Nuclear Magnetic Resonance Spectroscopy Analysis of Anaerobic Microbial Metabolic Response to Benzalkonium Chloride Disinfectant

Quaternary ammonium compounds (QACs) are disinfection agents used in industrial cleaning processes that are known to interfere with the proper functioning of anaerobic waste digestion directly impacting the quality and quantity of the biogas produced (i.e., CO2 and CH4). While the impact of these contaminants on waste digestors are well known, the impact these compounds have on the metabolic profile of an anaerobic digestor is less understood. This paper describes the use nuclear magnetic resonance (NMR) spectroscopy as a non-targeted tool to monitor variations in the metabolic profile of anaerobic bioreactor microcosms simulating the treatment of food production wastewater exposed to benzalkonium chloride (BAC), a key QAC. Using NMR, the variation in the metabolic profile of these wastewater microcosms is compared to variations in the quality and quantity of the biogas produced. A clear development of propionic, isobutyric, isovaleric, and other volatile fatty acids (VFAs) is observed indicating a disruption to the overall ability of the system to convert fatty acids to methane. The ability of NMR to successfully identify the overall metabolic profile, the occurrence of the individual VFAs, and the occurrence of BAC itself in one analysis helps to provide valuable information on the metabolic pathways involved in the disruption of these anaerobic processes

Practical IMRT QA dosimetry using Gafchromic film: a quick start guide

This work outlines a method for using Gafchromic film for dosimetry purposes, by scanning it with currently available commercial scanners. The scanners used were: Epson V800, Epson V700, Epson V37 series, specifically a V370 and a Canon multi-function office printer/scanner. The Epson scanners have 16 bit RGB resolution, the Canon has 8 bit RGB (Red Green Blue) resolution, and the V800 and V700 allow scanning in transmission mode. The V700 uses an Epson White Cold Cathode Florescent Lamp; the recently released V800 uses an Epson light emitting diode (LED) light source, while the V37 series uses a reflective mode and the Epson LED light source. The Epson V37 series scanners are designed for non-professional use so the cost has been kept at a low entry level point, so they would be a suitable option for a department wanting to use Gafchromic film or with limited needs that did not justify a more sophisticated and expensive unit. Note that the V800 or V700 scanners are not expensive in context, costing approximately the same as a 25 sheet box of Gafchromic film. The Canon was included to demonstrate that a scanner with 8 bit RGB resolution can be used for dosimetry. These general multi-function units are available in most departments, and they would allow Gafchromic film to be evaluated as a dosimetry tool without a significant investment. Furthermore, they are generally capable of scanning large format film (425 x 350 mm) in one part. Although this is not necessary for dosimetry, it is often useful for machine QA, where dividing the film into two parts to ensure accurate measurements is not practical. Moreover, this analytical method uses software that is freely or commonly available, particularly the image processing package ImageJ. Note ImageJ v1.48 was the version used. The results demonstrate that this method used with the scanners evaluated is a practical method of using Gafchromic film as a dosimeter for IMRT QA