is a life and death issue in less-developed
countries, where poor rubbish collection and
sanitation affects life expectancy. Expertise
from Leeds’ civil engineering department
is helping transform lives by transferring
knowledge on low-cost public sanitation.
year 1.8 million people die from diarrhoea,
90% of them children under five, according
to the World Health Organization. The WHO
says improved sanitation could bring these
cases down by 37.5%. Translate that into real
lives and bringing sanitation to the less-developed
world can make a big difference.
the specialism of Leeds civil engineering
professors Ed Stentiford (pictured, right)
and Duncan Mara. This year they are engaged
in EU-funded projects in Viet-nam, Thailand,
Bangladesh, Nepal and Colombia helping to
clean up towns and cities lacking the infrastructure
we take for granted.
key in these cash-strapped economies is to
sidestep high-tech solutions and use locally-available
technology and resources, processing waste
safely and recycling it or turning it into
compost and producing irrigation water from
sewage where possible.
principles are illustrated by Professor Mara’s
specialism – low-cost sewers –
which are currently being implemented in the
city of Cali in Colombia.
said: “Often engineers in developing
countries want hi-tech water treatment systems,
but these are high-cost too. They depend on
unreliable electricity and equipment that
can break down, needing expensive spares.
We try to convince them that they should make
the most of the resources they have to hand
like cheap land, plentiful labour and sunshine.”
concrete sewers of western cities, which run
under roads and require large-scale construction
are out of the question in places like Cali.
Instead, low-cost sewerage can bring sanitation
to poor districts at 20% of the cost. Small
diameter pipes run through back yards of houses
and carry away sewage that usually runs in
the sewage highlights another example of the
low-cost ethos advocated by the Leeds team.
Human waste is treated by aerating it to help
bacteria break it down. In our cities this
is done with equipment that stirs the sewage
slowly. In the developing world, where capital
is short and electricity unreliable, the Leeds
team recommends a different approach –
waste stabilisation ponds.
are large ponds where the sewage is allowed
to collect and green algae carries out the
aeration. The set-up costs are 10-30% of western
treatment systems and when the waste water
has been treated it can be used for irrigation
or fish farming. “Land is cheap and
there’s plenty of sunshine so the message
is to capitalise on what they have plenty
of,” said Professor Mara.
is the other half of the equation. Even in
the least developed countries each person
produces half a kilogram every day. Poor or
inadequate collection results in dumping in
streets, clogged sewers and drainage systems,
contamination of water sources and a profusion
of rats, insects and disease.
Stentiford advises on ways of tackling the
problem. These include changing popular attitudes,
organising effective collection and sorting
of waste to enable recycling where possible.
the Tan Hoa-Lo Gom canal project in Ho Chi
Minh City, Viet-nam, these ideas have been
put into practice. In the tightly-packed district,
rubbish collection was patchy and much ended
up in the waterways. Rubbish collected was
taken away in imported compactor trucks to
landfill, which made things difficult and
hazardous for the waste pickers who make a
living combing tips for recyclable material.
district now has an efficient collection system
and recycling has been made easier and safer.
Locally built tricycles carry away rubbish
to a transfer station. The garbage is not
densely packed and tables have been built
to aid the waste pickers.
improved waste collection and removed the
health risk. They’re handling waste
better now and getting it out of the city.
“Where rubbish was thrown into the canal,
it is now going to the transfer station and
landfill. With sorting they can get back 75%
of the value of plastic, for example, but
the next stage is to use organic material
by composting it,” said Professor Stentiford.
secret is to achieve the same performance
as the developed-world but not using the same
technology, as this would be too costly. In
many less-developed countries, labour is cheap,
so where material sorting is done by machine
in Europe it is a labour-intensive process
in these countries.”
to the UN, one-in-six of the world’s
population lacks adequate safe water supplies
and another 2.4 billion do not have adequate
sanitation. The Leeds team is making a small
difference to some of those lives.
use local staff and build on indigenous skills
by providing education and training for the
local people. We’re fighting a losing
battle against population growth so hopefully
we are making a difference by getting expertise
into these countries,” said Professor
top left – Waste pickers in Ho Chi Minh