Browsing by Subject "drinking water"
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Item Investigation of the microbiomes in two full-scale drinking water distribution systems(2018-08) Waak, MichaelThe drinking water distribution system (DWDS) microbiome can impact public health as well as distribution infrastructure. Though the majority of bacterial biomass in the DWDS is associated with biofilms on the walls of water mains and other surfaces, there is a lack of understanding about the biofilms due to the challenges of accessing them. Using culture-independent methods targeting marker genes, including real-time quantitative polymerase chain reaction (qPCR) and high-throughput sequencing of PCR amplicons, the microbiomes of two full-scale systems were investigated—a DWDS in the United States that maintains a chloramine residual and another in Norway that intentionally has very low or no residual disinfectant in the distributed water. This work demonstrates that residual chloramine is a fundamental factor affecting the microbiome in a chloraminated DWDS. Not all changes to the microbiome due to chloramine, however, may be desirable. Namely, non-tuberculous mycobacteria (NTM) and ammonia-oxidizing bacteria (AOB) in water-main biofilms benefit from residual chloramine, and both of these taxa pose possible concerns to water utilities and their consumers: NTM include some opportunistic pathogens (especially Mycobacterium avium complex, or MAC), and AOB may contribute to biologically accelerated chloramine decay. Still, chloramine appeared to generally work as desired. Biofilm biomass was significantly lower in the chloraminated DWDS, despite ostensibly more favorable conditions for bacterial growth, and most taxa in the bulk drinking water were not observed in the biofilms. Legionellae, which may include some opportunistic pathogens, were significantly reduced from the biofilms of the chloraminated DWDS, and no MAC were detected in either system. Characterization of the NTM indicated nearly all in the chloraminated DWDS were Mycobacterium gordonae-like species, while various phylogenetically-different species of novel NTM were present in the no-residual DWDS. Chloramine-derived ammonia also appeared to support an AOB community in the chloraminated DWDS comprised primarily of Nitrosomonas oligotropha-like taxa. Abiotic reaction of nitrite with the chloramine likely hinders complete biotic nitrification; nitrite-oxidizing bacteria (NOB) are denied available nitrite. Conversely, AOB, NOB, and ammonia-oxidizing archaea were all present in the no-residual DWDS despite little or no ammonia in the drinking water. Finally, corrosion-associated bacteria like Desulfovibrio spp. were common underneath corrosion tubercles in both systems. Microbiological activity may therefore contribute to corrosion of cast-iron water mains, regardless of whether a disinfectant residual is maintained in the bulk drinking water. This work provides novel evidence that residual chloramine alters the DWDS microbiome by reducing total biomass and diversity of water-main —though the remaining taxa may still pose management challenges. Future work will need to expand this type of research to other systems before general applicability to other systems can be assumed.Item Lessons from Drinking Water Professionals: An Assessment of Drinking Water Governance in Minnesota(2023-12) Calow, Peter; Lewandowski, MarcelleDrinking water is life-giving, essential, and finite. Its management is messy, complex, and far-reaching. In 2022, the Minnesota Department of Health (MDH) announced that it would be developing a statewide drinking water plan to guide the management of drinking water over the next ten years. To inform the development of that plan, MDH also chose to conduct an assessment of the current governance of systems impacting drinking water in order to identify challenges and opportunities in the systems themselves which the statewide plan could address. This report summarizes the input received from focus group conversations and a survey with drinking water professionals based on an established set of criteria known as the Governance Assessment Framework.Item Water Quality Status and Trends in Minnesota(Water Resources Research Center, University of Minnesota, 1977-08) Straub, Conrad P.; Goppers, Velta M.; DuChene, AlainThe approach taken was to examine the chemical data available on public water supplies based upon sample analyses by the Minnesota Department of Health. To utilize the published data and to establish relationships between some of the parameters, the data available were placed into a computer for easier retrieval. To characterize the quality of the various waters used as sources of supply in the State of Minnesota, a system for comparing existing quality with some accepted standards or criteria was developed. The chemical quality criteria used were based upon the U.S. Public Health Service Drinking Water Standards (USPHS/DWS) published in 1962, the Water Quality Goals Recommended by the American Water Works Association (AWWA), and the U.S. Environmental Protection Agency National Interim Primary Drinking Water Regulations (USEPA/NIPDWR). These comparison permitted as indication of the number of supplies and the populations they served that met various selected concentrations. Quality comparisons are indicated for hardness (as CaCo3), iron, manganese, chlorides, sulfates, nitrates, sodium, and filterable reside (total solids). Attempts were made to use some of the analytical data to identify specific aquifers supplying water and these results are reported in a subsequent section as are data obtained in the application of a simplified additive approach for calculating a water quality index for each supply.