Theses and Dissertations at Montana State University (MSU)
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Item Evaluation of mixed-oxidants against sodium hypochlorite for the disinfection and removal of biofilms from distribution systems(Montana State University - Bozeman, College of Engineering, 1997) Crayton, Cynthia Lynn; Chairperson, Graduate Committee: Anne CamperProblem Statement: As drinking water regulations are applied to smaller utilities, an area of emerging concern for the water industry is the installation of disinfection systems to meet the newly imposed standards. Since traditional disinfection technologies are usually beyond the safety, economic, and/or site restraint considerations for small systems, an alternative is required. The mixed-oxidants disinfection system (MIOX) appears to provide a reasonable alternative for small distribution systems as a safe, reliable, and cost effective technology that is easy to operate and is readily compatible with other treatment systems. The goal of this five-phase study was to evaluate the potential of the MIOX disinfectant (produced on-site using feedstocks of ordinary salt, water, and twelve volt electricity) against free chlorine for biocidal efficacy, biofilm/biofouling removal, biofilm regrowth potential, relative corrosion potential, and cost effectiveness. Although mixed-oxidants have been proven effective in potable water disinfection, biofilm removal is a new application for this alternative disinfection technology.Item Ammonia oxidation by a nitrifying community containing novel ammonia oxidizing archaea(Montana State University - Bozeman, College of Engineering, 2014) Olson, Andrew Jared; Chairperson, Graduate Committee: Anne CamperThe disinfection properties of chlorine have long been known. These properties have been leveraged in the disinfection of drinking water. However, in the presence of organic matter, chlorine can form potentially carcinogenic disinfection by-products (DBPs). As a result, the U.S. Environmental Protection Agency promulgated the Stage I and Stage II Disinfectants/Disinfection By-Products Rules, limiting the amount of DBPs that can be present in a distribution system. An economical solution for many drinking water utilities to meet these new regulations was to use to chloramine as a secondary disinfectant. However, chloramines are not without their own disadvantages: free ammonia is added during chloramine formation and released by chloramine decay. This free ammonia can then be used as an energy source by indigenous microoganisms during nitrification. Nitrification can have deleterious effects on drinking water such as decreased disinfectant residual, pH, dissolved oxygen, and alkalinity, as well as an increase in nitrite, nitrate, and heterotrophic bacteria. This study uses effluent from a nitrifying reactor simulating premise plumbing to quickly establish a nitrifying community in glass bead packed bed reactors. Importantly, ammonia oxidizing archaea have been identified in both systems while no known ammonia oxidizing bacteria have been found. Once this nitrifying community was established, the reactors were used as batch reactors with effluent recycle to measure ammonia oxidation during a two hour batch phase. A least squares regression analysis was performed to generate the kinetic constants v max and K m for the nitrifying community in the packed bed reactors. v max was calculated to be 2.23 hr -1. K m was calculated to be 2.35 mg L -1. This work will aid in the effort to characterize the nitrifying population in a premise plumbing system and mitigate nitrification in drinking water.Item Statistical methods in microbial disinfection assays(Montana State University - Bozeman, College of Letters & Science, 1997) DeVries, Todd AlanItem The influence of distribution system infrastructure on bacterial regrowth(Montana State University - Bozeman, College of Engineering, 2001) Van Andel, KristinItem Rapid in situ physiological assessment of disinfection in bacterial biofilms(Montana State University - Bozeman, College of Agriculture, 1994) Yu, Feipeng PhilipItem Effects of chemical seed treatment upon seed germination and stand establishment of forage crops and also upon nodulation of leguminous plants(Montana State University - Bozeman, College of Agriculture, 1957) Niffenegger, Daniel A.Item Action of monochloramine on biofilms of Pseudomonas aeruginosa and Klebsiella pneumoniae(Montana State University - Bozeman, College of Engineering, 1994) Srinivasan, RohiniItem Effects of culture conditions on the susceptibility of Legionella pneumophila to iodine disinfection(Montana State University - Bozeman, College of Agriculture, 1991) Cargill, Kari LisaItem Analysis and control of a biofilm disinfection model(Montana State University - Bozeman, College of Letters & Science, 2006) Szomolay, Barbara; Chairperson, Graduate Committee: Isaac KlapperThe goal of this dissertation is to study a complex biofilm model with a phenotypic structure presented in [34]. The model in [34] is extended - growth and detachment is added, making the new model more interesting in applications. The crucial feature of our model is that cells are able to enter an adapted resistant state when challenged with antimicrobials (adaptation). We study this model in both a qualitative and quantitative manner. Existence and uniqueness of solutions is shown as well as the existence and non-uniqueness of steady-state solutions. Another question of interest is the effective dosing of biocide, i.e. exploring dosing strategies that could minimize the number of living cells or biofilm thickness. Constant and periodic dosing regimes are modeled numerically and studied analytically. One of our main results is that on and off dosing is significantly better than the other dosing types. The model presented in this dissertation contributes to a better understanding of one of the resistant mechanisms in biofilms.Item Disinfection susceptibilities of detached biofilm clusters compared to planktonic cells and biofilms in single species and dual species cultures(Montana State University - Bozeman, College of Letters & Science, 2011) Behnke, Sabrina; Chairperson, Graduate Committee: Anne Camper; Albert E. Parker, Dawn Woodall, and Anne K. Camper were co-authors of the article, 'Comparing the chlorine disinfection of detached biofilm clusters with sessile biofilms and planktonic cells in single and dual species cultures' in the journal 'Applied and environmental microbiology' which is contained within this thesis.; Anne K. Camper was a co-author of the article, 'Differential chlorine dioxide disinfection tolerance of detached clusters, planktonic cells, and biofilms in monocultures and binary cultures' in the journal 'Biofouling' which is contained within this thesis.Detachment of cells and clusters from biofilms is an important process in the dissemination of microorganisms in industrial, environmental, and clinical settings but the disinfection susceptibilities of these cell clusters have not been sufficiently characterized. With the help of fluorescent microscopy and image analysis, naturally detaching cells and clusters from single species and dual species biofilms of Burkholderia cepacia and Pseudomonas aeruginosa grown in biofilm tubing reactors were analyzed for cluster size distributions and compared to the cluster sizes in chemostat cultures. The commonly used oxidizing agents free chlorine, chlorine dioxide and dissolved ozone were used for disinfection experiments and susceptibilities of detached clusters, planktonic cells, and intact biofilms in single species and dual species cultures were determined. Additionally, disinfection rates were calculated for chlorine and chlorine dioxide disinfection for all sample types and species. In experiments with chlorine as the disinfectant, a correlation between cluster sizes and disinfection efficacy was observed for single species only. Samples with the higher percentage of large clusters were more tolerant than samples with fewer large clusters. Chemostat samples and detached clusters from dual species reactors contained lower numbers of large clusters but were equally or less susceptible than their single species counterparts. Biofilms required chlorine doses up to ten times higher than chemostat or detached biofilm cells for total inactivation. Chlorine dioxide disinfection was independent of cluster size so that chemostat cells and detached clusters were similar with respect to log reductions and disinfection rates. Dual species chemostat cells, detached clusters, and biofilms were more tolerant to chlorine dioxide than the single species samples. As with chlorine, biofilms required much higher chlorine dioxide doses for total inactivation. Ozone was very efficient against B. cepacia chemostat cells and detached clusters but failed to inactivate biofilm samples with the concentrations used in this study. In general, detached clusters were more similar to chemostat cells and very different from biofilms with respect to disinfection susceptibilities and disinfection rates suggesting that biofilm-specific physical and physiological protection mechanisms may be lost shortly after the detachment event or may be absent in small clusters.