Kimberly L Ogden

Interests

Research

Bioreactor design, scale-up and optimization; algal cultivation; yeast and bacterial growth kinetics; bioremediation; water, energy, food nexus; alternative energy

Teaching

Bioreactor design, capstone process design

Courses

Scholarly Contributions

Journals/Publications

• Ogden, K. L., Saez, A. E., & Achilli, A. (2021). A hands-on course on intensified membrane process for sustainable water purification. Chemical Engineering Education.
• Ogden, K. L., Wall, G. W., Orr, E. R., Norton, E. R., Ray, D. T., Williams, C., Katterman, M. E., Attalah, S., Cruz, V. V., Dierig, D., Wang, G., Thorp, K. R., Hunsaker, D. J., Waller, P. M., & Elshikha, D. E. (2023).

  Water Use, Growth, and Yield of Ratooned Guayule under Subsurface Drip and Furrow Irrigation in the US Southwest Desert

  . Water Journal, 15(19), 15.
• Marquez, I., Saez, A. E., Ogden, K. L., & Achilli, A. (2022). A hands-on course on intensified membrane process for sustainable water purification. Chemical Engineering Education.
• Ogden, K. L., Acedo, M., Kiehlbaugh, K. M., & Gonzalez-Cena, J. R. (2020). Coupling carbon capture for a power plant with semi-automated open raceway ponds for microalgae cultivation. JoVE Journal - Environment. doi:10.3791/61498
• Ogden, K. L., F, R. D., & C, B. D. (2020). Process intensification education contributes to sustainable development goals. Part 1. Education for Chemical Engineers, 32, 1-14. doi:10.1016/j.ece.2020.04.003
• Ogden, K. L., F, R. D., & C, B. D. (2020). Process intensification education contributes to sustainable development goals. Part 2. Education for Chemical Engineers, 32, 15-24. doi:10.1016/j.ece.2020.05.001
• Attalah, S., Attalah, S., Waller, P. M., Waller, P. M., Steichen, S., Steichen, S., Brown, C., Brown, C., Gao, S., Gao, S., Ogden, K. L., Ogden, K. L., Brown, J. K., & Brown, J. K. (2019). Application of deoxygenation-aeration cycling to control the predatory bacterium Vampirovibrio chlorellavorus in Chlorella sorokiniana cultures. Algal Research, 39. doi:https://doi.org/10.1016/j.algal.2019.101427
• Attalah, S., Attalah, S., Waller, P. M., Waller, P. M., Steichen, S., Steichen, S., Gao, S., Gao, S., Brown, J. K., Brown, J. K., Ogden, K. L., & Ogden, K. L. (2019). Deoxygenation-aeration cycling-driven management of a predatory bacterium Vampirovibrio chlorellavorus in Chlorella sorokiniana algae culture.. Algal Research, 39. doi:https://doi.org/10.1016/j.algal.2019.101427
• Attalah, S., Waller, P. M., Steichen, S., Brown, C., Gao, S., Ogden, K. L., & Brown, J. K. (2019). Cost minimization of deoxygenation for control of Vampirovibrio chlorellavorus in Chlorella sorokiniana cultures. Algal Research, 42, 1061. doi:https://doi.org/10.1016/j.algal.2019.101615/
• Attalah, S., Waller, P. M., Steichen, S., Brown, C., Mehdipour, Y., Ogden, K. L., & Brown, J. K. (2019). Cost minimization of deoxygenation for control of Vampirovibrio chlorellavorus in Chlorella sorokiniana cultures. Algal Research, 42. doi:https://doi.org/10.1016/j.algal.2019.101615
• Khawam, G., Waller, P. M., Gao, S., Edmundson, S., Huesemann, M., Attalah, S., & Ogden, K. L. (2019). Simulation of shading and algal growth in experimental raceways. Algal Research, 41. doi:https://doi.org/10.1016/j.algal.2019.101575
• Khawam, G., Waller, P. M., Gao, S., Edmundson, S., Wigmosta, M., & Ogden, K. L. (2019). Model of temperature, evaporation, and productivity in elevated experimental algae raceways and comparison with commercial raceways.. Algal Research, 39. doi:https://doi.org/10.1016/j.algal.2019.101448
• Zhang, B., & Ogden, K. L. (2019). Nitrogen Balances and Impacts on the Algae Cultivation-Extraction-Digestion-Cultivation Process. Algal Research, 39. doi:https://doi.org/10.1016/j.algal.2019.101434
• Armstrong, N. R., Shallcross, R. C., Ogden, K. L., Achilli, A., Snyder, S. A., & Armstrong, E. (2018). Challenges and Opportunities at the Nexus of Energy, Water and Food,. MRS Energy and Sustainability, 5. doi:DOI:10.1557/mre.2018.2
• Gao, S., Waller, P. M., Khawam, G., Attalah, S., Huesemann, M., & Ogden, K. L. (2018). Incorporation of salinity stress, nitrogen stress, and shading into the HABG algae growth model.. Algal Research, 35, 462-470. doi:https://doi.org/10.1016/j.algal.2018.09.021.
• Gao, S., Waller, P., Khawam, G., Attalah, S., Huesemann, M., & Ogden, K. (2018). Incorporation of salinity, nitrogen, and shading stress factors into the Huesemann Algae Biomass Growth model. ALGAL RESEARCH-BIOMASS BIOFUELS AND BIOPRODUCTS, 35, 462-470.
• Li, M., Ogden, K. L., & Shadman, F. (2018). Analysis and Design of Adsorption Systems for the Combined Removal of Arsenic and Gallium from Wastewater. International Journal of Research in Engineering and Science.
• Li, M., Shadman, F., & Ogden, K. L. (2018). Algae-Based Sorbents for Removal of Gallium from Semiconductor Manufacturing Wastewater. Clean Technologies and Environmental Policy.
• Marrone, B. L., Lacey, R. E., Anderson, D. B., Bonner, J., Coons, J., Dale, T., Downes, C. M., Fernando, S., Fuller, C., Goodall, B., Holladay, J. E., Kadam, K., Kalb, D., Liu, W., Mott, J. B., Nikolov, Z., Ogden, K. L., Sayre, R. T., Trewyn, B. G., & Olivares, J. A. (2018). Review of the harvesting and extraction program within the National Alliance for Advanced Biofuels and Bioproducts. ALGAL RESEARCH-BIOMASS BIOFUELS AND BIOPRODUCTS, 33, 470-485.
• Ogden, K. L., & Ebrahimiaqda, E. (2018). Evaluation and Modeling of Bioethanol Yield Efficiency from Sweet Sorghum Juice.. Bioenerg. Res, 11, 443. doi:https://doi.org/10.1007/s12155-018-9909-0.
• Park, S., Steichen, S., Liu, X., Ogden, K. L., & Brown, J. (2018). Association of Vampirovibrio chlorellavorus with decline and death of Chlorella sorokoriana in an outdoor cultivation system.. J. Appl. Phycology. doi:https://doi.org/10.1007/s10811-018-1633-9
• Toscano, L., Ogden, K. L., Brown, J. K., Cervantes, D., Steichen, S., Samaniego, B., & Gao, S. (2018). Harvesting of chlorella sorokiniana by fungal-assisted palletization, and cellulase production: a case of study. J. Biobased Mater. Bioenergy, 12, 493-505. doi:https://doi.org/10.1166/jbmb.2018.1798
• Ebrahimiaqda, E., & Ogden, K. L. (2017). Simulation and cost analysis of distillation and purification steps in production of anhydrous ethanol from sweet sorghum. ACS Sustainable Chemistry and Engineering, 5(8), 6854-6862. doi:10.1021/acssuschemeng.7b01082.
• Lammers, P., Ogden, K. L., Waller, P. M., Olivares, J., & 10 other co authors, . (2017). Review of the cultivation program within the National Alliance for Advanced Biofuels and Bioproducts. Algal Research. Algal Research, 22, 166-186. doi:http://dx.doi.org/10.1016/j.algal.2016.11.021
• Qiu, R., Lopez, P., Gao, S., & Ogden, K. L. (2017). Effects of pH on cell growth, lipid production, and CO2 addition of microalgae Chlorella sorokiniana. Algal Research, 28, 192-199. doi:https://doi.org/10.1016/j.algal.2017.11.004
• Unkefer, C., Unkefer, C., Molnar, I., Molnar, I., Ogden, K. L., Ogden, K. L., Olivares, J., Olivares, J., Brown, J. K., Brown, J. K., 15 other cauthors, ., & 15 other cauthors, . (2017). Review of the algal biology program within the National Alliance for Advanced Biofuels and Bioproducts. Algal Research, 22, 187-215. doi:10.1016/j.algal.2016.06.002
• Wendt, L. M., Wahlan, B. D., Li, C., Kachurin, G., Ogden, K. L., & Murphy, J. (2017). Evaluation of a high-moisture stabilization strategy for harvested microalgae blended with herbaceous biomass: Part I – storage performance.. Algal Research, 25, 567-575. doi:https://doi.org/10.1016/j.algal.2017.05.016
• Zhang, B., & Ogden, K. L. (2017). Recycled wastewater from anaerobic digestion of lipid extracted algae as a source of nutrients. Fuel, 210, 705-712. doi:https://doi.org/10.1016/j.fuel.2017.09.026
• Ogden, K. L., Morales-Sánchez, D., Kyndt, J., & Marteniz, A. (2016). Toward an understanding of lipid and starch accumulation in microalgae: A proteomic study of Neochloris oleoabundans cultivated under N-limited heterotrophic conditions.. Algal Reserach, 20(12), 22-34. doi:http://dx.doi.org/10.1016/j.algal.2016.09.006
• Jia, F., Kacira, M., & Ogden, K. L. (2015). Multi-wavelength based optical density sensor for autonomous monitoring of microalgae sensors. Sensors, 15(9), 22234-22248. doi:10.3390/s150922234
• Ottman, M. J., Slack, D. C., Ottman, M. J., Ogden, K. L., & Martinez-cruz, T. E. (2015). The Water Use of Sweet Sorghum and Development of Crop Coefficients. Irrigation and Drainage, 64(1), 93-104. doi:10.1002/ird.1882
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  Reliable estimates of crop water use are essential to economic production of sweet sorghum under irrigated conditions. In Tucson, Arizona, USA, two planting dates, May 5th and June 15th, and four sweet sorghum varieties (M81E, ST, SM and A4) were evaluated to estimate crop coefficients (kc) based on the heat unit accumulation concept (GDD). One irrigation level at 50% depletion of available water capacity prior to irrigation and its effect on juice, biomass and ethanol yields was evaluated. Results show that it was possible to develop heat unit based kc´s for two day-neutral varieties (ST and SM) and that they required 25% less water than the photo-sensitive varieties. Peak crop coefficients were determined as 1.13, 1.05, 1.16 and 1.22 for M81E, ST, SM and A4. Results also showed that growing degree days accumulated to flowering were 2226 and 1759 GDD for ST and SM respectively. At a P-value of 5% there were differences in crop water use, juice yields and bagasse production among treatments. For the May planting there was a slight effect on ethanol yields but no effect for the June planting, showing that regardless of the planting date and variety they are more likely to be similar. Copyright © 2015 John Wiley & Sons, Ltd.
• Dong, B., Nam, H. o., Ogden, K. L., & Arnold, R. G. (2014). Cultivation of Nannochloropsis salina in municipal wastewater or digester centrate. Ecotoxicology and Environmental Safety, 103(1), 45-53.
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  Abstract: Meaningful use of biofuels for transportation depends on utilization of water from non-traditional, non-potable resources. Here it is hypothesized that (i) reclaimed wastewater or nutrient-rich side streams derived from municipal wastewater treatment are suitable for that purpose and (ii) use of those waters for algal growth can promote water quality through nutrient management. Experiments showed that metals levels in municipal wastewaters are unlikely to inhibit algal growth and lipid production, at least by metals tolerant microalgae like Nannochloropsis salina. Cells grew without inhibition in treated municipal wastewater or centrate derived from wastewater treatment at additions up to 75 percent v/v in their normal growth medium minus nitrogen and phosphorus. Although wastewater provides a suitable nutrient source for algal growth, not enough municipal wastewater is available to support a meaningful biofuels industry without efficient water recycling and nutrient recovery/reuse from spent algae. © 2014 Elsevier Inc.
• Kahl, A., Heller, D., & Ogden, K. (2014). Constructing a simple distillation apparatus to purify seawater: A high school chemistry experiment. Journal of Chemical Education, 91(4), 554-556.
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  Abstract: This experiment combines the chemistry of solution separation via distillation with the engineering design process to motivate students in a high school chemistry course. Students build upon their knowledge of phase changes and solubility to complete a project related to chemical engineering by desalinating a water sample similar to seawater. In general, students remove very little of the salt, but the emphasis is on the creation of the system rather than achievement of pure water. Resources for learning about distillation, an exercise description, exercise worksheets, and assessment plans are provided in the supporting information. This experiment fits well into a general chemistry curriculum or an environmental science course. It takes a minimum of 5 standard (1 h) class periods, but can be expanded or downsized as is appropriate. Student feedback was generally positive because the students enjoyed solving a "real-world" problem. © 2014 The American Chemical Society and Division of Chemical Education, Inc.
• Ogden, K. L. (2014). Algae as a Bio-Feedstock. Chemical Engineering Progress, November, 63-66.
• Ogden, K. L., Slack, D. C., Ottman, M. J., & Cruz, T. E. (2014). The Water Use of Sweet Sorghum and Development of Crop Coefficients. Irrigation and Drainage.
• Ren, M., & Ogden, K. (2014). Cultivation of Nannochloropsis gaditana on Mixtures of Nitrogen Sources. ENVIRONMENTAL PROGRESS & SUSTAINABLE ENERGY, 33(2), 551-555.
• Cheng, K., Ren, M., & Ogden, K. L. (2013). Statistical optimization of culture media for growth and lipid production of Chlorella protothecoides UTEX 250. Bioresource Technology, 128, 44-48.
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  PMID: 23196220;Abstract: The concentration of NaNO3, MgSO4·7H2O and proteose, in Chlorella protothecoides medium were optimized for algal biomass and lipid production by using response surface methodology with Box-Behnken design. The optimal concentrations were 0.45g/L of NaNO3, 6mg/L of MgSO4·7H2O, and 0.25g/L of proteose for maximum biomass production and 2mg/L of MgSO4·7H2O and no addition of NaNO3 and proteose for lipid accumulation. In optimized biomass production medium, a final biomass concentration of 1.19g/L was obtained, which was 1.8 times higher than that in the original medium. For lipid accumulation, a 12.9% lipid content was obtained from the biomass in the lipid production medium, which was three times higher than that from the original medium. The fatty acid profile of algae grown in the optimized medium demonstrated a higher unsaturated fatty acid content (i.e. methyl linoleate (C18:2) and methyl linolenate (C18:3)) than that of the algae grown in the original medium. The results provide a strategy for limiting the amount of nutrients required in large scale outdoor cultivation systems of C. protothecoides to make the production of algal biomass more economically attractive. © 2012 Elsevier Ltd.
• Jia, F., Chawhuaymak, J., Riley, M. R., Zimmt, W., & Ogden, K. L. (2013). Efficient extraction method to collect sugar from sweet sorghum. Journal of Biological Engineering, 7(1).
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  PMID: 23305036;PMCID: PMC3621779;Abstract: Background: Sweet sorghum is a domesticated grass containing a sugar-rich juice that can be readily utilized for ethanol production. Most of the sugar is stored inside the cells of the stalk tissue and can be difficult to release, a necessary step before conventional fermentation. While this crop holds much promise as an arid land sugar source for biofuel production, a number of challenges must be overcome. One lies in the inherent labile nature of the sugars in the stalks leading to a short usable storage time. Also, collection of sugars from the sweet sorghum stalks is usually accomplished by mechanical squeezing, but generally does not collect all of the available sugars.Results: In this paper, we present two methods that address these challenges for utilization of sweet sorghum for biofuel production. The first method demonstrates a means to store sweet sorghum stalks in the field under semi-arid conditions. The second provides an efficient water extraction method that can collect as much of the available sugar as feasible. Operating parameters investigated include temperature, stalk size, and solid-liquid ratio that impact both the rate of sugar release and the maximal amount recovered with a goal of low water use. The most desirable conditions include 30°C, 0.6 ratio of solid to liquid (w/w), which collects 90 % of the available sugar. Variations in extraction methods did not alter the efficiency of the eventual ethanol fermentation.Conclusions: The water extraction method has the potential to be used for sugar extraction from both fresh sweet sorghum stalks and dried ones. When combined with current sugar extraction methods, the overall ethanol production efficiency would increase compared to current field practices. © 2013 Jia et al.; licensee BioMed Central Ltd.
• Jones, L. A., & Ogden, K. L. (2013). Silica and titania nanoparticles impact on water quality: Experiments involving Ralstonia pickettii in nutrient-rich and poor media. Environmental Progress and Sustainable Energy, 32(2), 279-284.
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  Abstract: According to CDC, the public is being bombarded with ads for cleansers, soaps, toothbrushes, and hand lotions, all containing antibacterial agents. Nanoparticles, which are materials at length scales less than 100 nm, have previously demonstrated antibacterial and antimicrobial properties. One of the hardiest bacteria is a Ralstonia pickettii species isolated from an ultrapure water (UPW) facility. These bacteria survive in water that only contains parts per trillion levels of organic and inorganic contaminants. The focus of this article is to demonstrate the effects of silica and titania nanoparticles on Ralstonia pickettii bacteria in term of growth and yields. Solutions of nanoparticles and calcium fluoride were researched for their effects on the growth rate and cell yield of Ralstonia sp. bacteria in a protein-rich and protein-poor media. The collective effect of CaF2 and 15 nm silica nanoparticles reduces the growth rate by 57% and the cell yield by 29% in protein-rich media. Titania nanoparticles returned similar results, where in nutrient-poor environments little to no growth occurred but in nutrient-rich media, the titania and CaF2 reduced the growth rate by 64% and the cell yield by 34%. Conversely, larger silica nanoparticles in nonprotein-rich media have negligible effects on cell yield and growth rate. The diminished bacterial growth rate provides paralleled insight into the long-term effects of nanotechnology effluent on the United States' wastewater treatment processes, which utilize several species of bacteria. Extrapolation of these results to current toxicological studies suggests that unregulated industrial nanoparticles' expulsion may lead to degradation in water quality. © 2012 American Institute of Chemical Engineers.
• Ogden, K. L., Jones, L., & Jia, F. (2013). Comparative Study of Biosorption of Copper (II) by Lipid Extracted and non-extracted Chlorella sorokiniana. Clean, 41.
• Ren, M., Ogden, K., & Lian, B. (2013). Effect of culture conditions on the growth rate and lipid production of microalgae Nannochloropsis gaditana. Journal of Renewable and Sustainable Energy, 5(6).
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  Abstract: Microalgae Nannochloropsis gaditana (CCMP527) is an ideal candidate as a renewable and sustainable alternative oil source to traditional fossil fuel. It has advantages including high oil content, short growth cycle, and high biomass yield. Experimental data showed that with 5% CO2 enriched air and tris-HCl buffered f/2-Si medium, a maximum growth rate of 0.48 day-1 and a lipid yield of 0.32 g/l were achieved. Various carbon and nitrogen sources were investigated to determine the range of substrates that may be feasible for cultivation with minimal impact on productivity. The sources evaluated cover some of the compounds found in fertilizers and groundwater. When glucose was added into the medium, microalgae grew faster mixotrophically but the lipid yield was reduced by 86%. Adding high concentrations of nitrogen, 10 mM N in the form of nitrate, ammonium sulfate, glycine, and urea, resulted in variations in lipid yield from 0.02 g/l to 0.27 g/l. However, the growth rate increased slightly to 0.52 day-1 at the higher nitrogen concentration when nitrate and urea were the nitrogen sources. The major fatty acids were C16:0 and C16:1 regardless of the carbon and nitrogen sources, which are readily converted to fuels. While the amount of nitrogen affects productivity, the types of fatty acids produced are not affected hence making cultivation on impaired waters feasible. © 2013 AIP Publishing LLC.
• Crowe, B., Attalah, S., Agrawal, S., Waller, P., Ryan, R., Wagenen, J. V., Chavis, A., Kyndt, J., Kacira, M., Ogden, K. L., & Huesemann, M. (2012). A comparison of nannochloropsis salina growth performance in two outdoor pond designs: Conventional raceways versus the arid pond with superior temperature management. International Journal of Chemical Engineering.
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  Abstract: 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 780L conventional raceways, as well as in an experimental 7500L algae raceway integrated design (ARID) pond. The ARID culture system utilizes a series of 820cm deep basins and a 1.5m deep canal to enhance light exposure and mitigate temperature variations and extremes. The ARID culture reached the stationary phase 27 days earlier than the conventional raceways, which can be attributed to its superior temperature management and shallower basins. On a night when the air temperature dropped to -9°C, the water temperature was 18°C higher in the ARID pond than in the conventional raceways. Lipid and fatty acid content ranged from 16 to 25 and from 5 to15, respectively, as a percentage of AFDW. Palmitic, palmitoleic, and eicosapentaenoic acids comprised the majority of fatty acids. While the ARID culture system achieved nearly double the volumetric productivity relative to the conventional raceways (0.023 versus 0.013gL -1day-1), areal biomass productivities were of similar magnitude in both pond systems (3.47 versus 3.34gm-2day -1), suggesting that the ARID pond design has to be further optimized, most likely by increasing the culture depth or operating at higher cell densities while maintaining adequate mixing. © Copyright 2012 Braden Crowe et al.
• Cheng, K., & Ogden, K. L. (2011). Algal biofuels: The research. Chemical Engineering Progress, 107(3), 42-47.
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  Abstract: Microalgae are microscopic unicellular species, ranging in size from a few microns to hundreds of microns, that exist individually, or in chains or flocs, in freshwater and marine systems. Microalgae contribute approximately 40-50% of the oxygen in the atmosphere and simultaneously consume carbon dioxide to grow photoautotrophically. Maximizing lipid production at the molecular level involves a thorough understanding of the metabolic pathways, especially those associated with lipid synthesis, and with packaging and secretion. Significant research has been conducted on establishing the optimal nutritional composition and culture conditions for hydrocarbon production by microalgae. The production of hydrocarbons in microalgae cells is growth-associated and usually reaches its maximum around the early stationary phase of the algal growth cycle.
• Liu, Y., & Ogden, K. (2010). Benefits of high energy UV185nm light to inactivate bacteria. Water Science and Technology, 62(12), 2776-2782.
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  PMID: 21123906;Abstract: Inactivating and eliminating bacteria from ultra pure water (UPW) systems is always a significant problem for semiconductor and pharmaceutical industries. To alleviate the problem, ultraviolet (UV) radiation-both monochromatic UV254 light and high pressure UV185 light-is traditionally used for bacterial sterilization and in the case of the later, breakdown of trace organic molecules. The focus of this work is to understand the factors that influence the effectiveness of these UV treatments on Xanthomonas sp. bacteria typically found in UPW systems. In particular, the factors associated with the reactor condition, such as the light source and environment were investigated. It is shown that inactivation follows first order kinetics, and that the rates are comparable to others found in the literature for gram negative bacteria. Also, growth phase and harvesting conditions are shown to influence inactivation rate. Furthermore, it was determined that UV185 radiation, although limited by water absorption, significantly enhances the inactivation rate of bacteria if given suitable transmission distance. Rates of inactivation were enhanced by 40% when UV185 light is used in addition to UV254 light. © IWA Publishing 2010.
• Maketon, W., & Ogden, K. L. (2009). Synergistic effects of citric acid and polyethyleneimine to remove copper from aqueous solutions. CHEMOSPHERE, 75(2), 206-211.
• Maketon, W. K., & Ogden, K. L. (2008). Treatment of copper from Cu CMP waste streams using polyethyleneimine. IEEE Transactions on Semiconductor Manufacturing, 21(3), 481-485.
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  Abstract: Commercially available Cu CMP waste treatment processes involve: 1) pretreatment chemistry using oxidizers to break down complexed copper resulting in precipitation of copper in the form of copper hydroxide; 2) microfiltration of both slurry particles and copper hydroxide; and 3) ion exchange to remove Cu2+ ions. Ion exchange resins used to remove Cu2+ ions are limited to only removing cations and also have a low efficiency in binding Cu2+ ions. The treatment strategy to be evaluated here only requires using two processes to remove the copper from Cu CMP waste-filtration to remove the particles followed by chelation. This paper focuses on the chelation step. The chelator of interest is polyethyleneimine (PEI) bound to agarose beads. PEI removes both Cu2+ ions and Cu-complexes. The particles from slurry in the actual Cu CMP waste were removed by filtration before the experiment. The results show that PEI has a higher binding capacity for Cu2+ ions than ion exchange resins. Its performance and reproducibility did not change after multiple regenerations. Furthermore, PEI has the ability to bind Cu-complexes through electrostatic attraction. Although the bonds aren't strong, the result is more overall copper removal from the waste stream. The copper component of the Cu CMP waste was concentrated 12 fold using this system. © 2008 IEEE.
• Maketon, W., Zenner, C. Z., & Ogden, K. L. (2008). Removal efficiency and binding mechanisms of copper and copper - EDTA complexes using polyethyleneimine. Environmental Science and Technology, 42(6), 2124-2129.
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  PMID: 18409647;Abstract: Copper is used extensively in semiconductor circuits as the multilayer metal. In addition to copper, waste streams often contain chelating agents like EDTA, which is widely used in the process to enhance solubility of copper, and it tends to form copper-chelated complexes. PEI-agarose adsorbents in a packed-bed column are capable of removing these anionic complexes, but the competitive binding between this chelating agent and PEI for copper is not well understood and needs to be explored. The current work focuses on investigating copper sorption by PEI-agarose adsorbent in the presence of EDTA. The pH of the column is fixed at 5.5 using 0.1 M acetate buffer. The ratio of chelator to copper ions is varied. Copper binding capacity and copper breakthrough curves are compared and contrasted to results without additional chelator present. An excess of EDTA leads to an increase in the fraction of free dissociated (anionic) ligand that competes for electrostatic attraction on protonated amine groups and therefore leads to a decrease in sorption capacity in the column. However, this waste treatment technique is still feasible for the semiconductor industry as large volumes of copper-contaminated solutions from actual waste can be concentrated 12-fold. When equimolar (copper to EDTA) or higher concentrations of EDTA are present, acetate can be utilized to recover the metal; for low ratios of copper to EDTA, metal recovery is achieved using hydrochloric acid. © 2008 American Chemical Society.
• Ogden, K., & Ogden, G. (2007). Discovering the link between university and industrial environmental research. ASEE Annual Conference and Exposition, Conference Proceedings.
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  Abstract: The University of Arizona has run a Research Experiences for Teachers Program funded by NSF for 10 years. This RET site teams together the University of Arizona (UA), City of Tucson Environmental Management Division, Raytheon Missile Systems, Tucson Electric and Power Company, Tucson Unified School District (TUSD), Marana Unified School District (MUSD), Nogales School District, and other districts in Pima County, Arizona. Annually, 6 UA faculty from the Department of Chemical and Environmental Engineering, 4 to 6 industrial mentors, 2 project evaluators, 12 to 14 teachers (ideally elementary + half math and half science secondary teachers), 8 pre-service teachers, 2 teacher leaders, and 8 undergraduate or graduate engineering students are part of the RET Site activities. These individuals impact around 2000 students annually. The individuals comprise 4 teams consisting of 4 teachers from the same school, 2 preservice teachers, 2 engineering students, 1 faculty, and 1 industrial mentor. The overall objective is for teachers and pre-service teachers to work on environmental discovery-based research projects for 5 weeks during the summer, and transfer the knowledge learned directly to the K-12 classroom through core curriculum enrichment. The research plan provides a unique opportunity for participants to experience both laboratory projects and industrial scale applications. The projects focus on remediation of organics, metals removal, denitrification using alternative electron acceptors, and biofilm removal. In addition to research, the teams work together to improve classroom pedagogy. Teams attend workshops on current standards related to their discipline, inquiry based learning, stressing/encouraging problem solving as opposed to memorization, and minority and gender equity in the classroom. Teacher leaders from TUSD and MUSD lead some of these workshops. The pre-service teachers intern with the teachers during the following academic year to aid transfer of new knowledge gained from the RET experience into the classroom. In addition, project evaluators, faculty, industrial mentors, and engineering students visit the K-12 classroom during the academic year. © American Society for Engineering Education, 2007.
• Hollingsworth, J. R., Ogden, K. L., Field, J. A., Sierra Alvarez, R., Zhou, M., Sierra Alvarez, M. R., Zhou, M., Ogden, K. L., Hollingsworth, J. R., & Field, J. A. (2005). Anaerobic biodegradability and methanogenic toxicity of key constituents in copper chemical mechanical planarization effluents of the semiconductor industry. Chemosphere, 59, 1219-1228.
• Young, D. M., Young, K., & Ogden, K. L. (2005). Prediction of growth and biotransformation rates of hexahydro-1,3,5- trinitro-1,3,5-triazine (RDX) in the presence of barium. Applied Microbiology and Biotechnology, 68(3), 376-383.
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  PMID: 15666146;Abstract: The biotransformation of explosives has been investigated by many researchers. Bioremediation of soil and water contaminated with hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is becoming the method of choice for clean-up of a variety of sites. In this study, we investigated biotransformation of RDX in the presence of barium. Ba is a metal commonly found in combination with RDX at sites requiring remediation. RDX was biotransformed by both a consortium of bacteria and an isolate from the consortium under anoxic conditions using a rich medium. However, Ba inhibited cell growth under both aerobic and anoxic conditions and slowed biotransformation rates by 40%. RDX and Ba inhibited growth of the isolate more than growth of the consortium. An additive inhibition model is proposed that accurately predicts the reduced growth rates observed. © Springer-Verlag 2005.
• Ruiz, A., & Ogden, K. L. (2004). Biotreatment of copper and isopropyl alcohol in waste from semiconductor manufacturing. IEEE Transactions on Semiconductor Manufacturing, 17(4), 538-543.
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  Abstract: The generalized use of copper chemical-mechanical planarization (CMP) in integrated circuits manufacturing is increasing as the industry moves from previous technology to copper technology. With CMP being one of the main water consumers and producers of wastewater in the fab, more low energy/cost effective methods are being developed to avoid a future risk of violating discharge regulations for copper-containing wastewater. In addition, with the expected increase in water consumption, there is an incentive to find better ways to treat and recycle wastewaters. The possibility of using biological organizms to treat copper and organic-containing wastewater is studied. Two different approaches are combined to create a treatment strategy: adsorption on immobilized cells to treat copper and biodegradation by immobilized cells to treat organics [specifically isopropyl alcohol (IPA)]. Two previously developed bacterial systems are used. In addition, predictive models for the two cases developed in previous work are evaluated in this combined treatment. Continuous flow experiments were performed. Copper adsorbed to the immobilized cells and the binding capacity is comparable to other systems found in the literature. The IPA was totally degraded.
• Stanley, L. C., & Ogden, K. L. (2003). Biosorption of copper (II) from chemical mechanical planarization wastewaters. Journal of Environmental Management, 69(3), 289-297.
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  PMID: 14580729;Abstract: Copper Chemical Mechanical Planarization (Cu-CMP) is a critical step in integrated circuit (IC) device manufacturing. CMP and post-CMP cleaning processes are projected to account for 30-40% of the water consumed by IC manufacturers in 2003. CMP wastewater is expected to contain increasing amounts of copper as the industry switches from Al-CMP to Cu-CMP causing some IC manufacturers to run the risk of violating discharge regulations. There are a variety of treatment schemes currently available for the removal of heavy metals from CMP wastewater, however, many introduce additional chemicals to the wastewater, have large space requirements, or are expensive. This work explores the use of microorganisms for waste treatment. A Staphylococcus sp. of bacteria was isolated and studied to determine the feasibility for use in removing copper from Cu-CMP wastewater. A model Cu-CMP wastewater was developed and tested, as well as actual Cu-CMP wastes. Continuous-flow packed column experiments were performed to obtain adsorption data and show copper recovery from the waste. A predictive, empirical model was used to accurately describe Cu removal. Additionally, the immobilized cells were regenerated, allowing for the concentration and potential recovery of copper from the wastewater. © 2003 Elsevier Ltd. All rights reserved.
• Kulakov, L. A., McAlister, M. B., Ogden, K. L., Larkin, M. J., & O'Hanlon, J. F. (2002). Analysis of bacteria contaminating ultrapure water in industrial systems. Applied and Environmental Microbiology, 68(4), 1548-1555.
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  PMID: 11916667;PMCID: PMC123900;Abstract: Bacterial populations inhabiting ultrapure water (UPW) systems were investigated. The analyzed UPW systems included pilot scale, bench scale, and full size UPW plants employed in the semiconductor and other industries. Bacteria present in the polishing loop of the UPW systems were enumerated by both plate counts and epifluorescence microscopy. Assessment of bacterial presence in UPW by epifluorescence microscopy (cyanotolyl tetrazolium chloride [CTC] and DAPI [4′,6′-diamidino-2-phenylindole] staining) showed significantly higher numbers (10 to 100 times more bacterial cells were detected) than that determined by plate counts. A considerable proportion of the bacteria present in UPW (50 to 90%) were cells that did not give a positive signal with CTC stain. Bacteria isolated from the UPW systems were mostly gram negative, and several groups seem to be indigenous for all of the UPW production systems studied. These included Ralstonia pickettii, Bradyrhizobium sp., Pseudomonas saccharophilia, and Stenotrophomonas strains. These bacteria constituted a significant part of the total number of isolated strains (≥20%). Two sets of primers specific to R. pickettii and Bradyrhizobium sp. were designed and successfully used for the detection of the corresponding bacteria in the concentrated UPW samples. Unexpectedly, nifH gene sequences were found in Bradyrhizobium sp. and some P. saccharophilia strains isolated from UPW. The widespread use of nitrogen gas in UPW plants may be associated with the presence of nitrogen-fixing genes in these bacteria.
• McAlister, M. B., Kulakov, L. A., O'Hanlon, J., Larkin, M. J., & Ogden, K. L. (2002). Survival and nutritional requirements of three bacteria isolated from ultrapure water. Journal of Industrial Microbiology and Biotechnology, 29(2), 75-82.
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  PMID: 12161774;Abstract: Bacteria isolated previously from ultrapure water (UPW) systems were examined for their ability to survive in UPW, with the ultimate goal of elucidating potential carbon and energy sources for the bacteria. Two strains of Ralstonia pickettii isolated from different areas within the UPW system (pretreatment and polishing loop, and referred to as strains 3A1 and MF254A, respectively) and a strain of Bradyrhizobium sp. were compared to increase our understanding of the fundamental behavior of bacteria contaminating UPW. R. pickettii (3A1) grew significantly slower in R2A medium, with a final cell yield much lower than the isolate from the polishing loop. In addition, R. pickettii MF254A showed a broader substrate range than either strain 3A1 or Bradyrhizobium sp. In UPW, there appears to be a threshold cell concentration (approximately 106 colony-forming units/ml), whereby the cell numbers remain constant for a prolonged period of 6 months or more. Below this concentration, rapid proliferation is observed until the threshold concentration is attained. Preliminary experiments suggested that nitrogen gas (frequently added to UPW storage tanks) may contribute to growth of Bradyrhizobium sp. Above the threshold concentration, the strain of Ralstonia sp. isolated from the polishing loop was capable of cryptic growth with heat-killed cells in UPW. However, cryptic growth was not observed when the cells supplied as nutrients were killed using UV254 light. Furthermore, cryptic growth did not appear to contribute significantly to proliferation of Bradyrhizobium sp. or Ralstonia sp. 3A1 (isolated from the pretreatment loop). We believe that cryptic growth may aid survival of the bacteria in UPW, but further experiments are warranted to prove this phenomenon conclusively.
• Ogden, K. L., Castro, E., & Barber, J. (2002). Minimization of water usage for BOE etch processes. Ultrapure Water, 19(5), 16-21.
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  Abstract: Buffered oxide etch (BOE) is used to remove oxide layers from wafer surfaces in the semiconductor industry. Measures are being introduced to reduce water usage in semiconductor fabrication. A study was conducted to examine the effects of process variables on wafer quality during etch processing in order to minimize the number of quick dump rinse (QDR) cycles and the initial rinse time. The required amount of water was a function of the wet etchant temperature. pH measurements could be used to minimize the initial overflow rinse time.
• Ogden, K. L., Gadgill, J., & Akin, T. (2002). Biological denitrification of hydrolysates from octahydro-1,3,5,7 tetranitro-1,3,5,7-tetrazocine. Water Environment Research, 74(4), 338-345.
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  PMID: 12413134;Abstract: Alternatives for the destruction of common military explosives, including trinitrotoluene; hexahydro-1,3,5-trinitro-1,3,5-triazine; and octahydro-1,3,5,7 tetranitro-1,3,5,7-tetrazocine (HMX) are being investigated in the post-cold war period. One alternative combines chemical treatment (i.e., base hydrolysis of the explosives) and biological treatment (i.e., denitrification of the hydrolysate). This paper focuses on results of the biological part of the treatment process, during which Hyphomicrobium sp. bacteria were isolated from a seed obtained from a denitrification facility. The bacteria were enriched and maintained on a surrogate waste with methanol as the carbon source. The resulting culture is capable of anoxic growth in waste solutions containing up to 5000 mg/L of nitrite-nitrogen. The culture efficiently denitrifies both surrogate and actual hydrolysate wastes. A substrate inhibition model was used to accurately predict denitrification rates. Comparisons are made between denitrification rates obtained for surrogate versus actual wastes. Denitrification rates were higher when actual waste streams were used. This work demonstrates the feasibility of using Hyphomicrobium sp. bacteria to treat HMX hydrolysate and presents a model that can be used to design a large-scale system.
• McAlister, M. B., Kulakov, L. A., Larkin, M. J., & Ogden, K. L. (2001). Analysis of bacterial contamination in different sections of a high-purity water system. Ultrapure Water, 18(1), 18-26.
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  Abstract: Microbial contamination of high-purity water is a significant problem in semiconductor, pharmaceutical and food and beverage industries. Bacterial contamination in different parts of a high-purity water system was studied using plate counts, epifluorescence microscopy, and 16SrRNA gene sequencing. Oligotrophic bacteria strains were classified. Methods requiring direct culture of the bacteria failed to correctly estimate the extent of bacterial contamination. Use of membrane filtration followed by epifluorescence microscopy allowed the rapid and accurate determination of biocontamination levels.
• Ogden, K. L., Muscat, A. J., & Stanley, L. C. (2001). Investigating the use of biosorption to treat copper CMP wastewater. MICRO, 19(7), 81-95.
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  Abstract: Study results demonstrate the feasibility of employing immobilized bacterial cells to remove copper from wastewater.
• Croissant, J. L., Ogden, K. L., & Ogden, G. (2000). Teamed internships in environmental engineering and technology: A project report. Journal of Engineering Education, 89(2), 111-114+248+252.
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  Abstract: This paper is a summary report of the "Teamed Internships Program" (TIP), an Advanced Technological Education (ATE) grant through the National Science Foundation (NSF). This three-year project created internships encompassing regional industries, federal research facilities, and two- and four-year educational institutions. The project cultivated teamwork and communication skills for environmental technician and engineering students, developed instructional materials, and provided valuable contacts with industry. To foster faculty and teacher enhancement and student interest in environmental science and technology, insights from the program were incorporated into instructional materials and educational modules for dissemination to local secondary schools.
• Ogden, K. L., Garrick, J. B., Abkowitz, M. D., Grella, A. W., Hardy, M. P., Kaplan, S., Kingston, H. M., Lee, W. J., Levenson, M., Lutze, W. F., Sharp, J. M., Shewmon, P., Watson, J., & Yee, C. H. (2000). Improving Operations and Long-Term Safety of the Waste Isolation Pilot Plant - Interim Report. National Academies Press.
• Baygents, J. C., Glynn Jr., J. R., Albinger, O., Biesemeyer, B. K., Ogden, K. L., & Arnold, R. G. (1998). Variation of surface charge density in monoclonal bacterial populations: Implications for transport through porous media. Environmental Science and Technology, 32(11), 1596-1603.
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  Abstract: The forced convection of a monodisperse, monoclonal suspension of bacteria through a uniform, saturated porous medium has been investigated. Bench-scale column studies were carried out to measure the removal of microorganisms from suspension due to attachment to the surfaces of the solid phase. The columns were packed with 40-μm borosilicate glass beads, and bacterial sorption was measured as a function of depth in the column using a leucine radiolabel assay. The strains A1264 and CD1 were examined separately. Colloid filtration theory was used to interpret the data, and the average, or effective, affinity of the bacteria for the glass beads was found to decrease with distance traveled through the column. It is postulated that, under these circumstances, the cell/collector affinity (that is, the collision efficiency α) varied due to intrapopulational differences in bacterial surface characteristics. A simple bimodal probability density function, consisting of two Dirac delta functions, was found to satisfactorily represent the α distribution in the original bacterial population. This form of the distribution function was supported by capillary electrophoresis measurements on the bacteria, which showed intrapopulational differences in the surface charge density under the conditions of the transport experiments. These variations in surface charge density are significant in as much as they give rise to substantial differences in the colloidal interaction potentials and, presumably, large differences in cell affinity for negatively charged collectors such as glass beads or quartz.
• Glynn Jr., J. R., Belongia, B. M., Arnold, R. G., Ogden, K. L., & Baygents, J. C. (1998). Capillary electrophoresis measurements of electrophoretic mobility for colloidal particles of biological interest. Applied and Environmental Microbiology, 64(7), 2572-2577.
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  Abstract: The electrophoretic mobilities of three bacterial strains were investigated by capillary electrophoresis (CE) and were compared with results obtained by microelectrophoresis (ME). The CE measurements yielded bimodal electropherograms for two of the strains, thus illustrating for the first time that surface charge variations within a monoclonal population can be probed by CE. Intrapopulation variations were not detected by ME. The mobilities of three chemically distinct types of latex microspheres were also measured. Differences between the mean mobilities obtained by CE and ME were not statistically significant (P ≤ 0.50); the standard deviations of the CE measurements were typically 2 to 10 times smaller than those obtained by comparable ME measurements. The reproducibility of CE permitted batch-to- batch mobility variations to be probed for the bacteria (one of the strains exhibited such variations), and aggregation was evident in one of the latex suspensions. These effects were not measurable with ME.
• Rampley, C. G., & Ogden, K. L. (1998). Preliminary studies for removal of lead from surrogate and real soils using a water soluble chelator: Adsorption and batch extraction. Environmental Science and Technology, 32(7), 987-993.
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  Abstract: A technique for removing Pb from contaminated soil is to wash excavated soil with a solution containing a chelating agent specific for the heavy metal contaminant of interest. Parameters needed to demonstrate the plausibility of this remediation method include the amount of chelator adsorption to soil and the rate of Pb extraction. This paper investigates these parameters for a newly developed water-soluble chelator, Metaset-Z; which has a high specificity for Pb. Metaset-Z chelated Pb in aqueous solutions on the time scale of seconds. This chelator has a low affinity for quartz. Its adsorption is independent of ionic strength over the range tested. Minicolumn experiments demonstrated that Meteset-Z adsorption is also independent of polymer, Ca, and Pb aqueous-phase concentrations. Removal of Pb to below EPA requirements was achieved using both surrogate, quartz contaminated soil and a Superfund contaminated soil. A one-site semiempirical, equilibrium reaction model fit the surrogate soil extraction data well; a two-site reaction model fit the contaminated soil data well. Overall, this study shows that Meteset-Z can be used as a batch extractant for Pb-contaminated soil.
• Young, D. M., Kitts, C. L., Unkefer, P. J., & Ogden, K. L. (1997). Biological breakdown of RDX in slurry reactors proceeds with multiple kinetically distinguishable paths. Biotechnology and Bioengineering, 56(3), 258-267.
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  PMID: 18636641;Abstract: Biotransformation of RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) in slurry reactors was studied to determine the importance of supplementation of known biodegraders and the type of nutrient source required. Although addition of bacteria to the system increased the biotransformation rates, the increase may not justify the additional work and cost needed to grow the organisms in a laboratory and mix them into the soil. An inexpensive, rich nutrient source, corn steep liquor, was shown to provide sufficient nutrients to allow for the cometabolic biotransformation of RDX. The rate of RDX transformation was not constant throughout the course of the experiment due to the heterogeneous microbial population. Three kinetically distinct phases were observed. Regardless of the process, RDX biotransformation in slurry reactors was reaction rate limited under the test conditions. Model simulations based on experimental results demonstrate that, at cell densities of 5 g/L, bioremediation of RDX-contaminated soil is an attractive clean-up alternative.
• Young, D. M., Unkefer, P. J., & Ogden, K. L. (1997). Biotransformation of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) by a prospective consortium and its most effective isolate Serratia marcescens. Biotechnology and Bioengineering, 53(5), 515-522.
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  PMID: 18634047;Abstract: The biotransformation of hexahydro-1,3,5-trinitro-1,3,5 triazine (RDX) has been observed in liquid culture by a consortium of bacteria found in horse manure. Five types of bacteria were found to predominate in the consortium and were isolated. The most effective of these isolates at transforming RDX was Serratia marcescens. The biotransformation of RDX by all of these bacteria was found to occur only in the anoxic stationary phase. The process of bacterial growth and RDX biotransformation was quantified for the purpose of developing a predictive type model. Cell growth was assumed to follow Monod kinetics. All of the aerobic and anoxic growth parameters were determined: μ(max), K(S), and Y(X/S), RDX was found to competitively inhibit cell growth in both atmospheres. Degradation of RDX by Serratia marcescens was found to proceed through the stepwise reduction of the three nitro groups to nitroso groups. Each of these reductions was found to be first order in both component and cell concentrations. The degradation rate constant for the first step in this reduction process by the consortium was 0.022 L/g cells · h compared to 0.033 L/g cells · h for the most efficient isolate.
• Ogden, K. L., Ogden, G. E., Hanners, J. L., & Unkefer, P. J. (1996). Remediation of low-level mixed waste: Cellulose-based materials and plutonium. Journal of Hazardous Materials, 51(1-3), 115-130.
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  Abstract: Low-level mixed radioactive wastes containing cellulose-based materials and plutonium have been generated during various nuclear processing activities. Biological digestion of the organic- or cellulose- based material was examined as an environmentally acceptable and effective method of treatment for these and other similar wastes. Cellulase enzyme was used to initiate biodegradation prior to 90% destruction of the cellulose material by a sewage sludge consortium. Plutonium did not significantly effect the biodegradation. Bench-scale experimental data were used to design a batch treatment system. A cost and sensitivity analysis was performed to determine the optimal reactor size, materials of construction and media type. The sensitivity analysis indicated that while a 12-month treatment scenario using a carbon steel ball mill, sludge digester and vacuum thickener was the least expensive scenario evaluated on a levelized cost basis ($800 per ton of waste degraded per month), the 12-month scenario using stainless steel construction and the alternative dewatering system offered the most cost-effective treatment alternative and better corrosion resistance (levelized cost of $1130 per ton per month). The dewatering system consisting of a disk centrifuge and sludge dryer is capable of doubling the sludge solids content and produce an overall waste reduction of 67%. The proposed waste treatment system offers a cost savings of up to 31% compared to conventional disposal practices.
• Ogden, K. L., Davis, R. H., & Taylor, A. L. (1992). An adjustable expression system for controlling growth rate, plasmid maintenance, and culture dynamics. Biotechnology and Bioengineering, 40(9), 1027-1038.
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  PMID: 18601211;Abstract: An expression system has been designed in which host Escherichia col cells contain the pil operon controlled by a tac promoter; these cells are transformed with plasmids that contain the repressor gene, lacl, for the tac promoter, in combination with an expression system for a model protein, chloramphenicol acetyl transferase (CAT). Experimental and theoretical results show that plasmid-bearing cells can be maintained as dominant in continuous cultures without selective pressure when 12% or less of the cells' total protein is the model product protein, CAT. This is because the segregant cells produce pili greatly in excess of normal wild-type levels, and thus have more of a metabolic burden than do the plasmid-bearing cells that overproduce CAT. However, when the level of plasmid-directed CAT expression is increased above 12% of the cells' total protein, the growth rate of the plasmid-bearing cells decreases to a value lower than that of the segregant cells. Therefore, plasmid-containing cells lose their selective advantage at this expression level, and cannot be maintained as the dominant cell type in a continuous culture unless antibiotic or other positive selection methods are used. By controlling the growth-rate differential of this bacterial host/plasmid system, a variety of interesting competitive culture dynamics is investigated. All experimental measurements for continuous cultures are in very good agreement with theory using kinetic parameters determined from independent batch experiments.
• Ogden, K. L., & Davis, R. H. (1991). Plasmid maintenance and protein overproduction in selective recycle bioreactors. Biotechnology and Bioengineering, 37(4), 325-333.
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  PMID: 18597374;Abstract: A new plasmid construct has been used in conjunction with selective recycle to successfully maintain otherwise unstable plasmid-bearing E. coli cells in a continuous bioreactor and to produce significant amounts of the plasmid-encoded protein β-lactamase. The plasmid is constructed so that pilin expression, which leads to bacterial flocculation, is under control of the tac operon. The plasmid-bearing cells are induced to flocculate in the separator, whereas cell growth and product synthesis occur in the main fermentation vessel without the inhibiting effects of pilin production. Selective recycle allows for the maintenance of the plasmid-bearing cells by separating flocculent, plasmid-bearing cells from nonflocculent, segregant cells in an inclined settler, and recycling only the plasmid-bearing cells to the reactor. As a result, product expression levels are maintained that are more than ten times the level achieved without selective recycle. All experimental data agree well with theoretical predictions.
• Ogden, K. L., & Taylor, A. L. (1991). Genetic control of flocculation in Escherichia coli. Journal of Industrial Microbiology, 7(4), 279-286.
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  PMID: 1369457;Abstract: Escherichia coli cells form flocs or aggregates by overproducing type 1 pili. When the pil operon is placed under the control of a tac or lac promoter-operator sequence, the bacterial cells can be induced to form flocs by adding isopropyl-β-D-thiogalactopyranoside to the culture medium. This phenomenon of genetically induced flocculation can aid in the downstream processing of biological products. This paper describes the construction of two artificially controlled plasmids which cause cell flocculation. Cell aggregates 50 μm in mean diameter were obtained 1 h after the cells were induced.
• Henry, K. L., Davis, R. H., & Taylor, A. L. (1990). Continuous recombinant bacterial fermentations utilizing selective flocculation and recycle. Biotechnology Progress, 6(1), 7-12.
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  PMID: 1366518;Abstract: Selective recycle has successfully been used to maintain an unstable plasmid-bearing bacterial strain as dominant in a continuous reactor, whereas the culture reverts to 100% segregant cells when selective recycle is not used. The plasmid-bearing strain is slower growing and flocculent; however, when the cells lose their plasmid, the resulting segregant cells are nonflocculent and grow at a faster rate due to their decreased metabolic burden. Both types of cells exit a chemostat and enter an inclined settler where the flocculent plasmid-bearing cells are separated from the nonflocculent segregant cells by differential sedimentation. The underflow from the cell separator, which is enriched with plasmid-bearing cells, is recycled back to the chemostat, while the segregant cells are withdrawn off the top of the settler and discarded.
• Henry, K. L., Parnham, C. S., Davis, R. H., & Taylor, A. L. (1990). Competitive continuous fermentations with selective recycle. Applied Biochemistry and Biotechnology, 24-25(1), 651-662.
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  Abstract: An inclined settler is used to partially separate desired cells from undesired cells in the product stream of a competitive continuous fermentation on the basis of differences in sedimentation velocities owing to differences in floc-forming capabilities. A stream that is enriched in the desired cells is then selectively recycled to the bioreactor. Experiments with nonsegregating yeast cultures and segregating bacterial cultures have demonstrated that maintenance of the slower-growing strains is achievable using selective recycle, whereas washout of these strains by the faster-growing competing strains occurs in the absence of selective recycle. These results are in good agreement with theoretical predictions. © 1990 Humana Press Inc.
• Ogden, K. L., Davis, R. H., & Taylor, A. L. (1990). Continuous Fermentations with Selective Cell Recycle. Developments in Industrial Microbiology, 31, 53-58.

Proceedings Publications

• Elshikha, D. E., Attalah, S., Waller, P. M., Hunsaker, D. J., Thorp, K. R., Williams, C., Katterman, M. E., Sanyal, D., Wang, G., Dierig, D., & Ray, D. T. (2023, Spring).

  Guayule germination and growth under subsurface gravity drip and furrow irrigation in Arizona

  . In 2023 ASABE Annual International Meeting, Paper number 2300034, 19.

Presentations

• Litson, B., Potter, K., Arnold, R. G., Shirley, V., Colombi, B. J., Ratcliffe, E. L., Ogden, K. L., & Chief, K. (2018, May). IndigeFEWSS: Indigenous Food, Energy, and Water Security-Sovereignty. NSF INFEWS PI workshop. Washington, DC: National Science Foundation.
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  12. K. Chief, K. Ogden, E. L. Ratcliff, M. Kacira, B. J. Colombi, V. Shirley, R. Arnold, K. Simmons-Potter, B. Litson, “IndigeFEWSS: Indigenous Food, Energy, and Water Security-Sovereignty,” NSF INFEWS PI workshop, Washington, D.C., May 16-19, 2018.