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Monique Keiran: Sewage sludge a golden opportunity?

The new sewage-treatment schedule that the Capital Regional District proposed this month contains tight deadlines.

The new sewage-treatment schedule that the Capital Regional District proposed this month contains tight deadlines.

In order for this latest development to pan out, proponents of building a secondary treatment plant in the region must determine a new timeline and acquire all approvals and a site for the treatment plant by this time next year.

At stake is an $83.4-million grant from Public-Private Partnership Canada for a facility to handle material removed from liquid sewage. Project opponents might see the extension as yet one more year to cause delay.

Of course, if the CRD or either group of municipalities that is exploring sewage-treatment options doesn’t meet the March 2016 conditions, the larger initiative will churn on. Two other federal grants, worth $170 million, and the province’s contributions have roomier deadlines that could accommodate the region’s revised forecast for completion by 2023.

Delay, in fact, might result in better sewage-treatment options. For example, researchers announced in January that they had identified and successfully extracted appreciable amounts of rare metals from biosolid samples collected from cities across the U.S. Their study focused on 13 high-value minerals, including gold, silver, copper, iridium and platinum. Extrapolating their results, the researchers estimate $16 million worth of metals could be accumulating every year in the sewage of a city with one million residents.

Of that, the researchers say almost $3.5 million could come from gold and silver.

If we could extract every single nanoparticle, the researchers reported, each tonne of sludge might include as much as $360 worth of the precious metals. That equals the value of gold found in the low-grade ore some companies mine.

Based on estimates of how much — ahem — raw materials the good residents of Greater Victoria produce each year, our sludge attains a theoretical value of almost $11 million on the commodities markets. It wouldn’t finance a sewage-treatment plant’s construction, but could offset its operations — not bad, considering current plans call for the sludge to be landfilled.

But before you rush to stake a claim on what you flush, be aware that the valuation depends on the quality of source materials, among other factors. Just how much gold is contained within the nuggets of Greater Victoria residents remains unknown.

The scientists who struck pay dirt in dirt speculate that the biosolid precious metals come from households, medical offices and industry. Dental offices, for example, work with gold and silver, and minute amounts of that might wash down the drains. Hospitals use some metals in tests and treatments. Our own dental fillings and jewelry could shed molecules daily.

Foil packaging for food contains tiny amounts of gold and silver, which could become mixed with the food, eaten, and … you know. The copper pipes in our homes slough molecules, as does the lead solder that seals them. Any industry that makes circuit boards or computer chips or handles the metals directly or indirectly could also be adding to the bonanza.

But our ability to extract this gold is limited by technology. Technology to recover most or even many nanoparticles of rare minerals from sludge at an operational scale doesn’t exist.

If industry and other funders of applied research are motivated to find solutions, efficient and economical solutions often result. But that takes time, trial and error.

For example, the technology to recover phosphorus from sewage sludge has existed for years, but it remains costly and ridden with operational challenges. Some municipalities, including North Vancouver, build work-arounds into their new treatment-plant plans to add phosphorous recovery later — when and if market conditions or operational considerations improve.

With time and continued high mineral prices to lure and secure investment, research might eventually result in extraction technology that is operationally workable and worthwhile.

Which means the sewage-treatment issue in this region comes down to time. It comes down to finite deadlines for grants and for meeting federally legislated requirements.

It also comes down to premature timing in terms of the technology we’d like to use — in the best of all possible worlds — and what is currently available.

It’s a new take on a different kind of gold rush.

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