Infrastructure Models for Ecological Wastewater Management - Restorative Redevelopment of Devastated Ecocultural Landscapes - page 406

FIGURE 20.4 Single-home subsurface-flow constructed wetland in Akumal, Mexico.
Photo courtesy C. Sparks.
much less polluted, it usually requires less treatment to produce reuse-quality water.
In these instances, graywater can and should be viewed as a resource as opposed to
waste product, since it has such a high potential for reuse. A single-home graywater
system is shown in Figure 20.6.
VILLAGE-SCALE (CLUSTER SYSTEM) INFRASTRUCTURE
Wastewater management at the village scale is characterized by the use of a col-
lection network that collects the sewage from two or more homes and routes it to
a treatment facility that is owned by the community. This requires a much higher
degree of institutional support than the single-home model. For the cluster-system
infrastructure model to work effectively, a management entity must be in place to
operate and maintain the shared collection, treatment, and reuse system .
a lternative C olleCtion s ystems
Collection systems can consist of conventional gravity sewer and manholes, although
alternative systems that remove the majority of the solids from the wastewater before
transport are likely to be much more cost-effective for small communities (Mara
1996). A typical settled-sewage system is shown in Figure 20.7.
In many instances, these collection systems can be constructed of “new” pip-
ing materials like high-density polyethylene (HDPE). This type of piping system
is tough and flexible (minimizing the number of fittings). Because sections of pipe
are melted together (fusion welded), the result is a watertight piping system. These
factors are contributing to the popularity of HDPE pipe in developing countries.
Figure 20.8 shows a typical network of small-diameter HDPE sewer pipes.