Safe drinking water is essential for human health, yet over a billion people worldwide do not hav... more Safe drinking water is essential for human health, yet over a billion people worldwide do not have access to safe drinking water. Due to the presence and accumulation of biological contaminants in natural waters (e.g., pathogens and neuro-, hepato-, and cytotoxins associated with algal blooms) remain a critical challenge in the provision of safe drinking water globally. It is not financially feasible and practical to monitor and quantify water quality frequently enough to identify the potential health risk due to contamination, especially in developing countries. We propose a low-cost, small-profile multispectral (MS) system based on Digital Holographic Microscopy (DHM) and investigate methods for rapidly capturing holographic data of natural water samples. We have developed a test-bed for an MSDHM instrument to produce and capture holographic data of the sample at different wavelengths in the visible and the near Infra-red spectral region, allowing for resolution improvement in the reconstructed images. Additionally, we have developed high-speed statistical signal processing and analysis techniques to facilitate rapid reconstruction and assessment of the MS holographic data being captured by the MSDHM instrument. The proposed system is used to examine cyanobacteria as well as Cryptosporidium parvum oocysts which remain important and difficult to treat microbiological contaminants that must be addressed for the provision of safe drinking water globally.
Microbial contamination of groundwater by viruses, bacteria, and parasitic protozoa is a signific... more Microbial contamination of groundwater by viruses, bacteria, and parasitic protozoa is a significant human health problem when drinking water supplies are untreated or inadequately treated. The decision to treat groundwater supplies, if sufficient resources are available, often depends on the adequacy of pathogen and indicator organism attenuation in the subsurface. Microbial fate and transport processes govern attenuation in the subsurface. Hence, a thorough understanding of the mechanisms and factors affecting the fate and transport of microbial contaminants in the subsurface environment is essential for the protection of public health from waterborne disease. First, the various sources and types of microbial contaminants found in the subsurface are presented. Sources of microbial contaminants may be zoogenic (e.g., wildlife) or anthropogenic (e.g., septic systems). Second, the surrogates and indicators most commonly used to assess microbial transport and fate in groundwater are discussed. These include pathogenic and nonpathogenic bacteria, bacteriophage, and microbe-sized microspheres. Next, the key processes governing microbial fate and transport are described. Microbial transport is mainly controlled by advection, whereas the key processes governing the fate of microorganisms are retention onto aquifer solid surfaces and inactivation (or survival) of the microbes. Groundwater chemistry and moisture content are identified as two of the main physicochemical factors that influence the retention and survival of microorganisms in the subsurface. Finally, the importance of linking this fundamental science to the development of appropriate public policy and land use strategy is highlighted.
Journal American Water Works Association, Dec 1, 2005
This article consolidates and updates available information on Cryptosporidium removal by filtrat... more This article consolidates and updates available information on Cryptosporidium removal by filtration, with a focus on optimal and suboptimal filtration performance. Emphasis was placed on integrating various strategies for optimizing filtration processes with the most current information regarding pathogen removal by filtration. As this review underscores, in response to regulations such as the Interim Enhanced Surface Water Treatment Rule (IESWTR) and the Long Term 2 ESWTR, there is a need to develop methods to compare the relative effectiveness of treatment alternatives and to understand the most significant operational effects on filter performance. In many cases, filters operated at or near optimal conditions can achieve in the vicinity of 3‐log (or better) removal of Cryptosporidium. Operational conditions such as coagulant upsets and end‐of‐run (early breakthrough) filtration may significantly decrease oocyst removal by drinking water filters, even when filter effluent turbidities are low (<0.3 ntu).
This investigation examined the removal of Cryptosporidium and several surrogates by granular med... more This investigation examined the removal of Cryptosporidium and several surrogates by granular medium filtration. The study focused on coagulation impacts on removals. Inactivated C. parvum oocysts and non-inactivated Bacillus subtilis were seeded in two pilot plants. The pilot plant locations were chosen to represent different coagulation regimes. Under optimized coagulation conditions (filter effluent turbidity < 0.1 NTU), approximately 5 log10 removal of Crypto. was obtained in one location, and approximately 3 log10 in the other. This difference is likely related at least in part to the difference in coagulation regimes. Suboptimal coagulation produced a substantial deterioration of Crypto. removal in both locations. The trends seen for Bacillus were generally similar to those observed for Crypto.. Although turbidity may be of value for assessing coagulation impacts on Crypto. removal, particle counts may be a more sensitive parameter in this regard.
Journal American Water Works Association, May 1, 2003
Pilot‐scale studies were performed to evaluate Cryptosporidium parvum oocyst removal by a dual‐me... more Pilot‐scale studies were performed to evaluate Cryptosporidium parvum oocyst removal by a dual‐media filter during optimized, end‐of‐run, and breakthrough operating conditions. Oocyst‐sized polystyrene microspheres were also evaluated as surrogates for C. parvum removal by filtration. At optimal conditions, the pilot‐scale filter consistently achieved ~5‐log removal of C. parvum and microspheres. During end‐of‐run operation when filter effluent turbidity levels were &lt;0.1 ntu, median oocyst removals deteriorated to ~3 log. During early (0.1–0.3 ntu) and late (&gt;0.3 ntu) breakthrough, filtration oocyst removals deteriorated to ~2.1 and ~1.4 log, respectively. Microsphere removals by filtration were similar to oocyst removals during both stable and challenged operating periods, suggesting that microspheres are useful surrogates for investigating C. parvum removal.
... Filter Operation Effects on Pathogen Prepared by: Peter M. Huck and Monica B. Emeiko NSERC Ch... more ... Filter Operation Effects on Pathogen Prepared by: Peter M. Huck and Monica B. Emeiko NSERC Chair in Water Treatment, Department of ... mg/L polymer present) 191 Figure 7.12 Influent turbidity and coagulant dosages for full-scale testing at MWD's FE Weymouth filtration plant ...
Safe drinking water is essential for human health, yet over a billion people worldwide do not hav... more Safe drinking water is essential for human health, yet over a billion people worldwide do not have access to safe drinking water. Due to the presence and accumulation of biological contaminants in natural waters (e.g., pathogens and neuro-, hepato-, and cytotoxins associated with algal blooms) remain a critical challenge in the provision of safe drinking water globally. It is not financially feasible and practical to monitor and quantify water quality frequently enough to identify the potential health risk due to contamination, especially in developing countries. We propose a low-cost, small-profile multispectral (MS) system based on Digital Holographic Microscopy (DHM) and investigate methods for rapidly capturing holographic data of natural water samples. We have developed a test-bed for an MSDHM instrument to produce and capture holographic data of the sample at different wavelengths in the visible and the near Infra-red spectral region, allowing for resolution improvement in the reconstructed images. Additionally, we have developed high-speed statistical signal processing and analysis techniques to facilitate rapid reconstruction and assessment of the MS holographic data being captured by the MSDHM instrument. The proposed system is used to examine cyanobacteria as well as Cryptosporidium parvum oocysts which remain important and difficult to treat microbiological contaminants that must be addressed for the provision of safe drinking water globally.
Microbial contamination of groundwater by viruses, bacteria, and parasitic protozoa is a signific... more Microbial contamination of groundwater by viruses, bacteria, and parasitic protozoa is a significant human health problem when drinking water supplies are untreated or inadequately treated. The decision to treat groundwater supplies, if sufficient resources are available, often depends on the adequacy of pathogen and indicator organism attenuation in the subsurface. Microbial fate and transport processes govern attenuation in the subsurface. Hence, a thorough understanding of the mechanisms and factors affecting the fate and transport of microbial contaminants in the subsurface environment is essential for the protection of public health from waterborne disease. First, the various sources and types of microbial contaminants found in the subsurface are presented. Sources of microbial contaminants may be zoogenic (e.g., wildlife) or anthropogenic (e.g., septic systems). Second, the surrogates and indicators most commonly used to assess microbial transport and fate in groundwater are discussed. These include pathogenic and nonpathogenic bacteria, bacteriophage, and microbe-sized microspheres. Next, the key processes governing microbial fate and transport are described. Microbial transport is mainly controlled by advection, whereas the key processes governing the fate of microorganisms are retention onto aquifer solid surfaces and inactivation (or survival) of the microbes. Groundwater chemistry and moisture content are identified as two of the main physicochemical factors that influence the retention and survival of microorganisms in the subsurface. Finally, the importance of linking this fundamental science to the development of appropriate public policy and land use strategy is highlighted.
Journal American Water Works Association, Dec 1, 2005
This article consolidates and updates available information on Cryptosporidium removal by filtrat... more This article consolidates and updates available information on Cryptosporidium removal by filtration, with a focus on optimal and suboptimal filtration performance. Emphasis was placed on integrating various strategies for optimizing filtration processes with the most current information regarding pathogen removal by filtration. As this review underscores, in response to regulations such as the Interim Enhanced Surface Water Treatment Rule (IESWTR) and the Long Term 2 ESWTR, there is a need to develop methods to compare the relative effectiveness of treatment alternatives and to understand the most significant operational effects on filter performance. In many cases, filters operated at or near optimal conditions can achieve in the vicinity of 3‐log (or better) removal of Cryptosporidium. Operational conditions such as coagulant upsets and end‐of‐run (early breakthrough) filtration may significantly decrease oocyst removal by drinking water filters, even when filter effluent turbidities are low (&lt;0.3 ntu).
This investigation examined the removal of Cryptosporidium and several surrogates by granular med... more This investigation examined the removal of Cryptosporidium and several surrogates by granular medium filtration. The study focused on coagulation impacts on removals. Inactivated C. parvum oocysts and non-inactivated Bacillus subtilis were seeded in two pilot plants. The pilot plant locations were chosen to represent different coagulation regimes. Under optimized coagulation conditions (filter effluent turbidity < 0.1 NTU), approximately 5 log10 removal of Crypto. was obtained in one location, and approximately 3 log10 in the other. This difference is likely related at least in part to the difference in coagulation regimes. Suboptimal coagulation produced a substantial deterioration of Crypto. removal in both locations. The trends seen for Bacillus were generally similar to those observed for Crypto.. Although turbidity may be of value for assessing coagulation impacts on Crypto. removal, particle counts may be a more sensitive parameter in this regard.
Journal American Water Works Association, May 1, 2003
Pilot‐scale studies were performed to evaluate Cryptosporidium parvum oocyst removal by a dual‐me... more Pilot‐scale studies were performed to evaluate Cryptosporidium parvum oocyst removal by a dual‐media filter during optimized, end‐of‐run, and breakthrough operating conditions. Oocyst‐sized polystyrene microspheres were also evaluated as surrogates for C. parvum removal by filtration. At optimal conditions, the pilot‐scale filter consistently achieved ~5‐log removal of C. parvum and microspheres. During end‐of‐run operation when filter effluent turbidity levels were &lt;0.1 ntu, median oocyst removals deteriorated to ~3 log. During early (0.1–0.3 ntu) and late (&gt;0.3 ntu) breakthrough, filtration oocyst removals deteriorated to ~2.1 and ~1.4 log, respectively. Microsphere removals by filtration were similar to oocyst removals during both stable and challenged operating periods, suggesting that microspheres are useful surrogates for investigating C. parvum removal.
... Filter Operation Effects on Pathogen Prepared by: Peter M. Huck and Monica B. Emeiko NSERC Ch... more ... Filter Operation Effects on Pathogen Prepared by: Peter M. Huck and Monica B. Emeiko NSERC Chair in Water Treatment, Department of ... mg/L polymer present) 191 Figure 7.12 Influent turbidity and coagulant dosages for full-scale testing at MWD's FE Weymouth filtration plant ...
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