Pre-treatment techniques used for anaerobic digestion of algae

Rodríguez, Cristina; Alaswad, Abed; Mooney, Jerry; Prescott, T.; Olabi, Abdul–Ghani

doi:10.1016/j.fuproc.2015.06.027

Cited by 161 publications

(85 citation statements)

References 85 publications

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“…However, these cost/energy intensive pretreatment methods are not desirable for methane production through anaerobic digestion 16 . Moreover, chemical and thermal pretreatment methods may render the algal biomass unsuitable for optimal biomethane production due to generation of inhibitory compounds during the pretreatment 17 .…”

Section: Introductionmentioning

confidence: 99%

A method for simultaneous bioflocculation and pretreatment of algal biomass targeting improved methane production

et al. 2016

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A novel method for simultaneous bioflocculation and pretreatment of algae is revealed. The method includes bioflocculation of precultured algae (Chroococcus sp.) using pellet forming filamentous fungus (Aspergillus lentulusFJ172995) resulting in nearly 100% harvesting within 6 h without addition of any nutrient and carbon source at the optimized fungal/algal (F/A) ratio of 1:3. The algal-fungal interactions require metabolically active fungus with opposite charge. The bioflocculation process is replicable at reactor scale under continuous aeration. Simple incubation of harvested algal-fungal pellets under controlled conditions was associated with significant cellulase production (> 0.4 FPU mL -1 ) by the fungus leading to soluble sugar release ( ≈ 360 mg L -1 ) from algal cells. As a result, > 54% enhancement in digestibility and marked increase in methane production (up to 50 %) from algal fungal pellets during anaerobic digestion was noticed. The invention is a unique process of its kind and has potential application in algae based biofuel production including biomethane, biohydrogen and biodiesel as well as in extraction of valuables from microalgal biomass.

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Section: Introductionmentioning

confidence: 99%

A method for simultaneous bioflocculation and pretreatment of algal biomass targeting improved methane production

et al. 2016

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“…Chlorella kessleri, Scenedesmus) have recalcitrant cell walls, which make it difficult for anaerobic cultures to hydrolyze microalgal intracellular organic matter. Thus, to improve the biodegradability of microalgal biomass, pretreatments methods have been developed to disrupt or solubilize cell walls [112][113][114][115][116]. General insights from these studies are: (1) pretreatment methods are species-specific and their success depends on the nature of the cell wall; (2) mechanical pretreatments which consume electricity are more energy intensive than thermal, chemical and enzyme pretreatments; (3) chemical pretreatments usually have a low cost but produce inhibitory substances which could hamper the AD process; (4) for pretreatment mechanisms such as disruption of microalgal cell walls, the synergistic effects of the enzymes need further investigation; (5) combined pretreatments may provide energy and cost-effective options; (6) multi-objective optimization techniques could be used to obtain a high biogas yield with a positive energy balance; (7) enzyme/biological pretreatments have high selectivity, low inhibitory effects and higher probability of positive energy return [147]; (8) research on pilot/demonstration scale pretreatments is rare; (9) thermal pretreatments have been employed widely and proven to be the most efficient in microalgae pretreatment for AD; and (10) a detailed economic/energy analysis of microalgal AD for biogas production with pretreatment is still missing.…”

Section: Pretreatmentmentioning

confidence: 99%

Techno-Economic Analysis of Biogas Production from Microalgae through Anaerobic Digestion

Wu¹,

Moreira²,

Zhang³

et al. 2019

Anaerobic Digestion

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Microalgae are a promising feedstock for bioenergy due to higher productivity, flexible growing conditions, and high lipid/polysaccharide content compared to terrestrial biomass. Microalgae can be converted to biogas through anaerobic digestion (AD). AD is a mature technology with a high energy return on energy invested. Microalgae AD can bypass energy intensive dewatering operations that are associated with liquid fuel production from algae. A techno-economic assessment of the commercial feasibility of algae-based biogas production was conducted using Cyanothece BG0011 biomass as an example. BG0011 is a naturally occurring, saline cyanobacterium isolated from Florida Keys. It fixes atmospheric nitrogen and produces exopolysaccharide (EPS). Maximum cell density and EPS concentration of 2.7 and 2.1 g afdw 1 /L (for total algae biomass concentration of 4.8 g afdw/L) were obtained by air sparging. For an areal cell and EPS productivity of 12.4 and 9.6 g afdw/m2/day, respectively, the biomethane production cost was 14.8 $/MMBtu using covered anaerobic lagoon and high-pressure water scrubbing for biogas purification. Electricity production from biogas costs 13 cents/kwh. If areal productivity was increased by 33% from the same system, by sparging air enriched with 1% CO2, then biomethane cost was reduced to 12.16 $/MMBtu and electricity cost to 11 cents/kwh.

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“…Biological pretreatment of biomass is also very promising, mainly due to low energy consumption. 38 In the presented research work the biodegradability of untreated and pretreated microalgae was examined in anaerobic digestion. In order to accelerate the hydrolysis and increase the efficiency of biogas production two different pretreatments were applied -biological (bacterial) and thermal.…”

Section: 35mentioning

confidence: 99%

“…Higher temperature conditions stimulate cellulose and hemicellulose hydrolysis of algal cell wall components (mainly cellulose and hemicellulose), followed by formation and release of range of low molecular weight compounds (sugars, acids, etc.). 38,48 Heat also disrupts the hydrogen bonds in crystalline cellulose, causing the biomass to swell. 38 It was found, that bonds between and within the molecules forming the microalgae Scenedesmus cell walls were cleaved during the thermal pretreatment at 90 °C, which resulted in increased methane production by 2,2-fold with regard to untreated microalgae.…”

Section: 1 Thermal Pretreatmentmentioning

confidence: 99%

“…38,48 Heat also disrupts the hydrogen bonds in crystalline cellulose, causing the biomass to swell. 38 It was found, that bonds between and within the molecules forming the microalgae Scenedesmus cell walls were cleaved during the thermal pretreatment at 90 °C, which resulted in increased methane production by 2,2-fold with regard to untreated microalgae. 10 It is also known that time period of pretreatment is less important, as the temperature itself.…”

Section: 1 Thermal Pretreatmentmentioning

confidence: 99%

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Influence of Thermal and Bacterial Pretreatment of Microalgae on Biogas Production in Mesophilic and Thermophilic Conditions

Vidmar

Fanedl

Logar

et al. 2017

ACSi

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Microalgae biomass has a great potential in search for new alternative energy sources. They can be used as a substrate for the biogas production in anaerobic digestion. When using microalgae, the efficiency of this process is hampered due to the resistant cell wall. In order to accelerate the hydrolysis of cell wall and increase the efficiency of biogas production we applied two different pretreatments -biological and thermal under mesophilic and thermophilic conditions. During biological pretreatment we incubated microalgae with anaerobic hydrolytic bacteria Pseudobutyrivibrio xylanivorans Mz5 T . In thermal pretreatment we incubated microalgae at 90 °C. We also tested a combined thermal and biological pretreatment in which we incubated P. xylanivorans Mz5 T with thermally pretreated microalgae. Thermal pretreatment in mesophilic and thermophilic process has increased methane production by 21% and 6%, respectively. Biological pretreatment of microalgae has increased methane production by 13%, but only under thermophilic conditions (pretreatment under mesophilic conditions showed no effect on methane production). Thermal-biological pretreatment increased methane production by 12% under thermophilic conditions and by 6% under mesophilic conditions.

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Pre-treatment techniques used for anaerobic digestion of algae

Cited by 161 publications

References 85 publications

A method for simultaneous bioflocculation and pretreatment of algal biomass targeting improved methane production

A method for simultaneous bioflocculation and pretreatment of algal biomass targeting improved methane production

Techno-Economic Analysis of Biogas Production from Microalgae through Anaerobic Digestion

Influence of Thermal and Bacterial Pretreatment of Microalgae on Biogas Production in Mesophilic and Thermophilic Conditions

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