Permeable reactive barrier for groundwater remediation

This article aims to provide an overview of the upcoming technology of permeable reactive barriers for groundwater remediation. A comprehensive list of references and web-links are also provided for further in-depth understanding. A brief discussion on the Australian perspective on this emerging technology is also included.     

AHW-BGOA-DNN: a novel deep learning model for epileptic seizure detection

Neural Computing and Applications - “Brain–Computer Interface” (BCI)—a real-life support system provides a way for epileptic patients to improve their quality of life. In...     

Implications of particle size to transient stage of deep bed filtration

This study was aimed at investigating the effect of particle size, mostly in the submicron range, on break-through stage of filtration. Latex beads, with diameters ranging from 0.46- to 2.967-μm were filtered through filter grains of diameters 0.1-, 0.175- and 0.45-mm. Experimental conditions were chosen so as to obtain breakthrough curves. The experimental results showed that the initial efficiency follows the pattern reported by previous experimental and theoretical studies, i.e., lower efficiency for 0.825-μm particles which fall in the range of critical size. However, the particle removal during the transient stage increased with an increase in particle size for the range of sizes studied. This pattern is qualitatively confirmed by the theoretical predictions of Vigneswaran and Chang (1986) model. This study also provides experimental verification of the effect of the ratio of particle size and grain size at different stages of filtration.     

Hydrous iron oxide for removal of inorganic contaminants in simulated stormwater: A batch sorption kinetics study

Urban stormwater runoff, which consists of inorganic and organic contaminants, is a major source of pollutants to receiving waters and therefore they need to be removed. Simultaneous removal of contaminants, Cd²⁺, Cu²⁺, Ni²⁺, Zn²⁺ (heavy metal cations), and SeO₄²⁻ (oxyanion) from a simulated stormwater by a hydrous ferric oxide (HFO) was studied in batch and column sorption experiments. In the batch experiment the rate of sorption of the ions was rapid at the beginning and reached equilibrium in approximately 300 min. The amounts of ions sorbed were proportionate to the respective initial concentration of the ions added to the HFO. Cluster analysis showed that all heavy metals had similar sorption behavior, whereas Se had a distinctly different sorption process. Of the three different kinetic models tested the pseudo-first order kinetic model fitted the data the best. The column experimental results beyond 180 min were consistent with those of the batch experiment that the removal efficiencies of the ions were in proportion to the ion concentration in the feed. Below 180 min, Cu appeared to be preferentially removed than Zn.     

Characterization procedure for adsorption of DOC (Dissolved Organic Carbon) from synthetic wastewater

A characterization method to evaluate the composition of background organic matters in terms of adsorbability was presented and applied to synthetic and domestic wastewater. The binomial distribution of DOC (Dissolved Organic Carbon) fraction in relation of a characterizing variable, the Freundlich coefficient, k, was proposed to describe the initial composition of wastewater by a finite number of pseudospecies. This method was tested for removal of DOC by using granular and powdered activated carbons. These experiments enable us to get information on the distribution function of species in the solution. From the results obtained in this work, kinetic experimental data were predicted on the assumption that the diffusion coefficients were unchanged during the experiments. It was confirmed to be effective in determining the initial composition and describing the equilibria of the DOC. From the experiments, it was found that this synthetic solution has a sigmoid type isotherm on activated carbons. This implies that there are two different adsorption regions in a system, favourable and unfavourable cases, depending on the solution concentration. This unfamiliar problem can be solved by using a characterization method based on IAST-Freundlich model.     

Biofilter in water and wastewater treatment

Biofilter is one of the most important separation processes that can be employed to remove organic pollutants from air, water, and wastewater. Even though, it has been used over a century, it is still difficult to explain theoretically all the biological processes occurring in a biofilter. In this paper, the fundamental of biological processes involved in the biofilter is critically reviewed together with the mathematical modeling approach. The important operating and design parameters are discussed in detail with the typical values used for different applications. The most important parameter which governs this process is the biomass attached to the medium. The relative merits of different methods adopted in the measurement of the biomass are discussed. The laboratory-and full-scale applications of the biofilter in water and wastewater treatment are also presented. Their performances in terms of specific pollutant removal are highlighted.     

A continuous photocatalysis system in the degradation of herbicide

The performance of both batch and continuous photo-catalytic reactors was studied to evaluate their capabilities in removing the sulfonyl urea herbicide of metsulfuron methyl (MM). It was found in a batch reactor that the addition of a small amount of powder activated carbon (PAC) significantly increased the rate of degradation of MM. The continuous photo-catalytic system resulted in 57% of MM removal. When a small dose of activated carbon was added in the photo-catalytic system, MM removal increased to 78–86% MM removal for retention times between of 5.25–21 min (corresponding to withdrawal rates of 10–40 mLmin⁻¹). In this study, the pseudo first order rate constants of a continuous photo-catalytic system revealed that shorter retention times were associated with lower rate constants. Solid phase micro extraction/gas chromatography (SPME/GC) results showed that high concentrations of MM were broken down to small volatile organic compounds (VOCs) by photo-catalytic oxidation. PAC adsorbed the photo-products and increased the degradation of MM.     

A trust computed framework for IoT devices and fog computing environment

Wireless Networks - In this paper, we have demoralized the transmission processing concerns of fog nodes and IoT device layer attack during the handoff (mobility) of IoT devices in the fog...     

Performance Analysis in Digital Circuits for Process Corner Variations,Slew-Rate and Load Capacitance

The aggressive scaling of CMOS technology has inevitably led to vastly increased power dissipation, process variability and reliability degradation, posing tremendous challenges to robust circuit design. To continue the success of integrated circuits, advanced design research must start in parallel with or even ahead of technology development. In this paper, an attempt is made to analyze various circuits’ delay and power performance by introducing certain level of variation to important process parameters like threshold voltage (V_th), mobility of carriers (μ₀), oxide thickness (t_ox) and doping concentration (n_sd). Basic Monte Carlo simulation is carried out on these circuits to ascertain the stability in performances. A 16 × 1 multiplexer is considered for detailed analysis. SPICE characterization is done for three different input slew rates (0.1, 0.5 and 1 ns) against four different output load drive strengths (1×, 2×, 3× and 4× output capacitive load). From the obtained results, output slew rates and average power results are observed and discussed.