The Experts below are selected from a list of 10521 Experts worldwide ranked by ideXlab platform
Wen-cheng Liu - One of the best experts on this subject based on the ideXlab platform.
-
investigating the fate and transport of Fecal Coliform contamination in a tidal estuarine system using a three dimensional model
Marine Pollution Bulletin, 2017Co-Authors: Weibo Chen, Wen-cheng LiuAbstract:A three-dimensional Fecal Coliform transport model was developed and incorporated into a hydrodynamic and suspended sediment transport model to better understand the microbiological water quality in the tidal Tamsui River estuarine system of northern Taiwan, which includes three main tributaries: Dahan River, Xindian River, and Keelung River. The model was calibrated using the water level, salinity, suspended sediment concentration, and Fecal Coliform data measured in 2010. The predictive skill, a statistical approach, is used to evaluate the model performance. There was quantitatively good agreement between the simulation and measurement results. Further, the calibrated model underwent model sensitivity analysis by varying the model parameters which include the settling velocity, darkness decay rate, partition coefficient, and Fecal Coliform concentration in the sediment bed. The results indicated that the settling velocity played the most important role in affecting Fecal Coliform concentrations followed by partition coefficient, darkness decay rate, and Fecal Coliform concentration in the sediment bed. The model was also used to investigate the effects of salinity and suspended sediment on Fecal Coliform contamination. The salinity module was excluded in the simulations, resulting in an increase of Fecal Coliform concentration. However the effect of salinity on Fecal Coliform concentration is minor. If the suspended sediment transport was excluded in the simulations, the predicted results of Fecal Coliform concentration decrease to be underestimated the measured data. The modeling results revealed that the inclusion of the suspended sediment transport model in the simulations was of crucial importance because the Fecal Coliform concentrations were significantly influenced by the suspended sediment concentration in the estuarine system.
-
modeling Fecal Coliform contamination in a tidal danshuei river estuarine system
Science of The Total Environment, 2015Co-Authors: Wen-cheng Liu, Wenting Chan, Chihchieh YoungAbstract:A three-dimensional Fecal Coliform transport model was developed and incorporated into a hydrodynamic model to obtain a better understanding of local microbiological water quality in the tidal Danshuei River estuarine system of northern Taiwan. The model was firstly validated with the salinity and Fecal Coliform data measured in 2010. The concentration comparison showed quantitatively good agreement between the simulation and measurement results. Further, the model was applied to investigate the effects of upstream freshwater discharge variation and Fecal Coliform loading reduction on the contamination distributions in the tidal estuarine system. The qualitative and quantitative analyses clearly revealed that low freshwater discharge resulted in higher Fecal Coliform concentration. The Fecal Coliform loading reduction considerably decreased the contamination along the Danshuei River–Tahan Stream, the Hsintien Stream, and the Keelung River.
-
Modeling the transport and distribution of Fecal Coliform in a tidal estuary.
The Science of the total environment, 2012Co-Authors: Wen-cheng Liu, Wei-cher HuangAbstract:A laterally averaged two-dimensional Fecal Coliform transport model incorporated into hydrodynamic and salt modules was developed to simulate the fate and transport of Fecal Coliform in the tidal Danshui River estuary of northern Taiwan. We validated the developed model with measured data, including longitudinal velocity, salinity, and Fecal Coliform concentration, collected in 2000. The simulated results of current, salinity, and Fecal Coliform concentration quantitatively agreed well with the measured data. The model sensitivity analysis indicated that the mortality rate plays an important role in the distribution of Fecal Coliform concentrations along the tidal Danshui River estuary to Tahan Stream. The validated model was applied to investigate the effects of different freshwater discharges at upstream boundaries on the distributions of Fecal Coliform. The results revealed that low freshwater discharge resulted in a higher Fecal Coliform concentration at upstream reaches but had little influence on the downstream of the estuary.
Pierre Servais - One of the best experts on this subject based on the ideXlab platform.
-
Fecal Coliform removal in wastewater treatment plants studied by plate counts and enzymatic methods
Water Research, 2002Co-Authors: Isabelle George, P Crop, Pierre ServaisAbstract:Abstract Twelve wastewater treatment plants (WWTPs) were sampled in France and Belgium in 1999 and 2000 in order to estimate the Fecal Coliform (FC) removal efficiency of various types of treatment. Only one of these WWTPs was equipped with a specific step to eliminate microorganisms (UV disinfection preceded by sand filtration). FC abundance was measured in raw and treated sewage by plate counts on selective medium and rapid β - d -glucuronidase (GLUase)-based assays. Removal of culturable FC was the most efficient in treatments with high retention time (activated sludge process with nitrification and denitrification, lagooning), in biofiltration and in the treatment with a tertiary disinfection step. GLUase activity measurements showed the same removal pattern as plate counts except for UV disinfection, where no reduction of GLUase activity was measured. Specific loads of culturable FC and GLUase activity, i.e . daily amounts of culturable FC or GLUase activity in sewage per inhabitant-equivalent, were calculated in raw and treated wastewater for the different WWTPs.
-
Fecal Coliform removal in wastewater treatment plants studied by plate counts and enzymatic methods
Water Research, 2002Co-Authors: Isabelle George, P Crop, Pierre ServaisAbstract:Twelve wastewater treatment plants (WWTPs) were sampled in France and Belgium in 1999 and 2000 in order to estimate the Fecal Coliform (FC) removal efficiency of various types of treatment. Only one of these WWTPs was equipped with a specific step to eliminate microorganisms (UV disinfection preceded by sand filtration). FC abundance was measured in raw and treated sewage by plate counts on selective medium and rapid beta-D-glucuronidase (GLUase)-based assays. Removal of culturable FC was the most efficient in treatments with high retention time (activated sludge process with nitrification and denitrification, lagooning), in biofiltration and in the treatment with a tertiary disinfection step. GLUase activity measurements showed the same removal pattern as plate counts except for UV disinfection, where no reduction of GLUase activity was measured. Specific loads of culturable FC and GLUase activity, i.e. daily amounts of culturable FC or GLUase activity in sewage per inhabitant-equivalent, were calculated in raw and treated wastewater for the different WWTPs.
Diane S Herson - One of the best experts on this subject based on the ideXlab platform.
-
effect of total solids on Fecal Coliform regrowth in anaerobically digested biosolids
Water Research, 2008Co-Authors: Steven K Dentel, Diane S HersonAbstract:Fecal Coliform (FC) concentrations in anaerobically digested biosolids can increase during centrifugal dewatering and afterwards in storage of dewatered cake. The immediate increase after centrifugation (reactivation) has been demonstrated to be the revitalization of Fecal Coliforms that had become non-culturable. The increase during storage (regrowth) has been regarded as a subsequence of reactivated bacteria growing in a favorable environment. In this paper, however, regrowth is demonstrated without preceding reactivation, using intensive laboratory centrifugation to duplicate the levels of regrowth seen in full-scale centrifugation. Higher total solids (TS) levels of the dewatered biosolids lead to greater magnitudes of FC increase. The final TS level appears much more important than the level of shear imposed during centrifugation, based on comparison of different centrifugation/dilution procedures used to obtain similar TS levels. The greater TS levels also reduce methane production, suggesting that methanogens compete with, or inhibit, the Fecal Coliforms. The addition of bromoethanesulfonate as a methanogen-specific inhibitor decreased the production of methane gas, and also increased the number of Fecal Coliforms.
-
increases in Fecal Coliform bacteria resulting from centrifugal dewatering of digested biosolids
Water Research, 2007Co-Authors: Steven K Dentel, Diane S HersonAbstract:In many countries, the classification of biosolids for disposal purposes can be based, in part, on Fecal Coliform levels, with alternative criteria also available based on the stabilization process used, such as anaerobic digestion. The assumption that these alternative criteria provide equivalent protection may be flawed. This paper demonstrates that Fecal Coliform levels determined after digestion do not always indicate the bacterial levels after the same biosolids have been dewatered by centrifugation. In samples from mesophilic digestion, half had significant increases in Coliform numbers (P<0.05) with up to one order of magnitude increase during centrifugation, suggesting Coliform regrowth. Thermophilically digested samples had significant increases of several orders of magnitude during dewatering, more likely from reactivation of viable but non-culturable Coliforms than from regrowth. In other cases, centrifugation induced Coliform regrowth or reactivation upon incubation and storage of dewatered samples, but not digested samples. These 2-3 order of magnitude increases occurred with both 25 and 37 degrees C incubations. Coliform increases continued for up to 5 days, then gradually declined. However, by day 20 Coliform numbers were still 2 orders of magnitude greater than when originally sampled. The magnitude of the increases could be due either to regrowth or reactivation, but the nature of the longer-term increases--also seen in biosolids/soil mixtures--suggests regrowth. Differences in numbers between digested and dewatered samples could not be duplicated with high shear processing in lab-scale devices, with nitrogen purging to remove volatile or gaseous constituents, or with redilution using centrate. They could not be attributed to enumeration methods, to interference of Bacillus spp. on apparent Coliform counts, or to temperature changes. The increases have practical implications in the use of Fecal Coliform or alternative criteria to define pathogen content in biosolids.
-
reactivation and or growth of Fecal Coliform bacteria during centrifugal dewatering of anaerobically digested biosolids
Water Science and Technology, 2004Co-Authors: S Gillow, Diane S Herson, Steven K DentelAbstract:Fecal Coliform bacteria are used as indicator organisms for the presence of pathogens. In sludges, it has often been assumed that the counts of Fecal Coliforms after digestion (where the sludges may also be called biosolids) are representative of the counts when the sludge is disposed or recycled, such as by land application. The possibility has been raised, however, that dewatering processes can lead to increased counts of Fecal Coliforms and, by inference, human pathogens. This paper presents data from previous studies of this possibility; the results were inconsistent but showed observable increases in Fecal Coliforms at one treatment plant. Additional studies were then performed at another treatment facility, which showed statistically significant increases in Fecal Coliform counts after dewatering and two days of aging. The increases exceeded two orders of magnitude and included two centrifuge types and two biosolids types. Artifacts of media type and enumeration method have been excluded, and shearing of the material by commercial blender did not produce the same effects.
Paul B Tchounwou - One of the best experts on this subject based on the ideXlab platform.
-
the impact of rainfall on Fecal Coliform bacteria in bayou dorcheat north louisiana
International Journal of Environmental Research and Public Health, 2006Co-Authors: Dagne D Hill, William E Owens, Paul B TchounwouAbstract:Fecal Coliform bacteria are the most common pollutant in rivers and streams. In Louisiana, it has been reported that 37% of surveyed river miles, 31% of lakes, and 23% of estuarine water had some level of contamination. The objective of this research was to assess the effect of surface runoff amounts and rainfall amount parameters on Fecal Coliform bacterial densities in Bayou Dorcheat in Louisiana. Bayou Dorcheat has been designated by the Louisiana Department of Environmental Quality as a waterway that has uses such as primary contact recreation, secondary contact recreation, propagation of fish and wildlife, agriculture and as being an outstanding natural resource water. Samples from Bayou Dorcheat were collected monthly and analyzed for the presence of Fecal Coliforms. Fecal Coliforms isolated from these samples were identified to the species level. The analysis of the bacterial levels was performed following standard test protocols as described in Standard Methods for the Examination of Water and Wastewater. Information regarding the rainfall amounts and surface runoff amounts for the selected years was retrieved from the Louisiana Office of State Climatology. It was found that a significant increase in the Fecal Coliform numbers may be associated with average rainfall amounts. Possible sources of elevated Coliform counts could include sewage discharges from municipal treatment plants and septic tanks, storm water overflows, and runoff from pastures and range lands. It can be concluded that nonpoint source pollution that is carried by surface runoff has a significant effect on bacterial levels in water resources.
-
the seasonality of Fecal Coliform bacteria pollution and its influence on closures of shellfish harvesting areas in mississippi sound
International Journal of Environmental Research and Public Health, 2005Co-Authors: Paulinus Chigbu, Scott Gordon, Paul B TchounwouAbstract:Abstract: Runoff from agricultural lands and farm animal feedlots is one of the major sources of Fecal Coliforms in surface waters, and Fecal Coliform (FC) bacteria concentrations tend to vary with season because of seasonal variations in climatic factors. However, El Nino -Southern Oscillation (ENSO) events may affect the extent and patterns of seasonality in FC levels in coastal waters. Water quality monitoring data for shellfish management collected during El Nino (1990, 1992, 1997), and La Nina (1999, 2000) years were analyzed to evaluate the extent to which these events influenced Pearl River stage, and bacterial levels, water temperature, and salinity in the western part of Mississippi Sound. Models to predict FC levels in relation to various environmental factors were also developed. In 1990, 1992 and 1997, FC geometric mean counts peaked in late winter (January/February) reaching 120 MPN (February 1990), 165 MPN (January 1992), and 86 MPN (January 1997), and then decreased considerably during spring and summer (1.2 – 19 MPN). Thereafter, FC abundance increased slightly in fall and early winter (1.9 – 24 MPN). Fecal Coliform abundance during the 2000
Isabelle George - One of the best experts on this subject based on the ideXlab platform.
-
Fecal Coliform removal in wastewater treatment plants studied by plate counts and enzymatic methods
Water Research, 2002Co-Authors: Isabelle George, P Crop, Pierre ServaisAbstract:Abstract Twelve wastewater treatment plants (WWTPs) were sampled in France and Belgium in 1999 and 2000 in order to estimate the Fecal Coliform (FC) removal efficiency of various types of treatment. Only one of these WWTPs was equipped with a specific step to eliminate microorganisms (UV disinfection preceded by sand filtration). FC abundance was measured in raw and treated sewage by plate counts on selective medium and rapid β - d -glucuronidase (GLUase)-based assays. Removal of culturable FC was the most efficient in treatments with high retention time (activated sludge process with nitrification and denitrification, lagooning), in biofiltration and in the treatment with a tertiary disinfection step. GLUase activity measurements showed the same removal pattern as plate counts except for UV disinfection, where no reduction of GLUase activity was measured. Specific loads of culturable FC and GLUase activity, i.e . daily amounts of culturable FC or GLUase activity in sewage per inhabitant-equivalent, were calculated in raw and treated wastewater for the different WWTPs.
-
Fecal Coliform removal in wastewater treatment plants studied by plate counts and enzymatic methods
Water Research, 2002Co-Authors: Isabelle George, P Crop, Pierre ServaisAbstract:Twelve wastewater treatment plants (WWTPs) were sampled in France and Belgium in 1999 and 2000 in order to estimate the Fecal Coliform (FC) removal efficiency of various types of treatment. Only one of these WWTPs was equipped with a specific step to eliminate microorganisms (UV disinfection preceded by sand filtration). FC abundance was measured in raw and treated sewage by plate counts on selective medium and rapid beta-D-glucuronidase (GLUase)-based assays. Removal of culturable FC was the most efficient in treatments with high retention time (activated sludge process with nitrification and denitrification, lagooning), in biofiltration and in the treatment with a tertiary disinfection step. GLUase activity measurements showed the same removal pattern as plate counts except for UV disinfection, where no reduction of GLUase activity was measured. Specific loads of culturable FC and GLUase activity, i.e. daily amounts of culturable FC or GLUase activity in sewage per inhabitant-equivalent, were calculated in raw and treated wastewater for the different WWTPs.
