GB2198432A

GB2198432A - Apparatus for purifying drinking water

Info

Publication number: GB2198432A
Application number: GB08727703A
Authority: GB
Inventors: Robert Henry Underwood
Original assignee: MICROMESH ENGINEERING Ltd
Current assignee: MICROMESH ENGINEERING Ltd
Priority date: 1986-11-27
Filing date: 1987-11-26
Publication date: 1988-06-15
Anticipated expiration: 2007-11-26
Also published as: GB8727703D0; GB8628392D0; GB2198432B

Abstract

The apparatus may be plumbed into a domestic water supply and comprises an inlet (20) from which water passes through compartments containing an exchange resin (25). The exchange resin removes chemical contaminants and demineralises the water. The demineralised water passes through a mixture of dolomitic material and carbon (24) for dissolving small amounts of calcium and/or magnesium compounds and for filtering the water respectively, so that the water is pleasant tasting, but free of contaminants such as nitrate. <IMAGE>

Description

APPARATUS FOR PURIFYING DRINKING WATER This invention relates to an apparatus for purifying drinking water.

Water supplies for drinking are commonly contaminated with chemical products and there has been particular concern recently with the level of nitrates in drinking water due to the extensive use of chemical fertilisers in agriculture. There is concern that this can be harmful to children.

The present invention seeks to provide apparatus which can be used domestically to treat water from a mains supply to remove chemical contaminants and produce water having a desirable mineral content.

The present invention provides apparatus for purifying drinking water comprising a first treatment station comprising an exchange resin for removing chemical contaminants, the exchange resin being such as to demineralise water passing through the resin, and a second treatment station comprising calcium and/or magnesium compounds dissolvable by the water passing from the first treatment station.

Preferably, there is a third treatment station comprising a carbon filtration station for removing chlorine.

It is preferred that the exchange resin comprises a cation exchange resin and a weak base anion exchange resin. The anion exchange resin is provided downstream of the cation exchange resin, or preferably, is mixed with the cation exchange resin.

Strong acids produced by the cation ion exchange resin, such as hydrochloric, nitric, sulphuric and phosphoric acids, are removed by the anion exchange resin. Weak acids, such as carbonic and silicic acids, pass the first treatment station and are effective in mineralising the water to a desirable extent, by dissolving the calcium and/or magnesium compounds, which are preferably carbonates.

The water resulting from this treatment is surprisingly pleasant to taste as well as being substantially free of potentially harmful contaminants.

The cation exchange resin is strongly acidic anz removes the mineral ions bound to radicals such as nitrates, phosphates, chlorides and sulphates producing acids. This exchange resin could be, for example Relite CF.

The anion exchange resin is weakly basic and absorbs only the strong acids. It has almost no capacity to absorb weak acids such as carbonic acid. This resin may be for example Relite A329.

The exchange resin may include a colour indicator which provides an indication of approaching exhaustion of the resin. A suitably mixed resin comprising a cation exchange resin and a weak base anion exchange resin, together with an indicator, is commercially available as Relite M. 1.900. This comprises a macroporous exchange resin in bead form.

The water, after passing the resins, may percolate through doloritic material, sone of which is dissolved by the carbonic acid.

Any traces of strong acids which may leach from the resins will be absorbed by the dolomitic material along with any traces of the resins.

A bacteriastat may be included.

Some carbonic acid will pass through the dolomite material and provide a pleasant sparkle to the water.

The final filter is activated, silvered carbon which removes any unpleasant odours and tastes from the water as well as dissolved or suspended organic materials.

Reference is now made to the accompanying drawing wherein the sole figure illustrates apparatus according to the invention.

The apparatus shown comprises first and second chambers 11, 12 with a flow connection 13 connecting an outlet 14 at the bottom of the first chamber to an inlet 15 at the bottom of the second chamber. An inlet 2C is provided at the top of the first chamber and an outlet 21 is provided at the top of the second chamber.

The apparatus is plumbed into a water supply, such as a domestic mains supply, so that water passes from the inlet 20 of the first chamber through the outlet 21 from the second chamber to a tap.

The first chamber 11 and a part of the second chamber 12 form part of a first treatment station containing ion exchange resin 25 in granular form. The exchange resin comprises a mixture of a cation exchange resin and a weak base anion exchange resin.

The resin is held in compartments between porous or perforated supports 26a to 26f, which may be discs made of open-cell expanded polyethylene.

The top portion of the second chamber 12 has a compartment defined between supports 26e and 26f and serving as a second treatment station. This compartment contains a mixture of dolomitic material and carbon 24.

Porous filters 28, 29 are mounted in the chambers, at the inlet and outlet respectively, and serve to consolidate the supports and other contacts of the chambers.

It is envisaged that the second chamber may not contain exchange resins and the flow connection 13 include separable parts permitting separation of the chambers. This enables the first chamber, with the exchange resin, to be replaced independently of the second chamber.

The carbon granules may be held in a separate compartment from the dolomitic material, downstream of the latter.

Claims

1. Apparatus for purifying drinking water comprising a first treatment station comprising an exchange resin for removing chemical contaminants, the exchange resin being such as to demineralise water passing through the resin, and a second treatment station comprising calcium and/or magnesium compounds dissolvable by the water passing from the first treatment station.

2. Apparatus according to Claim 1, wherein the first treatment station includes a cation exchange resin and a weak base anion exchange resin upstream of the anion exchange resin.

3. Apparatus according to Claim 1, wherein the first treatment station includes a cation exchange resin mixed with a weak base anion exchange resin.

4. Apparatus according to Claim 1, 2 or 3, including a colour indicator at the first treatment station for indicating approaching exhaustion of the exchange resin or resins.

5. Apparatus according to any preceding claim, wherein the second treatment station contains dolomitic material.

0. Apparatus according to any preceding claim, includes3 a third treatment station for removing bacteria and other contaminants.

7. Apparatus according to Claim 6, wherein the third treatment station includes a carbon filter.

8. Apparatus according to any preceding claim comprising a first chamber defining the first treatment station and a second chamber defining the second treatment station, the first and second chambers being detachably connected together to permit replacement of the first chamber.

9. Apparatus according to Claim 8 as appendant to Claim 7, wherein the second chamber also defines the third treatment station.

10. Apparatus for purifying drinking water substantially as herein described with reference to the accompanying drawings.