This NBS uses a special substrate (mixture of urban by –products) asfilter media to capture pollutants (NOx, PM, CO, benzene, toluene,etc.) form the air of underground parking without waste generation.This NBS uses a rhizodegradation process in which contaminants aredegraded in the rhizosphere (area of soil surrounding the roots ofthe plants) by means of microbial activity which is enhanced by thepresence of plant roots. That takes place in soil to the process.

Some of the benefits:

• Reduction of gaseous contaminants and CO2 concentrationat the outflow position
• Balance of the flow, temperature, humidity andcontaminants concentration
• Depending on implementation design it adds aestheticsvalues to the urban street.

In the biofilter the contaminated air is introduced in the plenumchamber by a side inlet pipe. The air is injected through the pipe andthere are no additional physical distributors within the plenumchamber volume to control the air flow once it enters the chamber.The principal advantage of this design concept is its relativesimplicity and ease of construction.