Patent Publication Number: US-2004048762-A1

Title: Method of purifying or cleansing a body of liquid

Description:
BACKGROUND OF THE INVENTION  
       [0001] THIS invention relates to a method of purifying or cleansing a body of liquid, in particular a body of water, containing one or more contaminants, and to a biocide formulation for use in such method.  
       [0002] The treatment of water is required in many aspects of everyday life. These range from swimming pools, spas, Jacuzzis and other similar recreational applications to industrial and agricultural applications, to name but a few. Many different compositions and methods are provided for treating the water which is suitable for human and animal consumption. For instance, chlorine or bromine based salts are often used in swimming pools, spas, Jacuzzis, and the like. These products tend not only to be relatively expensive, but may also be hazardous and inconvenient to handle. There is, thus, always a need for new methods and formulations for treating water.  
       SUMMARY OF THE INVENTION  
       [0003] According to a first embodiment of the invention, a method of purifying or cleansing a body of liquid, in particular a body of water, containing one or more contaminants, includes the steps of contacting the body of liquid with a biocide comprising hydrogen peroxide (H 2 O 2 ) in combination with a catalyst for enhancing the activity thereof, the catalyst preferably comprising a superoxidedismutase formed from the combination of elemental copper (Cu), silver (Ag), manganese (Mn) and zinc (Zn) so as to eliminate, in whole or in part, the contaminant(s).  
       [0004] The biocide formulation is preferably an aqueous solution or suspension of the biocide.  
       [0005] The H 2 O 2 , is typically present in the biocide solution or suspension in an amount of about 0.000003% to about 15% v/v, preferably about 0.003% to about 3% v/v, in particular about 0.3% v/v.  
       [0006] The Cu, Mn and Zn are typically present in an amount of about 100 ppb to about 1000 ppm, preferably about 3 to 20 ppm, in particular about 10 ppm.  
       [0007] The Ag is typically present in an amount of about 100 ppb to about 1000 ppm, preferably about 3 to 30 ppm, in particular about 20 ppm.  
       [0008] According to a second embodiment of the invention, a method of purifying or cleansing a body of liquid, in particular a body of water, containing one or more contaminants, includes the steps of contacting the body of liquid with a biocide comprising a compound which reacts with H 2 O to form hydrogen peroxide (H 2 O 2 ), in combination with a catalyst for enhancing the activity of the H 2 O so formed, the catalyst preferably comprising a superoxidedismutase formed from the combination of elemental copper (Cu), silver (Ag), manganese (Mn) and zinc (Zn) so as to eliminate, in whole or in part the contaminant(s).  
       [0009] Th biocide formulation may be a solid composition in the form of a tablet which is soluble in water.  
       [0010] An example of the compound which reacts with H 2 O to form H 2 O 2  is odium perborate (NaBO 3 ). The compound is present in the tablet in sufficient concentration to form an amount of H 2 O 2  when dissolved in the body of liquid of about 0.000003% to about 15% v/v, preferably about 0.003% to about 3% v/v, in particular about 0.3% v/v.  
       [0011] The tablet further contains Cu—, Mn—, and Zn oxides, sulphates, phosphates or the like. These compounds typically release the elemental Cu, Mn and Zn in an amount of about 100 ppb to about 1000 ppm, preferably about 3 to 20 ppm, in particular about 10 ppm, when the tablet is dissolved in the body of liquid.  
       [0012] The tablet also contains silver oxide (Ag 2 O), silver acetate (CH 3 COOAg) or the like, which produces elemental Ag when dissolved in H 2 O, typically in an amount of about 100 ppb to about 1000 ppm, preferably about 3 to 30 ppm, in particular about 20 ppm, when the tablet is dissolved in the body of liquid.  
       [0013] The Cu, Mn, Zn and Ag combine to form the superoxidedismutase.  
       [0014] The tablet further includes a binder and/or effervescent.  
       [0015] The binder may be sodium silicate (Na 2 SiO 3 ) or any other suitable binding agent which is soluble in water.  
       [0016] The effervescent may be selected from sodium bicarbonate, tartaric acid, citric acid, sodium tartrate or sodium citrate, or any combination thereof.  
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
     [0017] The invention provides a method and biocide formulation for eliminating in whole or in part contaminants in a body of liquid, in particular a body of water.  
     [0018] The method comprises contacting the contaminated water, for instance, with a biocide comprising hydrogen peroxide (H 2 O 2 ) in combination with a catalyst for enhancing the activity thereof. The preferred formulation of the invention is preferably an aqueous solution or suspension including a catalyst comprising a superoxidedismutase formed from the combination of elemental copper (Cu), silver (Ag), manganese (Mn) and zinc (Zn) so as to eliminate, in whole or in park the contaminant(s)* The H 2 O 2  is typically present in the biocide solution or suspension in an amount of about 0.000003% to about 15% v/v, preferably about 0.003% to about 3% v/v, in particular about 0.3% v/v.  
     [0019] The Cu, Mn and Zn are typically present in an amount of about 100 ppb to about 1000 ppm, preferably about 3 to 20 ppm, in particular about 10 ppm.  
     [0020] The Ag is typically present in amount of about 100 ppb to about 1000 ppm, preferably about 3 to 30 ppm, in particular about 20 ppm.  
     [0021] Alternatively, the biocide is in the form of a tablet which is soluble in water. The biocide includes sodium perborate (NaBO 3 ) or any other suitable substance which reacts with H 2  to form hydrogen peroxide (H 2 O 2 ).  
     [0022] The tablet further includes Cu—, Mn— and Zn oxide, sulphate or phosphate, which form elemental Cu. Mn and Zn when dissolved in the water. Ag 2 O or CH 3 COOAg is also present in the tablet to form elemental Ag when dissolved in the water. The Cu, Mn, Zn and Ag combine to form the superoxidedismutase.  
     [0023] The tablet also includes either a binder or an effervescent. The binder is typically Na 2 SiO 3 , and the effervescent typically comprises:  
     [0024] sodium bicarbonate (54.25%);  
     [0025] tartaric add (37.5%);  
     [0026] citric acid (6.25%);  
     [0027] sodium tartrate (1%); and  
     [0028] sodium citrate (1%).  
     [0029] The biocide formulation and method may be used to treat water, for instance, in a wide range of applications. These include recreational applications such as swimming pools, spas, Jacuzzis, and so called supertubes, for example, agricultural applications such as crops e.g. sugar and other consumable crops, dams and hydroponics water supplies for example, in plant and animal applications such as Koi ponds, fresh water fish ponds and tanks, cattle and other livestock drinking water, and water supplies for indoor plants and outdoor plants, for example, industrial and commercial applications such as industrial plant water system, water cooling towers, water based air conditioning units, and industrial and commercial waste water, for example, sewage treatment such as raw sewage, sewage management systems and sewage spills, for example, and water for consumption such as bottled water, military deployment water purification systems, re-circulated/purified drinking water from waste water systems, water tanks and dams, for example. The effervescent tablet formulation of the biocide is preferably used to treat small bodies of water having a volume of 20 litres or less, preferably 5 litres or less, and more preferably 2 litres or less.  
     [0030] The contaminants to be treated are typically microorganimsms including anaerobic bacteria such as desufovibrio, leuconostc and desuffuicans, aerobic bacteria such as aerobacter, flavobacterium, faecal coliforms, oyptosporidiumn, bacillus mycoides, bacillus subtirls and enterobacterium, viruses such as cholera and fungi such as yeast, candidia and the like.  
     [0031] In order to evaluate the efficacy of the method and formulation of the invention, a leading water treatment company carried out the following independent tests on contaminated water using the formulation of the invention. Individual samples of the contaminated water were taken and dosed with different concentrations of a biocide formulation containing 0.06%, 0.03%, 0.02%, 0.01% and 0.004% v/v H 2 O 2  and a superoxidedismutase catalyst consisting of 10 ppm Cu. Zn and Mn, and 20 ppm Ag. The test samples were then plated out on agar plates and cultivated to establish growth versus “kill rate” over a 24-hour period. The control sample (to which no biocide had been added) measured 600 000 colonies at the 4 hour mark and a further 100 000 colonies at the 24 hour mark. The results of the test samples are set out in the table below.  
                                       Dose concentration of   Efficacy (percentage   Efficacy (percentage       biocide formulation   microorganisms   microorganisms       (ppm)   irradicated) - 4 hrs   irradicated) - 24 hrs                                            600   100   100       300   99.22   99.97       200   98.65   99.96       100   93.24   94.10       40   91.89   91.00                  
 
     [0032] In the light of the above test results, it is believed that the method and biocide formulation of the invention are capable of eliminating, at least in part micro-organisms form a body of liquid such as water. The chemical compounds for the biocide are not only readily available and cost effective, but are human safe, non-toxic, non-allogenic, fast acting, eco-friendly and provided in quantities which are well below OSHA regulations.