Dioxins and Furans Source Determination in Municipal Wastewater

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City of Portland

Biosolids contain trace amounts of chemicals, the source of which can originate from the food we consume, commercial and industrial wastewater discharges and surface run-off in the case of combined sewers.  Biosolids produced by the City of Portland’s Columbia Boulevard wastewater treatment plant (WWTP) historically contained elevated concentrations of dioxins and furans.  Elevated concentrations of legacy organic compounds such as dioxins and furans can negatively impact a biosolids management program.  SYLVIS has completed many studies in the identification, and impact of polycyclic compounds in biosolids.  After completing a desk-top review of pre-existing data, a follow-up study was designed and implemented by SYLVIS.  The purpose was to identify if, and what portions of the sewerage system may be contributing to atypical concentrations of dioxins/furans to biosolids at the Columbia Boulevard WWTP, and which may be amenable to practical source control initiatives. 

SYLVIS was retained by the City of Portland as part of a multidisciplinary team to develop the sampling methodology, conduct the sampling and assist in the identification of dioxin and furan sources.  Possible sources can be identified not only by concentration, but by a “fingerprint” as to their origin.  SYLVIS collected a series of wastewater and sediment samples to isolate catchment areas suspected of contributing greater than expected dioxin and furan concentrations.

The aggressive sampling, analysis and assessment initiative successfully identified catchment areas that contributed elevated levels of dioxins and furans.  SYLVIS provided recommendations to the City of Portland to further reduce dioxins and furans entering the wastewater collection system including source control initiatives and analysis and maintenance of infrastructure to mitigate impacts on biosolids quality.  Ensuring regulatory compliance is one aspect of biosolids product quality.  SYLVIS works with our clients to improve residuals quality.  These initiatives facilitate flexibility in end-use options and the beneficial use of residuals to realize their highest and best use.