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

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

Energies ◽

10.3390/en12050908 ◽

2019 ◽

Vol 12 (5) ◽

pp. 908 ◽

Cited By ~ 5

Author(s):

Tran Giang ◽

Siriporn Lunprom ◽

Qiang Liao ◽

Alissara Reungsang ◽

Apilak Salakkam

Keyword(s):

Hydrogen Production ◽

Reducing Sugars ◽

Simultaneous Saccharification And Fermentation ◽

Hydrogen Yield ◽

Microalgal Biomass ◽

Fermentation Time ◽

Chlorella Sp ◽

Volatile Solids ◽

Filter Paper Unit ◽

Simultaneous Saccharification

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.

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Improvement of hydrogen production from Chlorella sp. biomass by acid-thermal pretreatment

PeerJ ◽

10.7717/peerj.6637 ◽

2019 ◽

Vol 7 ◽

pp. e6637 ◽

Cited By ~ 6

Author(s):

Tran T. Giang ◽

Siriporn Lunprom ◽

Qiang Liao ◽

Alissara Reungsang ◽

Apilak Salakkam

Keyword(s):

Hydrogen Production ◽

High Growth ◽

High Growth Rate ◽

Hydrogen Yield ◽

Thermal Pretreatment ◽

Optimum Conditions ◽

Acid Pretreatment ◽

Microalgal Biomass ◽

Chlorella Sp ◽

Pretreated Biomass

Background Owing to the high growth rate, high protein and carbohydrate contents, and an ability to grow autotrophically, microalgal biomass is regarded as a promising feedstock for fermentative hydrogen production. However, the rigid cell wall of microalgae impedes efficient hydrolysis of the biomass, resulting in low availability of assimilable nutrients and, consequently, low hydrogen production. Therefore, pretreatment of the biomass is necessary in order to achieve higher hydrogen yield (HY). In the present study, acid-thermal pretreatment of Chlorella sp. biomass was investigated. Conditions for the pretreatment, as well as those for hydrogen production from the pretreated biomass, were optimized. Acid pretreatment was also conducted for comparison. Results Under optimum conditions (0.75% (v/v) H2SO4, 160 °C, 30 min, and 40 g-biomass/L), acid-thermal pretreatment yielded 151.8 mg-reducing-sugar/g-biomass. This was around 15 times that obtained from the acid pretreatment under optimum conditions (4% (v/v) H2SO4, 150 min, and 40 g-biomass/L). Fermentation of the acid-thermal pretreated biomass gave 1,079 mL-H2/L, with a HY of 54.0 mL-H2/g-volatile-solids (VS), while only 394 mL/L and 26.3 mL-H2/g-VS were obtained from the acid-pretreated biomass. Conclusions Acid-thermal pretreatment was effective in solubilizing the biomass of Chlorella sp. Heat exerted synergistic effect with acid to release nutrients from the biomass. Satisfactory HY obtained with the acid-thermal pretreated biomass demonstrates that this pretreatment method was effective, and that it should be implemented to achieve high HY.

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Growth of microalgal biomass on supernatant from biosolid dewatering

Water Science & Technology ◽

10.2166/wst.2013.805 ◽

2013 ◽

Vol 69 (4) ◽

pp. 896-902 ◽

Cited By ~ 19

Author(s):

E. Ficara ◽

A. Uslenghi ◽

D. Basilico ◽

V. Mezzanotte

Keyword(s):

Anaerobic Digestion ◽

Methane Production ◽

Biogas Production ◽

Treatment Plant ◽

Biomass Concentration ◽

Anaerobic Sludge ◽

Available Nitrogen ◽

Microalgal Biomass ◽

Production Values ◽

Average Specific Growth Rate

The paper reports the results of an experiment to assess the feasibility of including a photobioreactor within the design of a wastewater treatment plant, growing microalgae on the centrate from anaerobic sludge dewatering. The growth of algal biomass would take advantage of the available nitrogen and provide a substrate for biogas production by anaerobic digestion. Tests were carried out by semi-continuously feeding a photobioreactor with a centrate–effluent blend and by increasing the fraction of centrate. The experimental results show that the centrate does not induce any toxicity and, on the contrary, can be well utilized by microalgae, whose average specific growth rate (μ), on centrate as such, was between 0.04 and 0.06 d−1. The maximum biomass concentration in the photobioreactor effluent was 1.6 gSS/L at 10 days HRT (hydraulic retention time). Methane production tests led to biochemical methane production values of 335 ± 39, and 284 ± 68 mL 0°C, 1 atm CH4/g VS for the two tested samples, in agreement with literature values. Settling tests show that the settling capacity of microalgae, although satisfactory, could be effectively improved after mixing with activated sludge, confirming the potential to use the existing primary settler for microalgae thickening in order to feed microalgae for anaerobic digestion with primary/secondary sludge.

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Two-Stage Anaerobic Codigestion of Crude Glycerol and Micro-Algal Biomass for Biohydrogen and Methane Production by Anaerobic Sludge Consortium

Fermentation ◽

10.3390/fermentation7030175 ◽

2021 ◽

Vol 7 (3) ◽

pp. 175

Author(s):

Sureewan Sittijunda ◽

Napapat Sitthikitpanya ◽

Pensri Plangklang ◽

Alissara Reungsang

Keyword(s):

Methane Production ◽

Crude Glycerol ◽

Antagonistic Effect ◽

Biohydrogen Production ◽

Anaerobic Sludge ◽

Two Stage ◽

Microalgal Biomass ◽

Factors Affecting ◽

Production Of Hydrogen ◽

Stage Process

Optimization of factors affecting biohydrogen production from the codigestion of crude glycerol and microalgal biomass by anaerobic sludge consortium was conducted. The experiments were designed by a response surface methodology with central composite design. The factors affecting the production of hydrogen were the concentrations of crude glycerol, microalgal biomass, and inoculum. The maximum hydrogen production (655.1 mL-H2/L) was achieved with 13.83 g/L crude glycerol, 23.1 g-VS/L microalgal biomass, and 10.3% (v/v) inoculum. The hydrogenic effluents obtained under low, high, and optimal conditions were further used as substrates for methane production. Methane production rates and methane yield of 868.7 mL-CH4/L and 2.95 mL-CH4/L-h were attained with the effluent produced under optimum conditions. The use of crude glycerol and microalgal biomass as cosubstrates had an antagonistic effect on biohydrogen production and a synergistic effect on methane fermentation. The two-stage process provided a more attractive solution, with a total energy of 1.27 kJ/g-VSadded, than the one-stage process.

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Augmentation of Granular Anaerobic Sludge with Algalytic Bacteria Enhances Methane Production from Microalgal Biomass

Fermentation ◽

10.3390/fermentation5040088 ◽

2019 ◽

Vol 5 (4) ◽

pp. 88 ◽

Cited By ~ 1

Author(s):

Anna Doloman ◽

Yehor Pererva ◽

Michael H. Cortez ◽

Ronald C. Sims ◽

Charles D. Miller

Keyword(s):

Microbial Community ◽

Anaerobic Digestion ◽

Methane Production ◽

Algal Biomass ◽

Organic Substrate ◽

Anaerobic Sludge ◽

Success Rates ◽

Metabolic Capacity ◽

Microalgal Biomass ◽

Feed Composition

The efficiency of anaerobic digestion relies upon activity of the inoculum converting organic substrate into biogas. Often, metabolic capacity of the inoculum needs to be augmented with new capabilities to accommodate changes in the substrate feed composition. However, bioaugmentation is not a widely used strategy possibly due to the lack of studies demonstrating successful applications. This study describes the bioaugmentation of granular anaerobic sludge digesting mixed algal biomass in batch-scale reactors. The addition of an algalytic bacterial mixture to the granular consortium increased methane yield by 11%. This study also investigated changes in the microbial 16SrRNA composition of the augmented and non-augmented granular inoculum, which demonstrates a significant change in the hydrolytic microbial community. Overall, the studies’ results aim to provide a feasible checklist to assess the success rates of bioaugmentation of anaerobic digestion applications.

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Evaluation of acidogenesis products’ effect on biogas production performed with metagenomics and isotopic approaches

Biotechnology for Biofuels ◽

10.1186/s13068-021-01968-0 ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Anna Detman ◽

Michał Bucha ◽

Laura Treu ◽

Aleksandra Chojnacka ◽

Łukasz Pleśniak ◽

...

Keyword(s):

Microbial Communities ◽

Methane Production ◽

Bacterial Species ◽

Stable Carbon Isotope ◽

Anaerobic Sludge ◽

Methane Formation ◽

Microbial Composition ◽

Fermentation Products ◽

Core Microbiome ◽

Specific Species

Abstract Background During the acetogenic step of anaerobic digestion, the products of acidogenesis are oxidized to substrates for methanogenesis: hydrogen, carbon dioxide and acetate. Acetogenesis and methanogenesis are highly interconnected processes due to the syntrophic associations between acetogenic bacteria and hydrogenotrophic methanogens, allowing the whole process to become thermodynamically favorable. The aim of this study is to determine the influence of the dominant acidic products on the metabolic pathways of methane formation and to find a core microbiome and substrate-specific species in a mixed biogas-producing system. Results Four methane-producing microbial communities were fed with artificial media having one dominant component, respectively, lactate, butyrate, propionate and acetate, for 896 days in 3.5-L Up-flow Anaerobic Sludge Blanket (UASB) bioreactors. All the microbial communities showed moderately different methane production and utilization of the substrates. Analyses of stable carbon isotope composition of the fermentation gas and the substrates showed differences in average values of δ13C(CH4) and δ13C(CO2) revealing that acetate and lactate strongly favored the acetotrophic pathway, while butyrate and propionate favored the hydrogenotrophic pathway of methane formation. Genome-centric metagenomic analysis recovered 234 Metagenome Assembled Genomes (MAGs), including 31 archaeal and 203 bacterial species, mostly unknown and uncultivable. MAGs accounted for 54%–67% of the entire microbial community (depending on the bioreactor) and evidenced that the microbiome is extremely complex in terms of the number of species. The core microbiome was composed of Methanothrix soehngenii (the most abundant), Methanoculleus sp., unknown Bacteroidales and Spirochaetaceae. Relative abundance analysis of all the samples revealed microbes having substrate preferences. Substrate-specific species were mostly unknown and not predominant in the microbial communities. Conclusions In this experimental system, the dominant fermentation products subjected to methanogenesis moderately modified the final effect of bioreactor performance. At the molecular level, a different contribution of acetotrophic and hydrogenotrophic pathways for methane production, a very high level of new species recovered, and a moderate variability in microbial composition depending on substrate availability were evidenced. Propionate was not a factor ceasing methane production. All these findings are relevant because lactate, acetate, propionate and butyrate are the universal products of acidogenesis, regardless of feedstock.

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Improvement of methane production at alkaline and neutral pH from anaerobic co-digestion of microalgal biomass and cheese whey

Biochemical Engineering Journal ◽

10.1016/j.bej.2021.107972 ◽

2021 ◽

pp. 107972

Author(s):

Jack Rincón-Pérez ◽

Lourdes B. Celis ◽

Marcia Morales ◽

Felipe Alatriste-Mondragón ◽

Aida Tapia-Rodríguez ◽

...

Keyword(s):

Methane Production ◽

Cheese Whey ◽

Microalgal Biomass ◽

Neutral Ph

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Metabolomic Study of Heterotrophically Grown Chlorella sp. Isolated from Wastewater in Northern Sweden

Molecules ◽

10.3390/molecules26092410 ◽

2021 ◽

Vol 26 (9) ◽

pp. 2410

Author(s):

Jean Claude Nzayisenga ◽

Anita Sellstedt

Keyword(s):

Sustainable Development ◽

Butyric Acid ◽

Lipid Production ◽

Growth Conditions ◽

Northern Sweden ◽

Metabolic Intermediate ◽

Chlorella Sp ◽

Lipid Contents ◽

New Compounds ◽

Potential Use

There are numerous strains of Chlorella with a corresponding variety of metabolic pathways. A strain we previously isolated from wastewater in northern Sweden can grow heterotrophically as well as autotrophically in light and has higher lipid contents under heterotrophic growth conditions. The aims of the present study were to characterize metabolic changes associated with the higher lipid contents in order to enhance our understanding of lipid production in microalgae and potentially identify new compounds with utility in sustainable development. Inter alia, the amino acids glutamine and lysine were 7-fold more abundant under heterotrophic conditions, the key metabolic intermediate alpha-ketoglutarate was more abundant under heterotrophic conditions with glucose, and maltose was more abundant under heterotrophic conditions with glycerol than under autotrophic conditions. The metabolite 3-hydroxy-butyric acid, the direct precursor of the biodegradable plastic PHB (poly-3-hydroxy-butyric acid), was also more abundant under heterotrophic conditions. Our metabolomic analysis has provided new insights into the alga’s lipid production pathways and identified metabolites with potential use in sustainable development, such as the production of renewable, biodegradable plastics, cosmetics, and nutraceuticals, with reduced pollution and improvements in both ecological and human health.

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Microalgae Cultivation in Different pH, Temperature and Media for Lipid Production

International Journal of Life Sciences ◽

10.3126/ijls.v8i2.10227 ◽

2014 ◽

Vol 8 (2) ◽

pp. 13-17 ◽

Cited By ~ 1

Author(s):

Dakshayini Jayaramareddy ◽

Ravikumar Krishnappa ◽

Girisha Sirangala Thimmappa

Keyword(s):

Lipid Production ◽

Life Sciences ◽

Nutrient Supply ◽

Polar Lipids ◽

Microalgae Cultivation ◽

Microalgal Biomass ◽

Chlorella Sp ◽

Nonpolar Lipids

Lipids produced by microalgal biomass can be grouped into nonpolar lipids and polar lipids, which can be easily converted into biofuels. Microalgal samples were collected from three different ponds of Bangalore and cultured in the laboratory to find the effect of different pH, temperature and media on the production of biomass and lipids. Among these, pH-9, temperature -25°C and Beneck’s media was most suitable for production of biomass (35.80 g/L) and lipids from the isolated microalgae Chlorella sp. compare to Chladospora sp. (13.33 g/L). Chlorella sp. Showed 0.32 (OD) at pH-9, 0.43 (OD) at temperature-25°C and 2.94 (OD) in Beneck’s media. Our result revealed that nutrient supply along with measured variables affects the production of biomass and lipids in different microalgae.DOI: http://dx.doi.org/10.3126/ijls.v8i2.10227 International Journal of Life Sciences Vol.8(2): 2014; 13-17

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