Keywords: storm water filtration, hydraulic conductivity, clogging, compost, sand filters, gas production, drying, urban runoff treatment
Hydraulics stability of compost-based filtration media
The longevity of compost-based storm water filtration systems has not been widely studied. Hydraulic conductivity measurements of compost amended sand media (20% and 50% v/v) within columns were undertaken. The results show that the filtration media in both columns had a reduction in the total saturated hydraulic conductivity. A tracer test showed there was no blockage due to biological or chemical fouling of the compost-sand (20% v/v) media. Particle size distributions results for the compost-sand (50% v/v) media suggest that there was minor degradation of compost particles. It appears gas production causing physical blockage was the most likely cause of the decline. It is recommended that compost filters are not run continuously but have drying periods which would allow any gas build-up to escape.