Newsletter and Technical Publications
<International Source Book On Environmentally Sound Technologies
for Wastewater and Stormwater Management>
2. Integrated waste management
The description of problems facing communities without adequate
sanitation above shows the importance of addressing the problems in an
integrated manner. Simply solving the problem of wastewater without taking into
account of solid wastes and stormwater will not achieve sufficient sanitation
improvement to protect public health and the environment. UNEP IETC has
published an International Source Book on Environmentally Sound Technologies for
Municipal Solid Waste Management, which provides guidance on the selection of
technology for the management of solid waste. The present UNEP IETC Source Book
complements this publication, and is intended to provide the means to achieve
the integrated approach.
In discussing integrated waste management we need also to
consider solid wastes and wastewater produced by industry. In many instances
these may not differ in characteristics from domestic wastes, consisting
primarily of biodegradable organic substances. Industry, however, produces
numerous types of wastes which may be toxic to bacteria that are utilised to
treat domestic wastewater. The practice in many communities is for industrial
wastes to be disposed with domestic wastes.
One principle that logically emerges from adopting an integrated
approach to waste management is that different types of waste should not be
mixed (Figure 1.7). Solid wastes should not be dumped into stormwater drains,
but should be collected, recycled, reused, or treated and disposed separately.
Dumping of solid wastes in stormwater drains will not only restrict the flow of
stormwater, they contaminate stormwater. Treatment of the stormwater will
involve separating the solids and other contaminants from the water. Similarly
industrial wastes should be treated separately, and industrial wastewater should
be pre-treated if they are to be discharged to the sewer.
Figure 1.7a: Non-integrated waste management. Each waste is managed
individually without coordination.
Figure 1.7b: Integrated waste management.
All wastes should be considered together to achieve environmental
and public health improvement. Wastes should be separately collected and managed
A useful tool that can help towards achieving integrated waste
management is the waste management hierarchy. It has been used to direct waste
management towards achieving environmentally sound practice. The waste
management hierarchy in its most general form is shown in Table 1.2. In using
this tool for waste management we systematically go down the list to see if step
1 (Prevent or reduce waste generation) can be implemented, before considering
the next step (2) and so on. Only when steps (1) to (5) have been fully
considered that we consider disposal of the waste (step 6).
Table 1.2: The waste management hierarchy
||Prevent or reduce waste generation
||Reduce the toxicity or negative impact of the waste
||Recycle waste in its current form
||Reuse waste after further processing
||Treat waste before disposal
||Dispose in an environmentally sound manner
We cannot prevent the production of human excreta or stormwater,
but we can prevent other materials from being disposed with human excreta, or
solid waste with stormwater. We can use less water to achieve the same purpose
(e.g. flushing toilet) and hence produce less wastewater. We can avoid toxicity
of wastewater by preventing toxic household or industrial wastes to be disposed
with biodegradable organic wastes. A reuse example is the use of urine as a
liquid fertiliser, while composting can convert human excreta into a soil
conditioner. Other examples will be discussed in Section 2, but it should be
recognised that all waste management practices have costs as well as benefits.
The application of the waste management hierarchy therefore needs to consider
economics as well as other factors (e.g. some culture may not allow reuse of