Two-stage biohydrogen and biomethane production using granular activated carbon immobilized beads as support carrier

Biohydrogen and biomethane gases are popular alternatives to renewable energy as the production of these green gases can be generated using biomass. The first objective of this study was to assess the microbial growth of biofilm formation on granular activated carbon (GAC) in two-stage biohydrogen and biomethane production. The microbial growth of biofilm formation was studied based on 5 different inoculum percentages (v/v) of cow dung (2.5%, 5%, 7.5%, 10%, and 12.5%) and 5 different ratios of glucose concentration (2.5g/L, 5g/L, 7.5g/L, 10g/L, and 12.5g/L) added into the system using batch reactor. Based on the modified Gompertz modeling, it is shown that 15% inoculum has the highest biohydrogen and biomethane production rate at 0.88mmolH2/L.h and 43.87mmolCH4/L.d. The 10g/L of glucose addition has also contributed to the maximum specific growth rate of 0.99h-1 for biohydrogen and 0.85h-1 for biomethane based on Monod modeling. The second objective was to optimize and characterize the influence of alginate and chitosan on GAC immobilized beads using response surface methodology (RSM). Three main factors in the composite central design (CCD) were the concentration of GAC, the concentration of alginate-chitosan, and the drying method while the three responses were the bead diameter, stability, and swelling degree. Alginate and chitosan beads with desirability of 90% and 100% each contained 0.50 and 0.52g/L of GAC, 1.23 and 1.52% of alginate-chitosan and freeze-dried. Immobilized alginate and chitosan beads formed using the optimum factors were then added into the batch reactor for biohydrogen and biomethane production. When fitted into the modified Gompertz equation, biohydrogen production was higher when chitosan beads were added into the reactor, where Hm was 76.17mL with a maximum rate (Rm) of 1.92mL/h. Similar to biohydrogen production, biomethane production, Mm is higher by adding chitosan beads into the reactor (195.25mL) at a rate of 7.31mL/d. The third objective was to assess the energy recovery using GAC immobilized beads at different bioreactor operating conditions. Based on the techno-economic assessment, when the inflow rate of cow dung was 55L/day.cow, the working volume of the bioreactor was 132.00m3. Lab scale bioreactor fermentation was carried out in continuous batch showed the maximum biogas production was 934.54mL/gVS with a rate of 60.55mL/gVS.d and a lagged phase of 1.04 day. When converted to electricity, an estimated 14,681kWh of electricity can be generated daily, contributing to RM154,158.90 of revenue. The payback period of this system is 6 years with an ROI of 47.00%. Overall, this study has successfully evaluated the two-stage biohydrogen and biomethane production from cow dung by optimizing alginate-chitosan immobilized on GAC and estimated the energy recovery of anaerobic digester in the industry.

Text 125672 - Full Text.pdf Download (3MB) Text FK 2023 18 - Declaration Form.pdf Restricted to Repository staff only Download (545kB) Text FK 2023 18 - Full Text.pdf Restricted to Repository staff only Download (3MB) Official URL or Download Paper: http://ethesis.upm.edu.my/id/eprint/18935

Actions (login required)

View Item