Improvement of permeation flux by evaluating the effects of coagulated-humic acids flocs and pH during coagulation-microfiltration hybrid process for water treatment: Performance, fouling modeling, specific energy consumption, and processes comparison

Abstract

The objective of this study is to analyze the relation between flocs shape and the permeation flux stability in a pilot-scale Coagulation/Flocculation-Microfiltration hybrid process for humic acids removal from water under different coagulant dose and pH values. Besides, the treatment performance was examined. The results showed that at pH 7.1 and polychloride of aluminum coagulant of 10−1 mmol Al.L−1, coagulation/flocculation was effective in maintaining membrane permeability flux. Also, UV254, TOC, and turbidity removal efficiencies were almost ≥ 90%. In addition, this condition proved a potent effect on residual aluminum control and specific energy consumption, where they were, respectively, 0.0852 kWh.m−3 and 20 µg.L−1. Furthermore, humic acids fouling using four Hermia mechanisms (individual and combined) was modeled. Complete pores blocking and cake filtration appeared to be the major mechanisms of microfiltration membrane fouling. Finally, this hybrid process was compared with the most used technologies for the humic acids removal from water. It was concluded that the former process is more reliable, efficient, and cost-effective.