Sammy Sadaka

Pyrolysis kinetics of algal consortia grown using swine manure wastewater.

In this study, pyrolysis kinetics of periphytic microalgae consortia grown using swine manure slurry in two seasonal climatic patterns in northwest Arkansas were investigated. Four heating rates (5, 10, 20 and 40 °C min(-1)) were used to determine the pyrolysis kinetics. Differences in proximate, ultimate, and heating value analyses reflected variability in growing substrate conditions, i.e., flocculant use, manure slurry dilution, and differences in diurnal solar radiation and air temperature regimes. Peak decomposition temperature in algal harvests varied with changing the heating rate. Analyzing pyrolysis kinetics using differential and integral isoconversional methods (Friedman, Flynn-Wall-Ozawa, and Kissinger-Akahira-Sunose) showed strong dependency of apparent activation energy on the degree of conversion suggesting parallel reaction scheme. Consequently, the weight loss data in each thermogravimetric test was modeled using independent parallel reactions (IPR). The quality of fit (QOF) for the model ranged between 2.09% and 3.31% indicating a good agreement with the experimental data.

INFLUENCE OF AERATION RATE ON THE PHYSIO-CHEMICAL CHARACTERISTICS OF BIODRIED DAIRY MANURE - WHEAT STRAW MIXTURE

Animal manure is a prime candidate for thermochemical conversion (co-firing, gasification, and pyrolysis) except for its high moisture content. Biodrying is a promising solution to reduce manure moisture with minimum energy input. This study investigated the effects of different aeration rates; low (0.05 L/min/kg VM), medium (0.80 L/min/kgVM), and high (1.50 L/min/kgVM), on the biodrying of dairy manure mixed with wheat straw. The moisture content dropped in 21 days from 56% to 28%, 34%, and 35% wb under high, medium, and low aeration rates, respectively. The heating value of the mixture decreased from 16.19 MJ/kgdry to 14.31, 13.79, and 13.83 MJ/kgdry under high, medium, and low aeration, respectively. Evaluation of energy consumption to remove a unit mass of moisture showed that high aeration levels required the least energy input, 7.84 MJ/kgH2O, followed by low aeration at 7.93 MJ/ kgH2O, while the medium aeration had a relatively high energy cost for water removal, 9.09 MJ/ kgH2O. The high aeration level was superior in terms of both drying energy and time requirements to the other rates considered. Comparison showed that high aeration level biodrying (1.50 L/min/kgVM) exceeded the range of conventional drying energy demand. However, the ratio of external fossil fuel demand was much lower in biodrying (due to the auto-thermal effect) than in conventional drying.

Infrared Drying Characteristics of Long-Grain Hybrid, Long-Grain Pureline, and Medium-Grain Rice Cultivars

The objective for this study was to investigate the effectiveness of scaled-up infrared (IR) heating followed by tempering steps to dry freshly harvested rough rice. An industrial-type, pilot-scale, IR heating system designed to dry rough rice was used in this study. The heating zone of the equipment had catalytic IR emitters that provided heat energy to the sample as it was conveyed on a vibrating belt. The sample comprised freshly harvested rough rice of long-grain pureline (Cheniere), long-grain hybrid (6XP 756), and medium-grain (CL 271) cultivars at initial moisture contents of 23, 23.5, and 24% wb, respectively. Samples at a loading rate of 1.61 kg/m2 were heated with IR of radiation intensity 5.55 kW/m2 for 30, 50, 90, and 180 s followed by tempering at 60°C for 4 h, at a product-to-emitter-gap size of 450 mm, in one- and two-pass drying operations. Control samples were gently natural air dried in an equilibrium moisture content chamber set at relative humidity of 65% and temperature of 26°C to moi...