Alternative sorption filter materials effectively remove non-particulate organic pollutants from stormwater

Area of Science:

• Environmental Engineering
• Water Treatment Technologies
• Pollutant Removal

Background:

• Urban runoff carries diverse organic pollutants (OPs), including hydrophobic compounds in dissolved and colloidal forms.
• These hydrophobic OPs can form emulsions, complicating their removal from stormwater.
• Effective treatment technologies are crucial for mitigating non-particulate OPs in urban water systems.

Purpose of the Study:

• To evaluate the efficacy of sorption filters in removing non-particulate organic pollutants from urban stormwater.
• To assess the performance of different filter materials, including sand, granulated activated carbon, peat, and bark.
• To investigate filter behavior during normal operation and simulated stress conditions.

Main Methods:

• A pilot plant utilized column bed-filters with sand as a pre-filter, followed by granulated activated carbon, Sphagnum peat, or Pinus sylvestris bark.
• Samples were collected weekly, after rain events, and during stress tests with spiked sediment, petrol, or diesel.
• Analysis focused on the reduction of specific organic pollutants like hydrocarbons and polycyclic aromatic hydrocarbons (PAHs).

Main Results:

• All tested sorption filters demonstrated efficient reduction of aliphatic diesel hydrocarbons (C16-C35), benzene, and specific PAHs (phenanthrene, fluoranthene, pyrene) over 18 months.
• During stress tests, filters achieved 100% removal of PAH-16, petrol, and diesel aliphatics (C5-C35).
• Filters released dissolved organic carbon (DOC) and nanoparticles, potentially contributing to OP transport.

Conclusions:

• A combination of sand pre-filtration and series-arranged sorption filters (activated carbon, peat, bark) is recommended for effective non-particulate OP removal.
• Optimizing hydraulic conditions is essential for ensuring adequate water flow and filter performance.
• The study highlights the potential of these filter systems for improving urban stormwater quality.