Cyst Reduction

Cryptosporidium parvum and Giardia lamblia are protozoans, or single cell parasites, The parasites and spores are found in every region of the world and can be a contaminant in most water from lakes, streams and some groundwater sources under direct influence of surface water. Wastewater treatment facilities may discharge effluent containing the oocysts either due to overcapacity or inadequate treatment. Secondly, runoff from agricultural operations or from natural sources containing the spores can enter surface waters.

Under the Long Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR - LT2), systems must meet Cryptosporidium treatment requirements by using one or a combination of the treatment options, with the treatment requirements are determined by the oocyte level in the source water. Cryptosporidium levels >0.075 oocytes/liter require total Cryptosporidium treatment of at least 4.0-log and as much as 5.5-log (>3 oocytes/liter). States will approve the method used to demonstrate performance based upon EPA requirements and must approve the log credit claimed by the components of the system as well as the overall system. Filters are permitted as part of the overall treatment process and therefore are tested and qualified to determine minimum performance standards.