Geoscience Reference
In-Depth Information
10.1 Introduction
Sewage sludge, also known as biosolids, is defined in the Code of Federal
Regulations, Title 40, as the solid, semi-solid, or liquid residue generated during the
treatment of domestic sewage in a wastewater treatment plant (WWTP) (USEPA
1994
). In the United States, a significant proportion of biosolids are disposed of
through application to agricultural fields. There are anecdotal reports of illness and
in one case death after application of biosolids. This is a very politically-charged
issue in part due to public perception and concerns over health and safety having
resulted in lawsuits.
In July 2002, the National Research Council (NRC) issued a report expressing
concern over the practice of applying biosolids to farm fields in the United States
(Renner
2002
). In the 2002 report, the NRC states:
There is no documented scientific evidence that the Part 503 rule has failed to protect public
health. However, additional scientific work is needed to reduce persistent uncertainty about
the potential for adverse human health effects from exposure to biosolids. There have been
anecdotal allegations of disease, and many scientific advances have occurred since the Part
503 rule was promulgated. (NRC
2002
)
Across the United States as well as in many other countries, policy makers are
faced with the question of whether biosolids should be land applied or not. In this
chapter, we will give background on biosolids application in the United States focus-
ing on Ohio, discuss what is known on the potential environmental health impacts
of land application of biosolids, and show a recent study in which a geographic
information system (GIS) is being used to investigate those potential effects.
10.2 Biosolids Application in the United States
Biosolids became a disposal issue after the Clean Water Act was enacted in 1972
which laid out regulations for waste water treatment. Since then, land application
of biosolids from WWTPs, to agricultural fields has become commonplace in the
United States. Over 50% of biosolids produced in the United States are land-applied
with the remaining placed in landfills or incinerated (USEPA
2004
). The Clean
Water Act section 405 amendment in 1987 required EPA to set biosolids regula-
tions for minimizing environmental and health risks of identified toxic pollutants
while maximizing the use of biosolids (NRC
2002
).
Part 503, effective in 1993, was established by the U.S. Environmental Protection
Agency to oversee the national biosolids program and established treatment and
use requirements of biosolids, land application management practices, and con-
cern concentration limits and loading rates of chemicals. Apart from regulating
human pathogens, USEPA has adopted what it calls a “risk-based” approach to reg-
ulating ten heavy metals in biosolids: arsenic, cadmium, chromium, copper, lead,
mercury, molybdenum, nickel, selenium, and zinc. Table
10.1
shows the ceiling
