Bench-Scale Evaluation of Hydrothermal Processing Technology for Conversion of Wastewater Solids to Fuels.

Hydrothermal Liquefaction (HTL) and Catalytic Hydrothermal Gasification (CHG) proof-of-concept bench-scale tests were performed to assess the potential of hydrothermal treatment for handling municipal wastewater sludge. HTL tests were conducted at 300 to 350 °C and 20 MPa on three different feeds: primary sludge, secondary sludge, and digested solids. Corresponding CHG tests were conducted at 350 °C and 20 MPa on the HTL aqueous phase output using a ruthenium-based catalyst. Biocrude yields ranged from 25 to 37%. Biocrude composition and quality were comparable to biocrudes generated from algae feeds. Subsequent hydrotreating of biocrude resulted in a product with comparable physical and chemical properties to crude oil. CHG product gas methane yields on a carbon basis ranged from 47 to 64%. Siloxane concentrations in the CHG product gas were below engine limits. The HTL-CHG process resulted in a chemical oxygen demand (COD) reduction of > 99.9% and a reduction in residual solids for disposal of 94 to 99%.

Ultrasound-assisted hydrogenation of cinnamaldehyde.

The hydrogenation, employing hydrogen gas, of cinnamaldehyde was performed using Pd-black and Raney Ni catalysts at 298+/-3 K in a water-cooled (jacketed) reaction vessel. Sampling at pre-determined time intervals and GC/MS analysis yielded time-dependent product state distribution information. A kinetic modeling of the data revealed that cinnamaldehyde was both hydrogenated directly to the final product benzenepropanol, as well as a fraction being converted to the intermediate benzenepropanal, where the latter was subsequently hydrogenated to benzenepropanol. Comparing the ultrasound-assisted and blank (stirred) experiments revealed that a higher maximum relative concentration of the intermediate benzenepropanal was formed in the ultrasound experiments compared to the stirred experiment. The activity of the ultrasound experiments compared to blank were 9-fold and 20-fold greater for the Pd-black and Raney Ni catalysts, respectively. Finally, an application of the Bell-Evans-Polanyi principle to yield an estimate of the ratio of rate coefficients for benzenepropanal and benzenepropanol formation was performed by considering chemical group energy differences and surface adsorption energy differences in the first mechanistic step of hydrogenation.

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Raman scattering temperature probe of laser disk marking.

The laser-induced temperature rise in a dye/polymer system for optical storage was directly obtained by measuring the intensity ratio of the Raman scattered radiations (anti-Stokes to Stokes). The laser beam that writes is used to collect scattering data. Computer simulated laser-induced temperature distribution and its corresponding intensity ratio were used to extract the actual temperature information developed on the recording films. Experiments have been done at laser powers below and up to the point of threshold of marking.

Laser light scattering measurement of dextran-induced Streptococcus mutans aggregation.

Intensity fluctuation spectroscopy was used to study dextran-induced aggregation of Streptococcus mutans bacteria. Smoluchowski's theory of colloidal flocculation provided a consistent model of the agglutination process. Our experiments indicated that aggregation was inhibited by the negatively charged surfaces of the cells, while dextran polymers effectively bound organisms together. Our experimental data were consistent with the quantitative predictions of a polymer bridge model of agglutination.

Size determination of Streptococcus mutans 10499 by laser light scattering.

We have performed three different optical experiments to determine the mean size of the bacterial strain Streptococcus mutans 10449, a microorganism with dimensions comparable to the wavelength of the light used in our experiments. The three optical measurements give size values which are consistent with one another and favorably comparable to the consistency we found in identical measurements on a test system of polystyrene spheres of dimensions similar to the bacteria. Homodyne time correlation and power spectrum spectroscopy both depend on the coherence and monochromaticity of laser light for the determination of the mean diffusion coefficient of the scatterers. The Stokes-Einstein equation then relates the diffusion constant to the cell size. Differential light scattering relies for the interpretation of experimental data on the classical theoretical analysis of the angular distribution of scattered light from a scattering object. The three methods yield mean values for the radius of S. mutans 10499 of 0.324 +/- 0.006 mum, 0.0325 +/- 0.007 mum, and 0.315 +/- 0.009 mum, respectively. However, since intensity correlation spectroscopy provides a direct measure of polydispersity, it would appear to be the preferred single measurement technique for size determination.