The effect of cost-effective combined pretreatment on rice straw for lignin solubilization and the recovery of biomethane.

A sustainable lignocellulosic biomass-based biorefinery requires complete utilization and valorization of the biomass components. In the present study, a phase-separated pretreatment (chemo mechanicaldelignification followed by bacterial pretreatment) was performed to fractionate lignin and cellulose-rich residue from rice straw biomass (RSB) to utilize lignin for polyhydroxyalkanoates (PHA) and cellulose-rich residue for biohydrogen production. A higher lignin removal of 81.4% was obtained through combined H2O2–homogenizer pretreatment. The lignin was utilized as a substrate by Bacillus cereus for PHA production. The cellulose-rich delignified RSB was hydrolyzed with cellulase-secreting bacteria. A higher chemical oxygen demand solubilization of 38.2% was achieved in delignified and bacterially (Delig-Bac) pretreated RSB than bacterially pretreated (Bac) alone (22.9%) and control (3.43%). A higher cellulose solubilization of 35.8% was obtained in Delig-Bac pretreated RSB than Bac alone (21.5%). A higher PHA concentration, content, and yield of 480 mg/L, 56%, and 561 mg/g were obtained from 2.970 g/L of lignin. Higher biohydrogen production of 66 mL/gVS was achieved in Delig-Bac pretreated RSB. The economic analysis revealed that Delig-Bac was found to be economically feasible with a net profit of 4.18 USD/m3 when compared to Bac (−457.4 USD/m3).

Lignocellulosic biomasses (LCB) are sustainable and abundantly available feedstocks for the production of biofuel and biochemicals via suitable bioconversion processing. The main aim of this review is to focus on strategies needed for the progression of viable lignocellulosic biomass-based biorefineries (integrated approaches) to generate biofuels and biochemicals. Processing biomass in a sustainable manner is a major challenge that demands the accomplishment of basic requirements relating to cost effectiveness and environmental sustainability. The challenges associated with biomass availability and the bioconversion process have been explained in detail in this review. Limitations associated with biomass structural composition can obstruct the feasibility of biofuel production, especially in mono-process approaches. In such cases, biorefinery approaches and integrated systems certainly lead to improved biofuel conversion. This review paper provides a summary of mono and integrated approaches, their limitations and advantages in LCB bioconversion to biofuel and biochemicals.

The objective of this study was to evaluate the effect of surfactant on disperser homogenization pretreatment for macroalgae (Ulva intestinalis) to enhance biogas production. The macroalgae are subjected to surfactant coupled disperser pretreatment, which enhanced the liquefaction and improved the biomethane production. The outcome of this study revealed that 10,000 rpm at 20 min with a specific energy input of 1748.352 kJ/ kg total solids (TS) are the optimum conditions for surfactant disperser pretreatment (SDP), which resulted in the liquefaction rate of 20.08% with soluble organics release of 1215 mg/L and showed a better result than disperser pretreatment (DP) with a liquefaction rate of 14%. Biomethane production through the SDP method was found to be 0.2 g chemical oxygen demand (COD)/g COD, which was higher than DP (0.11 g COD/g COD). SDP was identified to be a synergetic pretreatment method with an energy ratio and net profit of about 0.91 and 104.04 United States dollars (USD)/ton, respectively.

The current study intended to improve the disintegration potential of paper mill sludge through alkyl polyglycoside-coupled disperser disintegration. The sludge biomass was fed to the disperser disintegration and a maximum solubilization of 6% was attained at the specific energy input of 4729.24 kJ/kg TS. Solubilization was further enhanced by coupling the optimum disperser condition with varying dosage of alkyl polyglycoside. The maximum solubilization of 11% and suspended solid (SS) reduction of 8.42% were achieved at the disperser rpm, time, and surfactant dosage of 12,000, 30 min, and 12 μL. The alkyl polyglycoside-coupled disperser disintegration showed a higher biogas production of 125.1 mL/gCOD, compared to the disperser-alone disintegration (70.1 mL/gCOD) and control (36.1 mL/gCOD).