Electrochemical Treatment of Textile Dye Bath Wastewater Using Activated Carbon Cloth Electrodes

The performance of electrooxidation (EO) treatment using activated carbon cloth (ACC) electrodes on textile dye bath wastewater was investigated. ACC electrode pairs were used as anode/cathode for EO experiments. The effect of current density (50–150 A/m2 ), operating time (0–90 minutes), and solution pH (6-11) were tested for removal of chemical oxygen demand (COD), color, and chloride, as well as the changes in conductivity. 95.5% COD and color removal efficiencies were obtained at current density (CD) of 100 A/m2 at solution pH of 10 for 90 minutes. Moreover, the chloride concentration decreased from 4254 to 35.5 mg/L and solution conductivity decreased from 160 to 131 mS/cm at the same conditions. Operating cost of the EO process was calculated to be 3.13 US$/m3 for 36 kWh/m3 energy consumption. The results indicated that the EO process with ACC electrodes achieved high pollutant removal from textile dye bath wastewater

Processes in model slopes made of mixtures of wettable and water repellent sand: Implications for the initiation of debris flows in dry slopes

Debris flows in slopes initially dry, such as post-wildfire debris flows, are initiated by surface runoff and sediment bulking due to reduced infiltration. Soil water repellency, extreme dry soils, and loose, cohesionless materials influence their initiation. The exact link between these features, the resulting infiltration processes and the initiation mechanism of a debris flow remains unclear. Here, we examine the relation between soil particle wettability and slope processes in physical models. Flume experiments were conducted in 10% increments of mass ratios of wettable to water repellent sand, subjected to artificial rainfall with monitoring of soil water content, pore water pressure, sediment and water discharge and failure mode. To date, wettability was considered only for the water repellent end, because it reduces infiltration, enhancing surface runoff. This study demonstrates that slight wettability changes, in the full wettable to water repellent range, impact a variety of slope processes. The two extremes, fully wettable and water repellent gave opposite responses, retrogressive slides for infiltration-initiated in wettable sand and erosion by surface runoff in water repellent sand. The transition was dominated by surface runoff and preferential flow, yielding a combination of erosion and slides. From the tests, a continuous capping effect generated by water repellency was a necessary condition for erosion and sand bulking i.e., the generation of runoff-initiated debris flows. The sensitivity of the model slope response to artificial rainfall was particularly acute at high ratios of wettable to water repellent sand. For mixtures above a critical ratio of wettable to water repellent sand, the measurements with an index test revealed a fully wettable material despite differences in the infiltration, saturation and pore water pressure built-up trends. Implications for post-wildfire debris flows and debris flows in slopes initially dry in general are discussed.postprin

Surfactant and irrigation effects on wettable soils: runoff, erosion, and water retention responses

Surfactants are chemical compounds that change the contact angle of water on solid surfaces and are commonly used to increase infiltration into hydrophobic soil. Since production fields with water-repellent soil often contain areas of wettable soil, surfactants applied to such fields will likely be applied to wettable soil, with unknown consequences for irrigation-induced erosion, runoff, or soil water relations. We evaluated surfactant and simulated sprinkler irrigation effects on these responses for three wettable, Pacific Northwest soils, Latahco and Rad silt loams and Quincy sandy loam. We studied three surfactants: an alkyl polyglycoside in solution at a concentration of 18 g a.i./kg, a block copolymer at 26 g/kg, and a blend of the two at 43 g/kg. From 2005 to 2009 in the laboratory, each surfactant was sprayed at a rate of 46.8 L/ha onto each soil packed by tamping into 1.2- by 1.5-m steel boxes. Thereafter, each treated soil was irrigated twice at 88 mm/h with surfactant–free, well water. Runoff and sediment loss were measured for each irrigation and soil samples were collected after each irrigation. While measured properties differed among soils and irrigations, surfactants had no effect on runoff, sediment loss, splash loss, time to runoff, or tension infiltration, compared to controls. Across all soils, however, the alkyl polyglycoside increased volumetric water contents by about 3% (significant at P less than or equal to 0.08) at matric potentials from 0 to -20 kPa, compared to controls. With a decrease in the liquid-solid contact angle on treated soil surfaces, surfactant–free water appeared able to enter, and be retained in pores with diameters greater than or equal to 15 mm. All in all, surfactants applied at economic rates to these wettable Pacific Northwest soils posed little risk of increasing either runoff or erosion or harming soil water relations. Moreover, by increasing water retention at high potentials, surfactants applied to wettable soils may allow water containing pesticides or other agricultural chemicals to better penetrate soil pores, thereby increasing the efficacy of the co-applied materials

Influence of surfactants on the sorption and transport of contaminants in saturated and unsatruated soils

Ph.D.Kurt D. Pennel

Soluble Microbial Products Removal Profile and Morphological Assessment of Submerged Ultrafiltration Membrane

Performance of ultrafiltration membranes were investigated with submerged membrane in terms of removal of soluble microbial products (SMP) (as proteins and carbohydrates) and fouling mechanisms. Cellulose (UC) and polyethersulphone (UP) membranes with different molecular weight cut off (MWCO) (5, 10, 30 kDa for UC and 5, 10, 20 kDa for UP) were tested in the bioreactor. The quality of permeate was compared in terms of SMP and COD. There was no significant difference in the total SMP removal effectives for both the UC and UP membranes with different MWCO characteristics. However, UP membranes were relatively more effective in removing soluble carbohydrates, while UC membranes were more effective in removing soluble proteins. The submerged membrane bioreactor achieved organic removal efficiencies ranging from 98.1±0.2% to 99.2±0.3% based on the soluble COD levels. Analysis of the membrane performance data by resistances-in-series model indicated that cake fouling was the dominant membrane fouling mechanisms. Increasing the MWCO was resulted in higher membrane flux but lower SMP removal. Morphological examination of the membranes by SEM and AFM showed significant accumulation of organisms on the membrane surface

Freeze-Drying as Sample Preparation for Micellar Electrokinetic Capillary Chromatography-Electrochemical Separations of Neurochemicals in Drosophila Brains

Micellar electrokinetic capillary chromatography with electrochemical detection has been used to quantify biogenic amines in freeze-dried brains of Drosophila melanogaster. Freeze-drying samples offers a way to preserve the biological sample while making dissection of these tiny samples easier and faster. Fly samples were extracted in cold acetone and dried in a rotary evaporator. Extraction and drying times were optimized in order to avoid contamination by red pigment from the fly eyes and still have intact brain structures. Single freeze-dried fly brain samples were found to produce representative electropherograms as a single hand-dissected brain sample. With utilization of the faster dissection time that freeze-drying affords, the number of brains in a fixed homogenate volume can be increased to concentrate the sample. Thus, concentrated brain samples containing five or fifteen preserved brains were analyzed for their neurotransmitter content, and four analytes; N-acetyloctopamine, N-acetylserotonin, N-acetyltyramine, and N-acetyldopamine were found to correspond well with previously reported values