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Removal of refractory organics in wastewater by coagulation/flocculation with green chlorine-free coagulants

2021; Elsevier BV; Volume: 787; Linguagem: Inglês

10.1016/j.scitotenv.2021.147654

1879-1026

Huihui Zhang, Hai Lin, Qiang Li, Changkun Cheng, Hui Shen, Zhiyong Zhang, Zhongzhi Zhang, Heming Wang,

Environmental remediation with nanomaterials

Coagulation/flocculation is considered an economical and practical technology to remove refractory organic matter from wastewater. Coagulants containing chlorine may release chloride ions into water, thereby resulting in corrosion. A green chlorine-free coagulant of polyaluminum ferric silicate (PSAF) was synthesized to treat non-oily (e.g., humus wastewater) and oily refractory wastewaters (e.g., lubricating oil wastewater). Results showed that the highest removal efficiency of humus substances in non-oily wastewater achieved 96.0% at pH 7.0 using PSAF alone. When treating oily wastewater, the dosage and addition sequence of PAMALAM significantly affected the coagulation performance. The removal efficiencies of turbidity, chemical oxygen demand, and total nitrogen were increased by 0.3, 1.8, and 5.9 folds, respectively, with the optimal adding sequence of PSAF +0.08% PAMALAM. More fulvic acid-like substances can be removed during this process. The analysis of zeta potential and floc properties revealed that charge neutralization, sweep, and adsorption/entrapment mechanisms existed during the single PSAF coagulation process, and PAMALAM mainly improved the adsorption, bridging, and sweep function. • A green chlorine-free PSAF coagulant was simply synthesized. • The PSAF was applied to treat non-oily and oily refractory wastewaters. • PAMALAM improved PSAF coagulation capacity to treat complex wastewater. • Treated oily refractory wastewater was characterized by 3D-EEM.