A Computer Automated, Hydraulically Integrated Serial Turbidostat Algal Reactor (HISTAR): Mathematical Modeling and Experimental Analysis.

Conceptually, the Hydraulically Integrated Serial Turbidostat Algal Reactor (HISTAR) has two components: (1) sealed turbidostats for producing a high quality algal inoculum, and (2) a series of unprotected inter-connected continuous flow stirred tank reactors (CFSTRs) for mass producing algae under approximated plug flow conditions. The hydraulic retention time of each individual CFSTR (\theta\sb{\rm n}) is set low enough (dilution is set high) that any suspended organisms (both contaminants and desired algae) entering the CFSTR would be washed to the next CFSTR well within their doubling time. However, as the turbidostats are employed to inoculate the first CFSTR on an almost continuous basis, the desired algae in the CFSTRs would quickly reach steady state densities. Various mathematical and computer models were developed to predict both the algal growth and contaminant washout trends in the series of CFSTRs. A microcomputer, along with the necessary software and hardware components, was used for process control, routine monitoring and data acquisition in the HISTAR system. During the first phase of experimentation, the production from the HISTAR system was evaluated. Results from the production studies indicated that the volumetric production ranged between 46.46 ($\pm$ 7.85)-66.84 $\pm$ 27.03) gms-dry (m\sp3 day)\sp{-1} for the turbidostats, and 40.92 ($\pm$ 13.53)-59.52 ($\pm$21.78) gms-dry (m\sp3 day)\sp{-1} for the series of CFSTRs. During the second phase of testing, a set of experiments was conducted to practically test the contaminant washout in the series of CFSTRs. Results from the washout experiments clearly demonstrated that the hydraulic retention time in each individual CFSTR (\theta\sb{\rm n}) plays the key role in the contaminant mitigation process. The robustness and washout capabilities of the CFSTRs were demonstrated when the CFSTRs, that succumbed to the wrath of more than 300 million live (and multiplying) rotifers in the CFSTRs at a 36 hour individual HRT (\theta\sb{\rm n}), were completely revived by simply adopting a faster flow rate (6 hr HRT). Results from the algal contaminant washout studies demonstrated that the algal contaminants, including ones with growth rates higher than the desired algal growth rates, can be effectively washed out without affecting the desired algal densities

Optimizing the Air Dissolution Parameters in an Unpacked Dissolved Air Flotation System

Due to the various parameters that influence air solubility and microbubble production in dissolved air flotation (DAF), a multitude of values that cover a large range for these parameters are suggested for field systems. An unpacked saturator and an air quantification unit were designed to specify the effects of power, pressure, temperature, hydraulic retention time, and air flow on the DAF performance. It was determined that a pressure of 621 kPa, hydraulic retention time of 18.2 min, and air flow of 8.5 L/h would be the best controlled parameters for maximum efficiency in this unit. A temperature of 7 °C showed the greatest microbubble production, but temperature control would not be expected in actual application. The maximum microbubble flow from the designed system produced 30 mL of air (±1.5) per L of water under these conditions with immediate startup. The maximum theoretical dissolved air volume of 107 mL (±6) was achieved at a retention time of 2 h and a pressure of 621 kPa. To isolate and have better control over the various DAF operational parameters, the DAF unit was operated without the unsaturated flow stream. This mode of operation led to the formation of large bubbles at peak bubble production rates. In a real-world application, the large bubble formation will be avoided by mixing with raw unsaturated stream and by altering the location of dissolved air output flow

Harvesting economics and strategies using centrifugation for cost effective separation of microalgae cells for biodiesel applications

Inefficient or energy-intensive microalgal harvesting strategies for biodiesel production have been a major setback in the microalgae industry. Harvesting by centrifugation is generally characterized by high capture efficiency (\u3e90%) under low flow rates and high energy consumption. However, results from the present study demonstrated that by increasing the flow rates (\u3e1L/min), the lower capture efficiencies (\u3c90%) can be offset by the larger volumes of culture water processed through the centrifuge, resulting in net lower energy consumption. Energy consumption was reduced by 82% when only 28.5% of the incoming algal biomass was harvested at a rate of 18 L/min by centrifugation. Harvesting algal species with a high lipid content and high culture density could see harvesting costs of $0.864/L oil using the low efficiency/high flow rate centrifugation strategy as opposed to$4.52/L oil using numbers provided by the Department of Energy for centrifugation harvesting

Image-Based 3-Dimensional Characterization of Laryngotracheal Stenosis in Children

A bench scale hydrothermal liquefaction (HTL) system was tested using dairy manure to explore biooil production and waste treatment potential. Carbon monoxide was used as the process gas and sodium carbonate (Na(2)CO(3)) as catalyst. At a 350°C process temperature, the HTL unit produced 3.45 g (± 0.21) of acetone soluble oil fractions (ASF), with an average Higher Heating Value of 32.16 (± 0.23) MJ kg(-1). A maximum ASF yield of 4.8 g was produced at a process temperature of 350°C and 1g of catalyst. The best ASF yield corresponded to 67.6% of energy contained in the raw manure. GC-MS analysis of ASF indicated that the highest quantities of phenolic compounds were formed when 1g catalyst was used. Chemical Oxygen Demand (COD) reduction in the dischargeable slurry was as high as 75%. The results point to an alternative dairy waste treatment technology with a potential to generate transportable biooils

Evaluating coagulation pretreatment on poultry processing wastewater for dissolved air flotation

Eleven metal coagulants and one polyelectrolyte were assessed for their suitability in assisting a dissolved air flotation (DAF) system aimed at treating poultry processing wastewater. Preliminary jar tests determined that a combination of 800 mg/L of FeCl(3) (ferric chloride) and 900 mg/L of Floccin 1115 would provide the best treatment by removing at least 98% of the total suspended solids (TSS) and 97% of the volatile suspended solids (VSS), while providing a 97% increase in water clarity. Final flotation tests suggested that the flocculated particles could be carried to the surface with 40% recycle ratio of the DAF. The resulting supernatant indicated 94.7% increase in clarity (± 1.4%), 97.3% reduction in TSS (± 0.5%), 96.6% reduction in VSS (±1.1%), 91% reduction in chemical oxygen demand (COD), and nearly 100% removal of fats, oils, and greases (FOGs). Despite the high removal efficiencies, flotation was found not to be critically necessary for treatment because the high concentration of coagulants caused settling of the flocs to occur just as rapidly. Potential coagulant overdosing is suspected at the higher end of the tested coagulant concentrations due to limited alkalinity in the wastewater. However, lack of residual metal (coagulant) ions in water may be linked to reactions leading to phosphate precipitation. The exact effect of the competing phosphate reaction on treatment efficiency is not clearly evident from this present study

Quantification of Tars, Particulates, and Higher Heating Values in Gases Produced from a Biomass Gasifier

Syngas from biomass gasifiers contains impurities such as tars and particulates, which can create difficulties for the downstream processes (e.g., internal combustion engines and the Fischer-Tropsch process). To design an efficient and effective gas cleaning system, it is important to accurately quantify the tars and particulates. The absence of an ASTM procedure for tars and particulates produced from a gasifier led to the development and testing of the protocol presented in this study. Syngas was generated from woodchips using a pilot-scale downdraft gasifier, which was designed and constructed in-house. The sampled impurities were analyzed using mass gravimetry, solvent evaporation, and weight differential methods. The higher heating value of the exiting gases was estimated from the syngas composition. The average tar and particulate concentrations of the sample runs were 1.8 to 3.1 g/m3 and 5.2 to 6.4 g/m3, respectively. The higher heating values of the syngas ranged between 4.38 and 4.55 MJ/m3

Phenolic contents, antioxidant potential and associated colour in sweet sorghum syrups compared to other commercial syrup sweeteners

Design and performance of an amperometric biosensor for E. coli O157:H7 that is based on a common dissolved oxygen probe is discussed. Anti-E. coli O157:H7 antibody was conjugated to horseradish peroxidase and immobilized on a nitrocellulose membrane that was placed over the oxygen probe membrane using a custom-fabricated polyvinyl chloride (PVC) insert. Upon bacterial cell binding, a decrease in enzyme activity resulted in a change in oxygen concentration that was detected with a Clark-type oxygen electrode probe. Validation experiments determined the effect of the outer membrane and insert on the Clarke electrode performance and linearity, and the effects of stirring on sensor response. The mechanism of enzymatic disruption is presumably steric hindrance due to binding of the bacterial cell and conformational change in antibody structure. Sampling various dilutions of heat-sterilized E. coli O157:H7 cells in water, as little as 50 bacterial cells/mL could be detected in approximately 20 minutes of sampling and processing procedures. Bacterial concentrations from 0 to 5000 cells/mL were tested, with 2.52 mg/L +/- 0.37 mg/L equivalents of oxygen produced from as few as 50 cells/mL, versus 6.26 +/- 0.64 mg/L when no cells were present in solution. Overall, the developed amperometric biosensor technology offered an efficient means of detection primarily due to its ease of use, cost-effectiveness, portability, and amenability to incorporation at existing water quality gaging stations

Transcriptomic Profiling of Adipose Derived Stem Cells Undergoing Osteogenesis by RNA-Seq

Acute and chronic toxicity studies were conducted on Daphnia pulex using synthetic lead and arsenic water samples. For acute studies, solutions with 0.25, 0.5, 1.0, 2.0, 5.0 mg/L lead and arsenic along with a control were used. The chronic studies were conducted for 21 days using 0.25, 0.5, 1.0 mg/L lead and arsenic solutions along with a control. Results indicated that the LC50 (48 hour) was 4.0 and 3.4 mg/L for lead and arsenic, respectively. Results from chronic studies suggest that the exposure to lead solutions significantly (P \u3c 0.05) impaired the reproduction rates of Daphnia at the 1 mg/L concentration. However, the reproduction rates were enhanced at low concentrations of arsenic (up to 0.5 mg/L). A second chronic study was conducted to confirm this finding. Results from the second study indicated that lead exhibited significantly higher (P \u3c 0.05) toxicity at 0.5 mg/L concentration, while reproduction rates in all concentrations of arsenic solutions were not significantly different from the controls. Metal analysis on exposed Daphnia, following nitric acid digestion procedures, indicated that Daphnia bio-accumulated 75.3-97.2% of the lead added to the experimental containers. This high lead biouptake coupled with the fast growth, high reproduction rates, and short life cycle all suggest that a Daphnia-based remediation (growth and partial harvest) may a viable treatment alternative that is worth considering. However, further field studies have to be conducted to verify this alternative. Biouptake or sequestration by Daphnia of arsenic at all tested concentrations was negligible, thereby, suggesting selective uptake or sequestration by daphnia under the tested pH and temperature conditions