Environmental Science & Engineering - www.esemag.com - September 2004
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Bear River’s unique greenhouse wastewater treatment process
By Hans Tammemagi
Nova Scotia is the recycling leader of Canada. Less
known, however, is that it also has a wastewater
treatment facility that is one of the first in North
America. It is situated in the picturesque town of
Bear River, nestled in a steep valley on a tidal river near
the west coast of the province. The town, which has gained
the nick name of “Little Switzerland” and is home to a
thriving artisan community, is well worth a visit even without
the treatment facility.
From the outside, the Bear River Solar Aquatics
Wastewater Treatment Facility looks like a greenhouse.
But inside, instead of flowers, there are tanks,
pipes, and a pond. It was designed and built
by EDM-Environmental Design &
Management Limited in 1995.
The process begins in the
blending tank with bioaugmentation,
where bacteria are added
by way of recycling of the secondary
solids from the clarifier.
The water is aerated to break up
the solid material and convert it
to prime material for the subsequent
ecosystems to feed on.
Sludge is not produced as in conventional
treatment systems.
The 12 solar tanks (1.5 metres high by
1.8 metres diameter) contain mini ecosystems and
water is gravity fed from one to the next. Inside each tank
are specially selected algae, zooplankton, phytoplankton,
snails, fish and plants that feed on the organic compounds
in the water. As the wastewater progresses from one tank
to the next, more and more of the organic compounds are
removed.
After the last tank, the wastewater flows into a 9.4
metres by 5.9 metres solar pond which is 2.9 metres deep.
The pond is divided into three sections with each containing
the same ecosystems as the tanks, only on a larger
scale. The water is aerated to help accelerate the consumption
of organic material. The effluent is then pumped into
a gravity clarifier/marsh where various marsh grasses provide
denitrification, nutrient uptake, phosphorous
removal, and final polishing and clarification.
Although it has not yet been necessary, the water could
also be passed through a swirl separator and a rotarydrum
filter where any remaining solids are removed and
sent to underground stabilizing tanks for aerobic digestion
and then applied to a reed bed for composting.
Finally, the effluent is UV disinfected and gravity fed
into the Bear River. Monitoring has shown that the final
water meets provincial environmental standards.
The solar aquatic system is cost-effective as it
provides secondary and tertiary treatment at
the same cost as traditional methods
providing only primary treatment. In
addition, the odourless and aesthetically
pleasing appearance allows
the system to be located close to
the sewage sources, thus reducing
collection system and
pumping costs. No complaints
have been received, although the
facility is located near the downtown
tourist district.
A strength of the system is the
high degree of diversity in the ecosystems.
Because of this, they are not as vulnerable
to toxins as systems that rely on only a few
specialized microorganisms. Furthermore, they are selfregenerating
and effectively run themselves, with little
operator intervention required.
The facility, which currently processes 68 cubic metres
(15,000 imperial gallons) of wastewater per day, was
designed so it can be easily expanded. It can also be readily
modified to clean the wastewater to a higher quality. A
facility with four-times larger capacity has recently been
constructed in Beaverbank, Nova Scotia.
Contact EDM-Environmental Design & Management
Limited,
e-mail: info@edm.ca.
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only accept orders from Canada and the United States.
