FLUID PROCESSING

Technical Field

[0001 ] The present invention relates to the treatment of fluids in order to reduce their biological loading. In particular the present invention finds application in the treatment of aqueous based fluids.

Background Art

[0002] Impure fluids often require processing in order to reduce contamination such as any active biological loading contaminating the fluid. Typical fluids which require processing to reduce- the active biological loading include aqueous solutions comprising water and/or alcohols. For example, water for domestic consumption, fluids used in food processing such as milk and alcoholic beverages, sewage, waste water streams, water in cooling towers, etc. These fluids need to be processed to remove biological contamination, reducing the active biological loading, such that they are fit for use.

[0003] Solutions comprising water represent common fluids which are processed to reduce the active biological loading. Most water is purified for human consumption but water purification may also be designed for a variety of other purposes, including meeting the requirements of medical, agricultural, chemical and other industrial applications.

[0004] Water purification can be achieved by a- variety of methods. Typically these methods include physical processes such as filtration and sedimentation, biological processes such as sand filters or activated sludge, chemical processes such as flocculation and chlorination and exposure to ultraviolet irradiation.

[0005] Chlorination is a known method of water purification and involves adding chlorine to a fluid in order to sanitize the fluid. Use of chlorine is known to be effective against bacteria and viruses and is known to be used in the sanitization of the water in swimming pools and as a disinfection stage in sewage treatment. However, disinfection by chlorination can be problematic. For example, chlorine can react with naturally occurring organic compounds to produce hazardous by products, which are potentially carcinogenic.

[0006] Iodine has also been used for water purification and is typically added to water as a solution, in crystallized form, or in tablets containing tetraglycine hydroperiodide. Although it is not as effective as chlorination, iodine also has the ability to destroy anaerobic and aerobic bacteria and is further known to destroy mould and fungi. Unfortunately, iodine treated solutions typically also have an undesirable yellow to brown colouration. The undesirable colouration of the treated water is unacceptable both in the marketplace and under government regulations. In addition native iodine has a very low affinity to water and is almost insoluble making it difficult to use effectively on its own.

[0007] Copper and silver have also been used to sanitize water as copper is a known algaecide and silver is a known microbiocide. Accordingly, dilute solutions containing silver and/or copper ions have been used in the treatment and sanitization of liquids. In addition, combined use of silver ions and hydrogen peroxide (H ₂ O ₂ ) has been used to provide an effective sanitization medium for aqueous systems. However, the technology has been hindered by difficulties in the use of silver or copper ions and H ₂ O ₂ . Whilst proper dosing levels have been achieved, the unstable H ₂ O ₂ once introduced into the fluid for treating readily attaches to organic contaminants altering the volume of free oxygen that was originally introduced. The testing and monitoring of these levels is problematic in the control of high quality water.

Summary of Invention

[0008] According to one aspect, the present invention relates to a method of processing a fluid to reduce the active biological loading in the fluid. This method comprises increasing the level of colloidal silver in the fluid, adding an iodine-based reagent to the fluid and adding a source of nascent oxygen to the fluid.

[0009] Whilst it known that the combined use of silver ions and a nascent source of oxygen can provide effective sanitization medium for fluids there is provided an unexpected and beneficial effect by further addition of iodine-based reagents. In the present invention, the nascent oxygen source is not only used as a catalytic response to sliver for sanitization, but it surprisingly also acts as a decolourising agent removing the yellow to brown colour caused by addition of iodine. The resulting fluid is sanitized and colourless, after treatment.

[0010] Additional algaecide or microbiocidal agents can also be added during the processing of the fluid. For example soluble copper containing salts and/or alkalising agents can be added.

Description of Embodiments

[001 1 ] Colloidal silver may be generated by electrolysis of solid silver. The term "colloidal silver" as used herein contains a mixture of solid insoluble silver particles and soluble silver cations.

[0012] The biological loading of a fluid refers to the level of biological contaminants in the solution. Typically, biological contaminants include suspended particles, parasites, bacteria, algae, viruses and fungi.

[0013] Fluids containing biological contaminants require processing in order to reduce the active biological contamination. The present invention relates to a method of processing a fluid to reduce the active biological loading in the fluid. Typically, the fluids contain water but are not limited so, For example, other exemplary fluids might contain water and/or alcohols such as methanol, ethanol, ethylene glycol and propanol. Another example of a fluid amenable to treatment by the process of the invention is milk.

[0014] The level of colloidal silver in the fluid may be increased in any of a number of ways. Thus, in some embodiments an aqueous solution of colloidal silver is added to the fluid being treated. This may be added in a batch wise process or in a continuous flow process, depending upon the engineering configuration of the fluid treatment facility. In some embodiments the level of colloidal silver can be increased in the fluid by electrolysis of solid silver in the fluid flow. Silver colloids form into a suspension and ionic silver is also present, being dissolved in -the solution. Without wishing to be limited by the theory it is thought that silver colloids and ionic silver attach to negatively charged bacteria, leading to their death. The colloidal silver is also believed to attach to the sulphur nodules of viruses, preventing the uptake of nutrients that are required by the viruses to multiply.

[0015] The proportion of ionic silver to solid silver in the colloidal silver may vary. The amount of ionic silver present in the colloidal silver ranges from 60% to 95% of the total amount of silver in the colloidal silver. The amount of solid silver present in the colloidal silver ranges from 5% to 40% of the total amount of silver in the colloidal silver. In some embodiments the colloidal sliver has from 70% to 90% ionic silver and from 10% to 30% solid silver. In some embodiments the colloidal silver used has about 80% ionic silver and about 20% solid silver. In some embodiments the colloidal silver used has about 85% ionic silver and about 15% solid silver. Whilst the colloidal silver can be added to the fluid it is typically generated within the fluid by electrolysis of solid silver in the fluid stream or flow. Electrolysis of the solid silver typically occurs by passing the fluid through a conduit containing solid silver, which is electrolysed to thereby increase the level of colloidal silver in the fluid.

[0016] The quantity of colloidal silver added to the fluid is in accordance with the active biological loading of the fluid and is sufficient to reduce the level active biological loading to acceptable limits for the desired purpose of the fluid. The concentration of colloidal silver is typically increased by less than about 100 g per litre. Even more typically the concentration of colloidal silver is increased by between about 30 to about 70 g per litre. Even more typically the concentration of colloidal silver is increased by about 50 g per litre.

[0017] In some embodiments the concentration of colloidal silver may be increased prior to the introduction of a nascent oxygen source and an iodine-based reagent which generate the catalytic and synergistic effects discussed above. However in other embodiments the concentration of colloidal silver may be increased simultaneously or after the addition of the nascent oxygen source and/or iodine- based reagent. The nascent oxygen and iodine-based reagent can be introduced independently, simultaneously, or in combination.

[0018] The method comprises the step of adding an iodine-based reagent to the fluid. Typically iodine can be dissolved in water or another suitable solvent (typically an alcohol such as methanol or ethanol) in the presence of potassium iodide. A linear tri-iodide ion complex results from mixing native iodine with iodide salts and the tri-iodide complex is soluble in water.

[0019] Whilst iodine is a known microbiocide, solutions containing iodine have an undesirable yellow to brown colour. In certain fluids this yellow colouration is acceptable, dependent on the end-use of the fluid. However, the present invention relates to a colour-free treated solution.

[0020] The use of an iodine-based reagent can also be further advantageous as iodine is an essential element for all human beings and is used to treat thyroidism, is required by growing embryos for brain development and is neither mutagenic nor carcinogenic.

[0021 ] In some embodiments, the present invention employs colourless iodine or an iodine-based reagent, which when dissolved in the fluid, is colourless. The iodine- based reagent can be selected from any one of the following: an iodate salt (IO ₃ ), periodate salt (IO ₄ ^" ), tri-iodide salt (13 ^" ) iodide salt ( ) iodine (I2) or a mixture thereof. The iodine based reagents can be generated by reacting native iodine and/or iodide salts with a suitable reagent such as calcium percarbonate (CaCO ₃ *1 .5H ₂ 0) or potassium peroxymonosulfate (KHS0 ₅ ). Native iodine or iodide salts can be converted to iodate salts and/or periodate salts which can be added in the fluid treatment process.

[0022] Additionally, iodide salts may be converted to native iodine by oxidation with agents such as calcium percarbonate or potassium peroxymonosulfate. [0023] Native iodine crystals are, readily soluble in alcohols such as ethanol at concentrations of up to fifteen precent weight by weight. By dissolving native iodine in ethanol, the solution can then be mixed with an oxidizing agent such as potassium peroxymonosulphate or calcium percarbonate. Once mixed the brown colouration of the solution caused by the dissolved iodine is neutralized by the peroxide reaction within the oxygen laden crystals. As the volatile solvent evaporates, white crystals laden with iodine and/or other iodine-based reagents are precipitated which are readily soluble in water. The final crystals are then able to be distributed loosely by hand compressed into a pill or capsule or dissolved in water as a high concentrate for liquid injection into the fluid to be treated.

[0024] Addition of the iodine-based reagent is made such that the addition reduces the active biological loading of the fluid. The quantity of the iodine-based reagent added to the fluid is made in accordance with the active biological loading of the fluid and is sufficient to reduce the level active biological loading to acceptable limits or the desired purpose of the fluid.

[0025] The nascent oxygen source can be used as a catalytic response to silver to effect sanitization. Typical nascent oxygen sources include but are not limited to hydrogen peroxide, ozone and chloride oxides. Preferably the nascent oxygen source is derived from hydrogen peroxide (H2O2). The nascent oxygen source can be added separately or in combination with the iodine-based reagent.

[0026] Addition of the nascent oxygen source is made such that the addition reduces the active biological loading of the fluid. The quantity of the nascent oxygen source added to the fluid is made in accordance with the active biological loading of the fluid and is sufficient to reduce the level active biological loading to acceptable limits or the desired purpose of the fluid.

[0027] The process of the present invention may also involve addition of one or more additional agents. [0028] In some embodiments an alkalizing agent can be added in the treatment of the fluid. Typical alkalizing agents include carbonate, hydrogen carbonate, citrate and acetate salts. More preferably, the alkalizing agents are selected from hydrogen carbonate, carbonate salts and mixtures thereof. Even more preferably, the alkalizing agents are selected from potassium hydrogen carbonate and sodium hydrogen carbonate. Addition of the alkalising agent is made in accordance with the active biological loading of the fluid in order to reduce the level active biological loading to acceptable limits for the desired purpose of the fluid. In some embodiments the alkalising agents can be added to the fluid as a solid. Preferably the alkalising agent is added as a dilute solution. More preferably the alkalising agent is added as a dilute aqueous solution, wherein the alkalising agent is dissolved in water.

[0029] In some embodiments suitable copper containing salts can be added to the fluid for treatment. The copper containing salts can include copper (I) and copper (II) salts but preferably include copper (II) salts. More preferably, the soluble copper containing salt is copper sulphate. The copper containing salts are at least partly soluble in the fluid and are preferably highly soluble in low concentrations. Addition of the copper containing salt is made in accordance with the active biological loading of the fluid in order to reduce the level active biological loading to acceptable limits for the desired purpose of the fluid. In some embodiments the copper containing salt can be added to the fluid as a solid. Preferably the copper containing salt is added as a dilute solution. More preferably the copper containing salt is added as a dilute aqueous solution, wherein the copper containing salt is dissolved in water.

EXAMPLES

[0030] The first experiments (Runs 1 , 2, 3 and 4) were designed to challenge the present invention by testing the efficacy of the colloidal silver in combination with iodine and the nascent source of oxygen. As will be described below, Melbourne tap water was sterilised and then seeded with high levels of coliform bacteria. The seeded tap water was then treated with colloidal silver, iodine and hydrogen peroxide, allowing 30 minutes contact time and then dispensing samples for analysis. [0031 ] Melbourne tap water was autoclaved to ensure that there was no residual chlorine or other bacteria present which might interfere with the test runs. Chemical analysis of the autoclaved tap Melbourne tap water show the following contents:

1 : Autoclave Melbourne tap water contents:

pH units 7.6

EC ps/cm 77

Turbidity NTC 1 .1

Fluoride mg/L 1 .0

Bicarbonate alkalinity mg CaC0 ₃ /l 6

Carbonate alkalinity mg CaCO ₃ /L 18

Hydroxide alkalinity mg CaC0 ₃ /L <2

Total alkalinity mg CaC0 ₃ /L 24

Copper mg/L 0.02

Silver mg/L <0.001

Hardness mg/L 25

Ca mg/L 8.8

Na mg/L 5.2

[0032] The sterilised Melbourne tap water was then used for the matrix, which was seeded with high levels of E.coli. The seeded water was passed through a S.H.-01 Model silver nanoparticle production unit. After exiting the silver nanoparticle production unit, the liquid was passed over two cylindrical type pills where a combination of H2O2 and colourless iodine crystals were slowly introduced into the liquid for treatment prior to exiting.

[0033] The second experiment (second part of Run 4) was designed to investigate the efficacy of the system where the seeded tap water was recycled through the unit for 60 minutes and then samples were taken for analysis. Details of the experiment, Runs 1 to 4, are outlined below:

Runs 1 to 3: 1 Bioball of E.coli NCTC 1293 (ATCC 8739) containing 1 .1 x 10 ^B cfu was added to 5 litres of sterilised Melbourne tap water.

3 samples were taken for initial analysis of seed level.

The silver nanoparticle production unit was turned on and the seeded water was run through at 4.1 1 litres per minute.

After approximately 1 litre of seeded water was expelled, the system was turned off and let stand for 30 minutes.

The silver nanoparticle production unit was re-started and the first litre out of the system was collected for analysis.

The sample was analysed for E.coli using Colilert (enzyme substrate technology most probable number method) in triplicate immediately (time = 0 minutes).

The sample was stored at room temperature and then re-tested in triplicate at 30 minutes and 60 minutes.

Run 4:

2 Bioballs of E.coli NCTC 1293 (ATCC 8739) containing 2.2 x 10 ⁸ cfu was added to 8 litres of sterilised Melbourne tap water.

3 samples were taken for initial analysis of seed level.

The silver nanoparticle production unit was turned on and the seeded water was run through at 4.1 1 litres per minute.

After approximately 1 litre of seeded water was expelled, the system was turned off and let stand for 30 minutes.

The silver nanoparticle production unit was re-started and the first litre out of the system was collected for analysis.

The sample was analysed for E.coli using Colilert (enzyme substrate technology most probable number method) in triplicate immediately (time = 0 minutes).

The sample was stored at room temperature and then re-tested in triplicate at 30 minutes and 60 minutes.

After the collection of the first litre of seeded water, the second litre out of the system was collected for analysis. As per the first litre, the sample was analysed for E.coli in triplicate immediately (time = 0 minutes) and then re- tested in triplicate at 30 minutes and 60 minutes. After the first 2 litres were collected, the system was momentarily turned off so the outlet hose could be inserted into the seeded water tank. The silver nanoparticle production unit was re-started and the seeded water was recycled through the system for 60 minutes.

A litre of sample was then collected and analysed for E.coli in triplicate immediately (time = 0 minutes).

After the collection of the first litre of seeded water, the system was turned off and let stand for 30 minutes.

The silver nanoparticle production unit was re-started and the next litre out of the system was collected for analysis.

Summary of Results:

[0034] Four challenge experiments using E.coli were run and the seeded water was pumped through the silver nanoparticle production unit unlit approximately 1 litre was expelled. The system was turned off and after 30 minutes contact time samples were taken (labelled "0" mins).

[0035] There was substantial reduction in viable E.coli at "0" minutes. After 30 and 60 minutes at room temperature the samples were re-tested. A significant reduction in viable E.coli (between 5.0 and 5.9 log reduction) was observed. 100% kill was observed after 30 minutes in Run 2 and after 60 minutes in Runs 2, 3 and 4.

[0036] Run 4 also investigated the viability of E.coli in the second litre of seeded water expelled after 30 minutes contact time. Similar log reductions were observed to results obtained from the first litre sample. The effect of recycling approximately 5 litres of seeded water through the silver generator for 60 minutes was investigated in Run 4. 100% kill was observed (ie 5 log reduction).

Table 2: Measurement of E. Coli concentration. E. coli Average E. coli Ave rag E. coli Average E. coli Average E. coli Average per per per e per per per per per per per

100mL 100mL 100mL 100mL 100mL 100mL 100mL 100mL 100mL 100mL

Initial 2000000 380000 440000 86000

1300000 1600000 680000 510000 630000 520000 1 10000 94000 94000

1600000 460000 500000 85000

0 690 >2400 >2400 15500

mins

660 >2400 >2400 13000 23000

610 >2400 >2400 1 1000

690 >2400 >2400 13000

30 36 1 2 1

mins

21 0 1 1 3

25 0 1 1

35 0 1 0

60 2 0 0 0

mins

2 0 0 0 1

3 0 0 0

0 0 0 0

Table 3: Measurement of E. Coli. concentration per 100 ml of treated water after 60

Table 4: Measurement of E. Coli. concentration expressed as Av Login.

[0037] A second set of experiments (Runs 5, 6 and 7) were also designed to challenge the present invention by testing the efficacy of the colloidal silver in combination with iodine and the nascent source of oxygen. Melbourne tap water was sterilised and then seeded with high levels of coliform bacteria, treating the seeded tap with colloidal silver, iodine and hydrogen peroxide, allowing 30 minutes contact time and then dispensing samples for analysis.

[0038] As above, Melbourne tap water was autoclaved to ensure that there was no residual chlorine or other bacteria present which might interfere with the test runs. Chemical analysis of the autoclaved tap Melbourne tap water is shown in Table 1 .

[0039] The sterilised Melbourne tap water was then used for the matrix, which was seeded with high levels of Pseudomonas aeruginosa. The seeded water was passed through a S.H.-01 Model silver nanoparticle production unit. After exiting the silver nanoparticle production unit, the liquid was passed over two cylindrical type pills where a combination of H ₂ O ₂ and colourless iodine crystals were slowly introduced into the liquid for treatment prior to exiting.

[0040] The first experiment (Run 5) was designed to challenge the S.H.-01 Model with high levels of Pseudomonas aeruginosa bacteria, running the seeded tap water through the system at 4.1 1 litres per minute, allowing 30 minutes contact time and then dispensing samples for analysis. In addition, the seeded tap water was recycled through the unit for 30 minutes and then a sample was analysed. The second and third experiments (Runs 6 and 7) repeated the procedure used in Run 1 , but using a slower flow rate of 2.0 litres per minute.

Run 5:

1 Bioball of Pseudomonas aeruginosa NCTC 12924 (A TCC 9027) containing 1 .1 x 10 ⁸ cfu was added to 7 litres of sterilised Melbourne tap water.

3 samples were taken for initial analysis of seed level. The silver nanoparticle production unit was turned on and the seeded water was run through at 4.1 1 litres per minute.

After approximately 1 litre of seeded water was expelled, the system was turned off and Jet stand for 30 minutes.

The silver nanoparticle production unit was re-started and the first litre out of the system was collected for analysis.

The sample was analysed using membrane filtration method and selective media (MPA-c) for Pseudomonas aeruginosa immediately (time= 0 minutes). The sample was stored at room temperature and then re-tested at 30 minutes and 60 minutes.

Immediately after the collection of the first litre of seeded water, the second litre out of the system was collected for analysis. As per the procedure used on the first litre, the sample was analysed for Pseudomonas aeruginosa immediately (time= 0 minutes) and then re-tested in triplicate at 30 minutes and 60 minutes.

After the first 2 litres were collected, the system was momentarily turned off so the outlet hose could be inserted into the seeded water tank. The silver nanoparticle production unit was re-started and the seeded water was recycled through the system for 30 minutes.

A litre of sample was then collected and analysed for Pseudomonas aemginosa immediately ('Recycled').

Runs 6 and 7:

1 Bioball of Pseudomonas aeruginosa NCTC 12924 (ATCC 9027) containing 1 .1 x 10 ⁸ cfu was added to 7 litres of sterilised Melbourne tap water.

3 samples were taken for initial analysis of seed level.

The silver nanoparticle production unit was turned on and the seeded water was run through at 2.0 litres per minute.

After approximately 1 litre of seeded water was expelled, the system was turned off and let stand for 30 minutes.

The silver nanoparticle production unit was re-started and the first litre out of the system was collected for analysis.

The sample was analysed using a membrane filtration method and selective media (MPA-c) for Pseudomonas aeruginosa immediately (time = 0 minutes). The sample was stored at room temperature and then re-tested at 30 minutes and 60 minutes.

Immediately after the collection of the first litre of seeded water, a second litre out of the system was collected for analysis. As per the procedure used for the first litre, the sample was analysed for Pseudomonas aeruginosa immediately (time = 0 minutes) and then re-tested at 30 minutes and 60 minutes.

After the first 2 litres were collected, the system was momentarily turned off so the outlet hose could be inserted into the seeded water tank. The silver generator was re-started and the seeded water was recycled through the system for 30 minutes.

A litre of sample was then collected and analysed for Pseudomonas aeruginosa immediately ('Recycled').

Table 5: Concentration of Ps.aeruginosa during Run 5.

* Colony size of Ps. Aeruginosa was significantly restricted. Table 6: Concentration of Ps.aeruginosa during Run 6.

* Colony size of Ps. Aeruginosa was significantly restricted

Table 7: Concentration of Ps.aeruginosa during Run 7.

mins

60 6.00 contact

time

Recycled 6.00 Water

30 mins

* Colony size of Ps. Aeruginosa was significantly restricted

Summary of Results:

[0041 ] Three challenge experiments using Pseudomonas aeruginosa were run and the seeded water was pumped through the sM vet nanoparticle production unit until approximately 1 litre was expelled. The system was turned off and after 30 minutes contact time samples were taken (labelled "0" mins). The flow rate for Run 1 was 4.1 1 litres per minute. The flow rate for Runs 2 and 3 was decreased to 2.0 litres per minute (which is a typical flow rate for domestic use).

Run 5 (Flow rate 4.11 L/min)

[0042] First litre sampled: There was no significant reduction in viable Pseudomonas aeruginosa at "0" minutes. After 30 and 60 minutes left at room temperature the sample was re-tested. A significant reduction in viable Pseudomonas aeruginosa (3.95 log reduction) was observed after 30 minutes and a 100% kill (6.13 log reduction) was observed after 60 minutes.

[0043] Second litre sampled: There was no significant reduction in viable Pseudomonas aeruginosa at "0" minutes. After 30 and 60 minutes left at room temperature the sample was re-tested. The level of Pseudomonas aeruginosa was not significantly reduced at 30 minutes (1 .35 log reduction), however at 60 minutes there was a significant reduction in viable organisms (3.23 log reduction).

[0044] It was noted that colony size was significantly restricted in samples tested at 30 and 60 minutes. [0045] 100% kill (6.13 log reduction) was observed in the seeded water recycled through the silver nano particle production unit for 30 minutes

Runs 6 and 7 (Flow rate 2.0L/min)

[0046] The results obtained for the first and second litres sampled were similar. There was no significant reduction in viable Pseudomonas aeruginosa at "0" minutes. After 30 and 60 minutes left at room temperature the sample was re-tested. Significant reductions in viable Pseudomonas aeruginosa, ie greater than a 3 log reduction, was observed for samples analysed at 30 minutes. 100% kill was$ observed for samples analysed at 60 minutes.

[0047] It was noted that colony size was significantly restricted in samples tested at 30 minutes.

[0048] 100% kill (6.00 log reduction) was observed in the seeded water recycled through the silver nano particle production unit for 30 minutes.

[0049] The words "comprise", "comprising" and grammatical variations thereof, when used in this specification and in the following claims, are intended to specify the presence of the recited features, but not preclude the addition of one or more other features, integers, components, steps or groups.