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Feature wateronline.com ■ Water Online The Magazine 30 A s advanced as monitoring has become, cryptospo- ridium (crypto) has seemingly slipped through the cracks. The accepted U.S. EPA method of detec- tion, mandated by the Long Term 2 Enhanced Surface Water Treatment Rule (LT2), is to catch oocysts (the infectious dormant form of crypto) in capsule filters. It is nei- ther simple nor cheap — and not terribly accurate, consider- ing its cost. So what if you could build a better crypto trap? A new, do-it-yourself crypto detection system has been developed by researchers at Lehigh University through a proj- ect funded by the Philadelphia Water Department (PWD) and tested in Philadelphia area waters, with promising results. So far, the "homemade" alter- native to the current stan- dard (EPA Method 1623) has provided very comparable detection results, but at a fraction of the cost. This allows for more units to be deployed throughout the watershed, possibly provid- ing utilities an additional tool for detecting cryptosporidium. Researcher Kristen Jellison, associate professor at Lehigh's Department of Civil & Environmental Engineering, calls the device a "biofilm sam- pler." It is simply a box containing microscope sample slides — at a cost of roughly $3 each — that is placed in a body of water at the location of interest. Jellison, who holds a Ph.D. from MIT and a B.S. from Cornell University, had done past work, along with others, in proving that biofilms are good receptors of oocysts, but the PWD pilot study marks the first time biofilms (which grow on the slides) have been used to monitor crypto in a watershed. "It's a very easy way to see if crypto are present in your watershed and where, without spending hundreds of dollars on the filters," said Jellison. Standard Filter Performance Problems As the next round of LT2 approaches — monitoring for large facilities (serving at least 100,000 people) begins in April 2015 — utilities of all sizes may recollect the pain points from using EPA Method 1623 in the initial round. The capsule fil- ters are prone to clogging in turbid conditions, which often necessitates a second filter to collect the required 10 liters of water for a valid sample. At $100 or more per filter, per sample, anything beyond the bare minimum gets expensive. "It racks up really quickly," stated Jellison. "A utility with a smaller budget is limited as to how often and how many different locations they can sample." Furthermore, the results of the EPA method are quite variable. In one study (McCuin and Clancy, 2003), oocysts were seeded in both clean tap water and raw source water, then repeatedly tested using EPA Method 1623. The range of recoveries — or how many oocysts were detected compared to the known quantity put in — was 23.5 to 71.2 percent for the tap water, and 19.5 to 54.5 percent for the raw water. The high incidence of undetect- ed oocysts means that crypto presence could be greater than tests indicate. "With recoveries so variable, it becomes questionable if you don't detect anything," Jellison noted. "Is it because it really wasn't there, or because you only had a 30 percent recovery? You may or may not catch it." The method can also be mis- leading in that it only provides a "snapshot" of place and time. The oocysts you gather in 10 liters of water at a single collection point, over the course of time it takes to collect a sample (perhaps 30 minutes), is almost coincidental. As Jellison pointed out, "You could have had an oocyst in there the day before or the hour after you leave, or even while you were there, but not in your 10-liter sample." The biofilm sampler improves on at least two of these pain points, creating the opportunity for better understanding of crypto occurrence in a waterbody. Biofilm Sampler Vs. Filter The first advantage is cost. Because the biofilm sampler's materials are so much cheaper than the filters required under LT2 guidelines, many samplers can be constructed and used for monitoring throughout the watershed. A second advantage is that the biofilm samplers can stay in the watershed for any length of time, which is a matter of convenience, opportunity (to catch more oocysts), and local factors. There is no optimal duration period established for the biofilm samplers; it may be variable according to Do-It-Yourself Crypto Detection Learn how to construct a simple and inexpensive tool for detecting cryptosporidium in your watershed — and why it's important. By Kevin Westerling, chief editor, Water Online Oocysts have an intense apple green color under immunofluorescence imaging and measure four to six microns in diameter. (Credit: H.D.A. Lindquist, U.S. EPA)