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).

Physical-chemical treatment of rainwater runoff in recovery and recycling companies: Pilot-scale optimization

“…From Table 7 it can be seen that the overall removal efficiencies obtained at pilot-scale are much lower than the ones obtained at lab-scale. [3] From Table 7 it can also be seen that for the tests on wastewater B better removal results are obtained after C/F, while for the tests on wastewater C better removal is obtained by treatment with SAF. Indeed, during coagulation/flocculation of wastewater C, smaller flocs were formed.…”

“…Thus, the base and acid storage tanks -provided with NaOH (29% solution) and HCl (30% solution), respectivelyremained unused. Based on the results of preliminary labscale tests [3] PAC Sachtoklar 39 was chosen as coagulant in a concentration of 0.04 mL commercial product per L wastewater (i.e., 50 mg PAC per L wastewater). The coagulation/flocculation pilot was used to perform tests on wastewater A, B and C, but only on wastewater A was the pilot also tested as a second treatment technique.…”

“…These leaching tests showed that up to 98% of the PAHs, PCBs and some metals were present in the particulate form (i.e., not passing a 0.45 mm filter). As such, the (potential) applicability of sedimentation, centrifugation, filtration and coagulation/flocculation techniques for the treatment of the investigated leachates was further investigated on lab-scale (Chys et al [1] and Blondeel et al [3] ).…”

“…[3] However, further pilot-scale optimisation is necessary in order to select an optimal (combination of) technique(s) for full-scale implementation. After all, for practical use, the treatment effectiveness is influenced by the large and highly variable flow rates, large volumes, relatively low concentrations, and large variabilities in the biochemical characteristics.…”

Terénní testování prototypu separátoru k dočištění srážkových vod

“…Při samotném splachu závisí také na proměnlivých přírodních podmínkách (počasí), zejména na intenzitě srážek, jež souvisí s následným odtokem vody a odnosem znečištění. Důležitým faktorem je i počet bezdeštných dnů před splachem, tedy doba, po kterou se znečištění na ploše kumuluje [3,4]. Tyto předpoklady potvrzují Lee a kol.…”