Combined coagulation/ceramic membrane ultrafiltration system for reclamation of degreasing washing water

AbstractCurrently, there is growing emphasis on wastewater reclamation and reuse around the world. In this study, a combined coagulation/ceramic membrane ultrafiltration system was used to treat degreasing washing water under high pH/alkalinity conditions containing surfactants, organic matter and other materials resulting from rinsing processes in the plating industry. Coagulant exists as sol or gel species that was not suitable for complexation with smaller surfactants and organic matter under high pH/alkalinity conditions. A pH neutralization process was introduced to improve the removal efficiency of the coagulant prior to coagulation. An optimal coagulant (ferric chloride), optimal coagulation pH 5, and optimal coagulant dosage (700 mg Fe/L) were proposed as a result of coagulation tests. Under slightly acidic conditions, species distribution of ferric chloride consisted of monomers and medium polymers that were favorable for the formation of surfactant–coagulant or organic matter–coagulant complexes...