Improving biogas production from microalgae by enzymatic pretreatment

Passos, Fabiana; Hom-Díaz, Andrea; Blánquez, Paqui; Vicent, Teresa; Ferrer, Ivet

doi:10.1016/j.biortech.2015.08.084

Cited by 91 publications

(27 citation statements)

References 17 publications

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“…This is common for complex cultures, such as the one of the present study, composed by several microalgae species, bacteria and other microorganisms with different cell wall compositions. The results are in accordance with previous studies, where microalgae methane yield was increased when non-specific enzymes were added confirming the synergistic effect [10,12,13].…”

Section: Biogas Production In Bmp Testsupporting

confidence: 92%

“…The most commonly used enzymes for microalgae pretreatment are commercial α-amylases, amyglucosidases, cellulases, xylanases, lipases or proteases [10,11]. Furthermore, it has been shown that using a mixture of commercial enzymes, the methane yield was higher than using a single enzyme specific for one substrate [10,12]. Regarding the use of crude fungal enzymes, those from Aspergillus lentullus were particularly effective at improving microalgae anaerobic biodegradability [13].…”

Section: Introductionmentioning

confidence: 99%

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Enzymatic pretreatment of microalgae using fungal broth from Trametes versicolor and commercial laccase for improved biogas production

et al. 2016

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Coupling microalgae production to wastewater treatment can reduce the costs of microalgae production for non-food bioproducts and energy consumption for wastewater treatment. Furthermore, microalgae anaerobic digestion can be enhanced by applying pretreatment techniques. The aim of this study is to improve the biogas production from microalgal biomass grown in urban wastewater treatment systems by applying an enzymatic pretreatment with crude fungal broth and commercial laccase. To this end, the fungus Trametes versicolor was cultured, and the enzymatic activity of the culture broth analysed by measuring laccase concentration. The results showed that both the fungal broth and commercial laccase pretreatment (100 U L- 1) over an exposure time of 20 min increased the methane yield in batch tests. Indeed, the fungal broth pretreatment increased the methane yield by 74%, while commercial laccase increased the methane yield by 20% as compared to non-pretreated microalgal biomass. In this manner, laccase addition enhanced microalgal biomass anaerobic biodegradability, and addition of T. versicolor broth further improved the results. This fact may be attributed to the presence of other molecules excreted by the fungus.Peer ReviewedPostprint (author's final draft

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Section: Biogas Production In Bmp Testsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Enzymatic pretreatment of microalgae using fungal broth from Trametes versicolor and commercial laccase for improved biogas production

et al. 2016

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“…Thus, both approaches perform as expected. Trials with standalone pretreatment with cellulases and other polysaccharases for 6 h–7 days at 37–50 °C [3, 16–18] have shown more mixed results, ranging from no effect at all on rate and yield [3] to increased yield only [16, 17], increased rate only [18] or a combination of both increased yield and rate at selected time points [19]. …”

Section: Introductionmentioning

confidence: 99%

Enhanced biomethane production rate and yield from lignocellulosic ensiled forage ley by in situ anaerobic digestion treatment with endogenous cellulolytic enzymes

Speda

Johansson

Odnell

et al. 2017

Biotechnol Biofuels

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BackgroundEnzymatic treatment of lignocellulosic material for increased biogas production has so far focused on pretreatment methods. However, often combinations of enzymes and different physicochemical treatments are necessary to achieve a desired effect. This need for additional energy and chemicals compromises the rationale of using enzymes for low energy treatment to promote biogas production. Therefore, simpler and less energy intensive in situ anaerobic digester treatment with enzymes is desirable. However, investigations in which exogenous enzymes are added to treat the material in situ have shown mixed success, possibly because the enzymes used originated from organisms not evolutionarily adapted to the environment of anaerobic digesters. In this study, to examine the effect of enzymes endogenous to methanogenic microbial communities, cellulolytic enzymes were instead overproduced and collected from a dedicated methanogenic microbial community. By this approach, a solution with very high endogenous microbial cellulolytic activity was produced and tested for the effect on biogas production from lignocellulose by in situ anaerobic digester treatment.ResultsAddition of enzymes, endogenous to the environment of a mixed methanogenic microbial community, to the anaerobic digestion of ensiled forage ley resulted in significantly increased rate and yield of biomethane production. The enzyme solution had an instant effect on more readily available cellulosic material. More importantly, the induced enzyme solution also affected the biogas production rate from less accessible cellulosic material in a second slower phase of lignocellulose digestion. Notably, this effect was maintained throughout the experiment to completely digested lignocellulosic substrate.ConclusionsThe induced enzyme solution collected from a microbial methanogenic community contained enzymes that were apparently active and stable in the environment of anaerobic digestion. The enzymatic activity had a profound effect on the biogas production rate and yield, comparable with the results of many pretreatment methods. Thus, application of such enzymes could enable efficient low energy in situ anaerobic digester treatment for increased biomethane production from lignocellulosic material.

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“…Microalgal biomass has ample post-application potential; it could be a source of highvalue products for use as biofuels and bioproducts (Mennaa et al, 2015;Molinuevo-Salces et al, 2016;Passos et al, 2015;Zhang et al, 2016).…”

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confidence: 99%

Performance of a microalgal photobioreactor treating toilet wastewater: Pharmaceutically active compound removal and biomass harvesting

Hom-Díaz

Jaén-Gil

Bello-Laserna

et al. 2017

Science of The Total Environment

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155

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In this study, a 1200L outdoor pilot scale microalgal photobioreactor (PBR) was used for toilet wastewater (WW) treatment and evaluate its ability to remove pharmaceutically active compounds (PhACs). The PBR was operated at two different hydraulic retention times (HRTs), which were 8 and 12days, during Period I (September-October) and Period II (October-December), respectively. Algal biomass concentrations varied by operating period because of seasonal changes. Nutrients (ammonia, nitrogen and total phosphorous) and chemical oxygen demand (COD) were monitored and efficiently removed in both periods (>80%), attaining the legislation limits. At the theoretical hydraulic steady state in both periods, pharmaceutical removal reached high levels (>48%). Two harvesting techniques were applied to the PBR microalgae effluent. Gravity sedimentation was efficient for biomass removal (>99% in 7min) in Period I when large particles, flocs and aggregates were present. In contrast, a longer sedimentation time was required when biomass was mainly composed of single cells (88% clarification in a 24h in Period II). The second harvesting technique investigated was the co-pelletization of algal biomass with the ligninolytic fungus Trametes versicolor, attaining >98% clarification for Period II biomass once pellets were formed. The novel technology of co-pelletization enabled the complete harvesting of single algae cells from the liquid medium in a sustainable way, which benefits the subsequent use of both biomass and the clarified effluent.

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Improving biogas production from microalgae by enzymatic pretreatment

Cited by 91 publications

References 17 publications

Enzymatic pretreatment of microalgae using fungal broth from Trametes versicolor and commercial laccase for improved biogas production

Enzymatic pretreatment of microalgae using fungal broth from Trametes versicolor and commercial laccase for improved biogas production

Enhanced biomethane production rate and yield from lignocellulosic ensiled forage ley by in situ anaerobic digestion treatment with endogenous cellulolytic enzymes

Performance of a microalgal photobioreactor treating toilet wastewater: Pharmaceutically active compound removal and biomass harvesting

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