ENVIRONMENT AND ENERGY
sustainably. Although planned use and functional markets
of wastewater for ecosystem services is a relatively recent
phenomenon, the valuation of treated wastewater use for
ecosystem services reveals favourable environmental and
economic benefits.
The informal use of untreated wastewater is already
occurring widely, out of simple convenience or as a matter of
sheer need, and all too often in the absence of appropriate
safety control measures. While measures that promote the
direct use of certain types of untreated wastewater may
be relatively easy to implement, the cost of developing
treatment systems for recovering wastewater from certain
specific human activities may be prohibitive in some cases.
There can also be a mismatch between the location
and timing of the source of wastewater, and its eventual
use. Wastewater management systems, therefore, need
to be designed based on its characteristics (e.g. origin,
components and level of contaminants) and the intended
end use of the effluent stream, including any useful by-
products, as these will dictate the most appropriate and
practical wastewater source.
There are strong economic arguments in favour of optimising
freshwater-use efficiency, managing wastewater as a
resource and eliminating (or at least reducing) pollution at the
point of use. Utilising wastewater at, or as close as possible
to, its source generally increases cost-efficiency due to the
lower costs of conveyance. The fact that so little wastewater
management is currently occurring, particularly in developing
countries, means that there are vast opportunities for water
reuse and for the recovery of useful by products, provided the
appropriate incentives and business models are in place to
help cover the substantial costs.
Recent market studies also show that there is a positive trend
in water and wastewater treatment investments in developing
countries. Worldwide, the annual capital expenditures on
water infrastructure and wastewater infrastructure by utilities
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have been estimated at USD100-billion and USD104-billion,
respectively (Heymann et al., 2010). Since wastewater
management is implemented at the local level, responses
and technical solutions will need to be location-specific. In
this respect, there are opportunities in further integrating
wastewater management, including sanitation and faecal
sludge management (FSM), with water resources and solid
waste management. This requires governance structures that
foster collaboration across institutional boundaries, as well as
accountability and compliance with regulations for wastewater
use and the extraction/use of recovered by-products.
25
Table 2: Framing
wastewater
management from a
resource perspective
Above all, wastewater management needs to be planned
from ‘upstream’, at the source, in order to complement
end-of-pipe solutions ‘downstream’. A number of pressures
on water resources are driving the need for the enhanced
use of wastewater. Population growth, urbanisation,
changing consumption patterns, climate change, loss of
biodiversity, economic growth and industrialisation all have
an impact on water resources and wastewater streams, with
repercussions on atmospheric, land and water pollution.
An improved approach to wastewater management will help
alleviate the impact of some of these pressures. From a
resource perspective (see Table 2), sustainable wastewater
management requires: i) supportive policies that reduce the
pollution load upfront; ii) tailored technologies that enable
fit-for-purpose treatment to optimise resource utilisation;
and iii) taking account of the benefits of resource recovery.
Such a perspective promotes the implementation of
innovative financial mechanisms, while embracing a
precautionary approach and the polluter-pays principle.
It is the responsibility of national governments to provide
the policy environment for equitable tariff structures that
help ensure the operation and maintenance of existing
infrastructure, and attract new investments along the
wastewater management cycle. PA
To be continued in future editions of Plumbing Africa.
November 2017 Volume 23 I Number 9