A Review on the Development of an Integer System Coupling Forward Osmosis Membrane and Ultrasound Waves for Water Desalination Processes.

This review considers the forward osmosis (FO) membrane process as one of the feasible solutions for water desalination. Different aspects related to the FO process are reviewed with an emphasis on ultrasound assisted FO membrane processes. The different types of membranes used in FO are also reviewed and discussed; thus, their configuration, structure and applications are considered. Coupling ultrasound with FO enhances water flux through the membrane under certain conditions. In addition, this review addresses questions related to implementation of an ultrasound/FO system for seawater desalination, such as the impact on fouling, flow configuration, and location of fouling. Finally, the mechanisms for the impact of ultrasound on FO membranes are discussed and future research directions are suggested.

Wastewater surveillance for SARS-CoV-2: Lessons learnt from recent studies to define future applications.

Wastewater-based epidemiology (WBE) is successful in the detection of the spread of SARS-CoV-2. This review examines the methods used and results of recent studies on the quantification of SARS-CoV-2 in wastewater. WBE becomes essential, especially with virus transmission path uncertainty, limitations on the number of clinical tests that could be conducted, and a relatively long period for infected people to show symptoms. Wastewater surveillance was used to show the effect of lockdown on the virus spread. A WBE framework tailored for SARS-CoV-2 that incorporates lessons learnt from the reviewed studies was developed. Results of the review helped outline challenges facing the detection of SARS-CoV-2 in wastewater samples. A comparison between the various studies with regards to sample concentration and virus quantification was conducted. Five different primers sets were used for qPCR quantification; however, due to limited data availability, there is no consensus on the most sensitive primer. Correlating the slope of the relationship between the number of gene copies vs. the cumulative number of infections normalized to the total population served with the average new cases, suggests that qPCR results could help estimating the number of new infections. The correlation is improved when a lag period was introduced to account for asymptomatic infections. Based on lessons learnt from recent studies, it is recommended that future applications should consider the following: 1) ensuring occupational safety in managing sewage collection and processing, 2) evaluating the effectiveness of greywater disinfection, 3) measuring viral RNA decay due to biological and chemical activities during collection and treatment, 4) assessing the effectiveness of digital PCR, and 5) conducting large scale international studies that follow standardized protocols.

Simulation and optimization of dynamic waste collection routes.

Smart waste collection strategies have been developed to replace conventional fixed routes with dynamic systems that respond to the actual fill-level of waste bins. The variation in waste generation patterns, which is the main driver for the profit of smart systems, is exacerbated in the United Arab Emirates (UAE) due to a high expatriate ratio. This leads to significant changes in waste generation during breaks and seasonal occasions. The present study aimed to evaluate a geographic information system (GIS)-based smart collection system (SCS) compared to conventional practices in terms of time, pollution, and cost. Different scenarios were tested on a local residential district based on variable bin filling rates. The input data were obtained from a field survey on different types of households. A knowledge-based decision-making algorithm was developed to select the bins that require collection based on historical data. The simulation included a regular SCS scenario based on actual filling rates, as well as sub-scenarios to study the impact of reducing the waste generation rates. An operation cost reduction of 19% was achieved with SCS compared to the conventional scenario. Moreover, SCS outperformed the conventional system by lowering carbon-dioxide emissions by between 5 and 22% for various scenarios. The operation costs were non-linearly reduced with the incremental drops in waste generation. Furthermore, the smart system was validated using actual waste generation data of the study area, and it lowered collection trip times by 18 to 42% compared to the conventional service. The present study proposes an integrated SCS architecture, and explores critical considerations of smart systems.

Modeling solute transport affected by heterogeneous sorption kinetics using single-rate nonequilibrium approaches.

Single-rate transport models are commonly used for interpreting sorption-related mass transfer in porous media, often with the intention of approximating the kinetics of the sorption process. Among the most commonly used single-rate models are the two-site first-order (TSFO) and the two-site radial diffusion (TSRD) models. We fitted the parameters of the TSFO and TSRD models to simulated breakthrough data of hypothetical column experiments in which sorption rates were described by a γ-distributed sorption sites (GS) model. Our objective was to determine the conditions under which the assumption of a single-rate sorption parameter will be applicable to systems with heterogeneous sorption rates. We were further interested in knowing in what manner the fitted single-rate nonequilibrium model parameters depend upon the conditions under which the data were obtained. The considered hypothetical cases covered a range of experimental conditions and involved compounds with different sorption characteristics. The study revealed that the goodness of fit of the single rate models in simulating the transport of solutes exhibiting heterogeneous sorption rates is affected by solute residence time and pulse injection duration. Compared to the TSFO model, the TSRD model generally results in better prediction of solute transport affected by heterogeneous sorption kinetics. In addition, for such systems, the nonequilibrium parameters fitted using the TSFO model and their counterparts in the TSRD model are highly correlated. Moreover, an increase in the fitted mass transfer timescale of each of the single-rate models is coupled with an increase in the associated fraction of instantaneous sorption sites. A strong correlation was found between the time of the experiment and the product of the fitted characteristic time for mass transfer, pulse duration, and solute residence time. The correlation explains many of the variations in the mass transfer timescale encountered when single-rate sorption approaches were utilized to model solute transport in previous miscible displacement studies.

A holistic approach for assessing traffic safety in the United Arab Emirates.

Traffic accident and fatality rates can be utilized as indicators of traffic safety, but cannot reflect the overall status of traffic safety in a country. This paper uses a holistic perspective approach to investigate traffic safety in the United Arab Emirates (UAE). Initially, 12 potential items were selected to investigate the issue of traffic safety in the country. The investigation included data collection and analyses from official police reports, survey among road-users and interview of traffic safety experts. Based on data analysis and interpretation, the main factors affecting traffic safety in the UAE along with their level of deficiency were identified. The study revealed that the main factors contributing to traffic safety in the UAE are driving behaviour, awareness, education and training, infrastructure, vehicle, law enforcement, coordination and quality of resources. Among these factors, a major deficiency was found in the "driving behaviour", a minor deficiency in "vehicle safety", and a moderate deficiency in the others. Based on the deficiency level of the factors recommendations were proposed to improve the status of traffic safety in the country.

Comparison of nonideal sorption formulations in modeling the transport of phthalate esters through packed soil columns.

Sorption of dimethyl phthalate (DMP), diethyl phthalate (DEP) and dipropyl phthalate (DPP) to two soil materials that vary in organic matter content was investigated using miscible displacement experiments under saturated flow conditions. Generated breakthrough curves (BTCs) were inversely simulated using linear, equilibrium sorption (LE), nonlinear, equilibrium sorption (NL), linear, first-order nonequilibrium sorption (LFO), linear, radial diffusion (LRD), and nonlinear, first-order nonequilibrium sorption (NFO) models. The Akaike information criterion was utilized to determine the preferred model. The LE model could not adequately describe phthalate ester (PE) BTCs in higher organic matter soil or for more hydrophobic PEs. The LFO and LRD models adequately described the BTCs but a slight improvement in curve-fitting was gained in some cases when the NFO model was used. However, none of the models could properly describe the desorptive tail of DPP for the high organic matter soil. Transport of DPP through this soil was adequately predicted when degradation or sorption hysteresis was considered. Using the optimized parameter values along with values reported by others it was shown that the organic carbon distribution coefficient (K(oc)) of PEs correlates well with the octanol/water partition coefficient (K(ow)). Also, a strong relationship was found between the first-order sorption rate coefficient normalized to injection pulse size and compound residence time. A similar trend of timescale dependence was found for the rate parameter in the radial diffusion model. Results also revealed that the fraction of instantaneous sorption sites is dependent on K(ow) and appears to decrease with the increase in the sorption rate parameter.

Aerobiological studies and low allerginicity of date-palm pollen in the UAE.

Date-Palm trees (Phoenix dactylifera L.) are the most abundant crop in the United Arab Emirates (UAE). The aim of this work was to conduct aerobiological studies on Date-Palm pollens and correlate that to allergenicity. An aerobiological survey was performed at three Date-Palm farms. Radioallergosorbent test (RAST) and total IgE were performed on 477 airborne allergic patients. Small mass bioactive constituents were fractionated and isolated by HPLC. Aerobiological studies demonstrate the short distance traveled by the Date-Palm pollens. Pollen counts were about 800 counts/m3 within the Date-Palm farms and decreased by about 80% just 100 meters away from the farm area and almost diminished beyond 200 meters. Scanning electron micrograph of the pollen grain showed a uniform smooth texture with an oval shape. Out of 477 airborne allergic patients having high total IgE counts, only 2.3% gave positive RAST for Date-Palm pollen. HPLC chromatogram separated the non-protein content of Date-Palm pollen into four distinct peak fractions. The present study revealed that Date-Palm pollens have a low allergic effect on airborne allergic people. The short distance traveled by the pollen, the smooth texture, the short pollination period and low molecular weight biomolecule content may be the main factors behind the low allergenicity.