Seawater ultrafiltration: role of particles on organic rejections and permeate fluxes

Deep reinforcement learning in an ultrafiltration system: Optimizing operating pressure and chemical cleaning conditions

Enhancing engineering efficiency and reducing operating costs are permanent subjects that face all engineers over the world. To effectively improve the performance of filtration systems, it is necessary to determine an optimal operating condition beyond conventional methods of periodic and empirical operation. Herein, this paper proposes an effective approach to finding an optimal operating strategy using deep reinforcement learning (DRL), particularly for an ultrafiltration (UF) system. Deep learning was developed to represent the UF system utilizing a long-short term memory and provided an environment for DRL. DRL was designed to control three actions; operating pressure, cleaning time, and cleaning concentration. Ultimately, DRL proposed the UF system to actively change the operating pressure and cleaning conditions over time toward better water productivity and operating efficiency. DRL denoted ∼20.9% of specific energy consumption can be reduced by increasing average water flux (39.5-43.7 L m^-2 h^-1) and reducing operating pressure (0.617-0.540 bar). Moreover, the optimal action of DRL was reasonable to achieve better performance beyond the conventional operation. Crucially, this study demonstrated that due to the nature of DRL, the approach is tractable for engineering systems that have structurally complex relationships among operating conditions and resultants.

Control of fouling formation in membrane ultrafiltration by ultrasound irradiation

The increasing application of membrane filtration in water and wastewater treatment necessitates techniques to improve performance, especially in fouling control. Ultrasound is one promising technology for this purpose as cavitational effects facilitate continuous cleaning of the membrane. This research studied the ultrafiltration of lake water in systems with constant permeate flux under medium frequency (45 kHz) ultrasound irradiation. Fouling was investigated by monitoring transmembrane pressure (TMP) using continuous or intermittent ultrasound irradiation and dead-end or crossflow operation. Best performance was observed with continuous ultrasound irradiation in crossflow mode. Intermittent irradiation reduced the rate of TMP build-up but nevertheless allowed irreversible fouling to develop.