Stormwater Runoff Treatment Using Compost Biofilters

摘要

Concerns with protecting the water quality of receiving waterbodies as a result of construction activities in recent years in the Greater Toronto Area (GTA) has prompted governmental agencies and academia to explore new stormwater treatment technologies that can be used in the thousands of construction sites across the GTA. In response, a sustainable, green technology has been developed that uses large volumes of compost material as engineered biofilters for stormwater runoff treatment. The use of biofilters will improve the sustainability of compost operations by identifying a valuable use for the compost. Specifically, during the spring and summer of 2006, laboratory and field experiments were conducted and hundreds of runoff samples were collected and analyzed. The maximum flow-through rate, without overtopping of a sock, per unit width, for an 8" diameter sock for the three compost materials tested wasrnapproximately 1.5 L s~(-1) m~(-1). The flow-through capacities of the 12", 18" and the 24" socks were approximately 50%, 200%, and 300% higher than the flowthrough capacity of the 8" sock. The average sediment removal efficiency of the 8" socks for 5, 10, and 15 rolls or socks was 34%, 48%, and 60%, respectively. The average sediment removal efficiency of the 18" socks for 5, 10, and 15 rolls placed in sequence was 69%, 84%, and 95%, respectively. The average sediment removal efficiency of 5 rolls of the 18" diameter sock steadily and gradually reduced from 70% to 62% to 58% to 56% and to 54% after 1, 5, 10, 15, and 20 consecutive exposure scenarios to sediment runoff conditions. Sediment removal efficiency of clay-size material was only 30% while for fine silt was around 50% and for coarse silt around 80%.