in large-scale biogas projects. Good fluidity and optimization of the degree of milling pre-treatment could, therefore, be applied on an industrial scale in the future.