Learning about emissions | GUEST OPINION

It seems unfathomable that there was a time when commercial composting did not exist. The end of the road for grass clippings and vegetable trimmings was once invariably a landfill. There, valuable organic materials were wasted in an airless tomb to remain unchanged for years while generating methane — one of the most potent greenhouse gases.

Today, we have the technology to safely compost these valuable organics from our homes and businesses. This not only significantly reduces our carbon footprint, it also creates natural mulches that minimize water and chemical usage, prevent toxic run-off from reaching lakes and streams, and add nutrients to depleted urban soils.

Despite this, we are sometimes asked by visitors and neighbors if there are reasons to be concerned about the emissions from the earthy piles that composting creates.

Compost emissions are the result of the natural process of organic material breaking down in nature.  Other emissions can come from compounds found in the material arriving at the plant. For instance, grass clippings may contain petroleum residues from lawn mowers or garden trimmings that may still retain residual amounts of herbicides and fungicides.  Be assured that responsible composters employ technologies that capture a majority of those emissions during processing.

Cedar Grove’s covered composting system is highly efficient in volatile organic compound (VOC) control and superior to fully enclosed systems that discharge emissions through biofilters. To compare, a large biosolids composting facility in Rancho Cucamonga, Calif., that processes its material in large buildings and vents air through biofilters is 94.6 percent effective in removing VOC’s. Cedar Grove’s covered composting process removes 96.5 percent.

Recent tests conducted by the Department of Ecology at two Washington composting facilities found the presence of some chemical compounds in the part per billion range, measuring far below threshold levels that constitute a health concern by Occupational Safety and Health (OSHA) standards. In addition, measurements were taken six inches above the feed stocks. The natural dispersion of these compounds beyond six inches dilutes them to a point that they pose no threat to workers or any person at or beyond the property lines. This also corroborates studies across North America and Europe that conclude the absence of evidence constituting a health concern from controlled commercial composting operations.

While composting poses no health threats, some have voiced concern about odor emissions. In response to these concerns, the Puget Sound Clean Air Agency is initiating an independent scientific study to identify major odor generators in the area.  This is in addition to a recent WDOE study which concluded that there exists no relationship between odors and the presence of compounds that are harmful to human health.

In the coming months, residents of Snohomish County and particularly of the Marysville/North Everett area will have an opportunity to learn more about emissions from composting operations. This will be valuable information as regional demand continues to grow for organics recycling that will likely result in an increase in the number of large scale composters in the county and surrounding areas.

Stephen Grose is the Director of Facilities at Cedar Grove Composting and can be contacted at stepheng@cgcompost.com.

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