Biofilters are often fitted into tight spaces within highly urbanized contexts. In these cases the cell may be constructed of concrete. This can be further waterproofed/have added resiliency from the application of a liquid sealant. Alternatively, a [[liner]] may be used. | Biofilters are often fitted into tight spaces within highly urbanized contexts. In these cases the cell may be constructed of concrete. This can be further waterproofed/have added resiliency from the application of a liquid sealant. Alternatively, a [[liner]] may be used. |