November/December 1995
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November/December 1995 |
by Guy Gagnon
The city of Jonquière, located in the Saguenay region of Quebec, has a population of 60,000. It is essentially an industrial city, with an area of 230 square kilometers (90 square miles). Given the many rivers and streams in the region, environmental quality is a very real concern.
Until 1990, it disposed of all of its sludge at the landfill of the Regional County Municipality of Fjord du Saguenay along with its domestic waste. However, with the landfill situation being what it is in the Saguenay region and the rest of Quebec, it became not only advantageous but also essential for the municipality to consider other sludge disposal techniques.
Since the city of Jonquière is surrounded by farmland and its sewage sludge is of high quality, municipal authorities opted to focus their recycling efforts on agricultural uses, composting and remediation of degraded sites. The Quebec Department of Environment and Wildlife applies the same sludge quality criteria to all of these disposal techniques.
Sludge-derived compost is a homogeneous mixture of sewage sludge and sawdust. It is applied in a manner that ensures proper composting of the materials used. The compost is sold in bulk or mixed with soil for the landscaping, revegetation and sodding contracts carried out by some of our private partners.
Impressive Results: Farmers Want More
Jonquière's water treatment system receives very little industrial wastewater. As a result, the sewage sludge contains low concentrations of heavy metals. Concentrations have so far been well below the standards set by the Quebec Department of Environment and Wildlife. Given the high quality of the sludge, all that remained to be done was to develop the reclamation approach, which had already been tested with positive results, in Quebec and elsewhere.
Since the summer of 1990, the first trials were carried out by joining forces with partners from the private and public sectors to conduct fertilization tests on agricultural land. Tests carried out resulted in an increase in crop yield of almost 50 percent. Encouraged by the enthusiasm of our partners and the significant increase in crop yields for that period, we implemented a permanent sludge reclamation program.
Since 1991, Jonquière has been working on this program on a full-time basis. The program is coordinated entirely by the municipality, with private firms providing analytical and sludge transport services and implementing agronomic studies.
In 1991, close to 40 percent of the 10,500 cubic meters (8,100 cubic yards) of sewage sludge generated was reclaimed and used in agriculture and as compost. Since the introduction of a winter sludge storage program in 1993, 75 percent of the total was re-used, including 40 percent for agriculture, eight percent for compost, nine percent toward site restoration and 19 percent stored and re-used the following summer of that year.
Ecology and Economy: Watchwords of Reclamation
The reclamation program has essentially two objectives. The first, an environmental objective, is to tap the fertilizing and organic soil conditioning potential of sludge in keeping with the principle of sustainable development. Through reclamation it is possible to divert sludge from landfill sites and use it for environmentally sound agricultural purposes. The second is an economic objective, and consists in reducing the cost of sludge disposal in both the short and long term. The municipality can realize significant savings on sanitary landfill costs.
The use of sludge in agriculture is the most advantageous means of disposal given its low operating and infrastructure costs. The cost of reclamation varies, depending on the type of use. In the first year of our program, the cost of reclaiming sludge for agricultural uses was roughly $8.50 Canadian per cubic meter of wet sludge ($4.80 U.S per cubic yard). This amount included a coordinator's salary and travel expenses and the cost of sludge analysis and agronomic studies. In addition, participating farmers benefit from significantly lower fertilization costs and increased crop yields.
A leader in the field since 1990, the city of Jonquière has developed an expertise that is available and exportable.
It has also put in place a program to control the release of liquid effluent into its sewer system with the objective of reducing potential releases of toxic substances.
The reclamation of sewage sludge for use in agriculture is not only an environmentally friendly and economic disposal technique, but a permanent solution to the problem of sludge management in urban centres.
For more information contact Guy Gagnon, Agricultural Reclamation Coordinator, City of Jonquière, 2710 Saguenay Boulevard, P.O. Box 2000, Jonquière, Quebec G7X 7W7. Telephone (418)699-6060; fax (418)699-6058.
Revised: March 14, 1997
Maintained by Kevin McGunagle,
mcgunaglek@ijc.wincom.net