Applying Biochar to Reduce Leachate Toxicity and Greenhouse Gas Production in Municipal Solid Waste (MSW)
Landfilling is the most popular waste disposal method worldwide. Landfilling is more economical than other methods (e.g. composting and recycling) as it requires less infrastructure and no specialized collection services. Despite our heavy reliance on landfills and all their perceived benefits, they also pose environmental concerns to the surrounding communities. Many landfill sites suffer from vermin, odors, windborne litter, and uncontrolled burning. Excess rainwater percolating through the waste layers becomes contaminated by the waste material and can potentially pollute groundwater and surface water if the landfills are built without engineered liners or systems to collect this leachate.
The bacterial activity in landfills generate Greenhouse gases (GHG) composed primarily of methane (50 to 55%), carbon dioxide (45 to 50%), and less than 1 percent other organic or inorganic gases. Methane is a potent GHG, with approximately 25 times the global warming potential of carbon dioxide (CO2), making landfills a significant contributor to global warming.
Biochar is persistent in the natural environment therefore, potentially provides long-lasting beneficial effects in a number of field, such as improving soil fertility, decontaminating land, carbon sequestration and decreasing GHG production. Additionally the development of large-scale hydroelectric projects means that there is an abundance of waste wood that can be made available for local biochar production. Furthermore, some of the landfill wastes can themselves be converted to biochar. To date, no research has been done in Labrador to assess biochar’s suitability for managing the harmful effects of landfills. The objective of this study is to study the effects of biochar application in landfill-cover on leachate toxicity and GHG emissions.
Multiple types of biochar with sand were tested for leachate decontamination suitability in this project. The results obtained through this study were encouraging as we observed significant reduction of a number of contaminants in the leachate and reduction of methane, a potent GHG in the ‘sand plus biochar’ treatment relative to the sand alone treatment. However, in some cases the effects were not substantial. It is worth noting that since the study took place over a single season, more investigation is needed in regard to waste type, waste decomposability, biochar-sand ratio and method of application. Therefore, it would be worthwhile to set up long-term studies to examine how treatments could possibly affect biotic and abiotic variables and change the functions and structures of microbial communities in landfill sites to alter the composition of leachates and GHG emissions. Further study is required to ascertain whether increased rate or prolonged period of application would increase the efficacy, as well as effect of an increased dose of biochar.
The results of this project could encourage private sectors to invest in research and development projects to divert biomass from landfills or to make use of the abundant waste wood resulted from the clearing of timbers in the lower Churchill River valley by Nalcor Energy Corporation.
The full report can be found here.