Environmental Engineering Reference
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put into practice the
'
paradigm shift
'
in dealing with wastewater that many experts
on the topic call for.
The discussions in this chapter lead us to conclude that research in the following
areas could contribute to the design of sustainable agroecological wastewater
treatment and production systems. As pointed out in Sect.
2
, wastewater-irrigated
agriculture remains largely invisible. The fact that few existing schemes have been
described limits the knowledge base that can be used for designing new systems. As
pointed out, a range of locally speci
c criteria play a role for any wastewater
irrigation agricultural scheme. Therefore, more empirical research on the ground is
needed in regions such as South America in general and Brazil in particular for
which very little research exists. Concrete agronomic information that is needed
includes data on crop types that perform well under wastewater irrigation (adding to
information like that given in Annex 3) and on suitable combinations of crops
(which does not exist so far, see Sect.
4.4
). Because most wastewater-irrigating
farmers operate outside of the law or in legal grey areas (see Sect.
3
), there should
be research on how to best integrate informal wastewater irrigation schemes into
partnerships. This is needed for moving from unplanned to planned wastewater use.
Land-use planners, particularly in the peri-urban areas of rapidly growing towns
and cities needs to develop a rigorous approach to accommodate effective and
sustainable reuse schemes.
Annexes
Annex 1 Wastewater Reuse Standards for Health Protection
Health-based targets for wastewater use in agriculture as given in the WHO
Guidelines (WHO
2006a
)
Exposure
scenario
Health-based target (DALY
per person per year)
Log
10
pathogen
reduction needed
a
Number of hel-
minth eggs per litre
≤
10
−
6a
Unrestricted
irrigation
≤
1
b,c
Lettuce
6
Onion
7
10
−
6a
Restricted
irrigation
≤
≤
1
b,c
Highly
mechanized
3
1
b,c
Labour
intensive
4
≤
(continued)
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