Biochar

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Biochar
Photo credit: K.salo.85

What Is It?[edit]

Biochar is a carbon-rich material produced by pyrolysis of organic feedstocks such as municipal, agricultural, and forestry wastes. It has a high surface area, which enhances soil aggregation, water holding capacity, and organic carbon content. However, biochar properties and effectiveness for pollutant sorption depends on feedstock and pyrolysis conditions. [1]

How is it being used?[edit]

No evidence was found of biochar being used for LID projects in Ontario yet.

  • If you have used biochar in LID design, please let us know.

Benefits[edit]

One study states that the mixing of biochar with compost did not decrease the phosphorus leaching from the mixture. [1] Based on this study, it would seem that biochar is ineffective for phosphorus removal. However, some other papers indicate that biochar mixed with sand was able to retain some trace organic contaminants (TOrCs), [2] and that after six months of operation, biochar-amended biofilters improved removal of total dissolved phosphorus and other TOrCs by greater than 60%. [3] Amendment of LID systems with biochar has shown promise for improved removal of heavy metals, bacteria, nutrients, and TOrCs. [4]

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  1. ↑ 1.0 1.1 Iqbal H, Garcia-Perez M, Flury M. Effect of biochar on leaching of organic carbon, nitrogen, and phosphorus from compost in bioretention systems. Science of the Total Environment. 2015;521-522: 37-45. doi: 10.1016/j.scitotenv.2015.03.060
  2. ↑ Ulrich B, Im E, Werner D, Higgins C. Biochar and Activated Carbon for Enhanced Trace Organic Contaminant Retention in Stormwater Infiltration Systems. Environ. Sci. Technol. 2015;49:6222-6230. doi: 10.1021/acs.est.5b00376.
  3. ↑ Ulrich B, Loehnert M, Higgins C. Improved contaminant removal in vegetated stormwater biofilters amended with biochar. Environ. Sci.: Water Res. Technol.,2017;3:726-734. doi: 10.1039/C7EW00070G
  4. ↑ Ulrich B, Vignola M, Edgehouse K, Werner D, Higgins C. Organic Carbon Amendments for Enhanced Biological Attenuation of Trace Organic Contaminants in Biochar-Amended Stormwater Biofilters. Environ. Sci. Technol. 2017;51:9184-9193. doi: 10.1021/acs.est.7b01164.

Low Impact Development. A stormwater management strategy that seeks to mitigate the impacts of increased urban runoff and stormwater pollution by managing it as close to its source as possible. It comprises a set of site design approaches and small scale stormwater management practices that promote the use of natural systems for infiltration and evapotranspiration, and rainwater harvesting.

Mineral particles which are smaller than 2 mm, and which are free of appreciable quantities of clay and silt. Coarse sand usually designates sand grains with particle size between 0.2 and 0.02 mm.

Decayed organic material used as a plant fertilizer. Compost helps to support healthy plant growth through the slow release of nutrients and the retention of moisture in the soil.

A shallow excavated surface depression containing prepared filter media, mulch, and planted with selected vegetation.

Refers to the conditions in which an organism lives and survives or the conditions in which an organism resides. These conditions can be described as aspects of a “physical”, “social” or an “economic” environment, depending on the perspective perceived by the observer.

A bioretention BMP featuring an impermeable liner and underdrain that prevents infiltration of runoff into the underlying native soil; provides sedimentation and filtration of urban runoff as it passes through the mulch layer, engineered filter media and vegetation root zone.

A bioretention cell that features an impermeable liner that collects and treats stormwater through sedimentation and filtration only (i.e., no infiltration).

Reduction of peak flow and increase of the duration of the flow event.

A bioretention BMP featuring an impermeable liner and underdrain that prevents infiltration of runoff into the underlying native soil; provides sedimentation and filtration of urban runoff as it passes through the mulch layer, engineered filter media and vegetation root zone.

A bioretention cell that features an impermeable liner that collects and treats stormwater through sedimentation and filtration only (i.e., no infiltration).

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