Combined process of electrically-membrane bioreactor and TiO₂ aerogel filtration for efficient wastewater treatment

A two-stage treatment for efficient removal of organic matter, heavy metal ions, and other contaminants from raw wastewater is presented in this manuscript. The two stages include electrically-enhanced membrane bioreactor (eMBR) and filtration using titanium dioxide (TiO₂) aerogel membrane. The aerogel membrane was highly porous (with 90% porosity), superhydrophilic, highly permeable (with water permeability of 850 LMH/bar), and contained networks of interconnected nanowires with nano-sized pores. The combined system removed 100% bacteria, 97.8% COD, 96.9% Zn²⁺, 99.3% Cr⁶⁺, and 84.1% Cd²⁺ from raw municipal wastewater sampled from Masdar City Wastewater Treatment Plant, Abu Dhabi, United Arab Emirates. Residual contaminants were removed from eMBR effluent by the aerogel membrane through surface charge interactions, nano-sized pores, and photodegradation. The aerogel membrane was characterized before and after filtration through Scanning Electron Microscopy, X-ray Diffraction, Fourier-Transforms Infrared Spectroscopy, Raman Spectroscopy, and Energy Dispersive X-ray spectroscopy. After filtration and chemical cleaning of the aerogel membrane, ˜90% flux recovery was shown. The cost of water production was US$1.03/m³, which was less than the cost of water production using seawater desalination and industrial wastewater treatment. The final effluent is suitable for advanced applications such as agricultural irrigation and industrial process heating/cooling, based on the pollutants measured.