JiYoung Lee

Rapid Assessment of Microbial Hazards in Metalworking Fluids

Industries that use metalworking fluids require a test method that can rapidly estimate the total number of bacteria. Such a test method would improve the ability to manage the metal working fluid by allowing near real−time decision making. The ability to manage the fluid more consistently and make critical decisions as they arise would reduce occupational exposures to contaminated metalworking fluid and likely result in fewer worker complaints and/or work stoppages. In this study, a filtration−based rapid adenosine triphosphate bioluminescence assay, which takes less than 10 min to perform, was evaluated as a test method for estimating total bacteria populations in metalworking fluid. This evaluation used two types of metalworking fluid (soluble and semisynthetic) that were inoculated usingPseudomonas aeruginosa and spoiled metalworking fluid. Daily parallel testing was completed on metalworking fluid samples using the rapid adenosine triphosphate assay and the standard plate count methods. Daily test results were evaluated by calculating r 2 values using statistical correlation and regression procedures for each fluid type. Study result sindicate the rapid adenosine triphosphate assay is strongly correlated to the standard plate count method for soluble and semisynthetic fluids, producing results of r 2 = 0.74 and r 2 = 0.89, respectively.

Microbial Responses after Disinfectant Change to Ozone in a Full-Scale Distribution System

Ozone is a promising alternative disinfectant when the concentration of organic carbon is high in the source water. The microbial responses to primary disinfectant change from monochloramine to ozone in a full-scale distribution system were investigated. Several water quality parameters including heterotrophic bacteria and a new parameter, growth potential (GP), were determined from the finished water and at three different distribution system locations before and after switching to ozone for a period of 12 months. The GP assesses the potential of the water to sustain growth of bacteria. The literature suggests that ozonation will result in a higher biodegradable organic carbon concentration and will therefore stimulate bacterial growth. Biodegradable organic carbon concentration (BDOC) and HPC increased but GP decreased after ozonation during the study period. In order to exclude seasonal effects, the data from the same seasons of the previous year were compared in the statistical analyses. Our findings showed that among the water quality parameters, HPC, disinfectant dose and total organic carbon (TOC) concentration showed statistically significant differences between the two years (paired t-test, p<0.05). When ozone was used as primary disinfectant the TOC was 1.5 times higher than when chloarmine was used, but the HPC and disinfectant dose were lower. Thus the switch of the primary disinfectant to ozone did not increase bacterial growth. At the lower dose, the disinfectant dose was effective enough to control bacterial regrowth in the distribution system during the study period.

Rapid Detection of Bacteria in a Water Distribution System

A water distribution system may be contaminated by bacteria through cross-connections, by intrusion of soil water after a pressure loss due to a power blackout…

Public Health Aspects of Riverbank Filtration

The quest for pure water began in prehistoric times. Recorded knowledge of water treatment is found in Sanskrit medical lore and in Egyptian inscriptions. Pictures of apparati to clarify liquids (both water and wine) have been found on Egyptian walls dating back to the fifteenth century B.C. Boiling of water, the use of wick siphons, filtration through porous vessels, and even filtration with sand and gravel, as means to purify water, are methods that have been prescribed for thousands of years. In his writings on public hygiene, Hippocrates (460–354 B.C.) directed attention principally to the importance of water in the maintenance of health, but he also prescribed that rain water should be boiled and strained. The cloth bag that he recommended for straining became known in later times as “Hippocrates’ sleeve.”

Rapid detection of bacteria in water

A rapid detection of bacteria in water is essential for a timely response. This applies primarily to drinking water, be it bottled water or water from a public supply system, but is equally important for the analysis of water from swimming pools and beaches, and ballast water from oceangoing ships discharging into coastal or inland waters of the US. There are several methods available today for a rapid test including PCR based methods, flow cytometry, and electro chemiluminescence, to name a few. All of the above methods work, but are complicated and/or require expensive equipment and highly trained analysts in a laboratory. The method described here is based on lysing the bacteria after capture on a membrane filter, and measuring the ATP in a luminometer after the addition of luciferin/luciferase. This bioluminescence test can be done onsite, in less than 5 minutes, with equipment that fits onto a clipboard. It is a fast screening test that indicates if there is enough biologically active material in the same to pose a threat to the consumer. If this is the case, an additional step using immunomagnetic separation may be used to identify the responsible organisms. Tests have been done with E. coli 0157:H7, pseudomonas, and logionella. These tests take about 30 minutes each, and allow a quick determination of bacterial threats in a field situation.