Development of a Rapid Biofiltration Media Using Local Materials

Stormwater360, in collaboration with Callaghan Innovation, has undertaken a laboratory study to investigate innovative engineered soils for use with a flow controlled biofiltration /retention system.

Typically biofiltration/retention systems use the soil or substrate to control the hydraulic conductivity and corresponding contact time and performance. This study investigated media options with an external flow control. This allowed a coarser substrate with higher hydraulic conductivity to be developed.

Hence the primary aim of this study was to develop an engineered substrate made from locally available materials that had both high hydraulic conductivity and effective contaminant removal. Such a substrate allows the size and cost of the biofiltration device required for a given catchment area to be reduced.

Four engineered substrates with different active ingredients were tested. The active ingredients were as follows:

• Contech Engineered Solutions BioFilter Engineered Media;
• Compost and Zeolite;
• Biochar; and
• Biochar and Zeolite.

Column tests quantified maximum hydraulic conductivity, dissolved metal removal at deferring hydraulic conductivity and influent concentrations. Potential leaching of other potential contaminants from the substrate was also quantified.

The study also predicted the plant growth potential of the engineered substrates by examining the physical and chemical properties of the blends.