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Method of water purification

a water purification and water technology, applied in water/sludge/sewage treatment, solid sorbent liquid separation, cation exchangers, etc., can solve the problems of ineffective current disinfection procedures, rapid spread of infection among pool users, and known contamination of public swimming pools, so as to maximize the surface area available and be convenient to use

Inactive Publication Date: 2008-05-01
SYDNEY WATER CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides a method for removing biological species from water using an aluminium based medium containing surface Al—OH groups. This method can be easily adapted to existing water treatment processes. The aluminium based medium can be in the form of hydrated alumina, which has the ability to strongly bind microorganisms, such as protozoa and bacteria. The invention can be used in a variety of applications, such as in municipal water treatment, swimming pools, and purification of domestic water. The use of hydrated alumina in a mixed filter bed with other materials such as activated carbon or sand can also be employed.

Problems solved by technology

Cryptosporidium can survive up to six months in a moist environment and have been known to contaminate public swimming pools.
Several outbreaks of cryptosporidiosis due to contaminated swimming pools have been reported. the contamination is usually due to faecal accidents in the pool and the spread of infection amongst pool users can be rapid.
This is partly due to the ineffectiveness of current disinfection procedures.
In many cases, cryptosporidiosis manifests as infectious diarrhoea with risks of complication in the immunocompromised / immunosuppressed population, for example the very young, the very old, transplant recipients and those undergoing immunotherapy.
Water treatment processes are not completely reliable for the removal of Cryptosporidium oocysts and in many cases oocysts breakthrough the plant into the reticulation system.
However, Cryptosporidium oocysts are unaffected by these disinfectants.
Therefore Cryptosporidium oocysts that enter into the reticulation system pose extremely serious public health concerns since no cure exists for cryptosporidiosis.
However, if Cryptosporidium contamination occurs, removal by filtration or coagulation / filtration through sand filters may not be completely effective.
The efficiency of superchlorination as treatment for deactivating Cryptosporidium is not guaranteed.
Thus whilst there are a number of processes well recognised for the treatment of water sources to produce potable water or to treat recreational waters, a significant problem remains in the ability of those processes to produce water, particularly potable water, that complies with strict regulatory requirements in relation to pathogenic microorganism content.
Regrettably, conventional water treatment processes have proven unreliable for their removal from water sources.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

Direct Adsorption on Alumina

[0062] The Cryptosporidium oocyst sample received from AWT was 5×106 oocysts / ml. Since the oocysts are approximately 5 μm in diameter, the area per oocyst of 1.9×10−7 cm2 means the number of oocysts required to cover a 1 cm2 substrate is 5×106. In these studies we have used 0.1 ml samples of the original 5×106 oocysts / ml sample.

[0063] Pure alumina (α-Al2O3) wafers were cut to an appropriate size and UV irradiated at (λ185 and 254 mm) for 1 hr in the presence of water vapour to remove any organic contamination. The UV irradiation in the presence of water vapour and oxygen produces ozone and hydroxyl radicals which clean the alumina surfaces rendering them hydrophilic. After UV irradiation a small droplet of distilled water was placed on the substrates to ensure the surfaces were hydrophilic, then blown dry under a gentle stream of nitrogen.

[0064] The blank substrates were examined under a Kombistereo Wild M32 light microscope having a magnification rang...

example 2

Column Separators

[0069] A glass chromatography column (28 mm O.D) containing a #3 glass sinter was chosen for column separations (see FIG. 5). In order to ensure the pores of the glass sinter were large enough to allow the Cryptosporidium oocysts through, a 10 ml sample of 1.5×106 oocysts / ml was passed through the glass sinter of the unpacked column.

[0070] The column permeate was collected and transferred to a microelectrophoresis cell and examined using dark field illumination. At the first stationary level about 125 negatively charged particles (oocysts) were observed. This demonstrated that oocysts could easily pass through the glass sinter.

(2.2) Silica Blank

[0071] The silica Ballotini) spheres were fractionated to a size approx 200 μm in diameter as described earlier. The glass column was packed to a depth of 5 mm with the fractionated large Ballotini spheres. 10 ml of distilled water was allowed to percolate through the packed column and the permeate collected. The permeat...

example 3

[0078] To investigate the various rapid rehydroxylation methods the alumina was heated to 610° C. and the powder treated either with H2O2 or NaOH. The powder was then dried in the oven at 110° C. to remove surface water and tested to see whether the powder fines floated or sank. The method developed involved taking a sample of the powder on the end of a spatula and then as approach the surfaces at an angle of 45° the powder was slowly moved through the air / water interface, the spatula was then slowly withdrawn and if the powder was not fully hydroxylated the powdered fines floated, whereas if the powder was fully hydroxylated in appeared to be wetted and ran off the end of the spatula.

NaOH Treated Alumina.

[0079] We tested the powders treated with 1×10−5, 5×10−4 and 1×10−2M NaOH for an hour. The powders treated with 1×10−5, 5×10−4 floated whereas the 1×10−2 M NaOH treated sample sank indicating that the particles of alumina had become hydrophilic.

H2O2 Treated Alumina.

[0080] We ...

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Abstract

The invention provides a method for the removal of biological species, such as Cryptosporidium, from water using aluminum based media which contains surface Al—OH groups.

Description

TECHNICAL FIELD [0001] The present invention relates to a method for the purification of water. More particularly, the present invention relates to the removal of microbiological contaminants from water. BACKGROUND ART [0002] The presence of microbial pathogens in water bodies, such as rivers, dams, seawater and swimming pools, where human contact is likely to occur, or, in water intended for human or animal contact and / or consumption, is a potential hazard with the potential to result in illness, disability or even death where these pathogens are inadvertently ingested by humans or animals, Accordingly, there exists a variety of methods for their removal so as to render contaminated water safe for human contact and / or consumption. [0003] Known methods of removing pathogens from contaminated water include mechanical filtration, i.e. physical exclusion based on the size of the microbial pollutants, chemical treatment such as chlorination and ozonation and electrolysis which generates...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B01D15/04B01J20/08B01J20/281C02F1/28
CPCC02F1/281B01J20/08
Inventor KARAMAN, MARILYN E.SHANKER, SIVARAJBUSTAMANTE, HERIBERTO ALEJANDROPASHLEY, RICHARD MARK
Owner SYDNEY WATER CORP
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