Infrastructure Models for Ecological Wastewater Management - Restorative Redevelopment of Devastated Ecocultural Landscapes - page 403

single-home level. Technologies likely to be effective at this level include gray-
water separation, settling tanks, subsurface-flow constructed wetlands, and local
irrigation.
For a small town near the edge of the marshes, the wastewater system will not be
large enough to allow many of the conventional “big-pipe” technologies to be cost-
effective, so the decision matrix narrows to cluster and single-home options. For
scattered rural dwellings, the choice is clear: the only option is to manage wastewater
at the single-home level.
SINGLE-HOME INFRASTRUCTURE
In the absence of any other planning and organization capacity, the single-home
system is the default infrastructure model, and technology selected for wastewater
management should be consistent with this model.
s ingle -h ome W asteWater m anagement o Ptions
The wastewater management options available to Iraqis at the single-home level have
a range of pros and cons. These management options include direct discharge to the
marshes, soak-away pits and latrines, and onsite treatment and reuse.
Direct discharge to the marshes has one overriding advantage, because it the
lowest up-front capital cost option. It is also current status quo. However, the direct
discharge of pathogens, especially trematode worms ( Schistosomosa spp .), creates
long-term health problems for people living in and near the marshes. Potentially
valuable water and nutrients are thrown away, and this model generates no eco-
nomic return.
Soak-away pits or latrines allow wastewater to soak into the groundwater (or into
the marshes), but due to the filtering effect of the soil and/or sand used in these
devices, pathogens are generally removed from the wastewater (especially larger
particle-sized pathogens such as geohelminths, tapeworms, and trematode worms).
These systems achieve the goal of pathogen removal but do not recover potentially
valuable water and nutrients.
Onsite treatment and reuse systems are advantageous in that they not only con-
trol pathogens but also recover water and nutrients for irrigation, thereby creating
the opportunity to generate an economic return for the citizens of the community.
Treated effluent can be reused to irrigate gardens or other agricultural produc-
tion areas. These benefits will likely be the greatest to residents living along the
perimeter of the marshes. A drawback to onsite treatment and reuse, however, is
that there is a cost involved in constructing the infrastructure and management
required for such a treatment and reuse system (even if it is managed at the single-
home level). The key to “bottom-up” (e.g., not supported by taxes) infrastructure
development is to introduce a system that is culturally acceptable, and it is appar-
ent to the community that the long-term benefits of the treatment system outweigh
its up-front capital cost.