How No-Flush Toilets & Effluent Sewers Sustainably Accommodate Growing Communities
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How No-Flush Toilets Can Help Make a Healthier World
Inadequate sewage systems and the lack of toilets in much of the developing world have created a major public health and environmental crisis. Now various innovators are promoting new kinds of toilets and technologies that use little or no water and recycle the waste.
My apartment in Kathmandu, where I lived for five years, had a toilet that looked very much like the one in my house in California. Nicer even; it was pastel porcelain and had dual flush.
But although flush toilets in Nepal and the rest of South Asia may work quite well, sewer systems have not kept pace. My toilet and all the others in my Kathmandu neighborhood were connected to pipes that carried the contents of toilets away from our residences and straight into a small river a half-mile away. Stray dogs lapped the water and children played nearby.
The rivers of the Indian subcontinent flow clean and clear from the Himalaya, then become little more than sewers as they run through major cities in the plains. New Delhi’s Yamuna River receives roughly half of the largely untreated sewage of a metropolis of 17 million. The Ganges, the holiest of Hindu rivers, is fouled by raw sewage from tens of millions of people as it flows 1,500 miles from the western Himalaya to the Bay of Bengal.
A movement is gaining momentum to do something about this major environmental and public health problem in South Asia and the developing world. The solution, many experts say, is not to invest in western-style flush toilets and centralized sewage systems but rather to develop toilets and decentralized waste-treatment technologies that use far less water. The latest development in this field is the decision by the Bill & Melinda Gates Foundation to invest $40 million in prize money and financial support to groups working on new toilet technology.
The goal of the Gates Foundation and other international and South Asian initiatives is to construct prototypes of inexpensive toilets that use little or no water and minimal energy. The new toilets must convert human waste into useful (or at least benign) components without using septic systems. Most important, they must protect water sources — rivers, streams, and groundwater — from the water-borne diseases so endemic in the developing world.
Full Article:
http://e360.yale.edu/feature/how_no-flush_toilets_can_help_make_a_healthier_world/2581/
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Effluent Sewers Sustainably Accommodate Growing Communities
Many rural communities that formerly relied on septic systems have outgrown that
technology. Some communities are experiencing widespread failure of aging systems.
Other communities are growing, but their soil conditions won’t accommodate additional
septic systems. Larger communities want to grow, but their existing sewer systems can’t
accommodate new connections. In all these cases, neither conventional septic systems
nor gravity sewer systems are feasible.
Effluent sewers are a proven and sustainable solution for decentralized and rural
wastewater collection across Canada, and in many other countries. Not only can effluent
sewers serve rural areas, but they are also a cost-effective way to serve fringe
development just outside towns that don’t want to expand their conventional sewer
system.
Victoria, Prince Edward Island: A Flexible System
Victoria is a small but popular tourist community with a peak season between June and
September. Victoria’s wastewater system, designed by Engineering Technologies Canada
(Stratford, PE), in cooperation with Harland Associates 02 Inc., consists of about 48
STEG systems. Effluent from these flows to a lift station that pumps it to the treatment
plant at a high point on the edge of town away from the tourist area. The effluent sewer
system also incorporates five residential STEP systems and two commercial STEP
systems. Campbell’s Concrete Ltd of Charlottetown, PE manufactured the interceptor
tanks, and Atlantic Purification Systems of Dartmouth, NS supplied the effluent sewer
and treatment equipment.
The treatment system consists of ten AdvanTex AX100 pods, with room to add an
additional five units if the community grows. The modular system accommodates the
large seasonal variation in flows. During the winter months, flows average 22,700 Lpd,
and only one-third of the treatment system is used. During the summer, flows rise to
49,200 Lpd, and the entire modular system is utilized.
After secondary treatment in the AdvanTex pods, the effluent is dispersed to the ground.
The system has two drainfields: a pressure dose sand bed and a drip irrigation system.
The pressure dose bed works all year round; the drip system comes online automatically
in mid-June and goes offline September 22. During these months, both drainfields are in
operation.
An extension to the existing effluent sewer is planned for further development expected
to occur on the edge of Victoria in the future.
Habitat Acres, Alberta: A Sustainable System
Sten Berg, a farmer, livestock producer, and consultant, wanted to create a sustainable
housing development on 27.5 hectares of his land near Sherwood Park, Alberta. Habitat
Acres, a 29-home planned community, is the result. It includes an 18.2-hectare nature
reserve, two waterfowl nesting areas, and the first self-contained effluent sewage
treatment system ever approved in Alberta.
To maximize open space and preserve wetlands, Berg wanted to reduce lot sizes from the
usual 0.8-hectare minimum, so conventional septic systems were out of the question. An
Orenco effluent sewer with AdvanTex treatment solved the problem. Onsite Specialties
Inc. of Sherwood Park, Alberta supplied the collection and treatment system.
Each of the 29 lots has a 4500-L concrete interceptor tank, supplied by Alberta Wilbert
Sales - Edmonton. Effluent is pumped to three AdvanTex AX100 pods. After treatment,
the effluent is discharged to a drip irrigation system.
The project at Habitat Acres was a finalist in the 2010 Emerald Awards, presented by the
Alberta Emerald Foundation. These awards ‘celebrate the outstanding achievements by
Albertans committed to protecting, preserving, and sustaining our environment.’
Many areas in Alberta have embraced effluent sewers for providing infrastructure for
new developments on the fringes of existing cities. Alberta Wilbert Sales Ltd has more
than 1500 interceptor tanks installed in areas including Grand Prairie and the County of
Strathcona.
Effluent sewers can be ideal solutions for villages and small cities, but there is no limit to
the number of lots connected to the collection network. Many larger cities have incorporated this technology into their overall sewer management system, where the effluent sewer serves thousands of homes and commercial lots. This allows the city engineers to choose the best option to serve the various areas in the city, without being limited to only gravity sewer.
Other Benefits of Effluent Sewer Systems
• In most systems that are built to serve new developments, the cost of the on-lot
equipment is included in the homeowner’s mortgage, so upfront investment by the
community or developer is minimal.
• The small-diameter collection lines can be installed in shallow, narrow trenches,
or directional drilled, minimizing disruption in the community. Lines follow the
contour of the land, avoiding difficult and expensive deep trenching.
• Service can begin as soon as the first household in a new development is
connected. No minimum velocity is required for the effluent sewer network as
solids are excluded, simplifying design, installation, and operation.
• Effluent sewer systems are watertight, eliminating infiltration and inflow common
to gravity sewers, and reducing the hydraulic loading on the treatment plant.
• Sludge management is greatly reduced through natural, passive anaerobic
digestion in the interceptor tanks, simplifying treatment plant design and
minimizing life-cycle costs.
• Since primary treatment occurs at each home or business, abuse of the system,
such as disposal of chemicals, generally affects only the household responsible.
• Risks are minimized and distributed as malfunctions generally affect only one
household at a time. In the event of a malfunction or natural disaster, the septic
tank provides reserve holding capacity.
• Properly maintained effluent sewer systems require fewer personnel and less
heavy equipment to service than other sewer systems do.
Together, effluent sewers and media filter advanced treatment form a sustainable and
robust system that uses minimal energy, safeguards groundwater and the environment,
and imposes costs fairly on the users. Communities of all sizes across Canada can benefit
from this proven technology.
Geoff Salthouse is International Project Engineer at Orenco Systems, Inc., Sutherlin,
Full Article:http://wilbert.ca/siteimages/Orenco%20Effluent%20Sewers%20serve%20Canadian%20communities_final.pdf
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Related Article:
Effluent-Only Sewers Offer Alternative to Traditional Systems
http://www.waterworld.com/articles/print/volume-28/issue-8/editorial-features/effluent-only-sewers-offer-alternative-to-traditional-systems.html