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November 2000
Love them or hate them, the spreading of biosolids on farm fields has become a hot issue in Ontario and it won't go away. Cities like Toronto, which used to incinerate their sewage sludge (which is what biosolids really are), are now adopting the practice of "beneficial reuse." This has become big business, and companies are fighting for a share of the business, making money by producing fertilizer or collecting fees by spreading sludge on farmers' fields.
Some do not welcome this trend. Take the recent fight in the Dundalk area, for example. Terratec Environmental Ltd. has a Certificate of Approval to spread biosolids from the city of Toronto in Grey County's Southgate, formerly known as Proton Township, and is looking for more sites. Extending the number of certificates in Southgate, however, requires the agreement of the local municipal council. Faced with pressure from local residents this fall, Southgate council rejected attempts to certify more sites in the township.
But not everyone sees biosolids in the same way. Some farmers welcome the product as a cheap fertilizer and soil conditioner. Greg Kitching is a big fan of the biosolids he spreads on his fields. An executive member of the Ontario Soil and Crop Improvement Association, he says the proof is in his yields and he can back up his assertions with five years of crop data.
Kitching cash crops 1,400 acres straddling the border between Wellington County and Halton Region, west of Toronto and north of Highway 401, putting manure from a 40-cow Holstein herd on fields close to the barn and biosolids on fields further away.
Biosolids increase soil organic matter, improve soil structure and increase water-holding capacity, an important factor on Kitching's gravel-bottomed fields. "You notice the difference the next year," says Kitching. "The soil is completely different."
The provincial Ministry of the Environment and the Ontario Ministry of Agriculture, Food and Rural Affairs define biosolids as the treated, more or less solid output of sewage treatment plants. (Not included in the definition is "septage" from private septic tanks, which is classified as "waste" because it isn't treated.)
Every year about 120,000 tonnes of sewage biosolids (one third of provincial production) are spread on 5,000 to 6,000 acres of farmland in Ontario, says Eileen Smith, Manager of Reduce, Reuse, Recycle, Client Services, MOE. The sludge that settles out in a sewage plant undergoes an anaerobic digesting process. In some plants, the liquefied sludge is thickened into a more solid material using either a centrifuge or a vacuum system. The dewatered sludge is incinerated or made into fertilizer.
Liquid biosolids contain a substantial amount of nitrogen and phosphorus, but relatively little potassium. The nitrogen content is often tied up in organic matter in the sludge and decreases with further treatment, such as dewatering.
Along with N, P and K, and desirable micronutrients, there may be traces of what the MOE calls "metals of concern." These include arsenic, cadmium, cobalt, chromium, copper, mercury, molybdenum, nickel, lead, selenium and zinc and are residues of just about everything that gets dumped down the drain, including heavy metals from industry and household chemicals that gets put down the toilet.
These metals may occur in Ontario soils naturally. The MOE stops biosolid applications on fields if soil analyses show levels twice as much as the provincial average. Municipalities aren't allowed to pay farmers to take biosolids, says the MOE's Murray Blackie, so there is no temptation to over-apply them to increase income.
Many rules to follow
Toronto has been spreading its sewage sludge since 1996, says Bob Pickett, director of the city's water pollution control, water and waste water services division. Toronto plans to spread half of the sludge from the city's largest plant at Ashbridge's Bay -- about 25,000 dry tonnes per year. Another 25,000 tonnes will be made into pelletized fertilizer at a city-owned plant, built by U.S. Filter, which should come on line next year. It's conceivable that all this fertilizer could be used within the city's borders, Pickett says.
A smaller sewage plant will continue to incinerate between 10,000 and 12,000 tonnes annually.
Contrary to popular belief, the major lenders don't object to their farmer-clients spreading biosolids on fields, as long as it is done lawfully. "We don't want to be seen to be setting policy for the MOE or the municipality," says Woodstock-based Ron Bolton, manager, agriculture department, Ontario region, Canadian Imperial Bank of
Commerce. Moreover, the charge that spreading biosolids devalues property is a myth, he says. "We don't see that happening anywhere."
However, many rules must be followed before biosolids can be spread. (See Guidelines For the Utilization of Biosolids and Other Wastes On Agricultural Land, 1996, www.don/will/get/address/later.com.) A site must receive a Certificate of Approval for an Organic Soil Conditioning Site and meet the conditions required by the Environmental Protection Act. Each field must have its own certificate. The hauler must hold an Organic Waste Management System Certificate.
Biosolids can be spread on a site once every five years. Plant-available N application rates must not exceed 135 kg of nitrogen per hectare over five years for crops, or four years for sod.
Soils must have a mineral type with low-to-average metal content having a pH greater than 6.0 and a low existing phosphorous level in the topsoil. There is a strict protocol for soil sampling, as well as for biosolid sampling which must be conducted twice a month when spreading. And there are minimum separation distance between spreading sites and water wells and residences.
The minimum distance can be reduced if the farmer is the owner and occupier of the individual residence. Distances can also be reduced if liquids are incorporated immediately or injected into the ground. The same goes for the minimum distance from natural watercourses, open municipal drains, ponds, lakes springs and wetlands, as well as catch basins. Basic distances are listed in Table 5. The absolute minimum distance is 10 metres.
The groundwater table should be at last 30 inches below the surface when spreading takes place. The degree of slope on fields is also taken into account and biosolids can't be spread on extremely steep slopes.
Dewatered sewage can be spread at rates of up to eight tonnes of solids per hectare every five years. High nitrogen content of the soil or the biosolids may be a limiting factor, says Michael Payne, waste management specialist with the Ontario agriculture ministry. Biosolids are better suited to some soils and crops than to others. As well, there is a restriction on crops that can be harvested from a field immediately following application of sewage biosolids. The idea is to let possible pathogens die off.
The disposal of sewage biosolids is getting to be big business. Terratec Environmental, for example, spreads biosolids for the Regions of Halton, Ottawa-Carleton, and the city of Toronto. It was recently acquired by Azurix North America of Hamilton, Ont., a division of Houston-based Azurix Corp.
Azurix Corp is a holding company formed in 1998 with the majority of stock split evenly between Enron Corp and Marlin Water Trust. (Public shareholders own the rest. It is traded on the New York Stock Exchange, listed under the short form AZRX. Azurix companies are located around the world, among them Wessex Water Services Ltd. in the United Kingdom, and there are water treatment facilities in Argentina as well. In its prospectus registered with the New York Securities Exchange, Azurix said it planned to spend U.S.$1.7 billion between 2000 and 2004 buying up assets. An analyst's report on Azurix says that only the Wessex company in the UK is providing cash flow at this time.
Another Azurix purchase in Ontario was Prism Berlie, which operates a state-of-the-art biosolid pelletizing plant in Windsor, as well as a similar plant in Smiths Falls in eastern Ontario.
Windsor's sludge appears to be particularly desirable for pelletizing, since the city has worked hard to keep factories from dumping waste into the sewers. Azurix doesn't like the sewage plant product referred to as "sludge."
"Biosolids are to sludge what gasoline is to crude oil," says Don Hoekstra, Regional Manager, Residuals Management, Azurix, North America. BF
Three years ago, the city of Windsor (pop. 175,000) decided that the way it dealt with sewage sludge was too smelly. Farmers can't get processed sludge spread for free on their farms any more. They now pay to have a pelletized fertilizer made from the sludge applied to their farms.
Through much of the 1990s, the city of Windsor (pop. 175,000) paid The Hern Group of Essex County to treat the city's biosolids and to spread it on farmland for free. The lime stabilization method used involves adding lime to a mixer truck filled with a dewatered sludge cake. The lime-sludge mixture was piled on a concrete slab and heated to a pH, as high as 11 or more, considered enough to kill pathogens.
Essex farmer William Borland arranged for the product to be spread on about 1,000 acres of farmland a year. All of the fields designated for spreading -- some 12,000 acres -- were licensed by the MOE. Farmers used it to supplement chemical fertilizers at savings for the farmer of as much as $90 an acre. "If you needed the lime you were in business," says Borland. A typical analysis in an 11-tonne application was 206 pounds of nitrogen, 131 pounds of phosphorus and 14 pounds of potash.
But odours from the treatment and storage of the treated sludge brought complaints to the city, which called for tenders. Thirteen tenders were discussed and the city opted for the most expensive solution, a pelletizing plant built by a private company, Prism Berlie, in partnership with the city. Documents from the city of Windsor show that reducing the odour doubled the cost of getting rid of the sludge to a total of $90 a tonne.
Prism Berlie, since purchased by Azurix North America, turns the dewatered sewage sludge or "cake" into pellets which are sold as a fertilizer. Windsor is the newest of six plants in Canada using the state-of-the-art Swiss Combi technique to do this.
Specialized horticulture is a higher-value market for the pellets than agriculture, says Don Hoekstra, Regional Manager, Residuals Management. Currently the market is 80 per cent agriculture and 20 per cent horticulture. Hoekstra hopes to balance that market to a 50-50 split, with half going to the higher-value horticulture market where it is used as a carrier added to a nitrogen fertilizer or as a carrier for a broadleaf weed control. The BB-sized pellets are sold at $20 a ton, but farmers currently receive "volume discounts and seasonal considerations" when they purchase it to spread on their fields. "That's a bargain," he says.
While the Windsor product is 3-5-0 on the N, P and K scale, it is also heavy in micronutrients and adds moisture retention characteristics to the soil. It's also a soil conditioner with high organic matter. Application rates vary from three to four tonnes per acre, based on the following crop and a soil tests.
The biosolids are roughly 65 per cent organic matter and take years to break down so the benefits are gradual, he says. Both active pathogens and cysts are killed in the pasteurizing heat treatment.
The Windsor sludge is of particular value because analysis shows it to be low in lead, cadmium and mercury, which have no place in the soil matrix. There is a decade of data backing claims about this product, he says.
Bernie Calhoun cash crops more than 800 acres near Essex and says that over the years sewage sludge has helped his farm a lot by adding organic matter. He considers it a good substitute for cattle manure. He has used the pellets as well, but says "I like it for free, I don't want to pay for it," stressing that human biosolids have a pejorative sound, especially to non-farm rural neighbours.
However, Borland, who was involved in spreading the lime-treated biosolids, doesn't think that the pellets are much improvement. As far as he is concerned, the new plant smells just as bad as the old biosolid treatment program did, at twice the price.
Nonetheless, the Windsor plant, which cost $10 million to build and will handle $60 million in business over the next 20 years, has been a hit in some circles. Prism Berlie built the plant with its own money, and will operate it for 20 years, then hand it over the city under a contractual agreement. Last year the Canadian Council for Public-Private Partnerships gave a silver award to Prism Berlie for its arrangement made with the city.
The Canadian Union of Public Employees protested outside the hotel where the award was presented last year, asserting that Azurix had a plan that would drastically reduce the number of municipal employees working in sewage treatment plants across the province.
Ironically, autoworker union locals, not always in step with other union brethren, had gone to Windsor city hall to complain about the odours from the lime-stabilized treatment system.
Back in Halton, Greg Kitching loves his biosolids, but is the first to admit that farmers elsewhere in the province may not be as satisfied. Biosolid application success depends heavily upon the contractor who spreads it, says Kitching. At issue are timing, typography and the crop grown following application. If every applicator handled biosolids as well as Halton does, the programs would be a success across the province, he says. "It's a win-win for society," he says.
Kitching has taken biosolids on some fields for 15 years, and application systems keep getting better. However, he thinks a standard may be necessary guaranteeing the quality of the product and that application drivers should be licensed.
His contractor pulls a drag hose behind a caterpillar tractor hauling 14-inch sweeps on a tool bar. The sweeps create a void in the soil, which fills with the liquid sludge. "Striping" of the crop, a sign of uneven fertilization, associated with straight shank incorporation that simply put the sludge in the ground, is less pronounced. When it is applied with the sweeps the liquid "is sticking where we want it," he says. It doesn't pool in low spots. And the application fits into Kitching's no-till system. Leakage into tiles isn't a concern. Most of Kitching's fields are naturally drained.
A Halton Conservation Club project, funded by federal Green Plan money, found that there was no increase in heavy metals in treated fields after five years. However, there are some areas of the county where biosolids can't be applied because fields naturally have high levels of lead.
Kitching says the liquid sludge that Halton applies contains more nitrogen than a dewatered product, adds moisture in a dry year and is cheaper for the taxpayer too.
On the minus side is potential for compaction, high handling costs and large storage requirements. Odour is stronger than with drier products, but Kitching hates to see the nitrogen lost through processing.
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