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May 1994 - April 2016
Publications
Publications (78)
Microalgal cultivation for biofuels and proteins holds significant promise but faces challenges in achieving economically viable biomass productivity under variable environmental conditions. This study introduces a forecast‐informed pond operation (FIPO) system that uses numerical weather prediction (NWP) ensemble forecasts and the biomass assessme...
Microalgae are one of the most versatile and promising organisms for biomanufacturing. To expedite research and development, we generated an improved genome assembly and annotation of the highly productive microalga Scenedesmus obliquus UTEX393 . We measured the systems level, multi-omic responses during exposure to 15 ppt (high) vs 5 ppt (low/cont...
Microalgae have received increasing attention as a potential feedstock for biofuel or biobased products. Forecasting the microalgae growth is beneficial for managers in planning pond operations and harvesting decisions. This study proposed a biomass forecasting system comprised of the Huesemann Algae Biomass Growth Model (BGM), the Modular Aquatic...
Accurate short‐range (e.g., 7 days) microalgae growth forecasts will be beneficial for both the production and harvesting of microalgae. This study developed an operational microalgae growth forecasting system comprised of the Huesemann Algae Biomass Growth Model (BGM), the Modular Aquatic Simulation System in Two Dimensions (MASS2) hydrodynamic mo...
We present a model-based assessment of alternative cultivation strategies for open pond algal biomass production within the conterminous United States (CONUS). Our assessment focuses on two basic cultivation strategies: (1) seasonal rotation of three representative freshwater algal strains that are well suited for warm weather, cold weather, and al...
Many algae research groups use elevated experimental raceways to characterize algal biomass productivity. Side walls and a relatively large paddlewheel shade the culture and lower productivity, particularly in winter and with low culture depth. This paper presents a four-step method to calculate shading for a given raceway shape: (1) develop a comp...
Chlorella sorokiniana (DOE 1412) emerged as one of the most promising microalgae strains from the NAABB consortium project and was found to have a remarkable doubling time under optimal conditions of 2.57 h−1. However, its maximum achievable annual biomass productivity in outdoor ponds in the contiguous USA has not yet been demonstrated. In order t...
A bench-scale photobioreactor system, the Laboratory Environmental Algae Pond Simulator (LEAPS), was designed and constructed to simulate outdoor pond cultivation for a wide range of geographical locations and seasons. The LEAPS consists of six well-mixed glass column photobioreactors submerged in a temperature controlled waterbath (− 2 °C to > 60...
Phosphorus and nitrogen are essential components of microalgal growth media. Critical to a wide range of biochemical processes, they commonly limit primary productivity. Recycling elemental phosphorus and fixed nitrogen after fuel conversion via hydrothermal liquefaction (HTL) of algae biomass reduces the need for mined phosphorus and synthetic nit...
Two innovative culturing systems, the LED-lighted and temperature-controlled 800 liter indoor raceways at Pacific Northwest National Laboratory (PNNL) and the Phenometrics environmental Photobioreactors™ (ePBRs) were evaluated in terms of their ability to accurately simulate the microalgae growth performance of outdoor cultures subjected to fluctua...
The cultivation efforts within the National Alliance for Advanced Biofuels and Bioproducts (NAABB) were developed to provide four major goals for the consortium, which included biomass production for downstream experimentation, development of new assessment tools for cultivation, development of new cultivation reactor technologies, and development...
To date, the algal biofuel industry has focused on the cultivation of monocultures of highly productive algal strains, but scaling up production remains challenging. Algal monocultures are difficult to maintain because they are easily contaminated by wild algal strains, grazers, and pathogens. In contrast, theory suggests that polycultures (multisp...
A microalgae growth model was developed for predicting biomass productivity in outdoor ponds under nutrient-replete conditions and diurnally fluctuating light intensities and water temperatures. The model was validated for three different species (Chlorella sorokiniana, Nannochloropsis salina, Picochlorum sp.), successfully predicting biomass growt...
Night biomass loss in photosynthetic algae is an essential parameter that is often overlooked when modeling or optimizing biomass productivities. Night respiration acts as a tax on daily biomass gains and has not been well characterized in the context of biomass production for biofuels. We examined the night biomass loss in three algae strains that...
This paper analyzes and evaluates the flow mixing in an open channel algal raceway for biofuel production. The flow mixing governs the frequency of how algae cells are exposed to sunlight, due to the fluid movement between the surface and the bottom of the algal raceway, thereby affecting algal growth rate. In this work, we investigated the flow mi...
The original Algae Raceway Integrated Design (ARID) raceway was an effective method to increase algae culture temperature in open raceways. However, the energy input was high and flow mixing was poor. Thus, the High Velocity Algae Raceway Integrated Design (ARID-HV) raceway was developed to reduce energy input requirements and improve flow mixing i...
The main objective of NAABB was to combine science, technology, and engineering expertise from across the nation to break down critical technical barriers to commercialization of algae-based biofuels. The approach was to address technology development across the entire value chain of algal biofuels production, from selection of strains to cultivati...
A microalgae biomass growth model was developed for screening novel strains for their potential to exhibit high biomass productivities under nutrient-replete conditions in photobioreactors or outdoor ponds. Growth is modeled by first estimating the light attenuation by biomass according to Beer-Lambert's law, and then calculating the specific growt...
The ARID (Aquaculture Raceway Integrated Design) system controls the diurnal and seasonal temperature fluctuation by controlling the surface area of the system. A finite difference model of the ARID raceway water temperature was developed in Visual Basic for Application. The input of this model is hourly meteorological data from an agricultural wea...
Accurate prediction of algal biofuel yield will require empirical determination of physiological responses to the climate, particularly light and temperature. One strain of interest, Nannochloropsis salina, was subjected to ranges of light intensity (5-850 μmol mâ»Â² sâ»Â¹) and temperature (13-40 C); exponential growth rate, total fatty acids (T...
The present study examines how climatic conditions and pond design affect the growth performance of microalgae. From January to April of 2011, outdoor batch cultures of
Nannochloropsis salina
were grown in three replicate 780 L conventional raceways, as well as in an experimental 7500 L algae raceway integrated design (ARID) pond. The ARID culture...
Microalgae are receiving increased global attention as a potential sustainable "energy crop" for biofuel production. An important step to realizing the potential of algae is quantifying the demands commercial-scale algal biofuel production will place on water and land resources. We present a high-resolution spatiotemporal assessment that brings to...
8.1 Introduction: Seaweeds and microalgae have a long history of cultivation as sources of commercial products (McHugh 2003; Pulz and Gross 2004). They also have been the subject of extensive investigations related to their potential as fuel source since the 1970s (Chynoweth 2002). As energy costs rise, these photosynthetic organisms are again a fo...
There is currently great interest in using microalgae for the production of biofuels, mainly due to the fact that microalgae can produce biofuels at a much higher productivity than conventional plants and that they can be cultivated using water, in particular seawater, and land not competing for resources with conventional agriculture. However, at...
In view of the fact that there are presently no cost-effective in situ treatment technologies for contaminated sediments, a 60-week-long phytoremediation feasibility study was conducted in seawater-supplied outdoor ponds to determine whether eelgrass (Zostera marina) is capable of removing polynuclear aromatic hydrocarbons (PAHs) and polychlorinate...
The nitrogen-fixing nonheterocystous cyanobacterium Plectonema boryanum was used as a model organism to study hydrogen generation by indirect biophotolysis in nitrogen-limited batch cultures that were continuously illuminated and sparged with argon/CO(2) to maintain anaerobiosis. The highest hydrogen-production rate (i.e., 0.18 mL/mg day or 7.3 mic...
Microalgae are expected to play a significant role in greenhouse gas mitigation because they can utilize CO2 from power plant flue gases directly while producing a variety of renewable carbon-neutral biofuels. In order for such a microalgal climate change mitigation strategy to become economically feasible, it will be necessary to significantly imp...
A historical perspective of the scientific study of ocean iron fertilization (OIF) over the last 15 yr prefaces a short synthesis of the multi-faceted issues raised by the 11 contributions to this Theme Section. These issues, which range from ethical to logistical, must be aired in discussions sur- rounding OIF and its commercial application as a p...
In order to evaluate ocean fertilization in the larger context of other proposed strategies for reducing the threat of the global warming, a wide range of different climate change mitigation approaches are compared in terms of their long-term potential, stage of development, relative costs and potential risks, as well as public acceptance. This bro...
Industrial society will move towards collapse if its total environmental impact (I), expressed either in terms of energy and
materials use or in terms of pollution, increases with time, i.e., dI/dt>0. The traditional interpretation of the I=PAT
equation reflects the optimistic belief that technological innovation, particularly improvements in eco-e...
Atmospheric carbon dioxide (CO2) concentrations are increasing and will cause unknown deleterious environmental effects if left unchecked. The Intergovernmental Panel on Climate Change (IPCC) has predicted in its latest report a 2ºC to 4ºC increase in global temperatures even with the strictest CO2 mitigation practices. Global warming can be attrib...
The most stringent emission scenarios published by the Intergovernmental Panel on Climate Change (IPCC) would result in the stabilization of atmospheric carbon dioxide (CO2) at concentrations of approximately 550 ppm which would produce a global temperature increase of at least 2 ^C by 2100. Given the large uncertainties regarding the potential ris...
When micro-porous and meso-porous silica particles were exposed to aqueous phenanthrene solutions for various durations it
was observed that sorbed-phase phenanthrene concentrations increased with aging time only for meso-porous but not micro-porous
silicas. Desorption equilibrium was reached almost instantaneously for the micro-porous particles wh...
The most stringent emission scenarios published by the Intergovernmental Panel on Climate Change (IPCC) would result in the stabilization of atmospheric carbon dioxide (CO2) at concentrations of approximately 550 ppm which would produce a global temperature increase of at least 2 C by 2100. Given the large uncertainties regarding the potential risk...
It is generally assumed that soil properties such as organic matter content, porosity, and mineral surface area have a significant effect on the bioavailability and leachability of aged petroleum hydrocarbons. In order to test this hypothesis, nine model soils or sorbents (i.e., fine and coarse quartz sand, montmorillonite and kaolinite clay, peat,...
Western industrialized societies are inherently unsustainable in their present form because they depend almost exclusively on a finite supply of nonrenewable minerals and fossil fuels. In addition, the resulting wastes cause various environmental problems ranging from widespread ecosystem disruptions to global warming. The most common response to t...
In order to determine whether bioavailability limits the biodegradability of petroleum hydrocarbons in aged soils, both the biodegradation and abiotic desorption rates of PAHs and n-alkanes were measured at various time points in six different aged soils undergoing slurry bioremediation treatment. Alkane biodegradation rates were always much greate...
A set of model soils (e.g., quartz sands, loams, clays, peat, silica gels) was spiked with crude oil, aged for 27 months in the laboratory, and subjected to bench-scale slurry bioremediation treatment for 90 weeks. At various times, slurry samples were removed from the bioreactors, analyzed for polynuclear aromatic hydrocarbons (PAHs), and assayed...
Petroleum and its derived fuels, as a result of their widespread worldwide use, are probably the most ubiquitous organic pollutants found in soil. Each year, approximately 40,000 barrels or equivalently 1,680,000 gallons of crude oil are spilled on land due to pipeline failures (Salani-tro 2001). There are more than 200,000 underground storage tank...
In an effort to determine whether bioavailability limitations are responsible for the slow or incomplete hydrocarbon biodegradation in aged soils, both the rate of desorption (rdes) and biodegradation (rbio) was measured for n-alkanes and polynuclear aromatic hydrocarbons (PAHs) at different times during the slurry biotreatment of six different soi...
Environmental science and technology alone cannot solve past and present pollution problems or meet the future challenge of sustainable development.
Science and technology alone cannot solve pollution problems or meet the challenge of sustainable development.
The pentacyclic triterpane C30 17α (H), 21β (H)-hopane, a biomarker commonly used in hydrocarbon bioremediation laboratory experiments and field studies, was found to be completely removed without the formation of the demethylated intermediate nor-hopane in a crude oil-contaminated soil undergoing slurry biotreatment, while PAHs such as benzo(e)pyr...
Sustainable development has been defined by political and corporate leaders as the combination of environmental protection
and economic growth. As a result, the concept of eco-efficiency has been promoted as the primary tool for achieving industrial
sustainability.
However, there are at least four reasons why technological improvements in eco-effi...
The pentacyclic triterpane C30 17α (H), 21β (H)-hopane, a biomarker commonly used in hydrocarbon bioremediation laboratory experiments and field studies, was found to be completely removed without the formation of the demethylated intermediate nor-hopane in a crude oil-contaminated soil undergoing slurry biotreatment, while PAHs such as benzo(e)pyr...
The rate and extent of polynuclear aromatic hydrocarbons (PAH) biodegradation in a set of aged model soils that had been contaminated with crude oil at the high concentrations (i.e.,>20,000 mg/kg) normally found in the environment were measured in 90-week slurry bioremediation experiments. Soil properties such as organic matter content, mineral typ...
Three types of bias: personal, institutional, and socio-cultural, will be examined together with their effects on public policy. Personal bias exists whenever a scientist, instead of being solely motivated by the search for empirical truth, tries to gain a personal benefit or advantage from research results or is unduly influenced by ideological co...
In an attempt to reduce the threat of global warming, it has been proposed that the rise of atmospheric carbon dioxide concentrations be reduced by the ocean disposal of CO2 from the flue gases of fossil fuel-fired power plants. The release of large amounts of CO2 into mid or deep ocean waters will result in large plumes of acidified seawater with...
Wetlands can potentially sequester vast amounts of carbon. However, over 50% of wetlands globally have been degraded or lost. Restoration of wetland systems may therefore result in increased sequestration of carbon. Preliminary results of our investigations into atmospheric carbon sequestration by restored coastal wetlands indicate that carbon can...
To assess whether petroleum hydrocarbons can be biodegraded in conjunction with in situ thermal treatment, a series of biodegradation experiments involving PAH (naphthalene, phenanthrene, anthracene, pyrene, chrysene, and perylene) and diesel fuel contaminated soils were performed at 25, 50, and 70°C. Experimental data indicate that the more volati...
Expedited artificial aging is described and demonstrated using a novel system that circulates a solution of supercritical carbon dioxide and a hydrophobic organic sorbate (phenanthrene) through a closed loop containing a porous substrate. Unlike traditional methods used to simulate the natural aging process, our approach allows for real-time monito...
Fluorescence spectroscopic characteristics of sorbed phenanthrene in porous silica provide information about its chemical state such as monomer vs dimer or higher aggregates, as well as a basis for high sensitivity detection. In this study, the chemical state and distribution of phenanthrene sorbed in two types of porous silica particles, mesoporou...
It is currently believed that science and technology can provide effective solutions to most, if not all, environmental problems facing western industrial societies. The validity of this optimistic assumption is highly questionable for at least three reasons: First, current mechanistic, reductionist science is inherently incapable of providing the...
It is commonly assumed that mass-transfer limitations are the cause for slow and incomplete biodegradation of PAHs in aged soils. In order to test this hypothesis, the biodegradation rate and the abiotic release rate were measured and compared for selected PAHs in three different soils. It was found that PAH biodegradation was not mass-transfer lim...
In this study, we determined the limits and extent of hydrocarbon biodegradation, earthworm and plant toxicity, and waste leachability of crude oil-containing soils. Three oils (heavy, medium, and light of API gravity 14, 30, and 55, respectively) were mixed into silty loamy soils containing low (0.3%) or high (4.7%) organic carbon at 4000−27 000 m...
Bioremediation has been used to treat soils contaminated with complex mixtures of organic compounds such as total petroleum hydrocarbons (TPH), oil and grease (O&G), or polycyclic aromatic hydrocarbons (PAHs). Despite the common use and cost-effectiveness of bioremediation for treating hydrocarbon-contaminated soils, it has been observed that a res...
In passive bioremediation of petroleum hydrocarbon contaminated soils, oxygen diffusion is the primary mechanism for supplying the oxygen which is required for microbial hydrocarbon biodegradation processes. It is the objective of this research to theoretically evaluate whether passive bioremediation can be a feasible treatment alternative for petr...
A series of solid- and slurry-phase soil bioremediation experiments involving different crude oils and refined petroleum products were performed in order to investigate the factors which affect the maximum extent of total petroleum hydrocarbon (TPH) biodegradation. Utilizing a comprehensive petroleum hydrocarbon characterization procedure involving...
During land treatment, environmental parameters are optimized to achieve the fastest and most complete biodegradation of petroleum hydrocarbons present in contaminated soils. This article provides specific guidelines for optimization of the land treatment process at a field site. In particular, the necessary steps in the land treatment procedure ar...
A 16 week laboratory study was conducted to assess the biotreatability of regulated (BDAT list) polynuclear aromatic compounds (PNA) in refinery API oil separator sludge. The three different treatments consisted of a biotic, nutrient amended, inoculated aerated slurry reactor, a second biotic oxygen-sparged reactor, and a sterile, nitrogen-sparged...
Laboratory landfarming experiments were conducted to study the bioremediation potential of weathered Michigan crude oil‐contaminated soils. It was found that landfarming was successful in removing up to 90% of the total petroleum hydrocarbons (TPH) in the soil within 22 weeks of treatment. Boiling point analyses of untreated and treated soils indic...
Addition of acetate or propionate to uncontrolled-pH batch cultures does not affect the initiation of solventogenesis but does enhance final solvent concentrations compared with those of unchallenged cultures. This observation can be explained in terms of the increased buffering capacity of the medium brought about by the added acids, resulting in...
The formation of butanol in continuous cultures of Clostridium acetobutylicum is regulated at the genetic level via expression of butyraldehyde dehydrogenase since increased in vitro activities of this key enzyme are associated with increased in vivo butanol formation rates in both acidogenic and solventogenic fermentations. Addition of glucose, bu...
In vitro activities of key enzymes and related parameters (ATP and ADP concentrations, intracellular pH (pH
i
), cell volume and the transmembrane pH) in various continuous and batch fermentations of Clostridium acetobutylicum were studied in order to investigate the regulation (genetic vs. enzyme level) of the solventogenesis process. In vitro act...
The mechanism primarily implicated in the solventogenesis process in batch fermentations of Clostridium acetobutylicum is examined in considerable detail. A variety of fermentations with or without pH control in the pH range of 3.7-6 have been carried out in order to examine which of a host of suspect parameters correlate with the initiation of sol...
The objectives of this paper are to demonstrate that various concentrations of carbon and energy substrates and metabolites affect the membrane PMF, that the Proton Motive Force PMF affects their transport, and that an altered (reduced) PMF affects the pH//i and cell metabolism. Finally, we shall examine how the above interactions may affect the de...
Summary Addition of 8–12 mM acetoacetate (AA) in uncontrolled-pH batch cultures ofC. acetobutylicum led to significant solvent production and averted the complete growth inhibition observed in control cultures. In controlled-pH cultures, the AA effect on solvent formation was not quite as pronounced, and that and the effect of 20 mM butyrate could...
In an attempt to reduce the threat of global warming, it has been proposed that the rise of atmospheric carbon dioxide concentrations be reduced by the ocean disposal of CO 2 from the flue gases of fossil fuel-fired power plants. The release of large amounts of CO 2 into mid or deep ocean waters will result in large plumes of acidified seawater wit...
A series of growth experiments were carried out with six strains of marine microalgae in batch and semi-continuous culture to measure maximum growth rates and biomass productivities, respectively. Experimental results confir med the hypothesis being tested that there is no correlation between maximum biomass productivity (i.e., CO 2 biofixation pot...
