Physical–chemical treatment of rainwater runoff in recovery and recycling companies: lab-scale investigation

ABSTRACT

Scrap material recovery and recycling companies are producing wastewater in which common pollutants (such as COD, nutrients and suspended solids), toxic metals, polyaromatic hydrocarbons (PAH) and polychlorinated biphenyls (PCB) frequently can exceed the discharge limits. Lab-scale optimisation of different possible physical–chemical treatment techniques was performed on the wastewater originating from three different companies in view of further testing at pilot-scale testing and implementation at full-scale. The lab-scale tests demonstrate that sedimentation or hydrocyclone treatment as stand-alone technique cannot be used for proper treatment of this type of wastewater. Dual bed filtration or coagulation/flocculation proved to be more promising with removal efficiencies of about 71–95% (dual bed filtration) and 61–97% (coagulation/flocculation) for the above-mentioned pollutants (metals, PAH and PCB).

KEYWORDS:

• Polluted rainwater runoff
• scrap materials
• sedimentation
• hydrocyclone
• sand filtration
• coagulation/flocculation
• activated carbon filtration

Acknowledgements

This project fits within the IWT-Tetra project REWARE (120118) and the LED H2O project. The LED H2O belongs to the LED network (www.lednetwerk.be) and is financially supported by The Flanders Knowledge Centre Water (Vlakwa vzw). The authors would also like to thank the various Flemish recovery and recycling companies – represented by COBEREC (www.coberec.be) – who gave their feedback on the ongoing tests, with special thanks to scrap collecting companies A, B and C for providing the wastewater and their strong collaboration. Finally, the interesting discussions with Els Verachtert from VITO (www.emis.vito.be) are greatly appreciated.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Flemish Agency for Innovation by Science and Technology (IWT) under Grant IWT-120118 and the Flemish Knowledge Center Water (Vlakwa) under Grant Vlakwa-LED.