About the author
Mike Muller has managed a
waterworks and rehabilitated
a city’s sewage system. As
DG of DWAF (1997–2005), he
also established the existing
regulatory system for water
and sanitation services. He is
currently a visiting professor at
the Wits School of Governance
and undertakes advisory work
out of the country.
Water Sewage & Effluent May/June 2018
innovations
Fertiliser is not going to
get any cheaper, and
agriculture needs to keep
its costs down. We should
therefore be encouraging
formal partnerships between
organised agricultural as
well as agri-business and
municipalities.
But this will have to be run as a business,
not an afterthought. We could even
hand the running of the wastewater
works over to agricultural co-ops, in the
same way that they run grain silos. And,
like the service providers who offer
pest control and fertiliser services, the
co-ops could sell sludge application
together with the technical advice on
how best to use it — which will probably
include using organic waste from the
previous harvest.
Since the whole business would
depend on ensuring that the
wastewater plants are properly run —
untreated sewage is not acceptable
in most applications — this would
finally provide municipalities with
an incentive to manage the whole
wastewater cycle. Communities would
be better off, farmers would be better
off — and so would the environment.
This really is a case in which the
maxim — there’s money in muck —
ought to be turned into reality. Over to
the farmers! u
enough to take the thousands of tons
that one mine’s wastewater would
produce every year. The rest could
only be sold as a high-grade iron ore,
and that would fetch a few dollars a ton
rather than dollars per kilogram.
That led me to the problem of
municipal
sludge.
Wastewater
treatment is a real challenge for
South Africa’s smaller municipalities.
Unlike water supply, few people toyi-
toyi because their wastewater is not
treated. And even environmental
protesters are usually more worried
about sewage flowing into the rivers
than what happens to the sludge that
is drying behind the settlement tanks.
Sludge management is one of the
last items on the municipal spending
priority list.
So, what should they do instead
of just dumping it in large unsightly
piles alongside the treatment plant?
This is one of the cases where
small municipalities should have an
advantage over large ones. That’s not
because there is less sludge. They are
nearer to a huge potential market for
their ‘product’.
There is a long tradition of using
sludge for agriculture in South Africa.
Back in 1997, when government
departments still worked together,
the Departments of Water, Agriculture
and Health cooperated to produce a
guide as to how sludge could safely
be used in agriculture. They were
predictably cautious, though, about
the circumstances in which sludge
could be used.
But, particularly in smaller urban
areas where there is not much
industry, the sludges from wastewater
treatment are useful, both as fertilisers
and as soil conditioners. It should be
possible to manage health concerns,
particularly with crops like maize that
are farmed mechanically. The sludge
is applied during land preparation,
ploughed in to reduce fly nuisance,
leaving a whole growing season for
any remaining pathogens to die off.
The challenge, however, is that
the sewage still must be minimally
processed to allow solids to settle
and be separated into a reasonably
concentrated liquid. This is where the
win-win opportunities become obvious.
Fertiliser is not going to get any
cheaper and agriculture needs to keep
its costs down. We should therefore
be encouraging formal partnerships
between organised agricultural as well
as agri-business and municipalities.
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