The core product of BS-AFRICA is a high quality ceramic water filter candle, which is used in 18 different water filter housings. This filter candle, or the Tulip filter, is made of ceramic, mixed with colloidal silver and filled with activated carbon.

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How can the filter remove bacteria?

For the BS-AFRICA water filter only the finest and purest diatom earth a sediment resulting from one celled algae deposited on the bottom of geological lakes and lagoons millions of years ago. This is the same material used in making the finest china porcelain. The filter elements are baked at temperatures higher than 1000 Celcius to provide a very porous ceramic. The chemically inert ceramic filter can be stored for eternity without losing its effectiveness.

BS-AFRICA ceramic filter particles from the water but leaves oxygen and minerals in the water. This is why BS-AFRICA water tastes better than boiled water, which has no oxygen left.

The filter blocks all particles larger than 0.4 micron and a large deal of the particles between 0.1 and 0.1 micron

Particles and bacteria can be blocked in two ways

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Particles > 0.4 µm : Direct blocking or sieving: Particles and baceria of 0.4 µm and more are trapped a pore that is smaller than the particle and they cannot enter the filter candle.

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Particles < 0. 4µm: Bridging. Smaller then 0.4µm particles are too small to be blocked by the pore size however when two smaller particles arrive at a pore at the same time they get stuck and form a bridge accross the pore by sticking to each other. Bridged particles do not always plug the pore but create an even smaller pore. This is what happens when the flow rate of the filter reduces over time between cleaning. This means a bit less water but also cleaner water!

How can the filter kill bacteria?

The Tulip water filter is impregnates with silver particles. Silver ions (Ag+) have kill micro-organisms even in relatively low concentrations. They have a highly fungicidal, bactericidal and algaecidel effect. Medical studies describe that silver disables the enzymes that microorganisms depend on to "breathe".

Below is a more detailed description about how silver interacts with bacteria.

Catalytic Oxidation

Silver, in its atomic state, has the capacity to absorb oxygen and act as a catalyst to bring about oxidation. Atomic (nascent) oxygen absorbed onto the surface of silver ions in solution will readily react with the sulfhydryl (-S-H) groups surrounding the surface of bacteria or viruses to remove the hydrogen atoms (as water), causing the sulphur atoms to form an R-S-S-R bond; blocking respiration and causing the bacteria to expire. Employing a simple catalytic reduction/oxidation reaction, colloidal silver will react with any negative charge presented by the organism's transport or membrane proteins and deactivate them.

Reaction with bacterial cell membranes

There is evidence that silver ions attach to membrane surface radicals of bacteria, impairing cell respiration and blocking its energy transfer system. One explanation is based on the nature of enzyme construction: Specific enzymes are required for a given biochemical activity to take place. Enzyme molecules usually require a specific metallic atom as part of the molecular matrix in order to function. A metal of higher valance can replace a metal of lower valance in the enzyme complex, preventing the enzyme from functioning normally. Silver, with a valance of plus 2, can replace many metals with a lower, or equal valance that exhibit weaker atomic bonding properties.

Binding with DNA

Studies by C.L. Fox and S.M. Modak with Pseudomonas aeruginosa, a tenacious bacteria that is difficult to treat, demonstrated that as much as 12% of silver is taken up by the organism's DNA. While it remains unclear exactly how the silver binds to the DNA without destroying the hydrogen bonds holding the lattice together, it nevertheless prevents the DNA from unwinding, an essential step for cellular replication to occur.

In the presence of air (oxygen in water), metallic silver forms silver oxide, which also has a bactericidal effect

Due to due to its adequate solubility. The destruction of viruses, bacteria, moulds, spores and fungi through contact with silver objects is termed the   oligodynamic effect. To primitive life forms, oligodynamic silver is as toxic as the most powerful chemical disinfectants. This, coupled with its relative harmlessness to animate life (i.e. mammals), gives oligodynamic silver great potential as a disinfectant. (I.E. click refresh button to see silver animation)

 

 

Can one filter really disinfect 7000 litres?

The capability of a candle to remove bacteria depends on its thickness. This was tested by the laboratorium Waterlab Noord in the Netherlands.

 

It was determined that when the thickness measuring tools fits around the candle the removal rate of the filter candle is still 99.999%, after that the bacteria removal rate will slowly reduce.