ENVIRONMENT AND ENERGY
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It is estimated that only 26% of urban and 34% of
rural sanitation and wastewater services effectively
prevent human contact with excreta along the entire
sanitation chain and can therefore be considered safely
managed. Sanitation and wastewater-related diseases
remain widespread in countries where the coverage of
these services is low, where informal use of untreated
wastewater for food production is high, and where
reliance on contaminated surface water for drinking and
recreational use is common.
In 2012, an estimated 842 000 deaths in middle- and
low-income countries were caused by contaminated
drinking water, inadequate handwashing facilities,
and inappropriate or inadequate sanitation services.
Improving sanitation and wastewater treatment is also a
key intervention strategy to control and eliminate many
other diseases, including cholera and some neglected
tropical diseases (NTDs), such as dengue fever,
dracunculiasis, lymphatic filariasis, schistosomiasis, soil-
transmitted helminths and trachoma.
Access to improved sanitation facilities can contribute
significantly to the reduction of health risks, and further
health gains may be realised through the provision of
safely managed sanitation services and safely treated
wastewater.
ECONOMIC EFFECTS
As the availability of freshwater is critical to sustaining
the economic welfare of any human community, poor
water quality constitutes an additional obstacle to
economic development. Poor water quality hampers
agricultural productivity in rural and peri-urban settings.
Contaminated water can directly affect economic
activities that use water, such as industrial production,
fisheries, aquaculture and tourism, and can indirectly
limit the export of certain goods due to restrictions (and
even bans) on contaminated products.
For example, in the Caribbean, many small island
economies are almost entirely dependent on the
health of their reefs for tourism, fisheries and shoreline
protection, but these reefs are threatened by the
discharge of untreated wastewater. While pollution
of natural environments may hinder economic
activities, tourism itself and the growing demand for
environmentally friendly facilities can provide leverage for
investments in the maintenance of natural environments,
and therefore act as an additional motivating factor for
improved wastewater management.
ENVIRONMENTAL EFFECTS
The discharge of untreated wastewater into the
environment has an impact on water quality, which in
turn affects the amount of water resources available for
direct use. Concerns over water quality are rising as an
important dimension of water security worldwide. When the discharge of wastewater causes environmental
damages, external costs (externalities) are generated
and the potential benefits of using wastewater are
lost. An economic argument for improved wastewater
management can be made in order to minimise the
negative impacts it can cause and to maximise the
benefits it can generate. If wastewater is recognised as
an economic good, appropriately treated wastewater
can have a positive value to both those producing it and
those consuming it.
Since 1990, water pollution has been increasing in
most rivers in Africa, Asia, and Latin America, due to
the increasing amounts of wastewater as a result of
population growth, increased economic activity and
expanding agriculture, as well as the release of sewage
with no (or only minimal levels of) treatment. Inadequate
wastewater management has also a direct impact on
ecosystems and the services they provide. WASTEWATER COLLECTION AND TREATMENT
There are essentially two types of wastewater collection
and treatment systems: Off-site systems, where waste is
transported through a sewerage network to a treatment
plant or disposal point, and on-site systems, where waste
is accumulated in a pit or septic tank. This tank can be
periodically emptied, or a new pit/septic tank can be
opened in another location.
Eutrophication, driven by excess nitrogen and
phosphorus, can lead to potentially toxic algal
blooms and declines in biodiversity. The discharge
of untreated wastewater into seas and oceans
partially explains why de-oxygenated dead zones are
rapidly growing: an estimated 245 000km 2 of marine
ecosystems are affected, and this affects fisheries,
livelihoods, and food chains. Certain on-site systems have leaching beds that
infiltrate the partiality treated water from septic tanks
into the ground (old and overstressed systems are a
significant cause of pollution in some areas). In the case
of emptying, waste is transported for treatment and/or
disposal. On-site systems can also include small-scale
sewerage systems that convey wastewater to treatment
plants located nearby.
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January 2018 Volume 23 I Number 11