Biosolids

Teck’s Highland Valley copper mine has been using bio-solids from the Greater Vancouver Regional District (GVRD) as a reclamation amendment. The five studies included in this project outline learnings regarding the use of bio-solids as a soil amendment for reclamation purposes, and are relevant to the oil sands region due to the presence of bio-solids at numerous camps and Fort McMurray’s sewage treatment plant. Study topics include how biosolids impact vegetation and soil of the reclaimed mine tailings lands they are used on, as well as if they could boost growth of biofuel crops on reclaimed lands and what their carbon sink potential may be.

Biosolids are a high-nitrogen organic fertilizer and can be effectively used in mine reclamation programs. They are not a substitute for adequate surface material physical properties. They do not show mobility of metals; in fact they seem to immobilize elements found in mine waste materials, thus improving forage quality. They release mineral nitrogen rapidly for 2 or 3 years, and then become humus. The addition of biosolids was more effective at enhancing properties related to soil quality and fertility and therefore more effective for building soil organic matter on reclaimed tailings sites than the traditional use of inorganic fertilizer. Studies showed improved vegetation production on both overburden capped waste rock and tailings, but increased vegetation growth may not result on all sites where soil moisture limitations are too restrictive. Biosolids show a potential for decreasing molybdenum availability for plant uptake and increasing the soil water holding capacity. Biofuel crop yields were below standard for biodiesel production, but further studies with an earlier seeding date are needed, as a late seeding date of mid-June may have placed restraints on the growth of the crop. The gross energy content of both canola and Indian mustard were comparable to currently used cellulosic ethanol feedstocks, whereas crambe was significantly lower.