Hydrogen sulfide (H2S) is a naturally occurring, highly toxic gas that is formed from the decomposition of sulfur compounds. In wastewater collection and treatment plants, H2S is a common source of concrete and metal corrosion that has resulted in huge economic loss. Corrosion in sewer treatment systems due to the release of H2S and its subsequent oxidation has been a worldwide issue that has huge economic relevance. Microbially-induced concrete corrosion reduces the lifespan of concrete and the remediation processes are expensive. In this project, the factors leading to the generation of H2S were studied. Different parameters were measured from a wastewater treatment plant. Wastewater samples were collected for measurement of chemical properties affecting H2S generation in the laboratory. Significant parameters were identified from the collected data and correlated with H2S generation. A statistical equation was formed using the significant parameters. Patterns followed by different parameters are discussed.
Efficient light-to-heat conversion using plasmonic nanoparticles inside polymeric membranes is beneficial for improving the efficiency of membrane distillation for seawater desalination. To meet growing freshwater demand in the globe, we proposed cost-effective refractory plasmonic based composite membranes as an alternative to metal-based plasmonic structures. The as-fabricated titanium nitride polymer (TiN/PVDF) composite membrane exhibited broad band light absorption in the wavelength range of 250 to 2500 nm.
There is a need to remove nitrogen and phosphorus from waters because if present in excess they initiate eutrophication which degrades the ecosystem by depleting oxygen, killing fish, and fostering algal blooms. Unlike other treatment methods such as reverse osmosis and adsorption via activated carbon, adsorption via biochar derived from date palm waste is a promising alternative as it does not cause secondary pollution or involve the use of costly raw materials. The objective of the study is to assess the main factors responsible for the adsorption of ammonium/phosphate in single and mixed solutions (dosage, influent concentration and flow rate). It was found that increases in inlet concentrations, increases in bed depths and decreases in flow rate increased removal efficiencies and dynamic adsorption capacities for ammonium and phosphate. The results will provide a basis for the removal of ammonium and phosphate using date palm biochar.
Water security is a crucial challenge facing most of the middle east courtiers including UAE. The country was categorized as one of the world's most water-scarce nations. Therefore, the development in the wastewater treatment technologies has become an attractive area for research nowadays. Biodegradable polymers such as polylactic acid (PLA) can replace conventional fossil-based materials used in membrane fabrication. The integration of nanomaterials in membrane's matrix aims to improve the membrane's hydrophilicity, mechanical strength, thermal stability and water flux, which are vital membrane properties needed to active efficient removal of contaminants. Multi-walled carbon nanotubes (MWCNT) and functionalized Graphene oxide (fGO) have recently attracted attention, as they have proved to have potential in various applications. The main objective of this work was to fabricate PLA membranes incorporated with negatively charged, self-assembled MWCNT-fGO using phase inversion method. Different concentrations of MWCNT-fGO up to 8 wt% of the polymer were fabricated.
The integration of membrane technology with nanotechnology has prompted revolutionary advances in the treatment of wastewaters. Graphene oxide and multi-walled carbon nanotubes have recently attracted attention, as they have proved to have potential in various applications. In this study, functionalized multi-walled carbon nanotubes (f-MWCNT)-graphene oxide (GO) composite was prepared and incorporated into polylactic acid (PLA) membranes via phase inversion. The effect of f-MWCNT-GO addition on the flux, heavy metals rejection and other characterization tests were investigated. Different concentrations of f-MWCNT-GO (2, 4, 6, and 8 wt.% of polymer) were used. The obtained results will demonstrate the potential application of PLA/f-MWCNT-GO in the treatment of wastewaters.
Here, bottom-up directional freezing experiments are conducted to obtain the optimal salinity gradient of the frozen. The salinity gradient is measured under small thickness and high resolution through the entire volume for a specific condition and under different freezing temperature and salinity conditions. This experimental work is distinctive at it gives the salinity measurement for each frozen layer instead of the overall frozen volume, and this gives the salinity gradient during freezing. Results obtained demonstrate there is an optimal freezing condition that enables the high salinity diffusion front to migrate/travel and leaving the lowest possible salinity level behind.
Fouling has been known as the major problem that limit the performance of membrane-based desalination processes as it causes a decrease in permeate flux with time which leads to an increase in maintenance requirements. These consequences are the result of the deposition of unwanted material on the surface of the membrane. One way to mitigate fouling tendencies is membrane surface modification by nanomaterials. In this paper, a set of experiments have been designed to investigate the antifouling behaviors of different nanomaterials. The performance of Graphene Oxide (GO) and Molybdenum disulfide (MoS2) nanomaterials were investigated by running bovine serum albumin (BSA) Deionized (DI) water as foulant for 10 hours. In addition, recovery of initial permeate flux have been tested after cleaning with DI water for 1 hour.
Freeze desalination is a promising unconventional method with the advantages of low energy consumption, enduring less corrosion, and suitable for higher brine concentration at normal pressure. Experimental study of salinity gradient development in freezing ice is limited, and a few literature addresses the time consumption of the freezing process. In this work, bottom-up directional freezing experiments are conducted to study salinity gradient development of the frozen brine under different salinity conditions. The obtained salinity gradient, on one hand is used to assess the deployment of successive freezing melting desalination method, and on the other to determine the localized brine properties used in first principle heat and mass conservation model development. Results suggest that the first principle model can be used to predict the freezing time. However, as the salinity decreases model discrepancies rise which requires further model tuning or relying on higher fidelity modeling.
The effect of crack propagation and bearings anisotropy in an overhung rotor system that is subjected to transient operation through critical whirl rotational speeds on the so called post-resonance backward whirl is investigated here. The equations of motion of the considered Finite Element model of the considered overhung rotor system with breathing crack model are numerically simulated to obtain the whirl response. The obtained whirl responses at transient operations in which acceleration effect is incorporated at different bearing conditions are evaluated for the appearance and excitation of the post-resonance backward whirl phenomena. Accordingly, the intensity and recurrence of these post-resonance backward whirl zones are found here to be affected by the crack propagation and bearings-induced damages. Therefore, capturing these damage-based post-resonance backward whirl can be proposed as damage detection approach in OH rotor systems.
Xenon oscillations is caused by the imbalance between three key parameters, flux distribution in the core, Xenon distribution, and Iodine distribution. To ensure the safe operation of nuclear power plants, nuclear operators are in need of simple and quick method to dampen such oscillations. One of such proven methods is the bang-bang method where the operator inserts and then withdraws the control rods at the right time and by the correct amount in order to eliminate xenon oscillations (Al Nuaimi et al., 2019). Finding the right time and control rods' worth for the insertion is the key to control these oscillations. The backward method along with Xenon Oscillation Elimination (XOE) code are used in this research to successfully dampen these oscillations.This research aims to find the optimum data fitting period for reactor measured data that will produce accurate results for ? and ?.
