James W. Blackburn

Converting crude glycerol derived from yellow grease to lipids through yeast fermentation

Cryptococcus curvatus, an oleaginous yeast was observed to grow on crude glycerol derived from yellow grease. When cultured in a one-stage fed-batch process wherein crude glycerol and nitrogen source were fed intermittently for 12 days, the final biomass density and lipid content were 31.2 g/l and 44.2%, respectively. When cultured in a two-stage fed-batch operation wherein crude glycerol was supplemented at different time points while nitrogen source addition was discontinued at the middle of the experiment, the biomass density was 32.9 g/l and the lipid content was 52% at the end of 12 days. Compared with other oil feedstocks for biodiesel production, lipid accumulated by C. curvatus grown on glycerol has high concentration of monounsaturated fatty acid, which makes it an excellent source for biodiesel use.

Use of sweet sorghum juice for lipid production by Schizochytrium limacinum SR21.

Stalk juice from sweet sorghum grown in Southern Illinois, USA, was examined for lipid production through microalgal fermentation. Juice concentrations at 100%, 75%, 50%, and 25% led to different biomass, lipid, and docosahexaenoic acid (DHA) production by Schizochytrium limacinum SR21. Biomass dry weight as 9.4g/l at 50% juice concentration was similar to that from pure glucose (10.9g/l). But with a 73.4% lipid content, this dose resulted in higher lipid and DHA production than those from pure glucose. Major fatty acids in cells grown on juice were identical to those fed by other substrates. Among the three sugars - glucose, fructose, and sucrose in sorghum juice, only glucose was utilized for growth. Spent medium after algal removal may be further processed for white sugar production in a traditional way since sucrose content remained the same throughout the algal fermentation process. Algal cells or lipids harvested can be utilized as fish meal, human nutrition supplements, or for biodiesel purpose.

Batch stage study of lipid production from crude glycerol derived from yellow grease or animal fats through microalgal fermentation.

A marine microalga, Schizochytrium limacinum SR21 has been found to grow fast on crude glycerol - a major by-product from the current biodiesel industry. Using crude glycerol derived from restaurant used oils (yellow grease), we have determined that glycerol concentrations of 25 and 35 g/l were the optimal ones for untreated and treated crude glycerol in batch cultures, respectively. Biomass dry weight as 8.3 and 13.3g/l were attained for these two doses, respectively. Higher concentrations of glycerol resulted in decreased cell growth due to substrate inhibition and methanol presence. With 35 g/l, the cellular lipid content was the highest - 73.3% among all the doses tested. Animal fats derived crude glycerol also supported algal growth and lipid production. Results from this study set a solid foundation for our ongoing fed-batch process to achieve maximal crude glycerol utilization and lipid production.

Bioremediation Scaleup Effectiveness: A Review

Abstract Bioremediation has been applied in laboratory-scale testing to simulate field-scale bioremediation applications. The simulations have focused on the development of concentration-time profile data in the laboratory to be modeled and used for predicting field-scale performance, particularly the time of treatment and the treatment concentration endpoints. This review reports on more than a dozen examples of bioremediation where both the laboratory-scale and field-scale data are provided. These data have been analyzed to examine how well the laboratory-scale kinetics predict the kinetics at field scale. In most cases, the laboratory-scale kinetics exceed field-scale kinetics and underpredict the time of treatment to a given endpoint in excess of 100% and by as much as 11,900%. In some cases, the laboratory-scale kinetic rate constants fall between ±100% of the field-scale kinetics, leading to predictions within 50 to 200% of the time of treatment to a given concentration level. Not enough examples no...

Effect of swine waste concentration on energy production and profitability of aerobic thermophilic processing

Abstract Improvements to aerobic thermophilic processing have led to the ability to recover significant amounts of energy as hot water (∼55°C). This energy can easily be made useful in swine production facilities as a source of heating for farrowing or nursery buildings, aquaculture tanks or greenhouses for most of the year. Work is underway to investigate alternative uses for the energy in the hot months. Potentially, the energy may be used to dry the residual solids from the process (∼40% of the original amount of solids) and these solids may be used for application as: (1) field fertilizer in the non-growing season, (2) a high value organic food fertilizer, and (3) dry solids for co-firing in electric power stations. Heat produced may also be used to generate induced draught in chimneys to aid in building ventilation, reducing electric power consumption, and also to power state-of-the-art refrigeration/chilling systems for cooling production buildings. This work makes use of a design and economic model for a given configuration of aerobic thermophilic treatment suitable for swine production facilities to evaluate the effects on economics and energy production of various swine waste concentrations. While actual waste from the animal may be in the 130 g l −1 dry solids range, waste for treatment is often diluted based on hog watering rates and building cleanout and flush systems. Some concentrations are as low as 15 g l −1 . Lower waste concentrations require larger initial expenditures related to increased reactor volumes and tend to strongly affect the profitability of the process. Straightforward engineering design considerations permit profitable use of this technology even in these low concentration ranges.

Importance of reaction structure in the periodic operation of six industrial chemical reactions

Periodic operation occurs when a reaction is run with periodic inputs in reactant flowrate, concentration, temperature or in other conditions. Periodic operation of chemical reactions leading to enhanced rates and yields as compared to steady-state operation has been reported for three decades. Emphasis has been on the study of reactions which are often catalytic and have varying reactor designs that affect the responses to periodic operation. The reported reactions often have mass transfer limitations, catalyst adsorption-desorption behavior, surface reactions, or temperature effects and the magnitude of the periodic response is often affected by these factors. The objective of this paper is to compare the reaction networks of six industrially important reactions ((1) 2,6-Tolylenediurethane from 2,6-tolylene diisocyanate and 1-butanol; (2) Chloramine from hypochlorous acid ammoniation; (3) Phthalic anhydride from naphthalene oxidation; (4) Biphenyl from the dehydrogenation of benzene; (5) Acrylonitrile from propyle ammoxidation; (6) Acetylene from methane cracking) to investigate the importance of reaction structure on the potential for conversion and selectivity improvement using periodic operation. Dynamic simulation techniques are used to solve the coupled differential equations representing the reaction rates. It is assumed for comparison purposes that there are no mass transfer limitations, that adsorption-desorption or surface reactions are not rate limiting, and the temperature is constant at the reaction conditions. One reactor design, the continuously stirred tank reactor, is used in order to compare reactions without reactor design-related effects. Differences in the periodic response are related to reaction structure factors such as the number of chemical components, the number of first order reactions, and the number of series reactions present. Reaction structure does not appear to be as significant as non-structural factors such as mass transfer, catalyst behavior, or reactor designs in creating periodic operation improvements.