From: Public Services and Procurement Canada
The aerobic biopile is an ex situ treatment technology based on the stimulation of the activity of aerobic or facultative aerobic microorganisms responsible for the biodegradation of contaminants in soil. Contaminated soils are excavated and placed in piles (biopiles) with heights generally between 0.91 m and 3.05 m, width and length without any restriction.
Biopiles must be designed and operated to provide optimal conditions of temperature, humidity, aeration, and nutrients to promote biodegradation of target contaminants. Biodegradation is usually accomplished by indigenous microorganisms; sometimes the addition of specific microorganisms may be required. Sometimes it may be necessary to add structuring agents such as wood chips and soil amendments to improve airflow through the biopile and promote biodegradation processes.
Sources:
The implementation of an aerobic biopile can include:
On-site storage may include amendments, nutrients, fuel, lubricants, and other site materials required for processing and operation of machinery, and equipment needed to implement the process.
Temporary piles of contaminated soil awaiting treatment or transport off-site may also be stored on the site.
Seepage water from excavation areas and/or runoff from sites can also be stored in tanks if it is contaminated. It can also be treated on site, which requires the storage of materials for the operation of the water treatment system.
All contaminated soils are normally excavated. Thus, there is little residue associated with this technology. The waste on site is typical of a construction site.
Dust from excavations, soil treatment areas or soil spread on the ground by the wheels or tracks of equipment may be emitted on the site.
Off-gases potentially resulting from the volatilization of contaminants from excavation walls or temporary piles, dewatering, if dewatering is required, leachate and runoff may need to be captured by appropriate management and treatment systems.
Natural biodegradation, particularly of hydrocarbons, can also produce off-gas emissions of non-contaminant products. These products may include carbon dioxide, ammonia, methane and/or hydrogen sulphide.
The technology applies to organic compounds that can be biodegraded under aerobic conditions.
Suitable for treating soils that have conditions favourable to biodegradation, including pH between 6 and 8, and moisture between 40% and 85%.
Notes:
Chlorobenzenes: suitable for chlorobenzene, dichlorobenzene and trichlorobenzene; Phenolic compounds: suitable for cresol, pentachlorophenol and tetrachlorophenol.
Less volatile and more recalcitrant compounds may require up to two years in treatment; readily degradable compounds may be remediated in weeks. High levels of treatment (contaminant reductions of 99% or more) typically require significantly more time than moderate contaminant reductions (70% to 90%).
Contaminated soils are excavated and will only be reused on site if they meet the environmental and geotechnical criteria allowed for the site. For this reason, little to no long-term consideration exists at the treated sites following backfilling and when the equipment and facilities have been dismantled.
Aerobic biodegradation of organic contaminants generally does not generate toxic metabolites or hazardous by-products. It generates products such as carbon dioxide and water.
Complementary technologies can be coupled with aerobic composting to improve its efficiency. These technologies include:
The following links provide examples of application:
It is difficult to reduce the concentration of petroleum hydrocarbons by more than 95% and to achieve residual contaminant concentrations of less than one part per million. A high level of treatment, a reduction in contaminant levels of 99% or more, has been observed in the past.
Unavailable for this factsheet
Composed by : Magalie Turgeon, National Research Council
Latest update provided by : Nathalie Arel ing., M.Sc., Frédéric Gagnon CPI., Sylvain Hains ing., M.Sc., Golder Associates Ltd.
Updated Date : March 21, 2022
