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Toxicity Test
The Portland Water District conducts a
test that further measures the impact of
wastewater effluent, or the water leaving
the plant, on aquatic life. The Whole Effluent
Test (WET) involves exposing test organisms
to various concentrations of effluent for
specific time periods. The tests measure
mortality and sublethal effects such as
fertilization or growth of the organisms.
It has been found that the species tested
seem to thrive in the effluent environment.
Mercury Test
Mercury is a naturally occurring metal found in the environment. Mercury
also enters the environment through incineration, coal-fired power plants,
mining, and disposal of consumer products made with mercury. Mercury ultimately
is transformed into methylmercury in lakes, rivers, and oceans. It
bioaccumulates in the aquatic food chain making consumption of fish hazardous to
those high on the food chain. Typically, mercury leaving Portland Water
District's wastewater treatment plants is minimal.
Mercury levels in Maine fish, loons, and eagles are among the highest in
North America. The best way to keep mercury at a minimum is to prevent it from
entering the environment in the first place. For more information, visit
www.maine.gov/dep/mercury.
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 Guided
by federal Clean Water Act standards, extensive monitoring is done
to ensure that the water and biosolids
leaving the treatment facilities meet strict requirements and are
safe for the environment. Wastewater received at the plant is monitored
to ensure that it isn't toxic to the biological process involved in
the treatment of wastewater and the water leaving the plant is tested
for biochemical
oxygen demand, total
suspended solids, and chemical and microbiological parameters
to ensure that clean water is being returned to the environment. Biosolids
are also monitored to ensure that they meet the strict standards for
beneficial reuse in compost and land spreading.
The primary wastewater laboratory is located at the East End Wastewater
Treatment Plant, however, smaller labs are located at each wastewater treatment
facility and conduct on-site process control work. Together, the wastewater
labs conduct over 20,000 tests a year to ensure the environment is protected.
The Portland Water District maintains the largest industrial pretreatment
program in the state. Roughly 30 industries in Westbrook and Portland
participate in the program that monitors and treats the waste at the
point of generation prior to discharge into the wastewater system.
An effective IPT program is an important aspect of environmental protection,
because wastewater plants are designed to treat domestic wastewater
only. Industrial wastewater discharge may hinder the biological treatment
required to properly treat domestic wastewater and may wreak havoc
on the system and contaminate the environment.
photo credit: Black Cow Photo |
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