Loading Criteria and Deposit Layer Characteristics as Causes of Sediment Settlement in an Estuary

Sediment compaction due to the extraction of groundwater and self-weight consolidation, and monitoring land settlement of the river delta using geodetic measurement has been executed in several studies, while sediment settlement in the estuary is hypothesized due to dynamic loads. The present study aimed to observe clues for the occurrence of sediment settlement due to loading variation and deposit layer characteristics in the estuary. This research was based on four loading data for examination, i.e., hydraulic head pressure, sediment transport rate, sediment deposition, and water density. Two years of previous research simulations, including the rainy and dry seasons, were recalculated to gain the load pressure and were considered to assess the maximum load prediction. This review found evidence that dynamic loads predominated in maximum pressure changes in boreholes (BH2) and (BH3), and were due to river discharge and tidal occurrence, respectively. The dynamic load of sediment in BH2 contributed more than in BH3, where it was almost nonexistent. Observing the sediment layer characteristics, both settled for almost a month and two weeks, respectively, showed sediment settlement of more or less than 2 and 8 mm. Despite insignificant loading changes, these findings can further our understanding of loading criteria and settlement in different geometric locations.

Membrane Distillation: Pre-Treatment Effects on Fouling Dynamics

In the research reported in this paper, membrane distillation was employed to recover water from a concentrated saline petrochemical effluent. According to the results, the use of membrane distillation is technically feasible when pre-treatments are employed to mitigate fouling. A mathematical model was used to evaluate the fouling mechanism, showing that the deposition of particulate and precipitated material occurred in all tests; however, the fouling dynamic depends on the pre-treatment employed (filtration, or filtration associated with a pH adjustment). The deposit layer formed by particles is not cohesive, allowing its entrainment to the bulk flow. The precipitate fouling showed a minimal tendency to entrainment. Also, precipitate fouling served as a coupling agent among adjacent particles, increasing the fouling layer cohesion.

Elaboration of a new calculation procedure of hydrocarbon deposit layer thickness in fuel channels of heat engines and power plants

The article is devoted to theoretical research connected with elaboration of a new calculation procedure for hydrocarbon deposit layer thickness. A common problem of deposit formation in heat engines and power plants is thoroughly investigated. In addition, the wall composition, temperature, time and a number of life cycles, etc. are mentioned as key factors that have direct influence on this heat phenomenon. The paper describes thermophysical properties of deposits in fuel feed systems of different engines. The literature search and analysis did not reveal any similar procedures of calculation of hydrocarbon deposit layer thickness that could be connected with electrical properties of a wall or a deposit. The paper presents new equations for calculating the deposit formation thickness and rate based upon thermal and electrical nature of this process. These new equations led to elaboration of the new calculation procedure of hydrocarbon deposit layer thickness on a metal wall for any fuel channel of a heat engine or a power plant based on liquid hydrocarbon fuel or coolant. The new calculation technique was verified by experiments in aviation kerosene boiling in volume, which clarified special features in the application of new equations. Owing to the universal character of the proposed technique, it can be used for calculating the deposit formation virtually in all the known heat engines and power plants, for various operating conditions, for different metal wall compositions, at various fuel flow rates and pressures, temperature regimes inside fuel-feed and cooling channels.

Structural Changes in French VF Treatment Wetland Porous Media during the Rest Period: An Ex Situ Study Using X-ray Tomography

Clogging constitutes a major operational issue for treatment wetlands. The rest period is a key feature of French Vertical Flow (VF) treatment wetlands and serves to mitigate clogging. An ex-situ drying experiment was performed to mimic the rest period and record structural changes in the porous media using X-ray Computed Tomography (CT). Samples containing the deposit and gravel layers of a first stage French VF treatment wetland were extracted and left to dry in a control environment. Based on CT scans, three phases were identified (voids, biosolids, and gravels). The impact of the rest period was assessed by means of different pore-scale variables. Ultimately, the volume of biosolids had reduced to 58% of its initial value, the deposit layer thickness dropped to 68% of its initial value, and the void/biosolid specific surface area ratio increased from a minimum value of 1.1 to a maximum of 4.2. Cracks greater than 3 mm developed at the uppermost part of the deposit layer, while, in the gravel layer, the rise in void volume corresponds to pores smaller than 2 mm in diameter. Lastly, the air-filled microporosity is estimated to have increased by 0.11 v/v.

A Laser Decontamination Technology for Radioactive Contaminated Metals

A large number of radioactive contaminated metals will be produced during the operation and decommissioning of nuclear facilities. Laser ablation is a clean and efficient surface decontamination method for radioactive metals. This study presents experiments to select laser decontamination parameters including laser power, laser pulse width, laser scanning speed and laser focal shift, as well as the construction of a laser decontamination prototype based on a fiber laser system of high power density, which can automatically ablate the radioactive deposit layer, oxide layer and shallow surface layer of metals to get an excellent decontamination result. Depending on this equipment, some engineering application tests were conducted in a nuclear power factory to verify the technology research result and equipment. Decontamination results which evaluate by decontamination factor show that the laser decontamination technology has a good result on the decontamination of radioactive surface contaminated metals.

Structural Characterisation of Deposit Layer during Milk Protein Microfiltration by Means of In-Situ MRI and Compositional Analysis

Milk protein fractionation by microfiltration membranes is an established but still growing field in dairy technology. Even under cross-flow conditions, this filtration process is impaired by the formation of a deposit by the retained protein fraction, mainly casein micelles. Due to deposition formation and consequently increased overall filtration resistance, the mass flow of the smaller whey protein fraction declines within the first few minutes of filtration. Currently, there are only a handful of analytical techniques available for the direct observation of deposit formation with opaque feed media and membranes. Here, we report on the ongoing development of a non-invasive and non-destructive method based on magnetic resonance imaging (MRI), and its application to characterise deposit layer formation during milk protein fractionation in ceramic hollow fibre membranes as a function of filtration pressure and temperature, temporally and spatially resolved. In addition, the chemical composition of the deposit was analysed by reversed phase high pressure liquid chromatography (RP-HPLC). We correlate the structural information gained by in-situ MRI with the protein amount and composition of the deposit layer obtained by RP-HPLC. We show that the combination of in-situ MRI and chemical analysis by RP-HPLC has the potential to allow for a better scientific understanding of the pressure and temperature dependence of deposit layer formation.

Influence of Spacer Design and Module Geometry on the Filtration Performance during Skim Milk Microfiltration with Flat Sheet and Spiral-Wound Membranes

Spacer design in spiral-wound membranes (SWMs) significantly affects the axial pressure drop in the flow channel but also the deposit layer removal. However, the effects of the spacer design and feed flow distribution in the module on the filtration performance have not yet been investigated during the highly fouling-susceptible fractionation of proteins from skim milk by SWMs. Therefore, a parallel spacer with no turbulence promotion and a less homogeneous feed flow distribution in the SWM was compared to a diamond spacer with regard to its impact on deposit formation and filtration performance. The experiments were conducted in a flat sheet test cell and in SWMs. The parallel spacer induced a more homogeneous deposit layer formation. However, no difference in filtration performance could be observed in the experiments with the test cell. Even though deposit layer formation dominates the microfiltration, its amount and spatial distribution could not be directly linked to the filtration performance. Furthermore, both spacers were assessed in SWM. Despite the higher crossflow velocity applicable in the more open channels of the parallel spacer, the performance of the parallel spacer was inferior to the diamond spacer. This was independent of the viscosity of the feed. Due to the high curvature of the membrane sheets close to the permeate collection tube, the cross-section of the flow channels in the SWM equipped with the parallel spacer was reduced. This resulted in a distinctly lower deposit layer control and performance, which could not be compensated by the resulting higher crossflow velocity far from the permeate collection tube.