Many industrial and agricultural applications require the treatment of water streams containing high concentrations of ionic species for closing material cycles. High concentration factors are often desired, but hard to achieve with established thermal or membrane-based water treatment technologies at low energy consumptions. Capacitive deionization processes are normally

Introducing fed-batch mode in early stages of development projects is crucial for establishing comparable conditions to industrial fed-batch fermentation processes. Therefore, cost efficient and easy to use small-scale fed-batch systems that can be integrated into existing laboratory equipment and workflows are required. Recently, a novel polymer-based controlled-release fed-batch microtiter plate is described. In this work, the polymer-based controlled-release fed-batch microtiter plate is used to investigate fed-batch cultivations of a protease producing Bacillus licheniformis culture. Therefore, the oxygen transfer rate (OTR) is online-monitored within each well of the polymer-based controlled-release fed-batch microtiter plate using a µRAMOS device. Cultivations in five individual polymer-based controlled-release fed-batch microtiter plates of two production lots show good reproducibility with a mean coefficient of variation of 9.2%. Decreasing initial biomass concentrations prolongs batch phase while simultaneously postponing the fed-batch phase. The initial liquid filling volume affects the volumetric release rate, which is directly translated in different OTR levels of the fed-batch phase. An increasing initial osmotic pressure within the mineral medium decreases both glucose release and protease yield. With the volumetric glucose release rate as scale-up criterion, microtiter plate-and shake flask-based fed-batch cultivations are highly comparable. On basis of the small-scale fed-batch cultivations, a mechanistic model is established and validated. Model-based simulations coincide well with the experimentally acquired data.

desalination and brine concentration tasks. [4,5] However, undesired water crossover is a major limitation in such processes applying ion-exchange membranes. The effect is twofold: 1) the water stream, which is to be desalinated, is desalinated less efficiently due to the unwanted removal of water; and 2) the brine stream, which is to be concentrated, is concentrated less efficiently, due to the unwanted crossover of water molecules into the brine stream. [6,7] Hence, the desalination and concentration efficiency of the processes are limited, while the energy demand to achieve a certain level of desalination or concentration is increased. This effect is especially pronounced when treating high salinity solutions, which goes hand in hand with high concentration differences across the membranes and the crossover of a large number of ions including their hydration shells through the ion-exchange membranes. [8,9] The issue of water crossover through proton exchange membranes is intensively studied and addressed in numerous publications. [10] Whereas, the mitigation of water crossover in cationexchange membranes (CEM) is an overlooked domain in ion transport and high salinity conditions are rarely studied. ED and FCDI FundamentalsElectrodialysis (ED) and FCDI are electrical potential driven desalination techniques. The ions move in an electric field toward the oppositely charged electrode, respectively. Thus, ions are selectively separated from the water. Electrodialysis uses a stack of ion-exchange membranes creating separate diluate and concentrate channels. Faradaic reactions convert the applied electric current in the electrode chambers filled with a rinse solution. [11,12] The principles of ED have already been described in 1940, and the first commercial application of ED for brackish water treatment is known since the early 1950s. A further field of application for ED is the food industry, where ED can be used to produce table salt or for the deacidification of apple juice. [13] Within the family of electrically driven desalination processes, FCDI is a novel technology, bearing promising potentials for the future of efficient water treatment. In 2013, Jeon et al., introduced FCDI, where static porous carbon electrodes from membrane capacitive deionization are replaced by carbon slurries, which allow for continuous desalination operation. [4,14,15] Undesired water crossover through ion-exchange membranes is a significant limitation in electrically driven desalination processes. The effect of mitigating water crossover is twofold: 1) The desalination degree is less reduced due to the unwanted removal of water, and 2) the brine concentration is increased due to decreased dilution by an unwanted crossover of water molecules. Hence, water crossover limits the desalination and concentration efficiency of the processes, while the energy demand to achieve a certain level of desalination or concentration increases. This effect is especially pronounced when treating high salinity solutions, which goes hand in hand with th...