INTRODUCTION
Water runoff frequently contains significant hazardous contaminants including indicator organisms such as fecal coliform. Such contaminants pose threats to humans directly during recreational uses of surface waters and seafood consumption; and to aquatic life through chronic and acute exposure to harmful bacteria. During stagnant or low flow conditions, the microorganisms flourish exponentially in environments rich in organic and inorganic nutrients. Treatment with water-soluble antimicrobials or disinfectants is not acceptable, as they would have an adverse effect on aquatic life when drained into the streams and surface waters. Also, water-soluble antimicrobials will dilute to sub-lethal levels allowing resistant bacterial populations to persist. Any antimicrobial media used to successfully control bacteria in stagnant or low flow conditions must not leach or dissolve into water, nor be consumed by the exponential bacteria growth. It should also provide adequate surface-area contact.
The Adsorb-it
/AM fabric has an antimicrobial nano-structure covalently bonded to its fibers which will not leach or dilute from the fabric, even with repeated washings. The patented antimicrobial kills microorganisms by molecular physical penetration, electrostatic attraction and electrocution. This physical, rather than chemical, mode of action does not lose strength with use, and does not promote adaptive organisms (super bugs). The antimicrobial spectrum is specific to single cell organisms such as bacteria, fungi, yeast, and algae. The antimicrobial is bonded to the Adsorb-it
Filtration Fabric which allows the flow of water and bacteria to pass freely in all directions.
OBJECTIVE
This initial study is intended to provide the percent microbial removal over time, and specify the surface area of the fabric per volume of inoculated water used. Presently, little if any information is available on the efficiency of surface-bonded antimicrobial fabrics in removing microorganisms in stagnant or low flow water conditions. The objective was to conduct a timed bacterial efficacy study on the Adsorb-it Filtration Fabric, covalently bonded to an antimicrobial nano-structure.
METHOD
Contaminated Water
Fecal coliform bacteria was used as the indicator species in this study. The bacterial seed mixture used was obtained from the clarifier at a local sewer treatment plant. A working standard of 40,000 cfu/100 ml was prepared from the seed mixture by adding 20 ml of the seed inoculum into eight liters of BOD phosphate buffered dilution water at pH of 7.2 and kept under aeration for 24 hours. The contaminated water was produced by adding 8 liters of the working standard to a plastic drum containing 80 liters of buffered distilled water at pH 7.2 and 10 grams of glucose as an organic substrate. This water was then aerated for 24 hours, and analyzed for fecal coliform bacteria. The laboratory determined that the contaminated water contained approximately 4,000cfu/100ml of fecal coliforms.
Test Container
Two containers measuring 18 inches long, 12 inches wide and 12 inches deep were used for the test. Each had a lid, which was kept closed except for sampling. The containers were insulated to maintain constant temperature for the duration of the experiment.
Antimicrobial Fabric Flotation Apparatus
A three-foot by one-foot strip of the treated Adsorb-it-/AM fabric was cut from a manufactured roll. The fabric was hot glued around the perimeter of a styrofoam frame, with a center cutout used for sampling. The material hanging below the frame was cut into one-inch strips, ending at the Styrofoam frame. This design allows three dimensional contact with the water as the fabric strips have a density greater than water, and hang down from the styrofoam float. A second apparatus was also constructed using untreated Adsorb-it fabric as the control for comparison.
PROCEDURE
The incubation containers were filled with 40 liters (10.6 Gals) of the synthetic contaminated water and allowed to equilibrate for 30 minutes. Initial samples were taken in sterile bacteria sample bottles. The antimicrobial flotation apparatus and the control flotation apparatus were positioned into each of the containers and the timed sampling sequence began. Water samples were taken using a 20 ml sterile glass tube. Four samples were taken from each corner of the container and two from the center; these were combined into sterile bacteria bottles for each timed sample event submitted for testing. The timed sequence of sampling progressed from minutes to hours. The samples were maintained at 4C, and submitted to the lab within 24 hours of sampling. The samples were analyzed by Method SM9222D for Fecal Coliform MF; the results are as follows:
RESULTS
/AM
