Geography Reference
In-Depth Information
their largely untreated sewage into the nearest water body. For example, in Canada
the third national sewage report of the Sierra Club (SC
2004
) on the 22 largest cities
revealed that five cities (Victoria, St. John, Halifax, St John's, and Dawson City)
annually released 140 billion L of mainly raw sewage into their local water bod-
ies, with three others (Montreal, Vancouver and Charlottetown) using only primary
treatment, which is essentially the skimming off the solids. These eight centres ac-
count for 40,000 L of effluent per second being dumped, which at best is barely
treated. By contrast Calgary and Edmonton treat all of their sewage in tertiary treat-
ment plants, which remove all of the waste. Edmonton's plants are described in
more detail in the next chapter as part of a more general recycling system(Chap. 6,
Table 6.1). These are examples of the way that new treatments for sewage can now
re-cycle a great deal of the treated product in a safe, if costly, manner through the
technological progress which converts the noxious solid matter from the sewage
into useable products and safely returns water to the natural system. Yet most cit-
ies still lag behind in the adoption of such new processes, which compromises the
health of their citizens and drastically reduces their degree of sustainability. Also,
despite this technical progress, or at least possible progress, at the end of the human
waste system only limited changes have taken place at the household level. The
flush toilets have not really altered since being invented by Thomas Crapper in the
mid nineteenth century, and still consume large amounts of water even with low
flush systems, while an alternative on an old idea, namely modern earth closet sys-
tems, has only been adopted by a very tiny minority. However there may be signs of
new advances in toilet development. For example, the Gates Foundation provided
over $ 6 million for what was called 'Reinventing the Toilet Challenge'; winners
were announced in 2012, with first prize going to Hoffman's electro-chemical sys-
tem. Although still in the developmental stage this system, or related alternatives,
may be of particular use in settlements of the developing world, for it is powered by
solar panels and creates useful products from human excreta, such as hydrogen for
cooking and the safe residue for fertiliser. Without the need for large inputs of water
it could bring sustainable and affordable toilets to the 40 % of the world population
that lacks access to sanitation, with estimated savings of over 1.8 million deaths
from diarrhoea (WHO
2012
). Although this technical progress shows what could
be done, the general adoption of such systems will still require major investments.
Related water disposal solutions that affect sustainability levels come from the
way that the run-off from roads and parking lots are treated. In the past the usual
approach was to channel it into the sewers, which, in storm conditions often leads
to system overloads and flooding. Many cities are now adding storm ponds into
their subdivisions; they store water from major storms and even out the flow into
the sewer system. Interest is also developing in reducing the size of the run-off
through the use of permeable pavements, especially in large parking areas which
means that rain water simply sinks into the ground through the gaps in the pav-
ing. But the problem of run-off is not simply a matter of flow. The run-off often
contains large amounts of pollutants, such as oil, chemicals, PCB's and other haz-
ardous products that come from the cars and trucks using the roads, thereby add-
ing to the levels of pollution in the sewer system. Although expensive treatment
