Enhancing Hydrogen Production from Chlorella sp. Biomass by Pre-Hydrolysis with Simultaneous Saccharification and Fermentation (PSSF)

Abstract

Simultaneous saccharification and fermentation (SSF) and pre-hydrolysis with SSF (PSSF) were used to produce hydrogen from the biomass of Chlorella sp. SSF was conducted using an enzyme mixture consisting of 80 filter paper unit (FPU) g-biomass−1 of cellulase, 92 U g-biomass−1 of amylase, and 120 U g-biomass−1 of glucoamylase at 35 °C for 108 h. This yielded 170 mL-H2 g-volatile-solids−1 (VS), with a productivity of 1.6 mL-H2 g-VS−1 h−1. Pre-hydrolyzing the biomass at 50 °C for 12 h resulted in the production of 1.8 g/L of reducing sugars, leading to a hydrogen yield (HY) of 172 mL-H2 g-VS−1. Using PSSF, the fermentation time was shortened by 36 h in which a productivity of 2.4 mL-H2 g-VS−1 h−1 was attained. To the best of our knowledge, the present study is the first report on the use of SSF and PSSF for hydrogen production from microalgal biomass, and the HY obtained in the study is by far the highest yield reported. Our results indicate that PSSF is a promising process for hydrogen production from microalgal biomass.

Optimization of Batch Dark Fermentation of Chlorella sp. Using Mixed-Cultures for Simultaneous Hydrogen and Butyric Acid Production

“…On the other hand, fermentation at initial pH 7 and any concentration or temperature can produce VFAs with higher yield. Acetic acid and butyric acid are the main products of the fermentation of microalgae at 35 °C, similar to the main products in the study by Giang et al [53] at the same temperature, while, at operating temperature 55 °C, the main VFAs generated were acetic acid and propionic acid. High butyric acid production in batch fermentation was obtained at initial concentration of 80 and 100 g-…”

“…Acetic acid and butyric acid are the main products of the fermentation of microalgae at 35 °C, similar to the main products in the study by Giang et al [53] at the same temperature, while, at operating temperature 55 °C, the main VFAs generated were acetic acid and propionic acid. High butyric acid production in batch fermentation was obtained at initial concentration of 80 and 100 g- Acetic acid and butyric acid are the main products of the fermentation of microalgae at 35 • C, similar to the main products in the study by Giang et al [53] at the same temperature, while, at operating temperature 55 • C, the main VFAs generated were acetic acid and propionic acid. High butyric acid production in batch fermentation was obtained at initial concentration of 80 and 100 g-VS/L at pH 7 with concentration of butyric acid production of 4.27 g/L (0.05 g/g-VS) and 3.81 g/L (0.04 g/g-VS), respectively (Table 3) .…”

“…The temperature of 35 • C produced lower total VFAs than 55 • C at initial pH 7, while yielding acetic acid and butyric acid as the main products. According to Giang et al [53], when the total acid production is increased, the hydrogen production yield will decrease, as the hydrogen synthesis byproduct found in fermented solution contains mostly acetic acid and butyric acid [36]. Thus, the temperature of 55 • C yielded not only the highest acetic acid production but also propionic acid as a product, resulting in low hydrogen gas production because propionic acid is produced through a hydrogen consuming reaction [55].…”

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

“…biomass was added to glass bottles containing 50 mL of distilled water. Mixed enzymes, including cellulase (Cellic ® CTec2), glucoamylase (Dextrozyme ® GA), and alpha-amylase (Termamyl ® SC) from Novozyme, Denmark, were applied to the glass bottle in the appropriate proportions, and the conditions were set according to Giang et al [ 37 ].…”

Biomass Waste as Sustainable Raw Material for Energy and Fuels

“…This alternative provides benefits by supporting high loads of solids, reducing quickly the initial viscosity of the substrate that leads to an increase of ethanol yield [32]. Specifically, the substrate is incubated with hydrolytic enzymes in a short time, generally between 8 and 24 h. Then, the SSF proceeds when the microorganism is inoculated, improving the saccharification process due to the different optimum temperatures of the enzymes (50 • C) and the traditional fermentation yeasts (30 • C) [33,34].…”