Civil & Environmental Engineering

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    Effect of coagulants in removing cyanotoxin-microcystinin drinking water treatment process
    (North Dakota State University, 2015) Xu, Yue; Roy, Dhriti; Khan, Eakalak
    The presence of cyanotoxins in source water is a worldwide problem. The most widespread cyanotoxin, called microcystins (MCs), produced from Microcystis Aeroginosa, can cause severe problems to the environment, animals and human health. A standard drinking water treatment process involves coagulation/flocculation process as primary treatment to remove cyanobacteria from source water. In coagulation/flocculation processes, a chemical coagulant is added to source water using rapid/slow mixing to facilitate bonding among particulates. As the process involves chemical and mechanical stress, cyanotoxin may get released to the drinking water. Coagulation/flocculation process can remove intact cyanobacteria effectively, however, study is limited to show the effect of coagulants in removing cyanotoxins during coagulation/flocculation. Our study would evaluate different types and concentration of coagulants to establish effective methods to remove cyanotoxins at the preliminary drinking water treatment. In this study, a jar test was conducted with microcystin-LR (MCLR) and microcystin-LA (MCLA) to show improved removal. A coagulation/flocculation process was used at laboratory bench scale. This study is important, as it establishes a method that would eliminate harmful cyanotoxins before they enter the secondary treatment process. The results would help drinking water facilities to remove cyanotoxins in the primary treatment where cyanobacteria and their toxins may be found in the source water.
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    3-D Printing: A New Approach to Water Filtration
    (North Dakota State University, 2015) Giesler, Steven
    People often find themselves in situations where clean drinking water is not readily available. One solution to this problem is the use of portable water filters. However, some water filters are too expensive or bulky to be economically sensible. A recent surge in additive manufacturing, involving the use of 3-D printers, has provided an alternative solution to this problem. This project’s primary objective is to test the usability of 3-D printed water filters. There are two major aspects to testing the filters: structural and performance. The filters will be designed with AutoCAD software and manufactured in a 3-D printer. Laboratory tests will be conducted to measure the performance of the water filters. The tests involve running manufactured wastewater with a known particle size distribution through the filters. Each filters’ performance is measured in three ways: net permeability, susceptibility to plugging and durability. The filters are expected to remove turbidity and Escherichia coli (E. coli) bacteria. Results show the current filters being tested can remove particles as small as 500 micrometers in size. This corresponds to conventional particle filtration (1 – 1,000 micrometers), but improvements in design are expected to screen out even smaller particles. Once an optimal design has been selected, new water filters will be manufactured from various polymers and modified with various surface coatings for specific contaminant removal. A survey has been conducted to explore peoples’ perceptions to the risks and benefits of 3-D printed water filters. It is important to gauge both professional and public responses to this new application. An individual may soon download a water filter design from an online website (or submit a personal design), have it manufactured at a local 3-D print vendor and then use the subsequent filter. The low-cost process will produce a small, portable and functional water filter.