Impacts of Filter Backwash Recycle on Clarification and Filtration

by James K. Edzwald – 2001 – Technology & Engineering – 287 pages
We thank Susan Boutros (President) and Jeff Runyan (Director of Protozoan Laboratory and Senior Analyst) of Environmental Associates Ltd. for Giardia and Cryptosporidium analyses and on their Quality Control data.

Biocidal Efficacy of a Flocculating Emergency Water Purification Tablet

Edmund M. Powers,1* C. Hernandez,1 S. N. Boutros,2 and B. G. Harper3

1U.S. Army Natick Research, Development and Engineering Center, Natick, Massachusetts 01760-5018
2Environmental Associates, Ithaca, NY 14850
3Material Test Directorate, U.S. Army Dugway Proving Ground, Dugway, Utah 84022-5000

Chlor-Floc (CF) emergency water purification tablets were tested for bactericidal, virucidal, and cysticidal efficacy in water at temperatures ranging from 5 to 25°C. The minimal required log reduction was achieved for bacteria, Giardia muris, and rotavirus, but CF did not achieve the required log reduction of poliovirus at any of the temperatures or times investigated. The biocidal properties of the CF tablet were equivalent to if not greater than those of the Globaline iodine tablet, and the CF tablet was a more rapid cysticide under several potential use conditions. Therefore, it is a suitable substitute for iodine tablets for emergency purification of drinking water. Clarification of turbid waters was effective, but filtration through a cloth is necessary to prevent flocculated sediment from entering the canteen. The CF tablets met military requirements for emergency water purification and are safe and acceptable for use by the military.


Authors: Boutros, Susan; Boutros, Edward; Moffa, Peter; Paterniti, Joe; Chorlog, John; Di Giovanni, George; Bowman, Dwight
Source: Proceedings of the Water Environment Federation, Disinfection 2007 , pp. 85-94(10)
Publisher: Water Environment Federation

The Miami Dade High-Rate Disinfection Pilot Study at the South District Wastewater Treatment Facility compared high-level disinfection with chlorine to high-rate disinfection using chlorine dioxide and to disinfection with ultraviolet light. This presentation discusses some of the analytical challenges presented by the Florida Department of Environmental Protection (FDEP) pathogen guidelines, how those challenges were met and suggests innovative method changes to meet the guidelines in the future.
FDEP’ rigorous pathogen guidelines define protozoan and virus limits for reuse water and set the standards for the pilot plant testing. For the protozoans, Cryptosporidium and Giardia, limits are defined in terms of “viable” oocysts and cysts. The standard EPA test, Method 1623 for Cryptosporidium and Giardia, gives total counts and information about protozoan morphology but does not measure viability. The results of Method 1623 counts were used to calculate physical removal and destruction with pilot scale tests, but those counts could not be used to calculate reduction in viability. Viability measurements were made by the focal detection cell culture method for Cryptosporidium and by live animal studies for Giardia with bench scale tests.
For viruses the FDEP guidelines recommend acceptable average limits as 0.044 plaque forming units (PFU)/100 liters or less than one 1PFU/ 2273 liters. The most probable number (MPN) assay used for the pilot study is considerably more sensitive than the plaque assay implied by the guidelines. The large volume and high solids used to simulate “worst case” conditions increased the analytical challenges. Method modifications were developed and validated at Environmental Associates Ltd. to accommodate each of the analytical challenges.
Surrogate assays were included to attempt to validate process control tools that would be cheaper and faster to run than pathogen assays. These assays included spores, coliphages and enterococci. Surrogate assays yielded mixed results with only some surrogates providing good predictive value. Pathogen levels varied by season, rainfall, time of day, day of week and year-to-year. The variability indicates that risk evaluation and treatment decisions need to be based upon large enough data sets to encompass these variations.
For new disinfection studies, method modifications are presented that will reduce cost and improve the accuracy and usefulness of the data.

Environmental Methods for Cryptosporidium

Jakubowski, Walter;Boutros, Susan;Faber, Walter;Fayer, Ron;Ghiorse, William;LeChevallier, Mark;Rose,
Journal American Water Works Association, Vol. 88, Issue 9, September 1996, Page Range 107-121, 15 pages

This report was prepared by the Working Group on Waterborne Cryptosporidiosis (Technical Task Force E, Developmental Status of Environmental Sampling, Water Testing, and Surrogate Indicators). Methods…