Solid Waste & Recycling

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The Taming of Ogopogo

I haven't seen the beast called "Ogopogo." Spanning hundreds of years, this lake dwelling creature -- seen by thousands and "filmed" by few (and documented on petroglyphs) -- suggests biology run amok...


I haven’t seen the beast called “Ogopogo.” Spanning hundreds of years, this lake dwelling creature — seen by thousands and “filmed” by few (and documented on petroglyphs) — suggests biology run amok without the benefit of science to confirm or deny its existence. Yet Ogopogo is so much part of the collective consciousness that it’s moved beyond the usual T-shirts and bumper stickers to compost produced at the Ogogrow Production Facility and sold as “Ogogrow.”

The name is fitting because the biosolids used to produce this compost is a bit of monster itself. If you can ensure that contaminants in this feedstock are minimal and control process odours, you still have the unique marketing challenge of convincing clients to buy back their own wastes.

British Columbia has a long history of managing biosolids and its Organic Matter Recycling Regulation (OMMR) specifically guides the production of these composts in a way that is largely deficient across the rest of the country.

The City of Kelowna has composted biosolids since 1995. Its first facility used an aerated static pile (ASP) process. Its first site was in a remote location and the odours from the process were managed.

The Ogogrow Production Facility was moved in 2006 as a joint facility between the Cities of Kelowna and Vernon. A more modern facility was built to handle increased quantities of biosolids and to further optimize the composting process.

Composting technology

The new facility continues to rely on ASP technology, albeit a much more sophisticated version. The facility uses ASP equipment manufac- tured by Engineered Compost Systems (ECS). A perforated floor system provides aeration for each of 12 zones. The current facility can accept about 10.5 dry tonnes/day of biosolids (although the facility can be expanded to three times this size).

Positive or negative aeration can be provided in each of the zones. As Steve Diddy, ECS Sales and Marketing Director points out, “The aeration reverses direction based on the temperature difference between the upper and lower portions of the zone. In positive mode the bottom cools and the top heats; the control system senses this, and reverses the aeration direction.”

This combination of positive and negative aeration has been designed to help ensure that all the composting waste is exposed to the appropriate pathogen-reduction temperatures.

A single aeration fan is used to aerate multiple zones. The aeration system has been developed to allow for the automatic adjustment of the aeration fans. This adjustment of horsepower allows for potential energy savings. “This feature saves over 30 per cent of energy costs when compared to on/off timer-controlled and single-fan per zone systems,” Diddy says.

Leachate is collected in the aeration floor and taken back to sumps located before the fans.

Facility operation

About 28,000 tonnes of biosolids were composted in 2007. To this about 92,000 square metres (or about 15,000 to 25,000 tonnes) of amendment material is added.

The biosolids are received in a Cover-All style building and mixed indoors. The feedstocks are mixed with a windrow turner, although a batch mixer is being purchased in 2008.

The mixed feedstock is placed in one of the 12 zones and the aeration system is set. The aeration settings vary according to the time of year.

The biosolids are composted in a zone for 21 days. After pathogen reduction requirements have been met the pile is broken down and the compost is placed in a curing block. Curing is currently done without the benefit of aeration although the facility is being upgraded with an aeration system to speed up and better control this part of the composting process.

Although the facility is more modern than its predecessor it does struggle with odour control. In 2007 it logged about 65 odour complaints with the primary sources being from leachate, exhaust air from primary composting and pile teardown.

After curing the compost is screened using a shaker screen. The screening system will also be upgraded in 2008, with the purchase of a trommel screen. The compost was analyzed six times in 2007 and results are presented in Table 1.

The compost meets all of OMMRs trace element requirements. It has a Nitrogen content reaching almost three per cent.

In 2007 about 46,000 cubic yards of compost was sold with average revenue per yard of just over $10. The operators have been able to sell most of their compost, although they had about 10,000 cubic yards left at the end of 2007.

The main markets for this compost include large re-sellers such as the Lake Country Compost distributors. Main uses of the compost include home use, horticultural uses and landscaping uses including at golf courses.

The costs to operate the facility were about $1.91 million in 2007, countered with about $423,000 of revenue for a net cost of about $54/tonne per tonne of biosolids received.

Although the operations are more modern, the facility will continue to evolve in 2008 to improve operations.

The Ogogrow Production Facility has demonstrated that biosolids can be composted but more importantly the product can be sold.

Paul van der Werf is president of 2cg Inc. in London, Ontario. Contact Paul at www.2cg.ca


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