Sustainable solutions to the big five
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Liquid waste
Grey and black water
Grey water collected from rainfall on a site can provide much of the water required to
flush toilets or wash clothes. Demand for this water can be reduced through the use of
waterless urinals and toilets. On-site sewage treatment is feasible but, like harvesting
rainwater for drinking, there is reluctance because of public health concerns and
current resistance to alternative technologies.
Storm water
Historically, storm water infrastructure has been used to ‘pipe out’ water from
urban areas which are at risk of flooding. It has therefore been necessary to provide
appropriate infrastructure to urban boundaries relative to the volume and flow rate
of water discharged. Where flow rates and volumes increased, the storm water
infrastructure had to be bolstered to support the additional demands on it.
Urban landscapes tend to be subject to higher volumes and faster flow rates of
surface water run-off than rural or heavily vegetated areas. This is because the
surface properties of urban landscapes (such as hard paving and roofing) tend to
make it easier for water to flow across and through them. However, storm water
systems are often below ground and interlinked with transport networks. This can
make the provision of increased infrastructure made necessary by expanding urban
environments both expensive and inconvenient. It can also cause problems elsewhere
within the water cycle, as the natural system may struggle to cope with heavier flow
rates.
Sustainable drainage systems (SUDS) offer an alternative, holistic approach to
drainage in developed areas. They work on the principle that ground covered in
vegetation retains water naturally, both in the vegetation and in the soil. By increasing
areas of natural vegetation and scaling back the space given over to hard landscaping,
it is possible to contain storm water in ‘green’ areas, effectively reducing urban storm
water run-off. Within the urban environment, these ‘collecting’ areas can take the form
of parks, gardens and pavements (all with minimal hard landscaping), but also green
roofs and water butts. Further benefits of SUDS include reduced infrastructure costs,
improved amenity spaces and enhanced wildlife habitats.
Gaseous waste
Vehicular pollution can be addressed in ways such as those discussed earlier in the
‘Transport’ section. However, in China, where pollution is currently at record levels, a
40% reduction in vehicle emissions in the Beijing area was recorded when cars were
simply banned over a four-day period.
Indoor air quality can be improved through reduced use of off-gassing VOCs, better
ventilation standards and regular maintenance of HVAC plant.
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