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- Creators: Chaudhari, Mahesh B
- Creators: Swette Center for Environmental Biotechnology
Description
Microalgae-derived lipids are good sources of biofuel, but extracting them involves high cost, energy
expenditure, and environmental risk. Surfactant treatment to disrupt Scenedesmus biomass was evaluated
as a means to make solvent extraction more efficient. Surfactant treatment increased the recovery of fatty
acid methyl ester (FAME) by as much as 16-fold vs. untreated biomass using isopropanol extraction, and
nearly 100% FAME recovery was possible without any Folch solvent, which is toxic and expensive. Surfactant
treatment caused cell disruption and morphological changes to the cell membrane, as documented by
transmission electron microscopy and flow cytometry. Surfactant treatment made it possible to extract wet
biomass at room temperature, which avoids the expense and energy cost associated with heating
and drying of biomass during the extraction process. The best FAME recovery was obtained from highlipid
biomass treated with Myristyltrimethylammonium bromide (MTAB)- and 3-(decyldimethylammonio)-
propanesulfonate inner salt (3_DAPS)-surfactants using a mixed solvent (hexane : isopropanol = 1 : 1, v/v)
vortexed for just 1 min; this was as much as 160-fold higher than untreated biomass. The critical micelle
concentration of the surfactants played a major role in dictating extraction performance, but the growth
stage of the biomass had an even larger impact on how well the surfactants disrupted the cells and
improved lipid extraction. Surfactant treatment had minimal impact on extracted-FAME profiles and,
consequently, fuel-feedstock quality. This work shows that surfactant treatment is a promising strategy for
more efficient, sustainable, and economical extraction of fuel feedstock from microalgae.
expenditure, and environmental risk. Surfactant treatment to disrupt Scenedesmus biomass was evaluated
as a means to make solvent extraction more efficient. Surfactant treatment increased the recovery of fatty
acid methyl ester (FAME) by as much as 16-fold vs. untreated biomass using isopropanol extraction, and
nearly 100% FAME recovery was possible without any Folch solvent, which is toxic and expensive. Surfactant
treatment caused cell disruption and morphological changes to the cell membrane, as documented by
transmission electron microscopy and flow cytometry. Surfactant treatment made it possible to extract wet
biomass at room temperature, which avoids the expense and energy cost associated with heating
and drying of biomass during the extraction process. The best FAME recovery was obtained from highlipid
biomass treated with Myristyltrimethylammonium bromide (MTAB)- and 3-(decyldimethylammonio)-
propanesulfonate inner salt (3_DAPS)-surfactants using a mixed solvent (hexane : isopropanol = 1 : 1, v/v)
vortexed for just 1 min; this was as much as 160-fold higher than untreated biomass. The critical micelle
concentration of the surfactants played a major role in dictating extraction performance, but the growth
stage of the biomass had an even larger impact on how well the surfactants disrupted the cells and
improved lipid extraction. Surfactant treatment had minimal impact on extracted-FAME profiles and,
consequently, fuel-feedstock quality. This work shows that surfactant treatment is a promising strategy for
more efficient, sustainable, and economical extraction of fuel feedstock from microalgae.
ContributorsLai, Yenjung Sean (Author) / De Francesco, Federica (Author) / Aguinaga, Alyssa (Author) / Parameswaran, Prathap (Author) / Rittmann, Bruce (Author) / Biodesign Institute (Contributor) / Swette Center for Environmental Biotechnology (Contributor)
Created2015-10-20
Description
Using a CH[subscript 4]-based membrane biofilm reactor (MBfR), we studied perchlorate (ClO[subscript 4]–) reduction by a biofilm performing anaerobic methane oxidation coupled to denitrification (ANMO-D). We focused on the effects of nitrate (NO[subscript 3]–) and nitrite (NO[subscript 2]–) surface loadings on ClO[subscript 4]– reduction and on the biofilm community’s mechanism for ClO[subscript 4]– reduction. The ANMO-D biofilm reduced up to 5 mg/L of ClO[subscript 4]– to a nondetectable level using CH[subscript 4] as the only electron donor and carbon source when CH[subscript 4] delivery was not limiting; NO[subscript 3]– was completely reduced as well when its surface loading was ≤0.32 g N/m[superscript 2]-d. When CH[subscript 4] delivery was limiting, NO[subscript 3]– inhibited ClO[subscript 4]– reduction by competing for the scarce electron donor. NO[subscript 2]– inhibited ClO[subscript 4]– reduction when its surface loading was ≥0.10 g N/m[superscript 2]-d, probably because of cellular toxicity. Although Archaea were present through all stages, Bacteria dominated the ClO[subscript 4]–-reducing ANMO-D biofilm, and gene copies of the particulate methane mono-oxygenase (pMMO) correlated to the increase of respiratory gene copies. These pieces of evidence support that ClO[subscript 4]– reduction by the MBfR biofilm involved chlorite (ClO[subscript 2]–) dismutation to generate the O[subscript 2] needed as a cosubstrate for the mono-oxygenation of CH[subscript 4].
ContributorsLuo, Yi-Hao (Author) / Chen, Ran (Author) / Wen, Li-Lian (Author) / Meng, Fan (Author) / Zhang, Yin (Author) / Lai, Chun-Yu (Author) / Rittmann, Bruce (Author) / Zhao, He-Ping (Author) / Zheng, Ping (Author) / Biodesign Institute (Contributor) / Swette Center for Environmental Biotechnology (Contributor)
Created2015-02-17
Description
To achieve nitrite accumulation for shortcut biological nitrogen removal (SBNR) in a biofilm process, we explored the simultaneous effects of oxygen limitation and free ammonia (FA) and free nitrous acid (FNA) inhibition in the nitrifying biofilm. We used the multi-species nitrifying biofilm model (MSNBM) to identify conditions that should or should not lead to nitrite accumulation, and evaluated the effectiveness of those conditions with experiments in continuous flow biofilm reactors (CFBRs). CFBR experiments were organized into four sets with these expected outcomes based on the MSNBM as follows: (i) Control, giving full nitrification; (ii) oxygen limitation, giving modest long-term nitrite build up; (iii) FA inhibition, giving no long-term nitrite accumulation; and (iv) FA inhibition plus oxygen limitation, giving major long-term nitrite accumulation. Consistent with MSNBM predictions, the experimental results showed that nitrite accumulated in sets 2–4 in the short term, but long-term nitrite accumulation was maintained only in sets 2 and 4, which involved oxygen limitation. Furthermore, nitrite accumulation was substantially greater in set 4, which also included FA inhibition. However, FA inhibition (and accompanying FNA inhibition) alone in set 3 did not maintained long-term nitrite accumulation. Nitrite-oxidizing bacteria (NOB) activity batch tests confirmed that little NOB or only a small fraction of NOB were present in the biofilms for sets 4 and 2, respectively. The experimental data supported the previous modeling results that nitrite accumulation could be achieved with a lower ammonium concentration than had been required for a suspended-growth process. Additional findings were that the biofilm exposed to low dissolved oxygen (DO) limitation and FA inhibition was substantially denser and probably had a lower detachment rate.
ContributorsPark, Seongjun (Author) / Chung, Jinwook (Author) / Rittmann, Bruce (Author) / Bae, Wookeun (Author) / Biodesign Institute (Contributor) / Swette Center for Environmental Biotechnology (Contributor)
Created2015-01-01
Description
The Combined Activated Sludge-Anaerobic Digestion Model (CASADM) quantifies the effects of recycling anaerobic-digester (AD) sludge on the performance of a hybrid activated sludge (AS)-AD system. The model includes nitrification, denitrification, hydrolysis, fermentation, methanogenesis, and production/utilization of soluble microbial products and extracellular polymeric substances (EPS). A CASADM example shows that, while effluent COD and N are not changed much by hybrid operation, the hybrid system gives increased methane production in the AD and decreased sludge wasting, both caused mainly by a negative actual solids retention time in the hybrid AD. Increased retention of biomass and EPS allows for more hydrolysis and conversion to methane in the hybrid AD. However, fermenters and methanogens survive in the AS, allowing significant methane production in the settler and thickener of both systems, and AD sludge recycle makes methane formation greater in the hybrid system.
ContributorsYoung, Michelle (Author) / Marcus, Andrew (Author) / Rittmann, Bruce (Author) / Biodesign Institute (Contributor) / Swette Center for Environmental Biotechnology (Contributor)
Created2013-08-13
ContributorsDietrich, Suzanne Wagner (Author) / Chaudhari, Mahesh B (Author)
Created2010-03-26
ContributorsChaudhari, Mahesh B (Author)
Created2010-09-13
ContributorsChaudhari, Mahesh B (Author)
Created2011-04-18
ContributorsChaudhari, Mahesh B (Author) / Dietrich, Suzanne Wagner (Author)
Created2011-03-09
ContributorsChaudhari, Mahesh B (Author) / Dietrich, Suzanne Wagner (Author)
Created2014-08-31
ContributorsChaudhari, Mahesh B (Author) / Dietrich, Suzanne Wagner (Author)
Created2014-08-31