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The adverse effects of air emissions from animal feeding operations (AFOs) on public health, environment, and quality-of-life have been well-documented. Regulations or lawsuits may force AFOs to reduce their air emissions. Since livestock barn particulate matter (PM) has relatively high particle density and diameter and many gasses adsorb onto PM, its filtration might reduce air emissions. A porous windbreak wall that imposes acceptable backpressure (< 12.5 Pa) and covers the fan could be a promising option. Seventy-two different porous windbreak wall scenarios were modeled to compare their backpressure on the fan as well as average airspeed over the ground. These scenarios were combinations of shape (box, chamfered, curved), size (lengths of 2, 2.5, and 3 fan diameters), presence or absence of an opening (opened and closed), screen porosity (mosquito screen or clean screen, SunBlocker 70% or clogged screen), and fan angle and height. Backpressure and airspeed decreased with increasing windbreak wall length. Generally, the box-shaped windbreak wall had lower backpressure and airspeeds than the other shapes. The increased backpressure with clogged screen even at two fan diameters (2d) was acceptable. The tilted fan commonly used in poultry houses had higher backpressure and airspeed over the ground than the non-tilted fan used in swine houses due to the former's lower surface area and tilt towards the ground. Overall, taking into account cost considerations and footprint size (for retrofittability), despite its higher airspeed over the ground (vs. larger footprints) and modest reduction in airflow rate, the 2d, open box model seems the most promising option. [ABSTRACT FROM AUTHOR]

Microalgae are a promising biofuels feedstock, theoretically yielding concentrations of triacylglycerides (TAGs) per unit area that are far higher than traditional feedstocks due to their rapid growth. Dunaliella is particularly advantageous as a feedstock because it is currently commercially mass cultured, thrives in salt water, and has no cell wall. Fourteen strains of Dunaliella have been investigated for growth rates and lipid production in mass culture and tested for enhanced lipid production under a range of environmental stressors including salinity, pH, nitrogen and phosphorus limitation, and light regime. The nuclear genome has been sequenced for four of these strains, with the objective of increasing carbon flux through genetic engineering. Electroflocculation followed by osmotic membrane rupturing may be a very energy and cost efficient means of harvesting the lipid bodies from Dunaliella. A technically feasible and scalable thermo-catalytic process to convert the lipids into replacements for liquid transportation fuels has been developed. The lipids were converted into long-chain alkanes through continuous thermal hydrolysis followed by fed-batch thermo-catalytic decarboxylation. These alkanes can be reformed into renewable diesel via conventional catalytic hydrocarbon isomerization reactions to improve cold flow properties, if desired. © 2013 American Institute of Chemical Engineers Environ Prog, 32: 916-925, 2013 [ABSTRACT FROM AUTHOR]

Pretreatment of lignocellulosic biomass for enhancing sugar yields has been studied extensively over the years. Conventional methods employed to preprocess biomass to make it conducive for enzymatic hydrolysis have been hampered by issues like poor energy efficiency and production of undesirable by-products. Ultrasonication, which involves the treatment of biomass through ultrasonic sound waves in a liquid medium without additional chemicals, is believed to have potential for biomass pretreatment. In this study the effects of ultrasonication on switchgrass, a potential feedstock for bioethanol production due to its high cellulosic content, were investigated. Results of compositional analysis and scanning electron microscopy conducted to visualize structural disintegration in sonicated samples were used to select pretreated samples for enzymatic hydrolysis at different enzyme loadings. Temperature controlled ultrasonication for 60 min at 100% amplitude in a stainless steel vessel, resulted in the highest carbohydrate conversions of 84.6% and 84.7% with Cellic® CTec2 and Alternafuel 200 L at 0.3 g enzyme protein g-1 dry biomass, respectively. However ultrasonication did not significantly impact composition of switchgrass and subsequent hydrolysis of untreated and treated samples was not significantly different. Based on the overall results, it is inferred that although ultrasonication alone did not provide enhanced sugar generation from switchgrass, its tendency to disrupt biomass structure could be utilized for preliminary size reduction steps and performance could be improved by further investigation of frequencies, amplitudes, enzyme loadings and process operation parameters. [ABSTRACT FROM AUTHOR]

A letter to the editor and a reply are presented in response to the article "Evaluation of carbon dioxide administration for on-site mass depopulation of swine in response to animal health emergencies" by R. E. Meyer, W. E. M. Morrow, and L. F. Stikeleather in the 2014 issue.