Removal of organic matter from wastewater using M/Al-pillared clays (M = Fe or Mn) as coagulants

Abstract

Abstract This work is about organic matter removal from Sidi Bel Abbes wastewater plant (Algeria) by coagulation on pillared clays (PILCs) under pH and PZC (point of zero charge), conditions. Two pillared clays, M/Al-PILCs (M = Fe or Mn), were synthesized, characterized, and studied as coagulants. Results showed that Fe/Al-pillared clay exhibits superior efficiency, with 18% higher removal rate than the common coagulants alum (AS) and ferric chloride (FCl), and that sedimentation time has positive effect on turbidity removal, with 95.85% removal rate during 30 min. Moreover PILCs will not cause pH go down too low, which is an advantage for achieving the best overall treatment. The IR and UV bands' reduction reveals the breakdown fragmentation of high molecular weight organic substances into smaller units. The highest total organic carbon (supercritical water oxidation analysis) and chemical oxygen demand adsorption capacities (48.52% and 61.85% respectively) obtained for Fe/Al-PILC can be related to increased basal spacing between adjacent layers, creating favorable adsorption sites in the microporous system. The suggested adsorption mechanism involves strong interactions between pollutants and PILCs leading to PILC–pollutant complex formation.