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Roughly 4,200 bulk tonnes of biosolids are produced by the Regional District of Nanaimo's (RDN) Pollution Control Centres every year. Since 1999, RDN biosolids have been beneficially used in agriculture, landfill closures, mine reclamation and forestry applications. Biosolids provide an alternative to chemical fertilizers as a means to improve soil fertility where nutrients are limited.

Since 2003, RDN biosolids have been used in Vancouver Island University's (VIU) Forest Fertilization Program. Through this program, 100 per cent of RDN biosolids are diverted from the landfill and applied to forested land to improve tree growth. This program demonstrates modern practices in forest ecology and stand management.

In February 2013, a new agreement between SYLVIS Environmental, VIU and the RDN was announced. SYLVIS assumes operational and qualified professional responsibilities for the application of biosolids at the woodlot. VIU assumes a research-focused role, and the RDN continues as the biosolids generator.

The tree branch on the top was not fertilized with biosolids and the tree branch on the bottom received biosolids applications.
Photo credit: SYLVIS Environmental
Tree Branch

What Are Biosolids?

Biosolids are nutrient-rich, humus-like materials that result from the treatment of wastewater. At a treatment plant, household wastewater from kitchens, bathrooms and laundries is separated and processed either as a solid or liquid. Storm sewer water, hazardous and industrial wastes are not accepted into the RDN's wastewater stream. The treatment process tries to mirror the natural breakdown of wastes in the environment. Micro-organisms are used to "digest" the solids, reducing volatile organics and pathogen concentrations. The end products of the solids treatment process are biosolids, a soil-like material that can be used beneficially. Biosolids contain nutrients, such as nitrogen and phosphorous, which are vital to healthy and productive soil. Biosolids also have a high organic matter content that allows the soil to hold more water, thereby decreasing run-off and erosion. Biosolids that meet regulatory standards are suitable for use as fertilizer and soil amendments in sectors such as agriculture, landscaping, landfill closure, mine reclamation and forestry.

Further research on biosolids can be found by following this link.

A tree core from the VIU Woodlot illustrates the increased tree growth response from juvenile spacing and biosolids applications. The center of the tree core is on the right hand side and the bark side on the left.
Photo credit: SYLVIS Environmental

Why Beneficially Use Biosolids?

Beneficially using our biosolids makes good environmental and economic sense. Applying biosolids returns nutrients to the land. Alternatively, they would be disposed of in the RDN Regional Landfill. Studying the effects of biosolids applications in the Forest Fertilization Project helps us to understand how to sustainably and locally manage our waste. Diverting biosolids from the landfill is also consistent with the RDN's Zero Waste policy.

Since biosolids applications began, VIU researchers have documented remarkable increases in tree growth at the woodlot site - from 50 per cent to 400 per cent. This is because biosolids contain significant amounts of nutrients also found in traditional fertilizers - nitrogen, phosphorus and potassium - as well as many micronutrients essential for healthy tree growth.

Unlike traditional fertilizers, nutrients from biosolids are released over a much longer period of time, providing the trees with a sustained source of nourishment and protecting water resources by greatly reducing the possibility of nutrient run-off.