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US-12617700-B2 - Methods for eradicating biofilms from plumbing systems

US12617700B2US 12617700 B2US12617700 B2US 12617700B2US-12617700-B2

Abstract

Disclosed are advantageous systems and methods for treating building water systems, especially the interior surfaces of premise plumbing, to remove biofilm and inactivate biofilm-associated pathogens, including protozoa, using disinfectant formulations at concentrations at in excess of those used for drinking water treatment, and further, in co-applying complexing agents to mitigate corrosion of the materials treated; and using these in conjunction with off-gas containment devices that allow flushing of taps without the liberation of toxic fumes.

Inventors

  • Aaron Rosenblatt
  • Gilbert Gordon

Assignees

  • GORDON & ROSENBLATT, LLC

Dates

Publication Date
20260505
Application Date
20230410

Claims (17)

  1. 1 . A method for inactivating biofilm-associated pathogens in a building water system, the method comprising contacting interior surfaces of the building water system with a solution comprising a mixture of chlorine and chlorine dioxide in a ratio by weight of from 80:20 to 20:80, each component of the mixture having a concentration of at least 1.5 mg/L and the mixture having a total concentration of up to 200 mg/L.
  2. 2 . The method of claim 1 , wherein the mixture of chlorine and chlorine dioxide is in a ratio by weight of 50:50.
  3. 3 . The method of claim 1 , wherein the concentration of each of chlorine and chlorine dioxide is at least 12.5 mg/L, at least 25 mg/L, or at least 50 mg/L.
  4. 4 . The method of claim 1 , wherein the solution has a temperature of between 20 to 55° C.
  5. 5 . The method of claim 1 , wherein the solution has a pH of about 6.5 to about 9.0.
  6. 6 . The method of claim 1 , wherein the solution has a pH of between 7.2 and 9.0.
  7. 7 . The method of claim 1 , wherein the solution has a pH of >7.5.
  8. 8 . The method of claim 1 , wherein the building water system has a free residual concentration of 0.8 mg/L or less chlorine dioxide and 0.4 mg/L or less chlorine.
  9. 9 . The method of claim 1 , wherein the interior surfaces of the building water system comprise a material selected from the list consisting of copper, brass, iron, galvanized steel, stainless steel, PVC, HDPE, and combinations thereof.
  10. 10 . The method of claim 1 , wherein the building water system is fed by a premise plumbing system.
  11. 11 . The method of claim 1 , wherein the building water system comprises a cooling tower.
  12. 12 . The method of claim 1 , wherein the chlorine and chlorine dioxide components of the mixture are contacted with the building water system separately such that the solution forms in situ.
  13. 13 . The method of claim 1 , wherein the biofilm-associated pathogens comprise a microorganism selected from the group consisting of Acinetobacter, Elizabethkingia ( Flavobacterium ), Escherichia coli, Klebsiella, Legionella , non-tubercular Mycobacteria (NTM), Pseudomonas, Stenotrophomonas , protozoa, and combinations thereof.
  14. 14 . The method of claim 1 , wherein the solution further comprises a complexing agent.
  15. 15 . The method of claim 14 wherein the complexing agent comprises sodium silicate.
  16. 16 . The method of claim 1 , wherein the contacting is carried out under turbulent flow conditions.
  17. 17 . The method of claim 16 , wherein the turbulent flow conditions have a Reynolds value of at least 4,000.

Description

CROSS REFERENCE TO RELATED APPLICATIONS This application is a continuation of U.S. patent application Ser. No. 16/875,943, filed May 15, 2020, which is a continuation of U.S. patent application Ser. No. 15/014,951, filed Feb. 3, 2016, issued as U.S. Pat. No. 10,696,572 B2 on Jun. 30, 2020, which claims priority as a continuation-in-part of International Patent Application PCT/US2015/043331, filed Jul. 31, 2015, which claims priority to U.S. Provisional Patent Application No. 62/032,143, filed Aug. 1, 2014, each of which is entirely incorporated herein by reference for all purposes. FIELD The present disclosure relates to methods for treating plumbing systems to eradicate, remove and/or disinfect biofilms and biofilm-associated pathogens using treatment solutions comprising a mixture chlorine and chlorine dioxide. BACKGROUND Plumbing associated infections cause tens of thousands of illnesses and deaths every year. Clinically significant plumbing-associated pathogens include Gram-negative environmental bacteria and free-living amoeba (FLA) that can enter plumbing systems in relatively small numbers, reproduce (amplify) to large numbers and release as respirable bio-aerosols from the plumbing into the environment. The only plumbing-associated disease requiring notification in the United States is Legionnaires' disease, a severe pneumonic infection caused by the bacterium Legionella. Premise plumbing systems are now recognized as the primary source of Legionnaires' disease. (Yoder et al., 2008) The US Centers for Disease Control and Prevention (CDC) has estimated there are as many as 18,000 cases of Legionnaire's disease annually. The US Occupational Safety and Health Administration (OSHA) has estimated that Legionnaires' disease results in about 4,000 deaths in the United States each year. Reported outbreaks of Legionnaires' disease have more than doubled in the past 10 years. Other plumbing-associated pathogens, such as Pseudomonas and non-tuberculous mycobacteria (NTM), may cause as much or more disease as Legionella, but lack of required reporting and other factors make quantification difficult. The primary disease transmission vectors for these plumbing associated pathogens are inhalation and aspiration. Since the early 20th Century, water treatment and disinfection practices implemented in the United States and other developed countries have virtually eliminated incidence of waterborne enteric diseases, such as typhoid and cholera that result from fecal contamination of the public water supply. The focus of these historic, successful efforts has been the control of “traditional pathogens”, waterborne pathogens of fecal origin that contaminate the source water and typically do not amplify in the potable water itself. The primary disease transmission vector for these traditional pathogens is ingestion. E. coli is a reference organism of choice in traditional water treatment; it is widely used as the primary indicator of fecal contamination. Current data suggest that E. coli is almost exclusively derived from the feces of warm-blooded animals; its presence in drinking water is considered an indication of substantial post-treatment fecal contamination or inadequate treatment. E. coli is extremely sensitive to chemical disinfection, such as chlorination. Its presence in a water sample is considered a sure sign of a major deficiency in the treatment program or in the integrity of the distribution system. However, the absence of E. coli does not, by itself, provide sufficient assurance that the water is free of microbial contamination. Constituents of water, pipe deposits and plumbing materials exert an initial chemical demand on oxidizing disinfectants, such as chlorine. The amount of disinfectant that remains after the initial oxidant demand is satisfied is called the “disinfectant residual”. “Ct”—the concentration of the disinfectant residual [C] multiplied by the contact time, “t”—is a key concept used in development of traditional disinfection protocols. Ct tables have been developed for each drinking water disinfectant for a number of challenge organisms, primarily suspended (planktonic), traditional (enteric) indicator pathogens such as E. coli and Giardia. In general, public drinking water supplies in developed countries are treated to government standards that make the water safe for intended use. In the United States, potable water supplied by community water systems is treated to National Primary Drinking Water Standards, a set of requirements developed by the United States Environmental Protection Agency (USEPA) under authority of the Safe Drinking Water Act (SDWA). Most regulatory mandates regarding drinking water have focused primarily on the quality of the water at the point it leaves the treatment plant. It is increasingly recognized that the quality of regulation-compliant drinking water can deteriorate after it enters the distribution system, the series of pipes that transport water from the tr