How to make a candle filter for the home kitchen

Transcription

1 How to make a candle filter for the home kitchen Home made and commercial candle filter Peter Morgan 2016

2 Introduction In days when good drinking water may be scarce or may be derived from suspect sources, it is a good idea to take steps to either buy or make a simple water filter to place in the kitchen which purifies water in a simple way. Commercial filter units are available in some hardware shops, and perhaps they may be preferred but they can be expensive. However the concept is simple and a home-made unit can be made for use in the family kitchen. The one part which must be commercially made to required standards is the actual candle filter itself. They are called candles because they are whitish in colour and often look like large, rather fat candles. Candle filters are made all over the world, notably in UK, India, Brazil and many other countries. They are made to very exacting specifications. Candle filters as they are often called are ceramic filters made of special kieselguhr or diatom earth which is a silica like sediment. The same material is used for making high quality china. The concept of filtering water using this method was invented by Henry Dalton in 1827 and was used by Queen Victoria. The concept is simple. The poor size within the ceramic filter material is so small that disease carrying bacteria cannot pass through, whereas the smaller molecules of water can pass through, albeit slowly. If a filter is placed between an upper and lower chamber, so that water placed in the upper chamber must pass through the filter to build up in the lower chamber, then the water in the lower chamber, which has a tap will be purified. The base of the candle filter has a threaded tube and two rubber or xx seals and this tube is passed through a hole in the base of the upper chamber and held watertight with a type of wingnut which pressed the flexible washers against the inner and outer surfaces of the base of the upper chamber. When secured properly the only water which can pass between upper and lower chambers will pass slowly through the candle filter itself. Peter Morgan March.2016 Harare The completed home-made candle filter 2

3 The parts In the home made unit the following parts are required. 2 x 20 litres plastic buckets with lids A suitable tap A quality commercially made candle filter The tap Many different types of simple tap are available. This one is derived from a boxed wine carton The candle filter A candle filter this one was made in Brazil The lower bucket Lower 20li. plastic bucket. A hole is cut on the side, near the base of bucket and the tap tightly fitted in and held with a hard setting bonding material. Many taps use a threaded tube and nut and washers. The lid has a central hole cut in it for the outlet of the candle filter to pass through. 3

4 The upper 20li bucket This has a hole cut in the base for insertion of the threaded tube of the candle filter. The surfaces around the hole must be smooth. The threaded part of the filter is fitted through the hole with a flexible washer on both sides and is secured with a wing nut. The protruding part of the candle filter passes through a hole in the lid of the lower bucket. The upper plastic bucket sits on the lid of the lower bucket with the protruding part of the candle filter passing through the hole in the lid of the lower bucket. It is wise to test to see if all the water from the upper bucket does pass through the candle filter. This can be checked by raising the upper bucket and observing where the water comes out. In this case a little water did drain through the thread. A small amount of hard setting adhesive sealed this, as shown. It is essential that all the water which passes from the upper to lower chamber passes through the filter itself. Left. The completed filter unit being tested in the garden. The tap is opened by twisting the handle. Right.The home-made unit standing next to the Indian commercial unit in the kitchen, which has been in regular use for many years. Both units will perform the same function. 4

5 Use and maintenance This method of purifying water is very effective and has been in use since 1827 in Britain and for generations elsewhere. We have used it successfully for many years. It is a valuable addition to any kitchen hardware. But some care and attention is required to keep it functioning properly.. The filter will clog up more quickly if the water introduced into the top chamber is turbid or cloudy. If water is placed in the upper chamber, it should be relatively clean and clear. Cloudy water can be allowed to settle first in other containers before it is introduced into the upper chamber. As time passes the flow rate through the filter will slow down as the tiny pores in the filter start to clog up. The recommendations by the manufacturers of the filter are to clean the surface of the filter with a plastic brush or a soft scouring pad if the flow rate slows down too much. A dark layer of sediment does build up around the filter in time. Soap should not be used for cleaning. In our own kitchen the original candle filter has rarely needed cleaning or changing. This is because the water we place in the top is very clear and actually is derived mainly from a tube-well (shallow borehole). Nowadays I collect water for the filter and for use in the kitchen from an underground tank. It is hand pumped into buckets with a high delivery Blair Pump and then conveyed into the kitchen. The water in this tank comes mainly from our tube-well. The tank can also receive rain water collected from a plastic rain catcher. Plastic rain catchers collect purer water than can be derived from the house roof. The water that is processed by the filter is used for drinking. The tank, much of which is underground is completely sealed, even against ants. The water inside remains in the complete darkness and any small sediments settle on the bottom. This hand pumped water is almost certain pure even before it is passed through the candle filter but the filter acts as an extra precaution. The underground tank can receive water either from a plastic rain catcher for from other sources like a well, tube-well or borehole. On the left, rainwater is being collected from the plastic rain catcher in the distance. On the right, the Old Man pumps out water from the tank with a homemade high delivery Blair Pump into a bucket. These buckets (or other containers) are then taken into the kitchen and used for drinking (after passing through the candle filter) or for other domestic use and cooking. This may seem like a weird way of gathering and using water, but it is entirely suitable under the conditions under which we live. Every day we have fresh and pure water long may it last! 5