Solid Waste & Recycling

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Project Green

Sustainable business practices are becoming a competitive necessity, and businesses (as well as government) can do more for the environment working together than apart. The Greater Toronto Airports Au...


Sustainable business practices are becoming a competitive necessity, and businesses (as well as government) can do more for the environment working together than apart. The Greater Toronto Airports Authority (GTAA) and Toronto and Region Conservation (TRCA), in partnership with the Region of Peel and cities of Toronto, Brampton and Mississauga, have embarked on an ambitious undertaking to put these principles into action. The objective is no less than to transform the area around Toronto Pearson International Airport into a world-class eco-business zone. Once in place, the Pearson Eco- Business Zone will be the largest eco-business initiative in North America.

Partnerships in “Project Green” leverage the airport area’s many advantages — infrastructure, diverse industrial and commercial base, talent pool, and green spaces — to make it a hub of green innovation. The Pearson Eco-Business Zone is Canada’s largest employment area comprised of more than 12,000 hectares of industrial and commercial land, 12,500 businesses, and 355,000 employees. Major sectors include automotive supply chain, logistics and warehousing, food processing, plastics, and aviation. It’s an ideal location to pool materials and group purchases, share best practices, cooperate to cut costs and minimize waste.

The TRCA has already received multi-year funding commitments from its partner municipalities and the GTAA to development and implement the initiative. The GTAA is taking a leadership role, while a variety of area businesses — Unilever, Bayer Inc., Woodbine Entertainment Group, Oxford Properties, Coca-Cola Bottling Co., Lange Transportation, Molson, and many others — assist with implementation by sitting on the project steering committee and undertaking innovative environmental projects on their sites.

With estimated total annual electricity use of close to 5.8 million MWh, natural gas consumption of 46 million GJ, and water use of 109 million m3, the area surrounding the airport represents enormous potential for conservation. To realize this potential, Partners in Project Green develops and implements projects and programs to help businesses realize cost reduction opportunities, including looking at energy, pooling green purchases and, most prominently, turning waste into revenue.

Organic waste

In partnership with YIELD Energy Inc., Partners in Project Green are working together to identify opportunities to turn organic waste from local food processors into green energy in the Pearson Eco-Business Zone.

“With the amount of food processors around the airport, the potential for green energy is massive,” says Ian Graham of Yield Energy. “The only limiting factor around the airport could be the land available for bio-gas plants, as opposed to the amount waste.”

With over 250 food processors in the zone, organic waste from a number of manufacturers could feed one or multiple bio-gas facilities. But the first step is to get a better picture of the organic waste being generated in the area.

To do this, Yield Energy is conducting a survey of food processors and restaurants to quantify the amounts and types of organic waste. This information will be used to identify potential sites and to develop the biogas business plan.

The proposed bio-gas facility(s) would utilize anaerobic digestion, which produces bio-methane gas from organic waste materials, which is then used to generate green electricity. In addition to electricity, the process also creates waste heat that can be provided to local businesses.

Interest in the project is high, and the background research is expected to be completed at the end of June 2009.

Components

A regional resource reutilization network is being developed; a number of stakeholders have been brought together to develop and implement a regional waste exchange. The group is currently looking at waste exchanges globally to better understand the conditions of success. Other components include: — An Eco-Efficiency program offers local busi nesses free walk-through assessments to identify energy, water and waste reduction potential, helps fund detailed audits, and provides assistance in implementing and financing projects.

A Green Building Retrofit program offers assistance for property managers and owners to reduce costs and improve the performance of their building stock.

A Resource Utilization program is receiving intense interest, with two initiatives underway to help turn general waste and food waste into new revenue streams for local companies. Other project initiatives that will bolster profitability, help retain employees, and enhance corporate image include: a Sustainable Transportation program to help address employee commuting options; Green Purchasing Blocks to drive down the cost of implementing green technologies; and, Green Site initiatives to help green their parking areas, as well as monthly networking and education events.

Organic waste processing

The new biogas process design solves the problem of separating foreign materials in two steps. The first step is a pre-treatment process using a specially designed shredder in combination with a modified piston press. The first step of the process separates more than 90 per cent of contaminants. The second step of the process removes the remaining 10 per cent contamination from the digester without interrupting the biogas production; the digested sludge is screened continuously and the floor of the digester is cleaned with an innovative technology.

Anaerobic digestion (AD) of wet organic waste reduces greenhouse gas emissions and produces renewable energy in the form of electricity and heat.

The main problems running AD plants with organic waste as input material are the result of foreign materials contaminating the organic wastes and disturbing the mechanical function of the plants. Waste, such as tins or plastics, should not be in the waste. Unfortunately, people are not careful when sorting their organic waste material. In the past, problems caused by inorganic contaminants disturbing the waste treatment process led decision makers to conclude that AD is unreliable, expensive and insecure.

While there is no way to clean the waste such that all contaminants are removed from the organic fraction before digesting, a solution exists in a reliable front-end system that removes as many contaminants as possible from the organic waste prior to entering the digester, plus an in-tank cleaning system to remove the rest of the contaminants during digestion.

Before pre-treating the organic waste material, it passes through a shredder, in this case one that’s impervious to metals or glass. The entire waste stream as received gets shredded and, as required, water is added to raise the total solids content to 25 per cent. This results in a pasty sludge with the inorganic waste particles in pieces no larger than 25 mm.

The conditioned sludge moves to the first step of contaminant removal: the pretreatment system, developed in cooperation with Fitec and Putzmeister. It’s based on a modified piston pump. The proprietary modifications include a specialized control system, a gate valve, a screening cylinder and a customized piston head. Pre-treatment leads to a fairly clean material that contains some plastic particles, sand, eggshells etc. most particles smaller than 12mm. This material is stored in an intermediate storage ready for hydrolization.

The removed contaminants and some organic residues remain in a pipe and are pumped through a double tube heat exchanger. The material is heated to temperatures over 70C and is held at this temperature for more than one hour. Fats and organic residues in the waste get pasty. A second stage press squeezes the contaminant fraction until the rest of liquids are separated. The remaining contaminant fraction has a total solid content of more than 45 per cent and contains very little organics.

Af

ter hydrolization, the pre-treated organic matter is fed to the AD. The slurry still contains some inorganic contaminants despite all efforts to remove it. Depending on the input material, these residual contaminants may include sand, glass particles, eggshells, parts of seashells, rubber rings or plastic particles that passed through the filter. Left untreated, these materials will accumulate in the digester and cause problems. Heavy grit material sinks to the digester floor and plastic floats up to the surface. Therefore, a scraper for daily cleaning of the digester floor and a skimming device to clean the surface were developed.

If you would like to share your organic waste for the study or learn more about Partners in Project Green please visit www.partnersinprojectgreen.com

Ian Graham is with Yield Energy Inc. in Toronto Ontario. Contact Ian at ian.graham@yieldenergy.com

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“Yield Energy is conducting a survey of food processors and restaurants to quantify the amounts and types of organic waste.”


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