Biomass and waste materials are converted to ethanol by gasification followed by fermentation of the synthesis gas using acetogenic bacteria such as Clostridium ragsdalei. Fuel ethanol is a high-volume, low-cost commodity, so capital and operating expenses must be very low to achieve profitable operation. The fermentation medium supplies minerals, metals, and organic co-factors needed to build cell biomass and the functional enzyme platform that conducts the conversion reactions. Research directed toward commercial deployment of synthesis gas (syngas) fermentation processes must consider cost and availability of medium components, and use economically viable medium. A method based on elemental accounting of cell composition was developed to assess the cost and function of fermentation media and their potential for commercial use for syngas fermentation to produce ethanol using C. ragsdalei. Cost of medium was reduced from $9.87 L-1 to $0.26 L-1. Additional cost reduction can be achieved by eliminating components that are not required, using commercial components purchased at bulk commodity prices, using H2S and NH3 from the syngas production in lieu of purchased sodium sulfide and ammonium chloride, and retaining the acetate buffer from ethanol distillation. These savings can reduce the medium cost below $0.01 L-1.
In order to solve the difficult problem of replacing batteries in wireless sensor network nodes in a forest, a method for collecting the weak electricity from a living tree and the surrounding soil is explored in this research brief. The weak electricity is one type of plant electricity. The method for collecting the plant electricity was tested on different kinds of trees. According to the experiments, the plant electricity was in the range of 300 to 900 mV, and there was no direct relationship between the magnitude of the plant electricity and the distribution of the electrodes used for collecting electricity from the tree trunk and the soil. Based on the above findings, a device for collecting plant electricity and a passive DC-DC boost circuit were designed and fabricated. A large number of tests indicated that the weak voltage of the collected plant electricity could be boosted to approximately 3 V without other additional power sources. Two parallel inputs of plant electricity were able to generate an output energy of 0.96 J, allowing a low power consumption wireless sensor node to collect and transmit data for one day. Furthermore, four parallel inputs of plant electricity were able to generate twice the energy of two inputs, which indicated a linear relationship between the number of inputs and the output energy. Therefore, collection and storage of plant electricity has practical value in solving the problem of powering wireless sensor network nodes in a forest.
The objective of this project was to explore national-scale data relationships between land use, primarily variables pertaining to agricultural production, and in-stream biotic conditions in the mainland U.S. Using the Causal Analysis/Diagnosis Decision Information System (CADDIS) and data from the USGS National Water Quality Assessment Program (NAWQA), benthic macroinvertebrate observed versus predicted (O/E) index values were analyzed against a number of land use and habitat variables in 115 sites across the U.S. Constituent loads, or the mass amounts of a chemical constituent entering the waterway per year, were estimated for each site using the USGS LOADEST program and were evaluated with respect to macroinvertebrate O/E and land use values. Relationships between variables, defined causally through CADDIS, were analyzed using simple linear regression to avoid analytical bias. Regression analyses indicated that forest and urban land cover were significantly correlated to macroinvertebrate O/E values (p = 0.0012 and p < 0.001). Consistent and relatively strong positive correlations were found between land use and nutrient loading (p < 0.001 for all constituents). However, contrary to expectations, no correlation was observed between agricultural land use and O/E values, while negative correlations were observed between all nutrient loading variables and O/E values. These national-scale data support the complex process relationship between agricultural land use and benthic macroinvertebrate condition.
This is the first study on successful long-term psychrophilic (20°C) dry anaerobic digestion (PDAD) of cow feces with wheat straw at 27% total solids (TS) in feed. Experimental results demonstrated the feasibility of cow feces and wheat straw PDAD in long-term operation of a laboratory-scale sequencing batch reactor. An average specific methane yield (SMY) of 182.9 ±16.9 NL CH4 kg-1 VS fed during 12 successive cycles (273 days) was obtained for feed TS of 27% at an organic loading rate 3.0 g TCOD kg-1 inoculum d-1 and treatment cycle length (TCL) of 21 days. A maximum SMY of 219.2 ±18 NL CH4 kg-1 VS fed with a maximum CH4 production rate of 10.2 ±0.8 NL CH4 kg-1 VS d-1 was achieved. The low levels of volatile fatty acid concentrations in the bioreactor indicated that hydrolysis was the reaction-limiting step. The SMY, methane production rate, and their reproducibility during 12 successive cycles indicate that PDAD of cow feces and straw (27% TS in feed) is as efficient as mesophilic DAD.
Improvement in the dry strength, wet strength, and vapor barrier properties of paper sheets has been shown through the sequential addition of chitosan (CS) and carboxymethyl cellulose (CMC) to the pulp solution. Examination of pulp solutions revealed the formation of aggregates due to electrostatic interaction between the unabsorbed CS and CMC. Tensile test results revealed 64% improvement in the dry modulus for sheets with 50% CS and 50% CMC with respect to the control sheet. The wet tensile test results showed that the control pure pulp sheet broke immediately, whereas the composite sheet with 50% CS and 50% CMC exhibited a wet modulus value of 39.5 MPa. The specific water vapor transmission rate (SWVTR) was also found to be the lowest for this particular composite, with a 32% decrease with respect to the control sample, which was again attributed to the formation of agglomerates that filled the void spaces.
The objective of this study was to quantify the in vitro three-dimensional kinematics of the stifle of three broiler breeds with varying prevalence of leg deformities and to determine the strain and function of the gastrocnemius tendon. Six pelvises were collected from each of three broiler breeds that represented varying susceptibilities to leg problems: the Athens-Canadian random bred, the Arkansas random bred, and a 2012 commercial broiler. The pelvises were mounted on a modified Oxford knee rig that allowed six degrees of freedom of the stifle while preserving the hip and hock joints. Stifles were flexed while kinematics and gastrocnemius tendon strain were measured continuously. Again, kinematic data collection occurred after gastrocnemius tendon transection. Stifle kinematics and gastrocnemius tendon strain varied significantly among breeds. The stifle from the Arkansas random bred birds showed a reversal to adduction and decreased internal rotation when compared to the Athens-Canadian random bred. Gastrocnemius tendon strain was positively correlated with the prevalence of leg deformities. Transection of the gastrocnemius tendon caused decreased flexion and a reversal in abduction/adduction in both the Athens Canadian random bred and the 2012 commercial broiler. Results suggest that kinematics of the broiler stifle are indicative of the prevalence of leg problems. In the healthy broiler stifle, the gastrocnemius tendon may serve to resist excess abduction caused by the collateral ligaments. The reversal from normal abduction to adduction in the stifles from the Arkansas random bred birds may occur to counterbalance the increased cranially oriented bodyweight of the faster growing breed.
The commercial enzymes Viscozyme and Pectinex were tested separately and in combinations to determine their effect on pectin, hemicellulose, and cellulose hydrolysis of sugar beet pulp (SBP). Use of each product separately resulted in high levels of SBP hydrolysis, and no synergistic effects were found when they were used in combination. Viscozyme treatments showed higher levels of hemicellulose, pectin, and cellulose hydrolysis. Hydrolysis yields from hemicellulose and pectin in Pectinex treatments were 7% to 9% lower than in Viscozyme treatments; levels of cellulose hydrolysis were similar except that Pectinex treatments had a significantly higher percentage of cellobiose and correspondingly lower glucose. Increasing the solids loading from 10% to 16% in a batch process increased hydrolyzate sugar concentrations but decreased yields (g sugar g -1 SBP). Adding SBP in a fed-batch process did not improve SBP hydrolysis yields over the batch process.
Algal biomass can be a potential substrate for anaerobic digestion. However, raw algae cells show a resistance to biological degradation, resulting in a slower methane production rate. Varying thermal and chemical pretreatments of algal biomass were investigated in an attempt to increase soluble organic matter (SOM) yield, which would result in enhanced methane production during subsequent anaerobic digestion. Scenedesmus sp. was harvested using three different procedures: with flocculation, with flocculation and drying, and without flocculation or drying. For all pretreatments and algae types, fluorescence micrographs were obtained to visually confirm the degradation of the algal cell walls. A complete 2Ã3Ã4 factorial design was applied for the algal biomass pretreatment study, including two heating temperatures (50°C or 90°C), three heating durations (10, 30, or 60 min), and four NaOH concentrations (0%, 3%, 6%, or 12% g NaOH g-1 DW of algae). For algae cells with no flocculant addition, SOM yield increased by 15% with a moderate pretreatment of heating at 50°C in 3% NaOH for 60 min. For dried algae, the baseline SOM yield was higher than in the other algae, such that there was only a noticeable increase with the more severe pretreatments. For flocculated algae, the most severe pretreatment increased SOM yield by 17.2%, but overall the SOM increase was less than with fresh algae. Flocculation appears to inhibit cell wall disruption, but thermal chemical treatment can hydrolyze some flocculant polymers, which eases the flocculation and facilitates cell destruction.
The feasibility of using cull peach, which is an agricultural waste generated in large quantities in the U.S. (13,000 MT in 2012), as a medium for the biological production of succinic acid by Escherichia coli AFP184 was investigated. The effects of corn steep liquor (CSL) supplement and exogenous hydrogen supply were also studied. Sucrose, the predominant but unmetabolizable sugar in cull peach medium, was converted to fermentable sugars (glucose and fructose) during sterilization and subsequently with invertase. Without CSL supplement, fructose consumption was incomplete and the final succinic acid concentration of 38.8 g L-1 was achieved with a yield of 0.75 g g-1 sugars consumed and a succinic acid:acetic acid molar ratio of 5.1:1. When CSL was supplemented to the medium, the final succinic acid concentration increased to 47.0 g L-1 and the yield increased to 0.85 g g-1 sugars consumed, but the succinic acid:acetic acid molar ratio remained at 5.6:1. With hydrogen sparging into the unsupplemented medium, the final succinic acid concentration increased to 45.5 g L-1, the yield increased to 0.84 g g-1 sugars consumed, and the succinic acid:acetic acid molar ratio increased to 7.7:1.
The feasibility of utilizing cellulosic biomass such as corn stover as an energy feedstock is dominated by factors such as facility location, feedstock availability, and transportation cost. Previous research showed the advantages of using a GIS-based method compared to a previously used concentric ring buffer method. Even though the GIS-based method proved to be more accurate because it precisely calculates the distance from the facility to the farms using a real road network and the hectares of crop-specific fields in a given service area, opportunities exist to further improve its accuracy. In this case study, two improvement parameters were implemented to the previously proposed GIS-based method to examine the effect of field-level yield variance and variable residue removal rates on the quantification of feedstock availability for a biorefinery. The new variable residue removal (VRR) method predicted on average 113,384 +/- 38,770 dry tons (DT) of additional residue per service area compared to the previous constant residue removal (CRR) method. The use of a constant removal rate of 3 DT ac(-1) in the CRR method clearly underestimated feedstock availability, given that residue removal rates are highly variable and subject to location, erosive forces, soil characteristics, crop type, yield, and field management. However, to prevent soil erosion and maintain soil productivity, conservation tillage practices require that at least 30% of the soil surface must be covered with residue after planting the next crop. Even with a reduction in total feedstock availability, the VRR method estimated comparable residue availability per service area to the CRR method, with only a 4 +/- 6% decrease per service area on average. Consequently, the VRR method turned out to be the preferred approach in the quantification of biomass feedstock availability.
OF THESIS EVALUATION OF SEPARATION METHOD ADDITIVES FOR THE RECOVERY OF PATHOGENS FROM FOOD MATRICES The microbiological testing of foods is a well-established science. Due to the severity of foodborne pathogen illnesses, the widespread use and implementation of rapid detection methods in food testing labs is increasingly important. The first step for successful testing is sampling. Surfactants have been highly used in food microbiology, but there is not much, if any, published research about the use of fatty alcohols and chemical dispersants as aids in microbial separation. The microbial extraction efficiency of Escherichia coli K12 and Listeria innocua from hot dogs, spinach, and milk was measured using chemical additives (surfactants, fatty alcohols, and a chemical dispersant) in a buffer solution. Dry matter content was calculated using the oven method to determine how clean the sample was at the end of processing. Tween 80 at 0.01% was found to be the most effective additive for microbial recovery for each food matrix examined. The addition of fatty alcohols to surfactants also showed much promise in aiding separation as well as in minimizing dry matter in the final solution. However, the use of Buffered Peptone Water as the diluting agent resulted in very high recovery percentages without the need for additives.
Yeast xylose utilization could be increased by isomerization of xylose to xylulose. In experiments using synthetic media containing glucose, xylose, and xylulose, xylose utilization was prevented and as a result xylitol production was very low. Glucose and xylulose utilization were 99.95% and 40.65%, respectively, for Saccharomyces cerevisiae and 100% and 49.15%, respectively, for Schizosaccharomyces pombe in the absence of furfural. Ethanol yield on sugars was higher at 0.5 g furfural L-1 (0.487 g ethanol g-1 sugars) compared to 0.0 g L-1 (0.450 g ethanol g-1 sugars) and 2.5 g L-1 (0.452 g ethanol g-1 sugars) furfural concentration for S. cerevisiae. However, for S. pombe, a xylose-consuming yeast, ethanol yields (0.426 to 0.518 g ethanol g-1 sugar) and final glycerol concentrations (3.79 to 5.42 g L-1) both increased with increasing furfural concentrations (0.0 to 2.5 g L-1). The kinetic model parameter values confirmed this observation. A higher inoculum-to-sugar ratio resulted in higher average rates of utilization of sugars: from 0.089 to 0.124 g xylulose L-1 h-1 (calculated for 120 h, as xylulose was not completely consumed during 120 h fermentation) and from 1.38 to 1.54 g glucose L-1 h-1 (calculated for the first 24 h, during which most of the glucose was consumed). The flux balance analysis (FBA) model simulation suggests an increase of ethanol of 1.047 mmol h-1 g-1 biomass due to the consumption of xylulose under the given conditions, and detoxifying furfural reduces the specific growth rate from 0.048 to 0.00043 g g-1 biomass h-1.
An optofluidic lab-on-a-chip system and subsequent sampling procedure were developed for detecting bacteria from soil samples utilizing light scattering detection of immunoagglutination assay. This system and protocol detected the presence of Escherichia coli K12 from soil particles in near real-time (10 min) with a detection limit down to 1 CFU mL-1, which is superior to the conventional methods, such as plate counting or polymerase chain reaction (PCR) assays. E. coli solutions were applied to the surface of a mock soil system and incubated overnight. The light scattering immunoagglutination assays using the optofluidic lab-on-a-chip showed two E. coli peaks over the soil depth, one at 1 cm and the other at 4 cm. Comparison with bacterial viability assay and Bradford protein assay revealed that smaller E. coli colonies were found at 1 cm depth and larger colonies at 4 cm, while free antigens adsorbed and desorbed more reversibly at both locations. The two peaks were explained by the two-step process of protein-surface interaction and gravitational force. The target molecules with small sizes (free antigens and single cells) arrived at the soil particle surface faster according to the diffusion model, and the larger E. coli colonies arrived later where the soil surface was already occupied. Because the free antigens adsorbed and desorbed in a more reversible manner, they could be found throughout the depth of the mock-up soil system, whereas the larger E. coli colonies traveled through the void space within soil particles via gravitational force and accumulated at the bottom of where the liquid reached. This work also demonstrates a device and procedure that could be potentially implemented in field studies. With proper soil sample handling protocol and light scattering detection of immunoagglutination assay in an optofluidic lab-on-a-chip, developing more complete bacteria subsurface transport models with actual field results can be achieved.
Spatial and temporal information on cattle location within a pasture can be instrumental in estimating potential nutrient loading to surface waters. To account for cattle variability over time and space, a population distribution model was added as a module to the Java-based, object-oriented ACRU2000 modeling system. The algorithms are composed of attractants of cattle (shade, water, and forage) and their weighting factors derived from multi-criteria decision analysis. The algorithms were developed using the techniques of habitat suitability index (HSI), and criteria weighting was developed with expert opinion using the analytical hierarchy process. The HSI model was calibrated and tested on beef cattle pastures in south Florida. Model verification efforts revealed that the modelâs performance was in good agreement with observed GPS collar data. The HSI model has enhanced the capability of ACRU2000 to represent the spatial variability and nutrient effects of cattle distribution within complex agro-ecosystems of south Florida.
Utilization of alfalfa could be greatly improved if the protein-rich leaves were efficiently separated and preserved from the fibrous stems. This work envisions a new harvest scheme combining three processes: mechanical leaf separation, pressing, and anaerobic storage. To quantify the effectiveness of leaf dewatering, experiments were conducted in which leaves were pressed in a replicated factorial design, including maceration and four levels of backpressure. The amount of press filtrate extracted varied proportionally with press backpressure from 211 to 612 L Mg-1 fresh leaves and was composed of about 90% water. The resulting partially dewatered leaves were successfully ensiled and were found to be chemically similar to high-quality, whole-plant alfalfa silages. Additionally, we demonstrated that nutritionally valuable components in the press filtrate could be conserved by anaerobic storage. Based on our work, protein and lactic acid could be obtained from the ensiled press filtrate in quantities as high as 300 and 143 kg ha-1, assuming an average annual leaf yield of 10 Mg ha-1 and optimal process conditions. However, more work is necessary to determine these values.
An integrated process has been developed for a sweet sorghum (Sorghum bicolor (L.) Moench) biorefinery in which all carbohydrate components of the feestock are used for production of fuel ethanol and industrial chemicals. In the first step, the juice is extracted from the stalks. The resulted straw (bagasse) then is pretreated using the soaking in aqueous ammonia (SAA) process, which does not result in significant loss of hemicellulose, to enhance subsequent enzyme hydrolysis for production of fermentable sugars. Following pretreatment the straw is hydrolyzed first with commercial enzyme product containing high hemicellulase activity (Accellerase XY). The xylose-rich solution obtained after solid/liquid separation is used for production of value-added co-products using suitable microorganisms. The value-added co-products produced to demonstrate the feasibility include astaxanthin and D-ribose. The residual solids then are hydrolyzed with commercial enzyme product containing high cellulase activity (Accellerase 1500) with the juice extracted in the first step being used as make-up water. By combining the sugar in the juice with the glucose released from the residual solids by enzyme hydrolysis high ethanol concentrations can be achieved, which results in lower distillation cost than if pure water is used for enzyme hydrolysis and subsequent fermentation as normally performed in cellulosic ethanol production.
This study investigates a 50 kW anaerobic digestion system to identify practical ways of improving energy utilization within the system. This digester system is operated with heat provided only from the biogas combusted in the engine-generator. Energy utilization in this study is thus considered as how best to apply this produced heat to overcome deficient operating temperatures in the colder winter months. A computer model was developed to simulate the system and was used to investigate outcomes of various design improvements. The most significant improvements could be obtained by increasing the heat recovered from the digester effluent and removing condensation from the biogas prior to combustion. The simulation results show that increasing the waste heat recovery unit effectiveness to 0.4 or higher allows for year-round performance without the need for supplemental heating. In addition, conditioning the biogas by chilling it from 35C to 20C (thus removing a portion of the moisture content) increases output energy from the engine-generator by almost 10%.
Fecal bacteria contamination of surface waters continues to be a critical water quality concern with serious human health implications, but relatively few land use specific data sets are available to guide management, restoration, policy, and regulatory decisions. In regions with substantial poultry production, litter application sites are often assumed to be major contributors to bacterial contamination, and grazing lands often receive a similar focus. Since most states use Escherichia coli as an indicator organism for fecal contamination, this study was designed to measure E. coli concentrations in runoff from small agricultural watersheds with various land uses. Specifically, three years of water quality data were collected from 13 watersheds and analyzed to evaluate the impacts of litter application and land use on E. coli concentrations in runoff. In this study, litter application did not impact E. coli concentrations in runoff, which can at least partially be attributed to the late summer target application date. Litter was produced and removed from poultry houses during hot, dry conditions unfavorable for E. coli survival. Thus, late summer application may be a recommended practice to minimize E.coli runoff from litter application sites. Cultivated watersheds with and without litter application produced the lowest E. coli concentrations in runoff, presumably due to limited wildlife presence and livestock exclusion. In contrast, the ungrazed native prairie reference site produced relatively high E. coli concentrations in runoff, presumably due to increased fecal deposition from abundant wildlife. The high concentrations of E. coli from grazed lands emphasize the need for livestock producers to follow best management practice recommendations to minimize bacteria contribution; however, it is important to note that high E. coli concentrations were measured in runoff from well-managed grazing lands as well as ungrazed native prairie, which indicates the difficulty of managing bacterial contamination.
Algal biomass harvesting from dilute suspensions of a culture is challenging. Although a flocculation process is commonly used to separate suspended solids from water, information on the flocculation characteristics of microalgae cells is limited. In this study, the flocculation characteristics of Nannochloropsis oculata (NO) were examined. Chitosan addition, adjustment of the pH of the growth medium, and electroflocculation techniques were examined. Adjustment of the algae growth medium pH to 11 resulted in over 99% flocculation efficiency. Although chitosan addition facilitated cell flocculation at a lower pH (pH 9), the high flocculant requirement is a disadvantage of this process. In general, the efficiency of electroflocculation improved with increasing current, operation time (OT), and settling time (ST), and 97.1% NO cell flocculation efficiency could be obtained at 0.3 A, 3 min OT, and 30 min ST. This study demonstrated that over 90% NO cell flocculation efficiency is achievable by adjusting the pH of the growth medium, chitosan addition, or electroflocculation. The process selection for commercial operations needs to be based on the characteristics of the harvested biomass required for a given application and the environmental impact and economic feasibility of the process.
