Field performance of two biofiltration systems treating micropollutants from road runoff

Abstract

The treatment efficiency of a vegetative filter strip and a biofiltration swale treating heavily loaded road runoff are evaluated. Concentrations measured in water drained from the two systems are compared to those in untreated road runoff collected from a reference catchment for a wide range of contaminants including organic carbon, nutrients (N and P), trace metals, and organic micropollutants (polycyclic aromatic hydrocarbons (PAH), total petroleum hydrocarbons (TPH), alkylphenols, bisphenol-A, phthalates), in both total and dissolved phases. Predominantly particulate pollutants, including Pb, Zn and PAH, were very efficiently removed (around 90%) for most events. However, poor particulate removal was observed during a winter period. Relatively few pollutants were significantly removed in the dissolved phase and observed concentration reductions tended to be lower than those of suspended solids and associated pollutants; as such, lower removals were observed for total concentrations of moderately particulate micropollutants, including bisphenol-A, alkylphenols and phthalates. In addition, some pollutants appear to be emitted from various biofilter components (filter media, drainage and lining materials), as low or negative concentration removals were observed during the first months of operation of the biofiltration swale.

Stochastic Method for Evaluating Removal, Fate and Associated Uncertainties of Micropollutants in a Stormwater Biofilter at an Annual Scale

“…Water sampling is detailed elsewhere [23]. Briefly, water was collected in proportion to flow volume in order to estimate event mean concentrations.…”

“…Water samples were collected within 24 h of each rain event and sent to partner laboratories within 24 h of collection where they are immediately filtered. Water was analysed for a large number of water quality parameters and micropollutants [23], which were analysed in the particulate and dissolved phases. The present work focuses on a subset of these parameters, chosen to represent the pollutants from different families and with varying properties: total suspended solids (TSS), organic carbon (OC), two trace metals (Cu and Zn), two PAHs (pyrene-Pyr and phenanthrene-Phen), bisphenol A (BPA), two alkylphenols (octylphenol-OP and nonylphenol-NP) and one phthalate (bis(2-ethylhexyl) phthalate-DEHP).…”

“…The initial sample and the soil cores were analysed for organic carbon and the same micropollutants as were analysed in water [23]; among these, the present work focuses on OC, Cu, Zn, Pyr, Phen, BPA, OP and NP.…”

“…At this location, turbidity was not measured continuously as the particulate fraction of pollutants was expected to be less significant, an assumption that was confirmed through the measurement campaigns [23]. Therefore, for most pollutants, outlet concentrations were randomly sampled within the log-normal (P < 0.05) total outlet concentration distributions (Table A4).…”

Green Infrastructures in Stormwater Control and Treatment Strategies

“…Studies in France [48] showed that predominantly particulate pollutants, including Pb, Zn and polycyclic aromatic hydrocarbons, were very efficiently removed (90%) in a filter strip and a swale treating road runoff. On the other hand, lower removals were observed during the first months of operation and for total concentrations of moderately particulate micropollutants.…”