A Scraped Surface Bioreactor for Enzymatic Saccharification of Pretreated Corn Stover Slurries

Dasari, Rajesh K.; Dunaway, Kyle W.; Berson, R. Eric

doi:10.1021/ef800434u

Cited by 71 publications

(61 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Free fall mixer is currently in use at DONG Energy's Integrated Biomass Utilization System pilot plant facility for pre-hydrolysis and SSF operation [4]. Horizontal operation of drum mixers provides advantages such as eliminating particle settling and formation of dead zones as well as improved heat transfer through reactor wall [140].…”

Section: Rotating Drumsmentioning

confidence: 99%

Biomass processing into ethanol: pretreatment, enzymatic hydrolysis, fermentation, rheology, and mixing

Volynets

Ein‐Mozaffari

Dahman

2016

Green Processing and Synthesis

View full text Add to dashboard Cite

Alternate energy resources need to be developed to amend for depleting fossil fuel reserves. Lignocellulosic biomass is a globally available renewable feedstock that contains a rich sugar platform that can be converted into bioethanol through appropriate processing. The key steps of the process, pretreatment, enzymatic hydrolysis, and fermentation, have undergone considerable amount of research and development over the past decades nearing the process to commercialization. In order for the commercialization to be successful, the process needs to be operated at high dry matter content of biomass, especially in the enzymatic hydrolysis stage that influences ethanol concentration in the final fermentation broth. Biomass becomes a thick paste with challenging rheology for mixing to be effective. As the biomass consistency increases, yield stress increases which limits efficiency of mixing with conventional stirred tanks. The purpose of this review is to provide features and perspectives on processing of biomass into ethanol. Emphasis is placed on rheology and mixing of biomass in the enzymatic hydrolysis step as one of the forefront issues in the field.

show abstract

Section: Rotating Drumsmentioning

confidence: 99%

Biomass processing into ethanol: pretreatment, enzymatic hydrolysis, fermentation, rheology, and mixing

Volynets

Ein‐Mozaffari

Dahman

2016

Green Processing and Synthesis

View full text Add to dashboard Cite

show abstract

“…It was difficult to obtain a liquid sample because free liquid was not present and solids dominated the solution. The percent of glucose released from the system at 20% solids is within 10% to 20% of what has been seen previously with corn stover (Dasari, et al, 2009;Dunaway et al, 2010).…”

Section: Resultssupporting

confidence: 72%

“…Then the reaction rate slows over the remainder of the reaction (Dasari, et al, 2009). An example of a typical conversion rate is shown in Figure 19.…”

Section: Resultsmentioning

confidence: 99%

Hydrolysis of concentrated dilute base pretreated biomass slurries.

Brockmann

Gregory²

View full text Add to dashboard Cite

Enzymatic hydrolysis is an important, but time limiting step in the process of converting biomass into ethanol. High solids concentrations are desired in order to minimize reactor size and achieve a higher concentration of glucose in the end product stream. However, higher solids concentrations lead to higher viscosities and hence, mixing and mass transfer becomes more difficult.In this study, a mixer designed to overcome the mass transfer limitations was used to conduct enzymatic hydrolysis of dilute-base pretreated corn stover, wheat, and miscanthus at high solids concentrations. This was done to determine if overcoming the mass transfer limitations would improve glucose release rates and yields, as was the case in a previous study on dilute acid pretreated corn stover. Solids concentrations were tested at 20%, 25%, and 30% for each substrate.The glucose yields during mixer trials were higher for lower solids concentrations for all three substrates, contradicting the previous results which showed that glucose release rates and yields were maintained as solids content increased in the mixer. The 20% solids corn stover released 70% more glucose than the 30% solids did. Yields for 20% solids were in the 60% range, which is low but close to the expected range. For wheat, 400% more glucose was released for 20% solids than 30% solids. Yields for 20% wheat solids were in the mid 60% range, which is also close to the expected range. For miscanthus, the increase was 36%. Yield for 20% miscanthus solids was below 40%, which was on the order of untreated sawdust in a previous study and indicates an ineffective pretreatment method for this substrate. The contradictory results indicate there v may be some effect other than mass transfer limitations that affects glucose release rates and yields.The slurries tested had much larger particle sizes and lacked the free water which gives the consistency seen with other pretreatment methods. This is most likely due to poor pretreatment. Due to the consistency, it was difficult to measure viscosity and, hence, determine if mass transfer limitations were overcome in these slurries.

show abstract

“…These have included gravitational tumbling in roller bottle reactors (Roche, et al, 2009a;Roche, et al, 2009b), horizontal paddle type bioreactors Roche et al, 2009a;), scraped surface bioreactors (Dasari, et al, 2009), and stirred helical bioreactors Zhang et al 2010a). achieved 35% solid loading and 62 g/L ethanol in a bioreactor with a horizontal rotating shaft with paddles, and this design provides sufficient mixing at very low rotation rates, meaning less power consumption (Zhang et al, 2010a).…”

Section: Conversion and Recoverymentioning

confidence: 99%

“…achieved 35% solid loading and 62 g/L ethanol in a bioreactor with a horizontal rotating shaft with paddles, and this design provides sufficient mixing at very low rotation rates, meaning less power consumption (Zhang et al, 2010a). Scraping blades can be used to prevent "dead zones," and keep the reactor surface clean to maximize heat/cooling transfer (Dasari, et al, 2009). Zhang et al (2010a) used a helical stirring system to 64.7 g/L ethanol from 30% solid loading of steam exploded corn stover.…”

Section: Conversion and Recoverymentioning

confidence: 99%