Gasification of Phycoremediation Algal Biomass

Microalgae have been utilized in wastewater treatment strategies in various contexts. Uncontrolled algal species are a cheap and effective remediation strategy. This study investigates the thermochemical potential of wastewater treatment algae (phycoremediation) as a means to produce renewable fuel streams and bio-products. Three gasification temperature levels were investigated in an auger gasification platform: 760, 860, and 960 °C. Temperature increases resulted in corresponding increases in CO and H2 concentrations in the producer gas from 12.8% and 4.7% at 760 °C to 16.9% and 11.4% at 960 °C, respectively. Condensable yields ranged between 15.0% and 16.6%, whereas char yields fell between 46.0% and 51.0%. The high ash content (40% on a dry basis) was the main cause of the elevated char yields. On the other hand, the relatively high yields of condensables and a high carbon concentration in the char were attributed to the low conversion efficiency in this gasification platform. Combustion kinetics of the raw algae, in a thermogravimetric analyzer, showed three consecutive stages of weight loss: drying, devolatilization, and char oxidation. Increasing the algae gasification temperature led to increases in the temperature of peak char oxidation. Future studies will further investigate improvements to the performance of auger gasification

Opportunities and Barriers to Bioenergy Conversion Techniques and Their Potential Implementation on Swine Manure

The objectives of this article are to offer a comprehensive evaluation of the opportunities and barriers for swine manure conversion technologies and to shed light on the gaps that might require further investigation to improve the applicability of these technologies. The challenges of manure management have been propagated alongside the global growth of swine production. Various technologies that target the production of energy, fuels, and bioproducts from swine manure have been reported. These technologies include pretreatments, i.e., drying, and solid separation; biological techniques, i.e., composting, anaerobic digestion, and biodrying; and thermochemical techniques, i.e., combustion, gasification, pyrolysis, liquefaction, and carbonization. The review highlights the yields and qualities of products, i.e., energy, gaseous fuel, liquid fuel, and solid fuel, of each technology. It exhibits that the choice of a conversion technology predominantly depends on the feedstock properties, the specifics of the conversion technique, the market values of the end products as well as the local regulations. The challenges associated with the presented techniques are discussed to ameliorate research and development in these areas. The notable finding of this paper is that there is a need for full-scale research in the area of thermochemical conversion of solid-separated swine manure

EFFECTS OF INITIAL MOISTURE CONTENT AND HEATING RATE ON WHEAT (OAKES) DRYING KINETIC PARAMETERS

The goal of this study was to determine the effects of initial moisture content and heating rate on the drying kinetic parameters of wheat under non-isothermal conditions. Wheat (OAKES) samples at initial moisture contents of 20.7%, 18.5%, 16.8%, and 14.8% wet basis (w.b.) were dried using a thermogravimetric analyzer. The analyzer was set at five heating rates (2, 3, 4, 5 and 10oC/min) to determine the drying kinetic parameters, i.e., activation energy, of the heated samples from room temperature of 30°C to 170oC. The experimental moisture ratio data were fitted to the four empirical models, namely Page, Newton, Logarithmic, and Henderson models. The goodness of fit criterion was used to determine the best-fitting model. Heating rate and initial moisture content affected the activation energy required for drying wheat. Increasing the heating rate expedited the drying curve. The heating rate of 10°C/min for wheat at an initial moisture content of 14.8% w.b. resulted in the greatest activation energy of 28.174 kJ/mol. The heating rate of 2°C/min for wheat at an initial moisture content of 20.7% w.b. resulted in the lowest activation energy of 14.760 kJ/mol. The Logarithmic and Henderson models were adjudged as best fit models for the entire drying curves by R2, RMSE, and X2. This study highlighted that the energy required to dry wheat from 20.7% w.b. to acceptable safe level could be minimized by reducing the heating rate

Influence of Pyrolysis Temperature and Production Conditions on Switchgrass Biochar for Use as a Soil Amendment

Biochars form recalcitrant carbon and increase water and nutrient retention in soils; however, the magnitude is contingent upon production conditions and thermo-chemical conversion processes. Herein we aim at (i) characterizing switchgrass (Panicum virgatum L.)-biochar morphology, (ii) estimating water-holding capacity under increasing ratios of char: soil; and, (iii) determining nutrient profile variation as a function of pyrolysis conversion methodologies (i.e. continuous, auger pyrolysis system versus batch pyrolysis systems) for terminal use as a soil amendment. Auger system chars produced at 600°C had the greatest lignin portion by weight among the biochars produced from the continuous system. On the other hand, a batch pyrolysis system (400 °C – 3h) yielded biochar with 73.10% lignin (12 fold increases), indicating higher recalcitrance, whereas lower production temperatures (400 °C) yielded greater hemicellulose (i.e. greater mineralization promoting substrate). Under both pyrolysis methods, increasing biochar soil application rates resulted in linear decreases in bulk density (g cm-3). Increases in auger-char (400 °C) applications increased soil water-holding capacities; however, application rates of >2 Mt ha-1 are required. Pyrolysis batch chars did not influence water-holding abilities (P>0.05). Biochar macro and micronutrients increased, as the pyrolysis temperature increased in the auger system from 400 to 600 °C, and the residence time increased in the batch pyrolysis system from 1 to 3 h. Conversely, nitrogen levels tended to decrease under the two previously mentioned conditions. Consequently, not all chars are inherently equal, in that varying operation systems, residence times, and production conditions greatly affect uses as a soil amendment and overall rate of efficacy