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Public drinking water supplies are clearly at risk for widespread distribution of pathogenic organisms and chemical contaminants that negatively impact human health. The most problematic contaminants in the desert southwest are Cryptosporidium, enterovirus, and Trichloroethylene (TCE). Methods of detection are well developed but require extensive laboratory analysis and time. Measurements need to be made as frequently as customers make demand on the water system, that is, frequently and at nearly all hours of the day. Unfortunately, there are no methods available to continually and cost‐effectively monitor water in real‐time for the presence of these contaminants.
We have developed a unique testing facility with a diverse array for continual monitoring sensors for detection of contaminants in water systems. This facility has devices to detect changes in water pH, conductivity, TOC, turbidity, chlorine, nitrate, and microbes based on particle size (to discriminate bacteria, spores, and protozoa). Detection of microbes can be performed based on changes especially in water TOC, turbidity, and the microbial particle size. Viability of the rganisms, as determined by plate counts, has a small role in detection capability; however overall water quality greatly impacts detection based on the role of sensor stability. The goal of this work is to develop an online monitoring scheme for detection of viruses in flowing drinking water. We use multiple approaches. One applies an electrodeposition process that is similar to the use of charged hollow fiber membrane cartridges typically employed for collection of viruses from environmental water samples. The second approach employs a cell culture as a sacrificial layer which is infected by only viable viruses. In both a spectroscopic measurement is performed using the evanescent wave that penetrates no more than 1 um from the surface of an infrared optical element in an attenuated total reflectance measurement scheme. The infrared measurement provides quantitative information on the amount and identity of material deposited from the water. Initial studies of this sensing scheme used proteins reversibly electrodeposited onto germanium (Ge) chips. An off line version of this approach indicated a detection limit of approximately 1,500 viral PFU. The results of those studies were applied to design a method for collection of viruses onto an attenuated total reflectance (ATR) crystal.
Spectral signatures can be discriminated between three types of protein and two viruses. There is potential to remove deposited material by reversing the voltage polarity. This work demonstrates a novel and practical scheme for detection of viruses in water systems with potential application to near continual, automated monitoring of municipal drinking water.