Biosolids Surplus is Too Much of a Good Thing for Two Canadian Cities

Biosolids market saturation has the rural cities of Kelowna and Vernon seeking solutions
Biosolids Surplus is Too Much of a Good Thing for Two Canadian Cities

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There’s a growing stockpile of biosolids fertilizer in the rural British Columbian cities of Kelowna and Vernon. Too much supply and not enough demand has city officials and Kelowna Biosolids Supervisor Gordon Light seeking a long-term solution.

“We’re producing more than there is demand for at this point,” says Light. “We have one customer (Nature’s Gold in British Columbia) that purchases more than half of what we produce.” That customer, who sells the end product at retail to individuals, golf courses, nurseries and landscape supply centers, now believes the market is saturated, but that wasn’t always the case. From 1995 to 2011, the cities couldn’t keep the soil conditioner, called OgoGrow, in supply. There were waiting lists, and the cities produced 30,000 to 50,000 yards of OgoGrow every year.

OgoGrow is made by mixing wastewater solids with wood chips, and that mixture is then composted at the Regional Biosolids Compost Facility. “It’s a very complicated equation,” Light says.

Popular with Okanagan gardeners, landscaping companies and construction contractors, OgoGrow generates revenue for the cities and helps keep treated solid waste out of local landfills. Light estimates sales of OgoGrow bring in around $500,000 per year. However, he noted that the cost to procure the wood chips is around $400,000 and total operating costs are substantially more.

Space limitations at the compost facility, the availability of an affordable supply of wood chips and the region’s increased production of wastewater solids have created a need for the cities to research and evaluate a more diversified and sustainable approach, including examining new processing methods, new beneficial use options and potential new markets.

A front-end loader in the city of Kelowna adds to the composting facility's growing stockpile of OgoGrow biosolids fertilizer. Market saturation has made a burden out of a beneficial material. —Photo Courtesy of the City of Kelowna

Exploring the options

Reducing the amount of biosolids is one option, Light says. Currently, neither the 9.5 mgd Kelowna treatment plant nor the 3.2 mgd Vernon plant has a digester, which could reduce biosolids by 50 percent, but comes with a price tag of around $32 million. “It’s something that would open a lot of avenues,” Light says.

The Kelowna plant could get a Class A biosolids rating with a digester, allowing the city to pursue land application. Currently, the plants’ biosolids don’t meet Class B rating. And burying the biosolids isn’t an option, according to Light. There’s no permit system in place, and he says it’s not a politically acceptable solution.

But there is another option on the table: the cities could expand the composting facility and look for more markets for OgoGrow. “We haven’t been aggressively marketing and actively selling the product,” says Light.

The odors of the accumulating biosolids have plagued the Kelowna plant, too. In 2011, the plant began adding more wood chips to the mix to slow the rate of decomposition, which helped control the smell. But several residents near the compost facility have complained.

The Kelowna plant relocated in 2006 at a cost of $7.5 million, and was joined by the City of Vernon. “When we first started there, we were over capacity for the amount of aeration we had for the amount of biosolids we had,” says Light. “We did generate quite a few objectionable odors.”

The facility underwent a $6.5 million upgrade in 2010, which added three times more aeration and four times the biofiltration. That, too, helped alleviate some odor issues.

However, while odor issues have calmed down, the demand for OgoGrow hasn’t gone up. The lingering stigma attached to treatment plants and odors could be an issue, Light says. A biosolids composting facility in a nearby district was shut down in 2015 due to odor issues. “We think that might have affected some of the sales of OgoGrow.”

OgoGrow is currently sold as a soil conditioner to wholesale markets. It’s not the same process the Milwaukee Metropolitan Sewerage District uses to turn biosolids waste into the widely distributed Milorganite fertilizer. “If you want to enter into a contract with a large box store, you need to have a guaranteed supply,” says Light. “It takes a big leap to go to the next step. Milwaukee is huge and can supply mass amounts. If we were 10 times bigger, we definitely would do that.”

Light says marketing strategists have studied having the treatment plant market the product on its own. “But they determined the distribution and packaging costs would kill us. And that would still leave all our eggs in one basket.”

The cities have posted an online survey to collect residents’ input on the issues surrounding biosolids production, which is a complex issue. “We’re trying to make it as simple as we can on the survey,” Light says. The city councils plan to use that community input along with technical and market reviews to determine the next steps in solving the Kelowna-Vernon biosolids problem.


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