|
 alford House believes wastewater is too precious to
dump down the drain. House, a North Carolina State University
water quality specialist, has underscored his point by creating
North Carolina's first and only self-contained wastewater treatment
system for an office building. The system which uses a constructed
wetland to imitate natural processes purifies and reuses 1,200
gallons of sewer water daily from the 60 employees who work in
the building, a refurbished schoolhouse on the shore of Jordan
Lake in Chatham County, NC.
 "We
think of it as mimicking nature," said House, who works
for NC State's Water Quality Group. "Nature has been cleansing
water for millions of years, so we figure it's got the process
figured out pretty well."
Like nature,
House's system uses soil, plants and microscopic organisms to
filter and treat the wastewater. The treated wastewater is used
to flush toilets in the building and to irrigate the lawn and
foundation plantings.
"It's
clear, it sparkles, and it looks like it's right out of the tap,
but it has nutrients in it, so it's liquid fertilizer,"
House explained. With the addition of a few minor cleansing steps,
the water could be made suitable for drinking.
Without the
system, the schoolhouse-turned-office building would probably
still be an abandoned eyesore, because it's too remote to be
hooked up to any municipal wastewater systems. The soils at the
site are unsuitable for traditional wastewater treatment options.
Built in the
1940s, the Bells School building -- named for the rural community
it served in eastern Chatham County -- housed first a public
school and then a parochial school before closing in the 1970s.
In the mid-1990s, Lyle Estill, president of software distributor
EMJ America, Inc., paid to have it renovated. EMJ America and
two smaller businesses are now located there.
"There's
no question that it's enhanced the facility, in addition to making
it possible," Estill said of the wastewater recycling system.
"Giving a tour of the building is greatly enhanced by the
greenhouse and the courtyard. It's a great place to bring a customer,
to bring a client."
In the spring,
EMJ received a Governor's Award for Excellence in Waste Reduction
from the NC Department of Environment and Natural Resources,
in part for its sponsorship of the water recycling project.
The wastewater
treatment system has three major components: A "hill/marsh"
wetland that mimics a set of sand dunes around a marsh; a wetland
designed to flood and drain like a tidal marsh; and a set of
greenhouse planters filled with tropical plants. Together, those
components create a web of life in which tiny microbes transform
waste nutrients into liquid fertilizer taken up by the plants,
or into harmless and odorless gas.
Each day,
1,200 gallons of wastewater from the building flow into a 2,000-gallon
septic tank near the building's courtyard. Every six to eight
hours, the wastewater is released automatically into the "hill/marsh"
wetland. As the water flows through three sand filters (the so-called
"hills"), sand, microbes and plant roots transform
and store potential pollutants. The water then flows into the
"tidal marsh" wetland. The flooding and draining cycles
of the wetland are controlled to influence the flow of nitrogen
and phosphorus from the system.
The water
is then disinfected by ultraviolet light and diverted to the
greenhouse, where tropical plants take up or transform the small
concentrations of remaining nutrients. Water leaving the greenhouse,
on its way to being reused in the building, is treated with chlorine
as a final disinfection. The entire process takes about 10 days.
The system
also serves aesthetic and educational purposes. Benches in the
courtyard and greenhouse make them inviting places for employees
to take a break. And House uses the system as an outdoor classroom
to teach children about how natural systems work, and about how
they -- as humans are part of those systems. "This is applied
ecology," he said.
Water is not
the only natural resource reused in the system: crushed building
brick and decking made from recycled plastic and sawdust are
used in the exterior courtyard, and windows from a condemned
building were utilized for the greenhouse.
House has
evaluated similar designs in a wide variety of situations and
believes the approach has many applications, especially where
expensive conventional wastewater treatment systems are not feasible
-- including small communities and buildings in rural areas such
as Chatham County. With some alterations, the system could be
maintained inside a building, making it useful in urban environments
and colder northern climates. Scaled down to one-third its current
size, he adds, the design would be a cost-effective wastewater
treatment option for a home.
House is now
developing water recycling projects in several areas, including
Gates and Craven counties, and is developing a way to monitor
the systems' functioning and nutrient content remotely, by Internet.
"If I can get measurements in real time, I can make adjustments
immediately, rather than having to send water samples to a lab
and then making adjustments in person," he said. 
|
