Water Washing (water + washing)

Distribution by Scientific Domains


Selected Abstracts


Flammability studies of sodium thiosulphate or metabisulphite impregnated wood using cone calorimeter

FIRE AND MATERIALS, Issue 2 2007
imkovic
Abstract Spruce wood boards impregnated with Na2S2O3 or Na2S2O5 were studied with the cone calorimeter. The presence of Na2S2O3 lowered the average heat release rate in comparison to untreated material. The total amounts of CO and CO2 production were reduced by the treatment and also the specific extinction area and mass loss rate decreased. Washing of the salt from the material with water caused partial loss of the properties. Addition of the second impregnation step using acids (HCOOH, H3BO3 or H3PO4) resulted in the fixation of the sulphur in wood, but gave not the results of single-step modification for thiosulphate. With Na2S2O5 and without acid, the CO and time-to-ignition values were higher and average heat release rate smaller in comparison to unmodified material. Combined one step Na2S2O5/H3BO3 treatment lowered the CO, CO2 and specific extinction area values in comparison to the modification with Na2S2O5, similarly like it was observed for Na2S2O3/H3BO3 two-step-treatment. According to time-to-ignition values, Na2S2O5 alone at 5% addition is a better flame retardant than Na2S2O3 at 7%, but the effect is diminished at 10% amount or presence of acids. The total smoke release curves showed decrease due to modification in both phases of the process. Introduction of water washing as well as the acid treatment further lowered the values. The best results were achieved with 15% Na2S2O3,2% H3PO4,H2O system. According to the total smoke release curve the specimen produced more than five times smaller amount of smoke than untreated material in the first phase of the process. It seams that the concentration of Na2S2O5 is less affecting the properties than the synergistic effect of the Na2S2O3 or Na2S2O5/H3BO3 system. Although the level of smoke is low, the presence of elemental sulphur causes smaller times-to-ignition than on starting material. Copyright 2006 John Wiley & Sons, Ltd. [source]


Hydrologic and geochemical controls on soluble benzene migration in sedimentary basins

GEOFLUIDS (ELECTRONIC), Issue 2 2005
Y. ZHANG
Abstract The effects of groundwater flow and biodegradation on the long-distance migration of petroleum-derived benzene in oil-bearing sedimentary basins are evaluated. Using an idealized basin representation, a coupled groundwater flow and heat transfer model computes the hydraulic head, stream function, and temperature in the basin. A coupled mass transport model simulates water washing of benzene from an oil reservoir and its miscible, advective/dispersive transport by groundwater. Benzene mass transfer at the oil,water contact is computed assuming equilibrium partitioning. A first-order rate constant is used to represent aqueous benzene biodegradation. A sensitivity study is used to evaluate the effect of the variation in aquifer/geochemical parameters and oil reservoir location on benzene transport. Our results indicate that in a basin with active hydrodynamics, miscible benzene transport is dominated by advection. Diffusion may dominate within the cap rock when its permeability is less than 10,19 m2. Miscible benzene transport can form surface anomalies, sometimes adjacent to oil fields. Biodegradation controls the distance of transport down-gradient from a reservoir. We conclude that benzene detected in exploration wells may indicate an oil reservoir that lies hydraulically up-gradient. Geochemical sampling of hydrocarbons from springs and exploration wells can be useful only when the oil reservoir is located within about 20 km. Benzene soil gas anomalies may form due to regional hydrodynamics rather than separate phase migration. Diffusion alone cannot explain the elevated benzene concentration observed in carrier beds several km away from oil fields. [source]


Evaluation of soluble benzene migration in the Uinta Basin

GEOFLUIDS (ELECTRONIC), Issue 2 2005
Y. ZHANG
Abstract Field sampling and mathematical modeling are used to study the long-distance transport and attenuation of petroleum-derived benzene in the Uinta Basin, Utah. Benzene concentration was measured from oil and oil field formation waters of the Altamont-Bluebell and Pariette Bench oil fields in the basin. It was also measured from springs located in the regional groundwater discharge areas, hydraulically down-gradient from the oil fields sampled. The average benzene concentration in oils and co-produced waters is 1946 and 4.9 ppm at the Altamont-Bluebell field and 1533 and 0.6 ppm at the Pariette Bench field, respectively. Benzene concentration is below the detection limit in all springs sampled. Mathematical models are constructed along a north,south trending transect across the basin through both fields. The models represent groundwater flow, heat transfer and advective/dispersive benzene transport in the basin, as well as benzene diffusion within the oil reservoirs. The coupled groundwater flow and heat transfer model is calibrated using available thermal and hydrologic data. We were able to reproduce the observed excess fluid pressure within the lower Green River Formation and the observed convective temperature anomalies across the northern basin. Using the computed best-fit flow and temperature, the coupled transport model simulates water washing of benzene from the oil reservoirs. Without the effect of benzene attenuation, dissolved benzene reaches the regional groundwater discharge areas in measurable concentration (>0.01 ppm); with attenuation, benzene concentration diminishes to below the detection limit within 1,4 km from the reservoirs. Attenuation also controls the amount of water washing over time. In general, models that represent benzene attenuation in the basin produce results more consistent with field observations. [source]


FREQUENCY OF SALMONELLA, CAMPYLOBACTER, LISTERIA AND ENTEROBACTERIACEAE DETECTION IN COMMERCIALLY COOL WATER-WASHED SHELL EGGS

JOURNAL OF FOOD SAFETY, Issue 4 2006
DEANA R. JONES
ABSTRACT The effect of cool water washing on shell egg temperature and pathogen detection was examined. Three temperature schemes were utilized in commercial dual washer systems: (1) HH = 48.9C, 48.9C; (2) HC = 48.9C, 23.9C; and (3) CC = 23.9C, 23.9C. HH eggsmaintainedthe highest surface temperature (26.25C in-line, 20.25C off-line and 23.25C combined, P < 0.05). The lowest temperatures were found in the CC eggs (21.25C in-line, 17.25C off-line and 19.25C combined). The frequency of Enterobacteriaceae detection in shell and membrane emulsions was greatest for the CC eggs (P < 0.05 for in-line and combined). There was no difference in Enterobacteriaceae detection for the off-line facility. Salmonella was detected in three of 384 samples from the in-line facility. They were found in HC (2) and CC (1) shell emulsions. Two of 384 samples were positive for Campylobacter from the in-line facility (CC). Three wash water samples were positive for Listeria in the off-line facility (1 HC, 2 CC). No pathogens were detected in the egg contents during this study. The results of this study indicate that warm followed by cool water washing has the potential of decreasing egg temperature while maintaining surface microbiology at an acceptable level. [source]


MAIN FACTORS CONTROLLING THE COMPOSITIONAL VARIABILITY OF SEEPAGE OILS FROM TRUJILLO STATE, WESTERN VENEZUELA

JOURNAL OF PETROLEUM GEOLOGY, Issue 3 2010
F. Galarraga
The organic geochemistry of eighteen samples of seepage oils from Trujillo State, Western Venezuela, was investigated. These oils are probably derived from the predominantly marine Cretaceous La Luna Formation which is near peak maturity for oil generation. A range of biomarkers (n-alkanes, acyclic isoprenoids, phenanthrene and alkyl-phenanthrenes, as well as dibenzothiophene and alkyl-dibenzothiophenes) were analysed by gas chromatography - mass spectrometry (GC-MS). The seepage oils have been modified as a result of water washing and biodegradation. A first group of samples were slightly biodegraded with the partial loss of n- and iso-alkanes. Other samples fall into two groups: those that are moderately degraded, with partial depletion of acyclic isoprenoids; and those that are severely altered, as indicated by the partial or total absence of hopanes. One objective of this work was to evaluate the factors influencing the compositional differences of the three samples sets. In-situ measurements, together with the interpretation of the geochemical data, suggest that diverse factors were responsible for these variations. These included different degrees of alteration due to biodegradation and water washing, as well as differences in flow rate towards the surface. [source]