Energy-efficient single-stage membrane rotating biological contactor for wastewater treatment

The current work developed a novel membrane rotating biological contactor (MRBC), integrating rotating biological contactors and membrane filtration by inserting a membrane sandwiched by two adjacent rotating disks inside the bioreactor. The MRBC utilizes the unique feature of rotating wipers attached to the shaft to wipe the membrane surface to annihilate membrane fouling. The integration is analogous to membrane bioreactor development that combines membrane filtration and conventional activated sludge process. Key parameters are systematically investigated to determine the synergistic influence of biological and filtration performance. The results show that the steady-state permeability is 231 % higher in the MRBC compared to the conventional external membrane-based rotating biological contactor, which is further enhanced with increased disk rotational speed. The increased disk rotational speed from 30 to 80 rpm positively impacts fouling mitigation by improving the contact between rotating wipers and the membrane. This marks reduced cake layer formation at the membrane surface, leading to enhanced membrane permeability. The projected full-scale energy audit of the proposed system consumes only one-fourth of the energy (0.16 kWh/m³) compared to the referenced membrane bioreactor, operated at a similar treatment capacity. MRBC offers a promising alternative to traditional wastewater treatment as a low-energy footprint process, which aligns with the requirements of sustainable development and is a promising alternative to energy-intensive conventional treatment systems.