Solid Waste & Recycling

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ATT

The City of Toronto is evaluating the potential to apply new and emerging technologies to manage up to 40 per cent of the city's solid waste stream that cannot be diverted through other means. The cit...


The City of Toronto is evaluating the potential to apply new and emerging technologies to manage up to 40 per cent of the city’s solid waste stream that cannot be diverted through other means. The city, through its new and emerging technologies search did not allow incineration to be considered as an option. It did, interestingly enough, allow for thermal treatment alternatives.

Of the 51 respondents to the Request for Information from the City, 28 were from companies that offered thermal solutions that were not defined as incineration according to Toronto’s definition of the term.

The city considers advanced thermal treatment technologies (ATT) of particular interest because of their relatively advanced stage of development, their ability to derive energy from residual waste, and their generally low emissions levels. ATT comprises the following processes:

– gasification

– pyrolysis

– plasma gasification

– depolymerization

Technology Description

There are several differences between incineration and ATT. The main differences, from an environmental standpoint, are that incineration uses excess air and there is ash and fly ash left as residue. ATT uses controlled air or no air and the residues are either glassy slag and/or fine particulate matter (char).

Gasification involves the degradation of waste at temperatures between 900 and 1400 Degrees C in a low-oxygen atmosphere to produce a combustible gas (referred to as syngas) and an inert, possibly vitrified, solid residue.

Pyrolysis is the thermal degradation of waste at temperatures in excess of 200 Degrees C in the complete absence of air. The end product is a mixture of solids (char), liquids (oxygenated oils), and syngas. Inert materials (i.e., metals) are not affected by pyrolysis.

Plasma uses a plasma torch at temperatures between 3,000 to 8,000 Degrees C in an oxygen-starved environment to completely decompose input waste material into very simple molecules in a process similar to pyrolysis. Products include syngas and a vitrified solid residue.

Depolymerization processes use high-energy microwaves in a nitrogen atmosphere to decompose organic material. The waste absorbs microwave energy and then chemically decomposes. The nitrogen blanket forms an inert, oxygen-free environment to prevent combustion. Temperatures in the chamber range between 150 to 350 Degrees C. At these temperatures, metal, ceramics and glass are not chemically affected.

The players, application and acceptability

The 28 companies proposing ATT as the solution for Toronto’s residual waste include some prominent Canadian players such as SNC-Lavelin (partnered with Compact Power), Kinectrics (formerly Ontario Hydro Technologies, teamed up with Plasma Environmental Technologies) and Enwave (formerly the Toronto District Heating Corporation).

It may be difficult for a company with a new and emerging technology to show a commercial-scale track record. However, if a company can show commercial success in another market, it has a great advantage over its competitors. One has to wonder why a company would spend the time and effort responding the city if it cannot provide any information on the degree to which its technology is proven or list any commercialization plans. (This was the cases for several submissions.)

Arguably, the two keys to a specific ATT are commercial capability and public acceptance. With continuing talk that the border may close to shipments of Toronto’s waste to Michigan and landfill capacity in the province in short supply, there are widely held views that a thermal technology solution may need to be fast-tracked. A system that has been proven elsewhere on a large-scale will have a huge advantage.

With respect to public acceptance of ATT, it’s important to ask if a particular technology will be considered incineration? Many of the ATT will be considered incineration under the definition found in the province regulations. Whether environmentalists concur will likely depend on the type of emissions (specifically dioxins and furans).

It may not matter if any ATT is considered incineration or not. A poll held in the fall of 2003 indicated 70 per cent of the city’s residents favored incineration.

Next steps

The next hurdle for all the companies vying for Toronto’s MSW contract is to respond to the Request for Qualifications (RFQL). The RFQL will require the vendors to demonstrate that they are technically qualified, have operational capability and are in good financial shape.

There are 28 waste companies with thermal technologies that feel they have the right solution for treating Toronto’s MSW. In my next column, I’ll examine some non-thermal technologies.

John Nicholson is a management consultant with Environmental Business consultants based in Toronto, Ontario. E-mail John at john.nicholson@ebccanada.com


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