Fouling control in ultrafiltration of secondary effluent using polyaniline/TiO₂ adsorption and subsequent treatment of desorption eluate using electrochemical oxidation

Performance of three adsorbents, polyaniline-modified TiO₂ (PANI/TiO₂), Dow resin IRA(a) and Dow resin IRA(b), in removing organics from secondary effluent (SE) was evaluated, and the objective of this study is to deliver a treatment loop including membrane fouling control using adsorption and treatment of correspondingly formed desorption eluate using electrochemical oxidation, so that the contaminants could be effectively handled within a wastewater treatment plant. Results show that PANI/TiO₂ is a promising adsorbent in the removal of effluent organic matter (>55%) and its regeneration was superior to the two others. Specifically, PANI/TiO₂ could remove over 70% of the fraction of biopolymers from the SE and therefore alleviated subsequent membrane fouling to a large extent, while the other two presented less antifouling effect due to limited removal of the major foulants, though they both showed comparable effect as PANI/TiO₂ in the removal of other organic fractions. BOD₅/COD of the concentrated desorption eluate was gradually increasing along with the extension of the electrochemical oxidation. It reached >0.4 after 4.5 h of treatment, which is of suitable biodegradability for recycling to the influent of the wastewater treatment plant. The improvement on BOD₅/COD was due to the mineralization of effluent organic matter and simultaneous minifying of their molecular size. Moreover, the operation cost of the treatment loop was estimated at about 0.12–0.15 USD/m³ for delivering effect fouling control and significant improvement on effluent quality.