Sewage
system overflows present a messy situation for everyone involved.
There's E.coli levels to monitor, equipment to repair, and
finally, heavy EPA fines to pay. A municipality may be charged
$27,000 for every day untreated wastewater seeps into public waters.
Events,
like the fire that shut down the North Harlem Wastewater Treatment
Plant and caused millions of gallons of raw sewage to flow into the
Hudson and Harlem Rivers, can't be prevented. However, having the
right rig of pumps and sensors coupled with diligent maintenance can
prevent mechanical failures, polluted waters, and penalties.
Accidents,
increased water flow into sewer lines, and equipment breakdowns can
cause sewage system overflows, or SSO's. When water is flushed down
toilets or spilled down drains of residential and business
properties, the liquid travels downhill through underground pipes to
a treatment plant strategically placed at the bottom of the slope.
The plant's location allows gravity to do most of the work. Once
dirty water reaches the plant, it's filtered and chemically treated
with decontaminants like chlorine and ultraviolet light to kill
harmful organisms before it's released into a body of water or
reused.
When
topography is level, lift stations pump water to a higher elevation
to generate enough potential energy to bring it to a treatment plant.
At its most basic level, a lift station consists of a sensor, a
switch, a reservoir and a pump. Sensors monitor changing water levels
and decide when to trigger a switch that turns the pump on or off.
"One
pump failing can be catastrophic," APG representative Doug Moore
said. "When lift stations have multiple pumps, there's a back up
in case one fails."
APG,
Automated Products Group, sells sensors utilized by lift stations in
wastewater treatment plants. There are many sensor solutions on the
market, ranging from simple float switches to sophisticated
ultrasonic sensors. Each level sensor is suited for a particular
environment and setup. For example, if a lift station only has one
pump, a float switch is a reliable, cost-effective option that's
durable and keeps employees away from hazardous material. A float
switch is a weighted sensor dangling from a
cable in a tank like a baited fishing line in a pool. As water level
rises, the sensor begins to float and the angle between the sensor
and cable changes. When a critical angle is reached, the pump is
turned off.
However,
servicing a large metropolitan area with a one-pump lift station is
not sustainable and so additional pumps and water
level sensors are needed. Employing multiple
float switches in a more powerful lift station means more cables
swimming in moving water that could lead to entanglement, sensor
failure, and SSO's. One way to avoid the mess while keeping the extra
horsepower is to use a float switch such as APG's TK that measures at
multiple water levels, discounting the need for extra switches.
Investing
in continuous level sensors may also insulate a municipality from EPA
censoring. While they're more expensive that a float switch, sensors
such as an ultrasonic sensors or submersible pressure
sensors allow for continuous level measurement
and a variable speed drive, prolonging a pump's life. On the
contrary, float switches can signal a pump to turn on or off once a
specific water level is reached which means a pump is either 100% off
or 100% on. Variable speed drives allow a pump's energy output to
match the work that needs to be done.
Taking
the time to research the correct setup for a wastewater treatment can
prevent system failures such as the one experience by the city of
Dubuque, IA. The city agreed to pay a $205,000 civil penalty fine,
spend $3 million on improvements to its wastewater treatment plant
over the next three years, and $260,000 on an extra credit
environmental project when it was found to be in violation of the
Clean Air and Water Act. Over 165 miles of sewer pipes, three major
pump stations, and eight lift stations comprises the city's water
treatment system that services 92,000 residents along the Mississippi
River. Approximately 39 SSO's and 687 violations regarding solids and
chemicals discharged into protected waters occurred during 2002 and
2007.
Maintenance
and improvement costs are minimal compared to staggering fines owed
to state and federal governments when treatment plants are found to
be noncompliant or fail completely. An advanced float switch like
that from APG costs $100 and can last five to ten years. But it's not
really about the money. By 2050, the United Nations estimates that
two billion people living in 48 countries will lack sufficient water.
In the year 2050, the same two billion will make up 21% of the
earth's projected human population.
Article Source: http://www.compensationsecrets.co.uk/