Environmental Engineering Reference
In-Depth Information
Islam is admirably well equipped to provide a sound foundation of rational decision
making for reuse.
Before investigating Islam and wastewater reuse, it is helpful to put the broader
issues of reuse and culture in context by seeing how powerfully culture can influence
reuse in a secular, technocratic society such as the United States. There is also a
technical context that is needed. What is meant by wastewater reuse, and what types
of reuse are culturally sensitive?
A wide variety of applications may use treated wastewater. Most often, treated
wastewater is used for irrigation of landscapes, fodder crops, and human food crops.
Direct recycle of highly treated wastewater for potable reuse is very rare. Indirect
potable reuse is more common, such as discharge of highly treated wastewater to
aquifers and rivers that supply raw potable water. Any category of reuse that involves
human contact with, or ingestion of, clean water of sewage origin can arouse hos-
tility from intended beneficiaries that are deeply emotional in nature (Dingfelder
2004). (This chapter does not consider reuse without scientifically justified levels of
treatment. It is worth noting, however, that farmers appropriate raw sewage in many
areas of the world by custom or desperation [Austin and Asano 1996; Ghosh 1991;
WHO 1989].)
It may surprise many readers that the United States has no uniform standards
for wastewater reuse (EPA 1992). These regulations are left to individual states and
vary widely among them. The states of California and Florida have the most expe-
rience with wastewater reuse. Both states experience significant water stress. Both
have extensive wastewater reuse infrastructure. The technical standards adopted by
these states for reuse are strict and essentially the same. They entail the highest
possible levels of treatment and disinfection for effluent exposed to direct public
contact (Crook 1998). These standards are achieved with redundant disinfection and
filtration systems that are expensive to build and operate. Reuse standards based on
the California-Florida model try to minimize risks to public health by essentially
removing all pathogens from treated effluent, which is sometimes, but erroneously,
referred to as a “no-risk” philosophy. (The “no-risk” label is technically a misnomer
because there are measurable risks in water reuse that drafters of the California
regulations carefully considered [Crook 1998].)
In contrast, the World Health Organization recommends reuse standards based on
a different public health philosophy. Reuse is a strong need in regions of water stress,
but many societies cannot afford “no-risk” reuse standards. The WHO standards
are based on an epidemiological assessment of the risk of acquiring illness from
ingesting food crops irrigated with reused wastewater (WHO 1989). In general and
highly simplified terms, a disinfection standard is considered sufficient if the risks
of additional illness are statistically indistinguishable from the background rate of
illness caused by pathogens of fecal origin. Some consider the WHO standards to be
less rigorous than the California-Florida model because of the potential insensitiv-
ity of epidemiological analyses to detecting actual infections caused by contact with
treated wastewater (Crook 1998).
California and Florida regulators would consider the WHO standards to be com-
pletely unacceptable for agricultural reuse. Yet both the California-Florida model and
WHO reuse standards are scientifically justified. Why is there such a large difference?
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