Unraveling the role of feed temperature and cross-flow velocity on organic fouling in membrane distillation using response surface methodology

Understanding the role of operating condition on fouling development in membrane distillation (MD) is critical for the further optimization of MD technology. In this study, organic fouling development in MD was investigated varying the feed inlet temperature from 35 to 65 degrees C and the cross-flow velocity from 0.21 to 0.42 m/s. The fouling layer thickness was estimated at the end of each experiment non-invasively with optical coherence tomography. The set of experiments was mined to model the initial flux decline, the near-stable flux, and the final foulant thickness responses by central composite design, a useful response surface methodology (RSM) tool. The results indicated a linear increment of the fouling thickness by increasing the feed inlet temperatures. Overall, the feed inlet temperature governed both the initial flux decline and the fouling deposition. The benefits in water productivity obtained by increasing the feed temperature were always offset by higher fouling deposition. Higher cross-flow velocities showed a positive effect on the initial flux, which however translated in larger values of the initial flux decline rate. On the other hand, the higher shear stress contributed to a decrease of the final steadystate fouling layer thickness. The proposed approach was proven to be a valuable tool to assess the role of the operating conditions on fouling and process performance in MD

Interaction between Iron Oxide Nanoparticles and HepaRG Cells: A Preliminary In Vitro

Nowadays, the use of iron oxide nanoparticles is widespread to label cells for magnetic resonance imaging tracking. More recently, magnetic labeling provides promising new opportunities for tissue engineering by controlling and manipulating cells through the action of an external magnetic field. The present work describes nonspecific labeling of metabolically competent HepaRG hepatocytes with anionic iron oxide nanoparticles. An interaction was observed between nanoparticles and studied cells, which were easily attracted when exposed to a magnet. No cytotoxicity was detected in the hepatocytes after 24 hours of incubation with iron oxide nanoparticles. Impact on HepaRG metabolization activity was assessed. Although a slight decrease in the metabolite generation was observed after exposure to nanoparticles (2 mM in iron), the enzymatic capacity was maintained. These results pave the way for 3D cultures of magnetic labeled HepaRG cells by using a magnetic field

Modeling, optimization and control in dead-end ultrafiltration

Ultra filtration (UF) is increasingly used as a complete- or intermediate surface water purification technique. Ultra filtration membranes have a high selectivity, are easy to scale-up and have become economically attractive during the last 15 years. However, the buildup of fouling during filtration severely influences the performance of a UF membrane. For this reason frequent cleaning of the UF membrane is required. In the short term, the membrane is cleaned by means of backwashing, and in the long term the membrane is cleaned with cleaning chemicals. Although backwashing and chemical cleaning are useful methods to prevent fouling, the execution of such procedures are still based on pilot plant studies and rules of thumb. The expectation is that systematic modeling; optimization and control will significantly reduce operational costs and increase overall controllability of the UF process. In this contribution the formulation of a hierarchical modeling, optimization and control framework will be discussed that can be used to optimize the overall UF process. There will be special attention for mathematical modeling and optimization of membrane filtration, backwashing and chemical cleaning. Noted is further that the proposed models, optimization routines and control algorithm were tested and validated experimentally, on lab scale as well as pilot scale

Development of a control system for in-line coagulation in an ultrafiltration process

A control system for the in-line coagulation applied in an ultrafiltration process was developed. The dosing strategy aims to apply a minimal coagulant dose while maintaining desirable process performance by regulating the initial filtration resistance. This is achieved by a feedback controller. It was found that the control system performs well; adaptation to changing conditions is achieved adequately and sufficiently fast. The initial resistance of the last filtration before the chemical cleaning phase can be controlled within an accuracy of approximately 3% (of the total resistance) or 9% (of the fouling resistance). Compared to the current dosing strategy, a significant reduction of coagulant consumption can be achieved