Co-generation of biohydrogen and biochemicals from co-digestion of Chlorella sp. biomass hydrolysate with sugarcane leaf hydrolysate in an integrated circular biorefinery concept

Abstract

Background A platform for the utilization of the Chlorella sp. biomass and sugarcane leaves to produce multiple products (biorefinery concept) including hydrogen, methane, polyhydroxyalkanoates (PHAs), lipid, and soil supplement with the goal to achieve the zero waste generation (circular economy) is demonstrated in this study. Microalgal biomass were hydrolyzed by mixed enzymes while sugarcane leaves were pretreated with alkali followed by enzyme. Hydrolysates were used to produce hydrogen and the hydrogenic effluent was used to produce multi-products. Solid residues at the end of hydrogen fermentation and the remaining acidified slurries from methane production were evaluated for the compost properties. Results The maximum hydrogen yield of 207.65 mL-H2/g-volatile solid (VS)added was obtained from 0.92, 15.27, and 3.82 g-VS/L of Chlorella sp. biomass hydrolysate, sugarcane leaf hydrolysate, and anaerobic sludge, respectively. Hydrogenic effluent produced 321.1 mL/g-VS of methane yield, 2.01 g/L PHAs concentration, and 0.20 g/L of lipid concentration. Solid residues and the acidified slurries at the end of the hydrogen and methane production process were proved to have compost properties. Conclusion Hydrogen production followed by methane, PHA and lipid productions is a successful integrated circular biorefinery platform to efficiently utilize the hydrolysates of Chlorella sp. biomass and sugarcane leaf. The potential use of the solid residues at the end of hydrogen fermentation and the remaining acidified slurries from methane production as soil supplements demonstrates the zero waste concept. The approach revealed in this study provides a foundation for the optimal use of feedstock, resulting in zero waste. Graphic Abstract

Unlocking the potential of sugarcane leaf waste for sustainable methane production: Insights from microbial pre-hydrolysis and reactor optimization

“…The MY obtained from this study (199.3 mL-CH 4 /g-VS) are comparable to the yields from other studies, ranging from 81.0 mL-CH 4 /g-VS to 223.6 mL-CH 4 /g-VS. However, the yield obtained from our research is relatively low compared to that of Sitthikitpanya et al [ 50 ] (346.7 mL-CH 4 /g-VS), which could be due to differences in pre-treatment methods and fermentation processes. MY can be influenced by several factors including the type of substrate used, the pre-treatment methods employed, fermentation processes, loading rates of bacteria and organic material, as well as the specific microbial consortium present.…”

Biohydrogen production through dark fermentation from waste biomass: Current status and future perspectives on biorefinery development

“…This might make the biorefinery system more reliable and enhance the synthesis of various products. For example, producing biobutanol apart from biohydrogen and biomethane [209,210] or improving both fuels' productivity [233,234].…”

“…[231,233].Integrated DF and photofermentation techniques are not economically viable as of current research developments, as per Ahmad et al[235] and Urbaniec et al[236]. The study by Ahmad et al examined the possibility of treating liquid pineapple wastes through DF and photo fermentation for biohydrogen production.…”

Microalgal Biomass as Feedstock for Bacterial Production of PHA: Advances and Future Prospects

“…Likewise, C. necator TISTR 1335 was fed a combination of Chlorella sp. biomass co-digested with sugarcane leaves to produce 60.9 wt% of PHA which contributes to the zero-waste generation concept ( Sitthikitpanya et al, 2021 ).…”