GB2473836A

GB2473836A - Water filter

Info

Publication number: GB2473836A
Application number: GB0916769A
Authority: GB
Inventors: John Griffith
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-09-24
Filing date: 2009-09-24
Publication date: 2011-03-30
Also published as: GB0916769D0

Abstract

A system and method of removing bacteriological contaminants from water comprises a pre-filter 1, a pump 4, a hollow fibre membrane module 10, and a clean water outlet, characterised in that the system is attached by attachment means to an input water container. The system may optional include an air reservoir 12, wherein air is compressed during the pump down stroke and is expanded during the pump return stroke thus enabling water to flow through the outlet during the return stroke and allowing two directional cross-flow in the hollow fibre membrane module. Advantageously the system provides a supply of biologically safe water in situations where there is no mains water supply e.g. developing countries and emergencies.

Description

Water Filter The invention relates to the supply of biologically safe water in situations where there is no mains water supply. In particular it provides safe water at the point of use.

In parts of developing countries, and in emergencies, there is no piped safe water supply. In some of these situations water is collected from a stream, pond or well, and carried in containers to the house, and stored in the same container. Some of the water is used for drinking, and there is a need for a system to remove biological contaminates which is portable and convenient to use. It is an object of the invention to provide such a system.

The invention uses a known method of bacteria removal, which is the membrane module. The membrane is made from a porous substance which allows the passage of water but holds back small particles including bacteria, and sometimes viruses.

Membrane systems now available for his application have various disadvantages. For example patent WO 2008/110172 describes a gravity fed system, in which the flow is slow, the user has to fill a container high up on a wall, taps have to be operated in a sequence for using and cleaning, and a clean and dirty outlet are close to each other.

Ideally a membrane system for this application should:-- 1. Have the purification device at the container the input water is stored in.

2. Provide a means of flushing the membrane to prevent the build up of contaminants inside the hollow fibres without operator procedures.

3. Provide sufficient flow to produce drinking water on demand.

4. Be convenient to use.

These objectives are achieved by clamping the device to the water container, and using a hand pump to push water through the membrane. Cleaned water then flows through a pipe into a drinking vessel. The flow is retained during the pump return stroke by means of an air reservoir, which compresses air during the pump down stroke, and continues to send water through the membrane by expanding during the return stroke. This gives maximum flow through the membrane, as it is being used during both pump strokes.

Flushing to clean the insides of the hollow fibres is done by a the known "cross flow" system, which consists of passing excess input water through the hollow fibres. In the invention this is achieved in two ways. Firstly, water flows up through the fibres into the air reservoir on the pump down stroke, and then down through the fibres on the return stroke. Secondly there is a restricted outlet back into the container above the fibres, which substantially increases the cross flow. This restricted outlet preferably has a spring loaded valve so that flow occurs above a predetermined pressure, and also acts as a relief valve to prevent excessive pressure in the membrane. 2.

Fig 1 is a sectional elevation showing the working parts.

Fig 2 is an elevation which shows how the system is held in a water container.

Fig 3 is a sectional plan view also showing how it is held in the container Fig 4 and 5 are part sectional elevation and plan views respectively showing optional features.

Input water passes through a gauze pre filter 1, incorporated in a removable part 2. It then passes a ball valve 3 and into a pump barrel 4, which has a piston with a resilient seal 5, connected to a piston rod 6, and a handle 7, Lifting the handle pulls water into the barrel. Pushing the handle through a passage 7, past a ball valve 8, and into the centre of the hollow fibres 9 of the membrane 10.

Excess water passes right through the fibres, and compresses air in the reservoir 12, which expands during the pump up stroke, pushing water back down the hollow fibres which continues the output flow. This achieves greater output from the membrane, and provides cross flow in two directions. The two directional cross flow may be more effective in removing contaminants than single directional flow.

The cross flow is increased in the upward direction by a pressure relief valve 13, which allows for a restricted flow of water back into the supply container. In addition this valve acts as a safety valve to prevent excess pressure damaging the hollow fibres, and also drains the contaminates which would otherwise build up in the input side of the system.

Cleaned water flows out through pipe 14, under which a drinking receptacle can be held.

The system can be held against the wall of a water container, such as a bucket 16 (fig 2), by threaded knobs 17 and brackets 18 (figs 2 and 3). The brackets are screwed onto the system by screws 20. In the event of the container, such a ceramic pot, not having a suitable wall, the brackets can be removed, and the system screwed onto board with a hole in it, which is placed as a lid on the container.

The contaminants on the insides of the hollow fibres may include a "bio film", which needs to be removed by a chemical wash. This is conveniently done by removing the pump piston assembly, placing a suitable tablet in the pump barrel, and pumping to fill the membrane with a disinfecting solution. Optionally a pot of suitable tablets 30 (figs 4 and 5) may be clipped onto the system, so they do not get lost.

The piston seal may need to be treated with silicone grease, and this may be conveniently stored in a container and lid (figs 4 and 5). 3.

Claims

CLAIMS1. A system and method of removing bacteriological contaminants from water, consisting of a pre filter, a pump, a hollow fibre membrane module, and a clean water outlet, characterised in that the system is attached by attachment means to the input water container.
2. A System and method according to claim 1, in which there is cross flow washing of the hollow fibres, by means of a restricted outlet back into the input water container which produces excess flow of water through the fibres.
3. A system and method according to claim 1 and 2, in which the restricted flow is achieved by a pressure relief valve.
4. A system and method according to claim 1, in which the pump is a single acting piston pump.
5. A system and method according to claim 1 and 4, in which there is an air reservoir, so that the air is compressed during the pump down stroke, and expands during the pump return stroke, so that water continues to flow through the outlet during the return stroke, and there is two directional cross flow in the fibres.