A brief analysis of possible hydraulic techniques for fouling and thermal polarization CID 2011756 in MD.TechniquePotential benefitsPotential challengesSelected referencesInduction of secondary flowNo extra equipment required, easy to adopt, strong effect on temperature polarization on up and down stream sides, high shear acting on the surface can remove the attached particles and fouling layer built up, the performance can be tuned simply by changing the coil diameter and pitch.Although for heat exchangers and low pressure membrane processes, the process has been well studied yet further studies are required to establish the effects for MD, ,  and Pulsating and intermittent flowsReduction in concentration and thermal polarization, relatively simple to incorporateAdditional operational and capital cost associated with the flow patterns generating equipment,  and Air spargingReduction in fouling and thermal polarizationAdditional cost related with air sparging equipment, air can occupy the part of membrane modules thus reducing the contacting area, the pores can be occupied by the injected air leading towards reduced vapor pressure and BackwashingRemoval of crystals, scales and deposits partially covering the poresThe pore wetting will occur leading to the post drying requirement, the effectiveness of the technique will be limited to remove deposition, scaling occurred within the pore or at pore mouth, no effect on thermal polarization and Rotating membranesReduction in concentration and thermal polarizationHigh energy consumption, design modification for MD can be complicated, may not be suitable for hollow fibers and Full-size tableTable optionsView in workspaceDownload as CSV
2.2. Multi-frequency power ultrasound pretreatment of CGM
Prior to the enzymolysis reaction, the CGM was pretreated by multi-frequency power ultrasound viz. sweeping frequency and pulsed ultrasound (SFPU) and sequential dual frequency ultrasound (SDFU). The traditional enzymolysis (Control) was conducted with AG 1879 magnetic stirring apparatus instead of ultrasound under the same conditions. All experiments were carried out in triplicate.
2.2.1. Ultrasound treatment with sweeping frequency and pulsed ultrasound (SFPU)
Fig. 1. The multi-frequency power ultrasound. (a) The sweeping frequency and pulsed ultrasound (SFPU), (b) sweeping frequency, (c) the sequential dual frequency ultrasound (SDFU), (d) sequential mode.Figure optionsDownload full-size imageDownload as PowerPoint slide
2.2.2. Ultrasound treatment with sequential dual frequency ultrasound (SDFU)
2.3. Enzymolysis of corn gluten meal
The enzymolysis apparatus consisted of a digital thermostat water bath (DK-S26, JingHong experimental apparatus Co., Shanghai, China), a pH meter (FE-20, Mettler Toledo Co., Shanghai, China) and an impeller-agitator (JJ-1, ZhongDa instrument Co., Jiangsu, China) at a speed of 100 r/min. After 10 min preheating at 50 °C, the solution was adjusted to pH 9.0, and 1 mL of enzyme was added to initial the reaction. The pH was maintained by continuous addition of 0.5 M NaOH during the enzymolysis process. The enzymolysis time was 60 min and the reaction was terminated by boiling the mixtures for 10 min and then centrifuged at 5030×g for 15 min after cooling to room temperature.
On the other hand, an effective transfer of products from gas/vapour chemistry into the liquid will also be supported by some mixture mechanism. From this point of view, the measurements by Koda et al.  would fit as they claim a higher efficiency of (observed products of) reactions of air and water vapour (HNO2 and HNO3). For reactions with a contributing liquid phase, gas/liquid mixture processes induced by bubble dynamics can clearly support the efficiency by supplying reagent into and transporting products out of the bubble.
2.4.3. Activated carbon treatment
0.6 g activated carbon powder was mixed with 100 mL ADE and the mixture was conducted at 150 rpm, 30.0 ± 1 °C for 30 min. Then the mixture was centrifuged (4000×g, 20 min) and the supernatant was used for citric ha peptide fermentation or electrodialysis treatment.
2.4.4. Electrodialysis treatment
Fig. 2 has shown the schematic of the electrodialysis system in this work which was designed by Shanghai Daming, China. The range of voltage applied was 0–25 V by using a transformer and the range of flow rate was 0–60 mL/min. Heterophase polyethylene ion-exchange membrane was used in this system for selective separation of ions and its characteristics were shown in Table 1. The membrane system consisted of 24 pairs and each membrane had an effective area of 15 × 20 cm2.
Fig. 2. Schematic of the electrodialysis system used in this work.Figure optionsDownload full-size imageDownload as PowerPoint slide