Long-term Environmental Performance of Stormwater Biofiltration Sorption Media in Sustainable Drainage Systems (SuDS)

In this climate impacted world, there is an increasing need for countries facing potential water extremes to improve the reuse potential of grey water and storm water. By implementing best management practices for the treatment of stormwater and urban run-off, contaminants can be removed, and the water recycled and reused. The effectiveness of stormwater treatment is impacted by the clogging of equipment or where contaminant storage exceeds performance design. Poorly or untreated stormwater runoff can impact the environment through the release of total dissolved solids (TDS), suspended solids (turbidity), phosphate, ammonia, and elevated chemical and biochemical oxygen demand (COD and BOD, respectively). This study evaluated the hydraulic and environmental performance of gravity flow stormwater filters over a three-year period with the average filter life cycle four months. Six bespoke gravity stormwater filters employing sorbent pillows, and including peat moss, were tested for their effectiveness, including for nitrite and nitrate. An improvement in water quality of 80-98% was recorded. Oil and grease were managed effectively (peat moss and sorbent pillows reduced BOD, COD, color, and turbidity) but not significantly when compared to conventional filter media. The findings demonstrate that stormwater biofilters can be an innovative, low-cost, and sustainable solution for both urban and sub-urban runoff management, addressing water quality and resource quantity challenges.