Bacteria Lab Test Results

KDF® Lab Test Results from Biological Research Solutions

Lab Test Results Show How KDF® Process Media Work in Water Treatment Processing for Bacteria Removal


KDF® Lab Test Results from Biological Research Solutions

Laboratory Service Performed: Analysis of the mode of action of KDF® water treatment process versus Pseudomonas fluorescens.

glass of water close up

Objectives:

Determine the effect of KDF® Process Media on bacteria removal in water. If there is biocidal action of KDF®, determine if the mode of action is by direct contact or by the release of soluble toxic compounds.

Experimental Plan:

The general experimental design was to compare bacterial survival in water that had been eluted through KDF® to bacterial survival following direct contact with KDF®.

Testing Protocol:

A number of preliminary experiments were done to develop a testing protocol. The following conclusions were derived from these preliminary experiments in resulted in the testing protocol described in Table 1:

  • Pseudomonas aeruginosa was first used for testing, but survival in deionized water or synthetic hard water was poor even in the absence of KDF treatment. Therefore a more hardy water bacteria, Pseudomonas Fluorescens, was used for all further experiments.
  • Initial testing was done in glass columns containing KDF 55-D, but the maximum flow rate that could be achieved by gravity feed was only 600 ml per hour (0.003 gpm). It was also difficult to flush the columns with sufficient volumes of water to approximate realistic use conditions. Therefore, a model water test system was constructed using 3/4 inch cpvc pipe.
  • The results of initial testing of the water system suggested several necessary modifications and the design of the test system used for the experiments reported heres.
  • Several tests of various combinations of water chemistry showed that the tap water could not be used and deionization was necessary. In order to minimize the aggressiveness of this water, AOAC synthetic hard water was injected through Injector #3 to achieve a final concentration of 100 ppm with a pH of approximately 7.
  • Since there were variable concentrations of endogenous bacteria in the system and in the pump feed lines, the system was flushed with 0.5 to 1ppm sodium hypo chlorite between each experiment.
  • Three gallons of water (1gpm) were run through the system for each sampling condition prior to sampling. Other experiments had shown (for example, the chlorine removal experiment describe below) that this volume of water was sufficient to rinse the system and reach equilibrium.
  • The carbon and bacterial filters were not effective or necessary and were not used after initial testing. When the testing protocol required bacterial injection, a fresh suspension of Ps. fluorescens in a glass reservoir was injected through Injection #1.
 

Results and Discussion:

Conclusions:

These studies have shown that KDF possesses inherent toxicity to Ps. fluorescens that requires direct contact for maximum efficacy. The mode of action is likely to be via a rapid reduction in redox potential as water-borne bacteria contact the column.

There seems to be great potential for this material to serve as an effective water treatment device to reduce or remove water pathogens such as Legionella pneumophila without the need for introduction of pesticides into the water.

By John W. Wireman, PhD
Dated July 31, 1990

Submitted by Biological Research Solutions, John W. Wireman, PhD, Dated: February 25, 1991

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This Reduction Oxidation Media is Tested and Certified by NSF International against NSF/ANSI Standard 61 for material requirements only.

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