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The impact of physical/chemical properties of gray water on microbial inactivation in gray water using chlorine was investigated through creating artificial gray water in lab, varying specific components, and then measuring microbial inactivation. Gray water was made through taking autoclaved nanopure water, and increasing the concentration of surfacants, the turbidity, the concentration of organic content, and spiking E. coli grown in tryptic soy broth (TSB); chlorine was introduced using Clorox Disinfecting Bleach2. Bacteria was detected using tryptic soy agar (TSA), and E. coli was specifically detected using the selective media, brilliance. The log inactivation of bacteria detected using TSA was shown to be inversely related to the turbidity of the solution. Complete inactivation of E. coli concentrations between 104-105 CFU/100 ml in gray water with turbidities between 10-100 NTU, 0.1-0.5 mg/L of humic acid, and 0.1 ml of Dawn Ultra, was shown to occur, as detected by brilliance, at chlorine concentrations of 1-2 mg/L within 30 seconds. These result in concentration time (CT) values between 0.5-1 mg/L·min. Under the same gray water conditions, and an E. coli concentration of 104 CFU/100 ml and a chlorine concentration of 0.01 mg/L, complete inactivation was shown to occur in all trials within two minutes. These result in CT values ranging from 0.005 to 0.02. The turbidity and humic acid concentration were shown to be inversely related to the log inactivation and directly related to the CT value. This study shows that chlorination is a valid method of treatment of gray water for certain irrigation reuses.
ContributorsGreenberg, Samuel Gabe (Author) / Abbaszadegan, Morteza (Thesis director) / Schoepf, Jared (Committee member) / Alum, Absar (Committee member) / Chemical Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
Turbidity is a known problem for UV water treatment systems as suspended particles can shield contaminants from the UV radiation. UV systems that utilize a reflective radiation chamber may be able to decrease the impact of turbidity on the efficacy of the system. The purpose of this study was to determine how kaolin clay and gram flour turbidity affects inactivation of Escherichia coli (E. coli) when using a UV system with a reflective chamber. Both sources of turbidity were shown to reduce the inactivation of E. coli with increasing concentrations. Overall, it was shown that increasing kaolin clay turbidity had a consistent effect on reducing UV inactivation across UV doses. Log inactivation was reduced by 1.48 log for the low UV dose and it was reduced by at least 1.31 log for the low UV dose. Gram flour had a similar effect to the clay at the lower UV dose, reducing log inactivation by 1.58 log. At the high UV dose, there was no change in UV inactivation with an increase in turbidity. In conclusion, turbidity has a significant impact on the efficacy of UV disinfection. Therefore, removing turbidity from water is an essential process to enhance UV efficiency for the disinfection of microbial pathogens.
ContributorsMalladi, Rohith (Author) / Abbaszadegan, Morteza (Thesis director) / Alum, Absar (Committee member) / Fox, Peter (Committee member) / School of Human Evolution & Social Change (Contributor) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2020-05
Description
The rising need for water reuse in the Southwest United States has increased awareness of the quality of wastewater. This need is caused by an increased population having basic water needs; inefficient water use, such as overwatering lawns and leaking pipes; and recent drought conditions all over the southwestern US. Reclaimed water is a possible solution. It's used for a variety of non-potable, or non-drinkable, reasons. These uses include: cooling power plants, concrete mixing, artificial lakes, and irrigation for public parks and golf courts. Cooling power plants utilizes roughly 41% of the total water consumed by the United States, which makes it the highest user of water in the US. The attention is turned to optimizing mechanical processes and reducing the amount of water consumed. Wet-recirculating systems reuse cooling water in a second cycle rather than discharging it immediately. Cooling towers are commonly used to expose water to ambient air. As the water evaporates, more water is withdrawn while the rest continues to circulate. These systems have much lower water withdrawals than once-through systems, but have higher water consumption. The cooling towers in wet-recirculating plants and other warm machinery have two major limitations: evaporation of pumped water and scale formation in the components. Cooling towers circulate water, and only draw as it evaporates, which conserves water. The scale formation in the components is due to the hardness of the water. Scale occurs when hard water evaporates and forms solid calcium carbonate. This formation can lead to reduced flow or even clogging in pipes, fouling of components or pipes, and reduced cooling efficiency. Another concern from the public over the use of reclaimed water is the possibility of there being fecal contamination. This fear stems from the stigma associated with drinking water that essentially came from the toilet. An emerging technology, in order to address these three issues, is the use of an electromagnetic device. The wires have a current flowing through which induces a magnetic field perpendicular to the direction of the flow, while the electrical field is proportional to the flow velocity. In other words, the magnetic and electrical fields will create an effect that will concentrate cations at the center of the pipe and anions at the wall of the pipe or the other way depending on the direction of the flow. Reversing the field will then cause the cations and anions to move toward one another and increase the collision frequency and energy. The purpose of these experiments is to test the effects of the electromagnetic device on the aforementioned topics. There are three tests that were performed, a surface tension test, a hardness test, and a microbial test. The surface tension test focused on the angle of a water droplet until it burst. The angle would theoretically decrease as the bond between water molecules increased due to the device. The results of this test shows a lower angle for the treated water but a higher angle for the untreated one. This means the device had an effect on the surface tension of the water. Hard water is caused by calcium and magnesium ions in the water. These ions are dissolved in the water as it travels past soil and rocks. The purpose of this test is to measure the free calcium ion amount in the water. If the free calcium number lowers, then it can be assumed it collided with the carbonate and formed calcium carbonate. This calcium carbonate causes a reduction in hardness in the water. The result of the test showed no correlation between ion concentrations in the treated/untreated system. The e. coli test focused on testing the effects of an electromagnetic device on inhibiting fecal contamination in water/wastewater at a treatment facility. In order to detect fecal contamination, we test for bacteria known as fecal coliforms, more specifically e. coli. The test involved spiking the system with bacteria and testing its concentrations after time had passed.The e. coli results showed no trend in the inactivation of the bacteria. In conclusion, the device had varying results, but multiple steps can be taken in the future in order to continue research.
ContributorsHernandez, Andres Victor (Author) / Fox, Peter (Thesis director) / Abbaszadegan, Morteza (Committee member) / Civil, Environmental and Sustainable Engineering Programs (Contributor) / Barrett, The Honors College (Contributor)
Created2014-12
Description
Legionella is a gram-negative bacterium with the ability for human infection by inhalation or aspiration of water containing the bacteria. Legionella live in aquatic environments and have been identified in cooling towers, humidifiers and respiratory therapy treatments, among others. Infection with Legionella bacteria leads to Legionnaire’s Disease or Pontiac Fever (Edelstein, 1993). Information regarding the means of aerosolization of Legionella bacteria has not yet been reported, therefore the relevance of experimentation was defined. The objective of this study is to determine the modes by which bacteria may be aerosolized under laboratory conditions. Specifically, to measure the amount of bacteria transported over a specific distance in a given amount of time and determine the most effective mode of bacterial aerosolization. Three methods of bacterial aerosolization were tested, these included an electric paint sprayer, an air paint sprayer and a hand-held spray bottle. E. coli was used as a surrogate for Legionella in experimentation due to its similar bacterial properties. Both bacteria are gram-negative, aerobic bacilli while Legionella is approximately 2 μm in length (Botzenhart, 1998), and E. coli is between 1 and 3 μm in length (Reshes, 2007). The accessibility and non-pathogenicity of E. coli also served as factors for the substitution.
In order to measure the aerosolization efficiency of each spray method, an air sampler was placed opposite to the position of the sprayer, on either side of a sealed box. Each sprayer was filled with E. coli concentrated at 104 CFU/ml in a PBS solution and sprayed for a time span of 1 and 5 seconds. For each of these time intervals an air sample was collected immediately following the spray as well as 5 minutes after the spray. Compared to the other two methods, the air spray method consistently showed the highest number of bacterial cells aerosolized. While all three methods resulted in the aerosolization of bacteria, the results determined the Air Spray method as the most efficient means of bacterial aerosolization. In this study, we provide a practical and efficient method of bacterial aerosolization for microbial dispersion in air. The suggested method can be used in future research for microbial dispersion and transmission studies.
In addition, a humidifier was filled with a spiked solution of E. coli and operated for a period of 1 and 5 seconds at its maximum output. Air samples were collected after 0 and 5 minutes. Immediately after the humidifier operation was stopped a small number of colonies were detected in the air sample and no colonies were detected in the air sample collected after a 5-minute elapsed time. This experiment served as a proof of concept for airborne pathogen’s transmission by a humidifier.
In order to measure the aerosolization efficiency of each spray method, an air sampler was placed opposite to the position of the sprayer, on either side of a sealed box. Each sprayer was filled with E. coli concentrated at 104 CFU/ml in a PBS solution and sprayed for a time span of 1 and 5 seconds. For each of these time intervals an air sample was collected immediately following the spray as well as 5 minutes after the spray. Compared to the other two methods, the air spray method consistently showed the highest number of bacterial cells aerosolized. While all three methods resulted in the aerosolization of bacteria, the results determined the Air Spray method as the most efficient means of bacterial aerosolization. In this study, we provide a practical and efficient method of bacterial aerosolization for microbial dispersion in air. The suggested method can be used in future research for microbial dispersion and transmission studies.
In addition, a humidifier was filled with a spiked solution of E. coli and operated for a period of 1 and 5 seconds at its maximum output. Air samples were collected after 0 and 5 minutes. Immediately after the humidifier operation was stopped a small number of colonies were detected in the air sample and no colonies were detected in the air sample collected after a 5-minute elapsed time. This experiment served as a proof of concept for airborne pathogen’s transmission by a humidifier.
ContributorsJohnson, Chelsea Elizabeth (Author) / Abbaszadegan, Morteza (Thesis director) / Stout, Valerie (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2015-12