25 April 2004
How-to make the particulate grog systems        see below

About trainings and demos
It is not particularly difficult to manufacture pottery water purifier systems, simply requiring initiative and a commitment to detail.  For production of  the candle systems it is best to learn the basics along with a local ceramist/ potter.  For the production of the particulate system, where no kiln or ceramist is required, all tasks implicit, silver treatment and packing of canisters, can be learned within a few weeks, and the necessary materials are generally available anywhere.  There is a very low capital cost for beginning production of particulate systems.

One of the ways of treating particulate grog is by pouring this into a container of silver nitrate solution.  The silver nitrate solution starts out white, as is still visible on the top.
For training in the candle, or disk production there is a set of variables that must be balanced, in order to achieve appropriate flow rates, starting with the understanding of local clays and their attributes.  Some other variables include:  amounts of grog and charcoal powder, firing temperature, water column height of the system, etc.  These variables can be brought to task in a longer workshop, four to six weeks, or finished by the ceramist in question, following a shorter workshop of two weeks.

Alternatively, if an aspiring filter project would like to fabricate particulate systems, in pvc pipe, this kind of production can be undertaken almost anywhere, not requiring kilns.  In this situation what is most important is a rigorous attention to the details of quality control, as well as appropriate testing of random samples.
 
How-to Make Particulate Grog Systems
For the particulate purifier there is no need to have a kiln, as is the case with the candle.  Particulate purifier grog is simply a pre-fired pottery or red brick, of good porosity and strength, that has been milled to a particulate/ powder.  Then this material is sized by screening, careful not to allow too many of the finer particles.  The use of too many of the fine particles may cause the system flow rate to be too slow. 

Methodologies of silver treatment are several.  The simplest are by using either colloidal silver or silver chloride.  This last starts out with saturation using silver nitrate.  Other methods of silver treatment require a kiln, so as to get a silver metal, ceramic bond.  More on this can be found at the Colloidal Silver link.

Shown here is the treatment of candles, immersing these in concentrated colloidal silver  (CS).  Candles can also be treated with silver nitrate and the particulate grog can be treated with CS.
Here are the steps of making a particulate grog system
1.  Treat the grog by pouring this into colloidal silver or silver nitrate, as shown at the page header.  Spread the grog out to dry.  In the case of silver nitrate this should be in subdued light, otherwise some silver salts may go through reaction to become silver oxide.  Following the drying of the grog this is ready to be inserted into the canister.
2.  Purchase several different types of red brick, from the local market, with a view towards determining which of these is most suitable.  The best crushed brick for use in the systems would be that which has a high percentage porosity, combined with good fracture strength.  As to good strength it is simply a good idea to avoid those bricks that were not fired to a high enough temperature.  Wherever strength is not good the bricks would be easy to crush or crumbly.
Aside from the silver grog of the system the other parts are pvc.  Several round grates, to contain the grog are fashioned from the same kind of pipe, fitting within the canister.  These grates are flattened and perforated.  At either end of pipe there are pvc tripods, also holding the central canister in place.
3.  Arrange the milling of the brick with a company that is equipped to do this.  One good possibility is to inquire about the milling from a company that deals with agricultural supplies.  A hammer mill can be quite appropriate, however the operator needs to take care not to mill the material too finely.  A good starting point is to use particles of mesh size between 20 and 100.
4.  In screening this powder discard any particles that pass 100 mesh.  Similarly remove any particles that will not pass the 20 mesh screen. 
5.  Prepare the pvc canister, readying this for the insertion of the powder.  Inside of the pipe diameter of the canister, shown, three small pieces of pvc section can be seen, having been glued in place, using a special pvc glue.  The height of these pieces is 33.0 cms, starting at the bottom end of the canister.
6.  Flat grates can easily be fashioned out of a piece of the round pipe, for use at bottom and top ends of the grog bed.  The grates help contain the grog.  It is possible to hold pvc in a candle flame, then with the heat bend this flat.  Then the grates can be perforated, with a hot screw driver, or other such implement.

One design for the canister system is shown here.  The terra cotta color indicates the location of particulate grog material.  At the two ends are the backflush beds, containing coarse, 10 to 20 mesh grog.

7.  Hold the canister upright, the legs of the tripod at the bottom end.  Now drop one of the grates into the pipe, so that this comes to rest on top of the tripod.
8.  While the grate acts as a sort of screen, to allow water to pass in and out of the system, the holes that were punched into this are large, and would also allow particles to pass.  For this reason a second screen is placed on top of the grate.  This is simply a piece of sheet plastic, e.g.. from a plastic bag, that has had many small pin pricks.  This screen allows water to pass, but not particles.
9.  Pour a measured amount of coarse grog into the canister, covering the screens with this.  This grog is that which will pass a 10 mesh sieve but will not pass 20 mesh.  This material allows for the periodic backflush required when turbid water is used.  Place another plastic sheet screen on top of this 20 mesh grog.
10.  Prior to pouring the grog into the canister, be sure to mix this well, pulling any smaller material up from the bottom.  Otherwise there may be a tendency for the smaller grog to sift through to the bottom of the container. 
11.  Pour this smaller grog ,20 to 100 mesh, into the canister.  This is the purification bed. 
12.  Now reverse the previous order of steps:  13.  place a plastic sheet screen on to the top of the purification bed,  14.  pour the 20 mesh grog on top of this.  15.  Insert the sheet plastic screen and grate.  16.  Drop the second of the pvc grates into place.  17.  Glue in place an additional three pvc tripod pieces.

With completion of these steps, and the overnight drying of the pvc glue, the system is nearly ready for use.  First, however, it is best to run several liter of water through, to remove any extraneous material.  Prior to use the systems, however some prototypes should also have been put through the rigors of quality control and the various testing procedures.

Please address inquiries and observations to:
Reid Harvey
Ceramic Designer
pottery@wlink.com.np

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