The rock cross vane, an in-stream boulder structure, consists of a U-shaped weir with the apex upstream at bed elevation and upward sloping arms that tie into downstream banks. The structure provides grade control, bank protection and scour pool development via a protected drop and arms that turn flow away from the banks. A physical model was used to measure the velocity distribution changes caused by a range of geometric configurations of the structure. Results showed linear and quadratic effects of drop ratio, cross product effects of drop ratio and arm angle, drop ratio and arm slope, and arm angle and arm slope on the velocity ratio (the average center velocity to the average outer velocity) of a cross section located two bankfull widths downstream of the drop. The Rock Cross Vane Rapid Assessment Tool (RCV-RAT) was developed to rate rock cross vane failures and assess the causes of structure weakness on NC stream restoration projects. Failure ratings were analyzed for significant correlations to project parameters, class effects of project, and correlations between dependent variables (alpha =0.05). Of the 120 rock cross vanes observed, 109 had at least one incidence of failure ranging from slight to extreme. From this data, an FMEA was developed to compare the risks of the various modes of failure for the rock cross vane and to adapt the FMEA for use in North Carolina stream projects. It was concluded that sufficient drop is necessary for scour pool development, while steep, narrow arms leading to a constricted flow area minimally contribute to scour pool development and may risk bank instability at the structure and at downstream banks. Rock cross vanes that can tolerate rapid lateral migration of the stream post-construction should be developed and tested due to the observed problems of structure side cutting. The final chapter reviews literature for the main effects of stream restoration on benthic macroinvertebrate communities and the expected return of benthic macroinvertebrate communities post-restoration to address what impacts the rock cross vane might have on benthic macroinvertebrates and to recommend practices that might reduce these impacts.

Environmentally sound treatment of by-products in a value-adding process is an ongoing challenge in animal agriculture. Thermophilic anaerobic digestion of wastes originating from agricultural production and animal processing represents a potential waste treatment technology to address environmental concerns such as odor emissions and removal of pathogenic microorganisms, while at the same time producing renewable energy (biogas) as a by-product. However, thermophilic digestion is subject to inhibition by ammonia and long chain fatty acids (LCFA), both of which are prevalent in manure and animal processing wastewater. Several swine manure collection methods under development separate the urine from the feces, which creates the opportunity to operate a digester on feces only, greatly reducing the ammonia load to the digester. One objective of this study was to determine whether operation on feces only would yield significant performance improvements for a thermophilic anaerobic digester operating on swine waste. Effluent from a continuously stirred tank reactor (CSTR) was used as the inoculum for batch tests in which the substrate contained three different concentrations of urine (urine-free, as-excreted urine:feces ratio and double the as-excreted urine:feces ratio). Inocula were acclimated to these same urine:feces ratios to determine methane production. Results show that both urine-free and as-excreted substrates were not inhibitory to anaerobic inocula. Anaerobic microorganisms can be readily acclimated to substrate with double the as-excreted urine concentration, which contained TKN concentrations up to 7.20 g-N liter-1. The sludge collected from the dissolved air flotation (DAF) wastewater treatment process in swine processing facilities is an example of a high-lipid substrate containing potentially inhibitory levels of LCFA. A second objective of this study was to determine the fundamental performance parameters for thermophilic anaerobic digestion of DAF sludge. Testing in a semi-continuous stirred tank reactor and in batch reactors was conducted to determine substrate degradation rates and biogas yield. Stable operation could not be achieved using pure DAF sludge as a substrate, possibly due to inhibition by long chain fatty acids or to nutrient deficiencies. However, a 1:1 ratio (w/w, dry basis) of DAF sludge and swine manure (feces only), resulted in stable and productive digester operation. In the semi-continuous stirred reactor at 54.5ï°C, a hydraulic residence time of 10 days, and an organic loading rate of 4.68 gVS/day/L, the methane production rate was 2.19 L/L/day and the specific methane production rate was 0.47 L/gVS (fed). Maximum specific methanogenic activity (SMA) in batch testing was 0.15 mmolesCH4 hr-1 gVS-1 at a manure/DAF substrate concentration of 6.9 gVS liter-1. Higher substrate concentrations cause an initial lag in methane production, possibly due to long chain fatty acid or nitrogen inhibition.

The objectives of this project were to develop operating conditions for a bench-scale sequencing batch reactor to match the design of a full-scale sequencing batch reactor system for treating swine waste and to determine the effects of continuous, low oxygen versus cyclic aeration schemes on sequencing batch reactor system performance. The low aeration technique was intended to develop conditions for low oxygen nitrification and simultaneous nitrification and denitrification so that a comparison could be made to a typical cyclic aeration reactor for biological nitrogen and phosphorus removal. The performance of the two reactor configurations was measured by the settling efficiency, mass removal efficiency, and accumulation of chemical oxygen demand (COD), suspended solids (SS), total Kjeldahl nitrogen (TKN), and total phosphorus (TP). The performance of the reactors did not meet expectations due to excessive loading and source inconsistency. Operational changes to the solids wasting mechanism and to the cyclic aeration system were made during the experiment in an attempt to stimulate reactor performance, which provided insight into the responses of the two types of reactors to these changes. The performance of the continuous aeration reactors met or exceeded the performance of the cyclic aeration reactors, while receiving a 73% lower supply of oxygen. The results support the potential for equipment and energy savings by utilizing low-oxygen continuous aeration for the treatment of swine waste with sequencing batch reactors.

The objective of this study was to investigate the effectiveness of sulfuric acid, sodium hydroxide, hydrogen peroxide, and ozone pretreatments for conversion of cotton stalks to ethanol. Sulfuric acid, sodium hydroxide, and hydrogen peroxide at concentrations of 0.5, 1, and 2% (w/v) were used to pretreat ground cotton stalk samples at a solid loading of 10% (w/v). Treatment temperatures of 90 degrees Celsius and 121 degrees Celsius at 15 psi were investigated for residence times of 30, 60, and 90 minutes. Ozone pretreatment was performed in the liquid phase at 4 degrees Celsius with constant sparging. Lignin, carbohydrate, and moisture content analyses were performed on the pretreated solids. The pretreated solids from sulfuric acid, sodium hydroxide, and hydrogen peroxide pretreatment (at 2%, 60 min, 121C/15psi) showed significant lignin degradation and/or high sugar availability and hence were hydrolyzed by cellulases from Trichoderma reesei and â-glucosidase at 50 degrees Celsius. The results showed that time, temperature and concentration were all significant (p is less than or equal to 0.05) factors in delignification for NaOH and xylan removal for H2SO4. Sulfuric acid pretreatment resulted in the highest xylan reduction (95.23% for 2% acid, 90 min, 121C/15psi) during pretreatment and the lowest cellulose to glucose conversion during hydrolysis (23.85%). Sodium hydroxide pretreatment resulted in the highest level of delignification (65.63% for 2% NaOH, 90 min, 121C/15psi) and the highest cellulose conversion (60.8%). Hydrogen peroxide pretreatment resulted in significantly lower (p is less than or equal to 0.05) delignification (maximum of 29.51% with 2%, 30 min, 121C/15psi) and cellulose conversion (49.8%) than sodium hydroxide pretreatment, but had a higher (p is less than or equal to 0.05) conversion than sulfuric acid pretreatment. Ozone pretreatment showed no significant changes in lignin, xylan, or glucan contents with increasing time. Quadratic models using time, temperature, and concentration as numeric variables were developed to predict xylan reduction for H2SO4 pretreatment and lignin reduction for NaOH pretreatment. In addition, linear models relating a modified severity parameter (log Mo) combining the pretreatment parameters with xylan or lignin reduction were developed and resulted in R-squared values of 0.89 and 0.78, respectively.

Current tobacco baling technology utilizes hydraulic power to press tobacco into bales. The high system pressures at which hydraulic systems operate pose a risk to workers. Hydraulic systems are costly and hydraulic oil leaks contaminate baled tobacco. A pneumatically driven, vertically oriented, multi-stroke baler was designed as an affordable alternative to current hydraulic balers. Pneumatics was chosen due to the lower system operating pressure and absent risk of tobacco bale contamination. The transmission of power was achieved through a reversible pneumatic gearmotor turning left and right hand acme threaded rods coupled together to form a powerscrew. The plunger was driven by a scissor-jack design and was used to take advantage of the non-linear force response of tobacco. The scissor-jack was driven by acme nuts traveling along the acme rod of the powerscrew. The baler was tested with burley tobacco grown during the 2007 season at the Central Crops Research Station in Clayton, NC. The compressive force and plunger displacement was measured for each bale produced. These readings were used to determine the compressive force as a function of plunger travel and the compressive force as a function of bale density. The baler required 3-4 presses to produce burley bales roughly 42 inches cubed and weighing approximately 500-600 pounds.

Ammonia emission from animal feeding operations has potential negative impacts on the environment and public health and it also reduces the nutrient value of animal waste. When conditions are not suitable for land application, broiler cake (or litter) may be stored in stockpiles which may contribute to ammonia emission. In this study, summer and winter ammonia emission factors from broiler cake stockpiles stored in a naturally ventilated shed were developed. The lab experiment measured relative ammonia emissions as affected by type of cover and depth of cake. Scrubbers were used to measure ammonia concentration both in the field and lab studies. In the field, the integrated horizontal flux (IHF) method and Fickâs law of diffusion were used to determine ammonia emissions due to forced and natural convections, respectively. The ammonia emission due to natural convection was <0.01% of total emission. However, it may be necessary to calculate emissions based on concentrations measured only during conditions of forced convection. In summer, the estimated total ammonia-N loss was 0.8 % of total N. In winter, the total ammonia loss was 1.4 % of total N during the first 7 d and 2.5 % for the whole 15-d period. The estimated average daily ammonia emission factor in summer (7 d) was 24.5 g NH3-N/m3-d of cake or 7.0 g NH3-N/AU (500 kg LW)-d. The estimated daily ammonia emission factor for the first 7 d in winter was 35.6 g NH3-N/m3âd or 42.5 g NH3-N/AU-d. The total ammonia lost during the 15-d winter study was 33.8 g NH3-N/m3-d or 40.2 g NH3-N/ AU-d. Ammonia losses from the tarp covered cake were significantly lower than the control and double depth treatments by 45% and 49%, respectively, at the end of study. Ammonia losses (g/m3) are lower from stockpiles with lower surface area per unit volume.

This thesis reports a field study on characterizing particle size distribution (PSD) of particulate matter (PM) emitted from a commercial layer operation in the Southeastern U.S. across three seasons from October of 2008 to April of 2009. Six low-volume (1m3/h) total suspended particulate (TSP) samplers were used to collect PM samples in two high-rise layer houses. A laser diffraction particle size analyzer (LS13 320) at North Carolina State University (NCSU), a laser scattering particle size analyzer (LA-300) at University of Illinois at Urbana-Champaign (UIUC) and a Coulter Counter Multisizer 3 (CCM 3) at Texas A&M University (TAMU) or USDA-ARS cotton production & processing unit in Lubbock, TX were used to measure PSD of PM samples collected by the TSP samplers. Particle size distributions measured by these three instruments were compared. Results of the study indicate that TSP concentrations across the three seasons ranged from 888 to 5333 µg/m3. Total suspended particulate concentration was affected by season, animal activity, floor, and equivalent air flow rate factor. It was observed that TSP concentration in winter was higher than in spring; concentration on the second floor was higher than that on the first floor; the more active the animals were, the higher the TSP concentration; and the more the fans were on, the lower the concentration. Compared with PM concentration, PSD (characterized by the mass medium diameter, MMD, and geometric standard deviation, GSD) was affected by season, animal activity, floor and equivalent flow rate factor to a lesser extent. Overall MMDs of PM samples collected in fall, winter and spring, measured by the laser diffraction particle size analyzer were 19.21±1.27 µm, 17.13±0.81µm and 18.44±1.44µm, respectively. Geometric standard deviation (GSD) was relatively constant and not affected by those factors (season, animal activity, floor, and equivalent air flow rate factor). The overall GSD was 2.65±0.08. Significant but constant differences in MMDs and GSDs were detected when comparing PSDs measured by the different instruments. In general, the LA-300 provided the largest MMDs, whereas the CCM 3 gave the smallest MMDs. The LS13 320 provided the largest GSDs, whereas the CCM 3 gave the smallest.

Currently, the plant-available nitrogen (PAN) coefficient of hog anaerobic lagoon effluent does not differentiate for land application by broadcast (e.g. drag hose) or irrigation (e.g. traveling gun). There is a need to determine PAN coefficients for traveling gun and drag hose by measuring ammonia (NH3) emissions, and accounting for partial nitrogen (N) mineralization. Ammonia emissions were measured for four application periods (fall, spring, 2 summer) with the integrated horizontal flux (IHF) method on Bermudagrass grown on Cainhoy sand in Garland, NC. Ammonia concentration was measured using acid scrubbers. Nitrogen mineralization was estimated based on published literature. During application by traveling gun 3 to 9% of applied-N was lost as NH3 before it hit the ground (soil or canopy surface). Total NH3 emission from the ground ranged from 13 to 26% of applied-N, 96 h after start of the application. The first 4 h accounted for 65 to 81% of the NH3 emission. The N loss during application (in the trajectory) ranged from 4 to 11%. Due to uncertainties in the NH3 emission measurement, additional studies are needed with improved methods to account for losses in the trajectory and subsequent mist formation during application. Ammonia-N emission using the drag hose, ranged from 1 to 5%. Based on literature, the organic-N mineralization rate was assumed to be 50%. The PAN, thus obtained, was 0.65 for traveling gun, and 0.85 for drag hose. A model was used to simulate NH3 emission from hog lagoon effluent applied with both the traveling gun and drag hose. The model underestimated NH3 emission from traveling gun treated plot for all four periods. The model overestimated emissions from drag hose treated plot in two of the three periods. The model was sensitive to increase in soil pH and moderately sensitive to changes in all other selected parameters (total ammoniacal-N concentration and pH of effluent, linear partition coefficient of soil, and wind speed).

Use of plants for swine waste management involves the removal of nutrients from the swine wastewater by the plants and the utilization of the plant biomass for other useful purposes such as feed supplement and soil amendment. Duckweed has gained much interest for this purpose in the past decades because of its high growth rate and high protein content. The goal of this research was to study the characteristics of duckweed growth and nutrient uptake from swine wastewater in order to improve the efficiency of duckweed nutrient recovery. In the first part of this research, nutrient distribution and transport in a quiescent duckweed-covered pond containing swine lagoon liquid were investigated and described mathematically. A superior duckweed strain for total protein production in swine wastewater Spirodela punctata 7776 was used as a subject of the study. Diffusive transport of ammonium was shown to be a limiting process in nitrogen removal by duckweed plants in static ponds. In addition, a pH profile developed along the depth of the pond, creating an additional barrier to ammonia volatilization from the pond covered with a duckweed mat. In the second part of the research, growth and nutrient uptake characteristics of Spirodela punctata 7776 in artificial swine medium were examined in sterile batch cultures. Growth of Spirodela punctata 7776 corresponded to the amount of nitrogen storage in its biomass rather than the nutrient concentration in the growth medium. The relationship followed Monod-like kinetics with a maximum specific growth rate of 0.2381 g/g/d. Reduction in the specific growth rate of Spirodela punctata 7776 was observed in the culture with higher crop density, which signified the adverse effects of surface crowding. A mathematical expression to represent the effects of crop density (mass per unit area) on specific growth rate was developed, which can be used in optimization of crop density management in duckweed nutrient recovery systems.

The feasibility of inducing a resting stage in cultures of Clostridium ljungdahlii and Clostridium autoethanogenum was evaluated. Additionally, the effects of medium pH and benzyl viologen, a electron mediator, were tested separately for resting C. ljungdahlii cultures. Cells were grown on nitrogen-rich basal media, a modified Reinforced Clostridial Media and DSMZ 640 for C. ljungdahlii and C. autoethanogenum respectively, and then transferred to nitrogen-limited media to induce the resting stage. The performance of the resting cultures was evaluated by product formation (ethanol and acetate), culture stability, and cell viability. It was found that C. ljungdahlii was able to be induced into a stable non-growing stage with basal medium supplemented with vitamins and trace elements and devoid of the major nitrogen sources: yeast extract, beef extract, and proteose peptone, RCM.NA.SVE. However, there was no significant product formation in the resting cultures of C. ljungdahlii. Three pH levels, 6.8 (the control), 5.5, and 4.5, were tested for affects on C. ljungdahlii resting cell performance. The medium pH of resting cultures in NG.RCM.NA.SVE did not improve product formation of non-growing C. ljungdahlii cultures. The more acidic pH of the non-growing media reduced the culture viability from 100 % at pH 6.8 to 44.4 and 11.1 % at pH 5.5 and 4.5 respectively. Three levels of benzyl viologen concentration were tested for affects on C. ljungdahlii resting cell performance: 0, 50, and 100 part per million. The addition of benzyl viologen did not enhance the cultures? product formation capabilities. The benzyl viologen in the resting cell media also negatively affected the culture viability leaving only 33.3 and 55.5 % of the cultures viable with 100 and 50 ppm benzyl viologen respectively. C. autoethanogenum cultures were not able to be induced into stable non-growing cultures. With various nitrogen-source limitations from the basal medium cultures experienced either significant increases or decreases in culture density over time. The ethanol product selectivity in both non-growing and growing cultures of C. autoethanogenum in nitrogen-limited media was improved from the growing C. autoethanogenum in the basal medium. The ethanol to acetate production ratio was improved to 1:4.5 in two different nitrogen-limited media (one without yeast extract or trypticase peptone in which the culture density decreased, and only devoid of yeast extract in which the culture grew) from 1:7 in the basal growth medium. All cultures of C. autoethanogenum remained viable after transfer from the growth media to the non-growth media. From these studies it appears that ethanol is a primary metabolite for both C. ljungdahlii and C. autoethanogenum on sugar substrates.