The industrial wastewater from a carbon monoxide production unit was treated by physico-chemical processes in order to achieve a quality level appropriate for reuse. In preliminary tests, coagulation/flocculation (CF), sand filtration and activated carbon adsorption were investigated in order to select the materials and the process conditions. Based on the results a combined treatment was proposed: CF followed by down-flow filtration in a combined medium (sand and granular activated carbon). The results obtained in a bench-scale treatment unit showed that the combined treatment removed wastewater turbidity (95%), total suspended solids (97%), volatile suspended solids (81%), chemical oxygen demand (74%) and dissolved organic carbon (65%). Polycyclic aromatic hydrocarbons (PAHs) were removed to non-detectable levels. The residual conductivity of the treated wastewater is a matter of concern, and considering the water characteristics of this industrial process, a reuse scheme was proposed based on on-line monitoring and control of conductivity and partial reuse of the treated wastewater.

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