Environmental Engineering Reference
In-Depth Information
Box 5: Risk management of metals and metalloids
Identify geographical areas with elevated risks from speci
c metal
sources.
Perform testing of soil and plant samples to verify the level of the risk
from speci
c metal(s).
Identify alternative crop varieties of the same desired crop that take up the
least metal or convert the toxin to less toxic forms when grown in high-
risk areas.
Develop irrigation, fertilization and residue management strategies that
help to minimize metal uptake by plants.
Recommend crop restrictions, i.e. using other crops that have lower risks
of contamination with metals and metalloids and/or pose a lesser risk to
human health due to levels of dietary intake.
Zone the affected area(s)
for non-agricultural
land use or
land
rehabilitation
Source: Simmons et al. (
2010
); (Mateo-Sagasta et al.
2013
)
Much concrete advice on low-cost measures for managing health risks of
wastewater irrigation has been published in recent years. These recommendations
can be used to set the framework for wastewater-irrigated agriculture by reducing
health and environmental risks. Examples of publications include the following:
On-farm practices for the safe use of wastewater in urban and peri-urban hor-
ticulture: a training handbook for farmer
field schools (Keraita et al.
2012b
).
List of health-protection measures and associated pathogen reductions for
wastewater reuse in agriculture (USEPA
2012
).
Measures for dealing with chemicals (Simmons et al.
2010
).
Addressing health risks from farm to fork (Amoah et al.
2011
).
Safe use practices for vegetable production (Keraita et al.
2012a
).
Reduction of vegetable contamination using simple,
low-cost
reservoirs
(Moscoso Cavallini
2013
).
While much information is available on health and environmental risks of
wastewater irrigation and on measures to reduce them, less has been published on
agricultural aspects of the practice. Filling this gap in knowledge can make an
important contribution to support setting up new wastewater reuse schemes and
improving existing ones. Emphasizing the positive potential of wastewater irriga-
tion for agricultural use (rather than exclusively the potential risks) can serve to
motivate local stakeholders to address the issue of wastewater. To achieve this aim,
small scale, locally adapted systems must be developed that can be set up at low
cost and generate income. Wastewater treatment would then ideally be a side effect
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