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Introduction
Publications
Publications (38)
The specific focus of this study was on the effects of flocculation duration, intensity, and scheme (i.e., single or multistage) on floc formation (time and size) and treated turbidity (settled and filtered). The results showed that floc formation times were 2–8 times longer under charge neutralization conditions compared with sweep flocculation co...
This presentation will demonstrate a next-generation jar test procedure which uses a single-variable optimization approach along with a granular media filtration system to optimize coagulation conditions (i.e. dose and pH). The role of mixing in the coagulation and flocculation processes under different coagulation mechanisms will be discussed. The...
The electrophoretic mobilities (EPM’s) of fifteen different microbes (6 viruses, 5 vegetative bacteria, 2 bacterial endospores, 2 protozoa) and one microbial particle surrogate (Polystyrene microspheres) were measured, and five models were used to convert EPM's of these microorganisms to zeta potentials. The Helmholtz-Smoluchowski, Hückel-Onsager,...
Jar testing is a reliable tool for optimizing coagulation conditions (i.e. dose and pH) in drinking water treatment. Optimizing coagulation conditions through settling, as is the case with most conventional jar test or plant-scale optimization procedures, typically leads to overdosing chemicals. Our next-generation jar test procedure uses a single-...
Turbidity reduction by coagulation-flocculation in drinking water reduces microbes and organic matter, increasing effectiveness of downstream treatment. Chitosan is a promising household water coagulant, but needs parameters for use. This study tested the effects of chitosan dose, molecular weight (MW), degree of deacetylation (DD), and functional...
The challenge of providing safe and reliable drinking water is being exacerbated by accelerating population growth, climate change, and the increase of natural and anthropogenic contamination. Current water treatment plants are not effective at the removal of pervasive, hydrophilic, low molecular weight contaminants, which can adversely affect huma...
The primary objective of this study was to conduct a quantitative analysis of the hydraulic efficiency of a 1:25 bench-scale swimming pool and to determine whether the recirculation efficiency could be increased by modifying parameters such as turnover rate, inlet/out configuration, and extent of mixing within the pool. Salt tracer studies were con...
Removal of Cryptosporidium-sized microspheres and Cryptosporidium parvum oocysts from swimming pools was investigated using diatomaceous earth (DE) precoat filtration and perlite-sand filtration. In pilot-scale experiments, microsphere removals of up to 2 log were obtained with 0.7 kg DE/m² at a filtration rate of 5 m/h. A slightly higher microsphe...
Removal of Cryptosporidium parvum oocysts and Cryptosporidium -sized microspheres was evaluated in full-scale swimming pools via high-rate sand filtration (31–34 m/h) with coagulation. Results showed that at least 90% of C. parvum oocysts and microspheres were removed by filtration with an initial dosage of coagulant B (1.56 mg/L), D (1.9 mg/L or 3...
The goal of this study was to investigate the removal of organics and disinfection by-product (DBP) precursors in an optimized pilot-scale hybrid coagulation-ceramic membrane system treating two surface waters with low specific ultraviolet values (SUVA254 < 3 L/mg-m). The average removal of dissolved organic carbon was 30% with coagulation pretreat...
A case study was conducted to evaluate the seasonal performance of conventional and phosphate-amended biologically active filtration (BAF). Performance was evaluated in terms of general water quality parameters, disinfection by-product (DBP) precursors, and operational parameters. BAF successfully reduced dissolved organic carbon and dissolved orga...
As human health concerns over disinfection byproducts (DBP) in drinking water increase, so does the need to development new materials that remove them rapidly and at high-capacity. Ion exchange (IEX) is an effective method for the removal of natural organic matter (NOM), especially anion exchange resins (AERs) with quaternary ammonium functional gr...
Cryptosporidium species are the most common cause of gastrointestinal illness in treated recreational water venues. In order to protect public health during swimming, Cryptosporidium-sized microsphere removals by high-rate sand filtration with six coagulants were evaluated with a 5.5 m3 pilot-scale swimming pool. A sand filter without coagulation r...
The goal of this project was to identify optimal coagulation pretreatment conditions and cleaning protocols in a pilot-scale ceramic membrane system. A matrix of coagulation conditions (coagulant dose and pH) was investigated using aluminum sulfate and ferric chloride at two source waters (river and lake). Increasing backwash frequency to every 30...
USEPA Method 1623 is the standard method in the United States for the detection of Cryptosporidium in water samples, but quantitative real-time polymerase chain reaction (qPCR) is an alternative technique that has been successfully used to detect Cryptosporidium in aqueous matrices. This study examined various modifications to a commercial nucleic...
The use of United States Environmental Protection Agency (USEPA) Method 1623 for the detection of Cryptosporidium in water often results in low and variable rates of recovery. According to data disseminated in Method 1623, less than a quarter of tested surface water samples had Cryptosporidium recoveries of 60% or greater. This research explored va...
The EPA method 1623 is designed specifically for the detection of Cryptosporidium and Giardia, but the method has some issues with low and variable recoveries. Ultrafiltration has been used effectively for microorganism recovery from water samples but is not approved by the EPA. To determine the efficacy of using ultrafiltration, 10-L tap water and...
Cryptosporidium has caused the majority of waterborne disease outbreaks in treated recreational water venues in the USA for many years running. This research project evaluated some common US swimming pool filters for removing Cryptosporidium oocysts, 5-µm diameter polystyrene microspheres, and 1-µm diameter polystyrene microspheres. A 946 L hot tub...
The goal of this project was to identify optimal coagulation pretreatment conditions and cleaning protocols in a pilot-scale ceramic membrane system. A matrix of coagulation conditions (coagulant dose and pH) was investigated using aluminum sulfate and ferric chloride at two source waters (river and lake). Increasing backwash frequency to every 30...
Waterborne disease outbreaks in U.S. swimming pools have been increasing in recent years, and the majority of the outbreaks are caused by Cryptosporidium oocysts. This research project evaluates sand filtration for swimming pools without and with an amendment, perlite. The evaluation was formed on the basis of removing 5-μm polystyrene microspheres...
Cryptosporidium is a chlorine-resistant protozoan parasite responsible for the majority of waterborne disease outbreaks in recreational water venues in the USA. Swim diapers are commonly used by diaper-aged children participating in aquatic activities. This research was intended to evaluate disposable swim diapers for retaining 5-μm diameter polyst...
Hollow-fiber ultrafiltration (UF) is a technique that is increasingly viewed as an effective alternative for simultaneously recovering diverse microbes (e.g., viruses, bacteria, parasites) from large volumes of drinking water. The USEPA has organism-specific methods, including Method 1623 for Cryptosporidium and Giardia and the virus adsorption-elu...
This study focused on ultrafiltration as a technique for simultaneously concentrating and recovering viruses, bacteria and parasites in 100-L drinking water samples. A chemical dispersant, sodium polyphosphate, and Tween 80 were used to increase microbial recovery efficiencies. Secondary concentration was performed to reduce sample volumes to 3-5 m...
The current project explored various modifications to United States Environmental Protection Agency Method 1623. Method 1623 is a performance-based method for the analysis of Cryptosporidium and Giardia in water. The various modifications that were tested included: filter type, slide type, methanol fixation, elution buffer, IFA kit, and sample resu...
The long-term performance of granular media filters used in drinking water treatment is ultimately limited by the efficiency of the backwash process. This paper demonstrates that it is possible to develop quantitative predictions of backwash efficiency based on filter operating conditions. An experimental investigation into the effect of backwash r...
Removal of Cryptosporidium oocysts from drinking water is essential because of their potential to cause waterborne disease outbreaks. Removal is challenging, however, because of their prevalence in natural waters and resistance to chlorine disinfection. Detection of Cryptosporidium in drinking water samples is expensive, slow, and frequently unreli...
The ability to simultaneously concentrate diverse microbes is an important consideration for sample collection methods that are used for emergency response and environmental monitoring when drinking water may be contaminated with an array of unknown microbes. This study focused on developing a concentration method using ultrafilters and different c...
Extended terminal subfluidization wash (ETSW) is an advanced granular media filter backwashing strategy that can be employed for reducing or even eliminating the filter ripening turbidity spikes commonly encountered immediately after restarting a backwashed filter. ETSW is based on sound scientific principles, but there is not yet sufficient data a...
A new filter backwashing strategy, extended terminal subfluidization wash (ETSW), aimed at reducing particle passage into the filtered water during the initial filter ripening sequence immediately following backwashing has been evaluated on pilot-scale filters at a conventional water treatment plant using alum as the sole coagulant. Turbidities and...
The increased passage of particles and microorganisms through granular media filters immediately following backwashing is a common problem known to the water treatment community as filter "ripening" or maturation. While several strategies have been developed over the years to reduce the impact of this vulnerable period of the filtration cycle on fi...
Backwash water chemistry can have significant detrimental effects on filtered water quality under some circumstances. Water utilities experiencing adverse backwash water chemistry can significantly improve water quality, protect public health, and help ensure regulatory compliance by applying the information set forth in this article. Depending on...
Backwash water chemistry can have significant detrimental effects on filtered water quality under some circumstances. Water utilities experiencing adverse backwash water chemistry can significantly improve water quality, protect public health, and help ensure regulatory compliance by applying the information set forth in this article. Delayed start...
Issued as final report Gwinnett County (Ga.). Department of Public Utilities
