title: Coagulation-flocculation mechanisms in wastewater treatment plants through zeta potential measurements.
abstract: Based on the polyelectrolyte-contaminant physical and chemical interactions at the molecular level, this article analyzed and discussed the coagulation-flocculation and chemical precipitation processes in order to improve their efficiency. Bench experiments indicate that water pH, polyelectrolyte (PE) dosing strategy and cationic polyelectrolyte addition are key parameters for the stability of metal-PE complexes. The coagulation-flocculation mechanism is proposed based on zeta potential (ζ) measurement as the criteria to define the electrostatic interaction between pollutants and coagulant-flocculant agents. Polyelectrolyte and wastewater dispersions are exposed to an electrophoretic effect to determine ζ. Finally, zeta potential values are compared at pH 9, suggesting the optimum coagulant dose at 162mg/L polydadmac and 67mg/L of flocculant, since a complete removal of TSS and turbidity is achieved. Based on the concentration of heavy metals (0.931mg/L Sn, 0.7mg/L Fe and 0.63mg/L Pb), treated water met the Mexican maximum permissible limits. In addition, the treated water has 45mg O2/L chemical oxygen demand (COD) and 45mg C/L total organic carbon (TOC). The coagulation-flocculation mechanism is proposed taking into account both: zeta potential (ζ)-pH measurement and chemical affinity, as the criteria to define the electrostatic and chemical interaction between pollutants and polyelectrolytes.
authors.affiliation: Centro de Investigación y Desarrollo Tecnológico en Electroquímica, Unidad Tijuana, Carretera libre Tijuana-Tecate km 26.5, esq. Blvd Nogales Parque Ind. El Florido CP 22444, Tijuana, B.C., Mexico. Electronic address: elopez@cideteq.mx.
authors.forename: E A
authors.initials: EA
authors.lastname: López-Maldonado
authors.affiliation: Centro de Investigación y Desarrollo Tecnológico en Electroquímica, Unidad Tijuana, Carretera libre Tijuana-Tecate km 26.5, esq. Blvd Nogales Parque Ind. El Florido CP 22444, Tijuana, B.C., Mexico; Centro de Graduados e Investigación en Química del Instituto Tecnológico de Tijuana, Blvd. Alberto Limón Padilla s/n, Mesa de Otay, C.P. 22500, Tijuana, B.C., Mexico.
authors.forename: M T
authors.initials: MT
authors.lastname: Oropeza-Guzman
authors.affiliation: Centro de Investigación y Desarrollo Tecnológico en Electroquímica, Unidad Tijuana, Carretera libre Tijuana-Tecate km 26.5, esq. Blvd Nogales Parque Ind. El Florido CP 22444, Tijuana, B.C., Mexico.
authors.forename: J L
authors.initials: JL
authors.lastname: Jurado-Baizaval
authors.affiliation: Centro de Graduados e Investigación en Química del Instituto Tecnológico de Tijuana, Blvd. Alberto Limón Padilla s/n, Mesa de Otay, C.P. 22500, Tijuana, B.C., Mexico.
authors.forename: A
authors.initials: A
authors.lastname: Ochoa-Terán
mesh_terms: D003102:Colloids / Q000737:chemistry; D004573:Electrolytes / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste; D007526:Isoelectric Point; D008855:Microscopy, Electron, Scanning; D011108:Polymers / Q000737:chemistry; D012666:Semiconductors; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D003102:Colloids; D004573:Electrolytes; D007220:Industrial Waste; D011108:Polymers; D014874:Water Pollutants, Chemical
keywords: Coagulation–flocculation mechanism; Contaminant–PE interaction; Electroplating wastewater; Polyelectrolyte complexing capacity