Landfill technology and research wins award of excellence

Calgary, AB – A sustainable landfill bio-cell technology, developed by University of Calgary researcher Dr Patrick Hettiaratchi, was recognized last week with an Environmental Award of Excellence by the Consulting Engineers of Alberta at their 2006 Showcase Awards.

Currently a pilot project with the city of Calgary, the technology has the capacity to help alleviate Calgary’s growing need for landfill space. The technology creates a recyclable and reusable landfill, and generates enough gas to keep the landfill self-sustaining.

Judges of the awards called the research “very innovative and collaborative effort” and “forward thinking at its best”.

The project is a leading edge full-scale pilot and research facility that was constructed last year. It treats 85,000 tonnes of residential and commercial waste.

The implementation of the biocell technology to the landfill stands to increase the landfill’s lifespan from 30-40 years to more than 100 years. As it incorporates enhanced methane production/extraction as part of the process, it also has the potential to produce large amounts (300kW) of electrical energy.

“Since oxygen will need to be piped into the biocell during the aerobic mode of operation, which will require some energy, the extracted methane can be used in the operation of the biocell as well,” says Dr Hettiaratchi. “It is significant that the biocell is self-sufficient, but certainly excess gas reserves could provide an economic benefit.”

The project’s research combines some currently established practices of using landfills for both composting and gas production. Individually, these concepts are not new, but the combination of these approaches is what makes this research different, according to Dr Hettiaratchi.

The biocell is an enclosed landfill and the concept is based on a multi-year cycle. It will be operated first in the anaerobic mode for several years with a high rate of methane production. Gas production and extraction is the objective during the anaerobic mode.

Within the biocell, as the waste decomposes, the resultant leachate is collected from the bottom of the cell and recycled back into the top of the cell. The resulting increase in moisture within the biocell increases biological activity and thus greater amounts of methane are produced (slow methane production is an issue for current landfills). After 3-4 years, methane production decreases to a point where gas extraction from the cell is no longer cost efficient and the cycle switches to an aerobic phase.

Composting is the objective in later years of the cycle, which is accomplished by introducing oxygen into the cell. In the final year of the cycle, the biocell is mined for recovery of recyclables and compost and is ready to begin the cycle again.

When technology is fully implemented, several biocells will be operated concurrently: some in anaerobic mode and others in aerobic mode.

Dr Hettiaratchi’s research is conducted through University of Calgary Faculty of Engineering’s Centre for Environmental Engineering Research and Education, and he is being supported with a strategic grant from NSERC.