How the cleansing systems works
Farmer's Weekly, 15 June 2001
The water that comes out of the wineries is
very acidic, and it has to be neutralised. If it is then
pumped untreated into an evaporation pond, the sediment
(the skins, pips and fining material) settles on the bottom.
The layers build up, creating stagnant conditions.
Anaerobic microbes thrive where there is no oxygen, and
they get to work generating gas. The water becomes toxic
and bubbles with foul gases while septic sludge forms on
To remedy the situation, two things have to happen. First
the large solids must be screened out and the fine solids
removed by means of a delta separator. The clear effluent
can be used either directly for irrigation (pumped into large
irrigation dams where it is diluted with run-off water) or
it can be ponded.
If the water goes into a pond, micro-organisms have to be
added, and oxygen has to be introduced at the bottom of the
pond to counter the latent anaerobic conditions.
The selected microbes can be
introduced in the form of an air-dried powder, and the water
has to be aerated. The simple way of doing this is a fountain
that circulates the water and ensures that it absorbs oxygen
as it is sprayed into the air.
This certainly prevents stagnation, but it is not very efficient.
It does not get the oxygen to bottom where the helpful bacteria
really need it.
A better way is to force the air right down to the bottom
of the pond to reverse the anaerobic conditions. But thats
easier said than done.
If the air is released in big bubbles it stirs things up,
and those bubbles shoot straight back to the surface, in this
way giving up little oxygen to the water. "What we have
to do," says Bob Hadley of Bio-Systems SA, "is deliver
the oxygen in tiny bite-sized bubbles something the
microbes can get their teeth around."
The device that does the trick is an injector that produces
such tiny bubbles that the air looks like white foam in the
The effect is almost miraculous. If the pond has been seeded
with the right microbes, the anaerobic conditions disappear
in a matter of days, and so does the unpleasant smell.