A
Comparison Between Distribution Devices used to Split
On-site Wastewater Effluent Between Percolation
Trenches
Laurence
Gill, Titiksh Patel, Niall O’Luanaigh
Department
of Civil, Structural & Environmental Engineering, University of Dublin,
Trinity College
Abstract
A
rigorous site assessment is now required in Ireland in order to design an
on-site wastewater
treatment
system. A critical component of an effective gravity-operated on-site system
is the distribution box, which must be able to promote an equal split of
effluent between percolation trenches. Comparisons were made both in the
laboratory using clean water and also on-site using a V-notch distribution
box on two different types of wastewater effluent (septic tank and secondary
treated). The trials carried out on distribution devices in the laboratory
showed that flow distribution was sensitive to both the off level
installation angles and variable flow rates.
The
flow regime experienced at distribution devices has been continuously
monitored using tipping bucket instrumentation over six month periods which
established that
the
most common flow rates at the distribution unit were in the range of 0.1 to
2 L min-1. Laboratory tests were also carried out on three other
distribution devices (a stilling chamber and two in-line flow splitter
devices) which revealed that a flow splitter with upstream baffle plates
achieved the best performance under
varying installation angles and
flow rates.
Keywords.
Distribution devices, flow rate, installation angle, on-site wastewater
treatment systems,
septic tank.
Introduction
Poor
distribution of on-site wastewater effluent between subsoil percolation
trenches is often the cause of septic tank / soil percolation system
failures. Poor distribution results in hydraulic and biological overloading
of one or more of the percolation trenches. Even if the soil hydraulic
conductivity is adequate for transmitting the liquid away from the trenches,
the formation of a biomat may restrict wastewater percolation from the
trench (Van Cuyk et al., 2001). Hence, equal distribution of the effluent is
essential to prevent the failure of the system whereby all of the effluent
passes into one distribution line to the exclusion of the others. Equal
distribution to soil absorption components can be particularly difficult to
achieve when relying on gravity to promote such a split.
Conclusion
The
laboratory trials using clean water showed that the Flow Splitter
device with baffles showed the best flow splitting efficiency and was
relatively insensitive to a range of off-level installation angles. In
contrast the
stilling chamber design proved very sensitive to being off level and also to
different flow rates.
Eleventh
Individual and Small Community Sewage Systems
Conference
Proceedings
20-24
October 2007 (Warwick, Rhode Island, USA)
Publication
Date: 20 October 2007
ASABE
Publication Number 701P1107
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Nova Scotia invention fixes
common environmental problem
Department of Environment & Labour
A Nova Scotia invention may mean a healthier environment and lower costs for
homeowners.
There are more than 100 thousand domestic septic systems in Nova Scotia,
almost all of which use a network of pipes in a soil bed to disperse treated
effluent. If the dispersal pipes are not exactly level, one side of the
disposal bed can become overloaded and fail. The failure creates
environmental and health risks and the repair is expensive.
A Wellington Nova Scotia septic system consultant, Ken Burrows, came up with
idea of the flow balancer to solve the problem. He took it to the
Environmental Innovations Branch of Nova Scotia Environment and Labour.
"The Department helped us understand what kind of financial assistance
might be available and what kinds of test results regulators would need to
see," Mr. Burrows said, we finalized and tested the design."
"The concept is simple," said Dr. Satish, "but we needed
experimental results to prove the concept and demonstrate its effectiveness
to regulators."
The device forces the effluent flow into two equal streams. This ensures
that the effluent is evenly distributed through the disposal bed. The
balanced flow means that the work of filtering the effluent is spread evenly
across the disposal bed.
The National Research Council's Industrial Research Assistance Program
provided funding for prototype development. "Environment and Labour
helped me make the connections with the University and the funding agencies
to bring this to life," said Mr. Burrows.
Nova Scotia Environment and Labour provided financial support for the patent
application and marketing. "Assisting environmental innovation is a
core business of our Department," said Environment and Labour Minister
Kerry Morash. "We're always ready to help make smart ideas like this
one a reality."
The developers have applied for a patent and are discussing manufacturing
plans.
"This is just the latest in a series of successes we've had working
with the engineering faculty at Dalhousie," said Mr. Morash.
"Their ability to apply science to real-world environmental management
problems means we'll have more successes in the future."
A Nova Scotia invention will make domestic septic systems safer and more
reliable.
The Flow Balancer allows septic disposal fields to last longer, meaning less
risk to the environment and lower costs for the property owners.
Contact: John Perkins,
Environment and Labour
Tel: (902) 424-6427
Email: perkinsje@gov.ns.ca
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Wellington
inventor provides solution for environmental snag. Septic systems would
become safer: A Wellington inventor providing an answer for a common
environmental problems?
NEW
RELEASE, The Laker, August 2004
Ken Burrows, environmental consultant and inventor, smiles with pride at the
suggestion; however, he becomes more serious when discussion turns to his
Nova Scotia invention that will make domestic septic systems safer and more
reliable.
Burrow's, a QPII, operates a family business that selects septic systems for
residential housing and oversees the installation and approval of these
on-site systems.
He credits his invention to working for many years as a developer and
serving a term as director of Waste Water Nova Scotia Society (WWNS).
MLA Gary Hines, also a director of WWNS, recently congratulated Burrows on
his invention, mentioning that the subject of flow balance was a hot topic
with the board and Robert Anderson, of the Nova Scotia Department of
Environment and Labour, at an annual general meeting of WWNS a couple of
years ago.
"It is nice to see private sector and government working to provide
Nova Scotians with more professional and efficient sewage disposal,"
Hines said. "The cost of this new device is very minimal, approximately
$60 if production costs meet predictions."
Burrows thought up the idea of the flow balancer and took it to the
Environmental Innovation Branch of Nova Scotia Environment and Labour.
"The department put me in touch with Mysore Satish at Dalhousie
University's faculty of engineering," Burrows said. "Together, we
finalized and tested the design."
The device forces the effluent flow into two equal streams. This ensures
that the effluent is evenly distributed through the disposal bed. The
balanced flow means that the work of filtering the effluent is spread evenly
across the disposal bed. The National Research Council's Industrial Research
Assistance Program provided funding for prototype development.
"Environment and Labour helped make the connections with the university
and the funding agencies to bring this to life," said Burrows.
Nova Scotia Environment and Labour is also providing financial support for
the patent application and marketing.
"Assisting environmental innovation is a core business or our
Department, said Environment and Labour Minister Kerry Morash. "We're
always ready to help make smart ideas like this one become reality."
The developers have applied for a patent and are discussing manufacturing
plans. Burrows has been keeping busy in other areas as well.
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