Polluted rainwater runoff from waste recovery and recycling companies: Determination of emission levels associated with the best available techniques

- Rainwater runoff from storage areas at recovery and recycling plants is polluted.
- It is characterized by highly fluctuating composition and flow rates.
- A significant fraction of the pollution is associated with particles.
- Atmospheric deposition plays an important role in the contamination.
- Best available techniques include removal of suspended solids to levels ⩽60 mg/l.

Rainwater falling on outdoor storage areas of waste recovery and recycling companies becomes polluted via contact with the stored materials. It contains various pollutants, including heavy metals, polycyclic aromatic hydrocarbons and polychlorinated biphenyls, and is characterized by a highly fluctuating composition and flow rate. This polluted rainwater runoff is legally considered as industrial wastewater, and the polluting substances contained in the rainwater runoff at the point of discharge, are considered as emissions into water. The permitting authorities can set emission limit values (discharge limits) at the point of discharge. Best available techniques are an important reference point for setting emission limit values. In this paper, the emission levels associated with the best available techniques for dealing with polluted rainwater runoff from waste recovery and recycling companies were determined. The determination is based on an analysis of emission data measured at different companies in Flanders. The data show that a significant fraction of the pollution in rainwater runoff is associated with particles. A comparison with literature data provides strong indications that not only leaching, but also atmospheric deposition play an important role in the contamination of rainwater at waste recovery and recycling companies. The prevention of pollution and removal of suspended solids from rainwater runoff to levels below 60 mg/l are considered as best available techniques. The associated emission levels were determined by considering only emission data from plants applying wastewater treatment, and excluding all samples with suspended solid levels >60 mg/l.The resulting BAT-AEL can be used as a reference point for setting emission limit values for polluted rainwater runoff from waste recovery and recycling companies. Since the BAT-AEL (e.g. 150 μg/l for Cu) are significantly lower than current emission levels (e.g. 300 μg/l as the 90% percentile and 4910 μg/l as the maximum level for Cu), this will result in a significant reduction in emissions into water.

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