Patterned Membrane in an Energy-Efficient Tilted Panel Filtration System for Fouling Control in Activated Sludge Filtration

A membrane bioreactor enhances the overall biological performance of a conventional activated sludge system for wastewater treatment by producing high-quality effluent suitable for reuse. However, membrane fouling hinders the widespread application of membrane bioreactors by reducing the hydraulic performance, shortening membrane lifespan, and increasing the operational costs for membrane fouling management. This study assesses the combined effect of membrane surface corrugation and a tilted panel in enhancing the impact of air bubbling for membrane fouling control in activated sludge filtration, applicable for membrane bioreactors. The filterability performance of such a system was further tested under variable parameters: Filtration cycle, aeration rate, and intermittent aeration. Results show that a combination of surface corrugation and panel tilting enhances the impact of aeration and leads to 87% permeance increment. The results of the parametric study shows that the highest permeance was achieved under short filtration–relaxation cycle of 5 min, high aeration rate of 1.5 L/min, and short switching period of 2.5 min, to yield the permeances of 465 ± 18, 447 ± 2, and 369 ± 9 L/(m2h bar), respectively. The high permeances lead to higher operational flux that helps to lower the membrane area as well as energy consumption. Initial estimation of the fully aerated system yields the energy input of 0.152 kWh/m3, much lower than data from the full-scale references of <0.4 kWh/m3. Further energy savings and a lower system footprint can still be achieved by applying the two-sided panel with a switching system, which will be addressed in the future.

Modeling and Analysis of a Shape Memory Alloy-Based Adaptive Regulator for Thermal Management

The goal of this work is to develop and model an adaptive thermal management system formed by shape memory alloy (SMA) helical springs and stretchable selective emitters. Emitters are prepared by depositing a metallic layer on an elastomeric film (3M VHB 4910). Strain changes in the film induce alterations of the surface corrugation of the metallic layer, which enables adjustments of its emissivity spectrum. SMAs are materials that undergo moderate recoverable deformations driven by temperature changes. SMA springs are used here as adaptive deformation enablers (both as actuator and thermal sensor). The thermal management system is created by connecting stretchable emitters and SMA springs in series. When the temperature of the system is increased by sunlight irradiation, the SMA springs undergo contractions which elongate the stretchable emitters, flattening their corrugated metallic layer, thereby leading to an increase in their solar reflectivity and allowing radiative cooling. When the system temperature is decreased, the SMA springs relax and allow the emitters to recover their original surface corrugation, leading to an increase in their solar absorptivity and allowing radiative heating. This repeatable process allows the system to exhibit open-loop adaptive regulation of its temperature under varying solar irradiation. A reduced-order model of the system is derived to perform feasibility studies of the concept and results demonstrating the functionality of the system are presented.