Development of Microfiltration Membrane Cell for UVC Dose-Response Studies, and Determination of Methods for Prevention of Membrane Biofouling Using UVC Radiation

Biofouling is considered to be one of the greatest operational challenges of reverse osmosis (RO) filtration for the production of potable water. Biofilms that form on the surface of a membrane filter quickly reduce the performance of the filter, and therefore these filters require constant treatment. Radioluminescence membrane biofouling control (RMBC) has been proposed as an alternative to the prevalence of chemical disinfection for the control of biofouling on RO units. Ultraviolet-C (200-280 nm) radioluminescence (UVC-RL) phosphors can convert a single beam of X-rays into large quantities of UVC. In RMBC, incorporating these phosphors into the feed spacers of an RO unit could allow for effective prevention of biofilm formation. In order to determine the dose of X-rays, and therefore the costs, of preventing biofouling with this technology, the critical UVC dose for biofouling prevention must first be experimentally derived. The objective of this study was to develop the procedures and methods for deriving the UVC dose-response required to prevent biofilm formation on membrane filters. This study required a lab-scale membrane cell that emulates an RO unit while also allowing the surface of the membrane filter to be continuously exposed to UVC radiation, but such an apparatus has not been developed. Therefore, a large portion of this research was designing and constructing this membrane cell. This membrane cell is a crossflow unit that has a built-in, high UV-transmitting, fused silica glass window. Once the membrane cell was constructed and proven to be capable of withstanding the flow of pressurized liquid, the continuous flow configuration for operating the membrane cell was established. Then, the experimental methods were developed for growing and quantifying biofilm grown by a model biofilm-forming organism (Escherichia coli ATCC 25922) on the membrane filter (polyvinylidene fluoride, 0.1 μm). Biofilm was shown to be quantifiable in terms of cell density (CFUs/cm2) and mass density (mg/cm2). Once these methods were established, the methods for deriving the UVC dose-response of biofilm prevention were also established. Though the UV dose-response itself was not determined in this study, UVC was able to reduced biofilm growth on the membrane surface in terms of 2-to-3 log removal. Using these methods, the research to find the UVC dose-response of biofouling prevention can start

SLIDES: Costs and Benefits of Development: An Industry Perspective

Presenter: Glenn Vawter, Executive Director, National Oil Shale Association 12 slide

Keynote. Motivation: Theory into Practice

This paper is based on Dr. Vawter\u27s keynote address at the Southeast Professors of Middle Level Education Symposium

SLIDES: Costs and Benefits of Development: An Industry Perspective

Presenter: Glenn Vawter, Executive Director, National Oil Shale Association 12 slide

Grade separation

Thesis (Civil Engineering)--University of Kansas, Civil Engineering, 1923

Take a P.A.U.S.E. for Student Success

Because of the COVID-19 pandemic, our middle level students and teachers have suffered both great stress and loss. This loss and stress can result in the acting out behavior of students whose emotional maturity may not be fully able to cope. One middle school cancelled in-person classes in an attempt to ameliorate behavior issues. This article will examine the causes of the anti-social behavior and offer suggestions on the social-emotional health of both students and teachers. Strategies and resources will be listed in an effort to provide support to educators

Elevation and frequency of occurrence of floods in Squaw Creek basin in Ames, Iowa

Typescript (photocopy). Thesis (M.S.)--Iowa State University, 1963. Includes bibliographical references

Giant microwave photoresistance of two-dimensional electron gas

We measure microwave frequency (4-40 GHz) photoresistance at low magnetic field B, in high mobility 2D electron gas samples, excited by signals applied to a transmission line fabricated on the sample surface. Oscillatory photoresistance vs B is observed. For excitation at the cyclotron resonance frequency, we find an unprecedented, giant relative photoresistance (\Delta R)/R of up to 250 percent. The photoresistance is apparently proportional to the square root of applied power, and disappears as the temperature is increased.Comment: 4 pages, 3 figure