Coupling of titanium dioxide loaded carrier and denitrification biofilm for the advanced treatment of micro-polluted water.

Abstract

TiO₂ was immobilized on a polypropylene polyhedral (PP) ball using polyamide (PA) hot melt adhesive to generate floating photocatalyst TiO₂-PA/PP with high photocatalytic activity, which was further coupled with denitrification biofilm to form TiO₂-PA/PP biofilm system. The analysis of SEM, EDS, XRD, and FTIR confirmed that TiO₂ was immobilized on the surface of PP without any changes in the crystal structure of TiO₂. The photocatalytic experiments showed that the degradation efficiencies of p-phenylenediamine, sucrose, humic acid, and bovine albumin by TiO₂-PA/PP were 58.3%, 48.0%, 97.1%, and 66.6%, respectively. •O₂^- and h⁺ were the key reactive oxygen species (ROSs) in photocatalytic degradation of organic matter in the TiO₂-PA/PP system under solar irradiation. In the synthetic water, 95.5% humic acid and 43.2% nitrate were simultaneously removed in TiO₂-PA/PP biofilm reactor, confirming the coupling of photocatalytic degradation and denitrification. In the actual micro-polluted surface water, the coupling photocatalytic and biofilm reactor reduced chemical oxygen demand (COD) by 68.4% and nitrate by 38.9% in 480 min. This study provided a new option for the in-situ removal of organic matter and nitrate from micro-polluted surface water.