Enhancement of Biological Activated Carbon (BAC) Process to Improve Removal Efficiency of Micropollutants

Objectives In this study, the removal efficiency of micropollutants in the biological activated carbon (BAC) process was investigated, and a method for improving the removal efficiency of micropollutants in the BAC process of water treatment plants was proposed. Methods Dibromo-methylparaben (Br2-MP) was selected as the target micropollutant. Batch and lab-scale column experiments were conducted to evaluate the removal efficiencies of Br2-MP in the conventional BAC process and the BAC with enhanced biofilm properties by the addition of phosphorus (P) and hydrogen peroxide (H2O2). Biodegradation kinetics were evaluated using results from batch and lab scale column experiments. Results and Discussion As a result of comparing the removal efficiency of Br2-MP in a batch experiment with the same biomass concentrations (2.0±0.2×107 cells), the biodegradation rate constant (kbio) of the enhanced BAC process was found to be 1.2 times higher than that of the conventional BAC process due to its higher biological activity (enhanced BAC: 3.4±0.3 mg·C/g·hr, conventional BAC: 2.9±0.4 mg·C/g·hr). Comparison of removal efficiencies of Br2-MP in batch experiments with the same wet weight of BAC (1 g) showed that the biodegradation rate constant (kbio) of the enhanced BAC process was 1.9 times higher than that of conventional BAC process due to higher biomass (enhanced BAC: 3.5±0.4 µg·ATP/g·GAC, conventional BAC: 2.3±0.2 µg·ATP/g·GAC). Through the batch experiments, the enhanced BAC process was efficient in removing Br2-MP via increasing both biomass concentrations and activity of attached microorganisms. Lab-scale column experiments conducted under different water temperatures (5 and 25℃) and empty bed contact time (EBCT: 5-40 min) conditions showed higher removal efficiency of Br2-MP in the enhanced BAC process than the conventional BAC process throughout the entire period of operation. In particular, the removal efficiency of Br2-MP between the enhanced and conventional BAC processes showed significant differences at low temperature (5℃) and short EBCT (5 min). At 5℃ and 25℃, the kbio of the conventional BAC process was 0.0229 min-1 and 0.0612 min-1, respectively, and the kbio of the enhanced BAC process was 0.0470 min-1 and 0.1421 min-1, respectively, These results showed that the enhanced BAC process had two times higher biodegradability of Br2-MP than the conventional BAC process. These results showed a similar trend to the results from the batch experiment. In an experiments simulating the impact of frequent EBCT changes during summer, the enhanced BAC process maintained a relatively stable removal efficiency of Br2-MP compared to the conventional BAC process. Conclusion The enhanced BAC process showed superior biodegradation of micropollutant compared to the conventional BAC process. Considering economic costs (e.g., costs of adding phosphate and hydrogen peroxide) and water quality, it appears to be an efficient alternative to operate the enhanced BAC process intermittently, limited to cases where EBCT is shortened, such as summer, or when water temperature is low, such as in winter

Betti numbers and the integral closure of ideals

We study the nondecreasing, strict increasing and exponential growth of Betti numbers. Tools are provided for measuring these. Let $(S,\underline m)$ be a local ring with maximal ideal $\underline m$ and $R = S/I$ for an ideal I of S. Put $J = (I:\underline m)$. If the integral closure $\bar I$ of I is properly contained in the integral closure $\bar J$ of J, then for any finitely generated R-module M the sequence b\sbsp{i}{R} (M) of Betti numbers of M is nondecreasing. If dim $\underline mJ/\underline mI \geq 2$, then for any finitely generated non-free R-module M the sequence b\sbsp{i}{R} (M) has strong exponential growth with a lower exponential bound $\sqrt{{\rm dim}\underline mJ/\underline mI}.$ For each artinian local ring R we derive an invariant $B(R)$ such that if $B(R) \u3e 1$, then for any finitely generated non-free R-module M the sequence b\sbsp {i}{R} (M) is strictly increasing and has strong exponential growth with a lower exponential bound A for any $1 \u3c A \u3c B(R)$

Studies for separation of heavy metals from wastewater with freshly precipitated magnetite

Durch eine Fällungsflockung mit Eisen- oder Aluminiumsalzen kann die Abtennung von Schwermetallen aus Abwässern verbessert werden. Die resultierenden Produkte sind häufig stark wasserhaltige, amorphe Hydroxide, die oft schlechte Flockungseigenschaften zeigen und unter Umständen Probleme bei der technischen Abtrennung aus der wäßrigen Phase bringen können. Der Einsatz von Magnetit kann hier von Vorteil sein, da Magnetit ferromagnetisch ist und mit Hilfe von Magneten sehr schnell sedimentiert werden kann. Die vorliegenden Untersuchungen ergaben, daß reiner Magnetit aus Eisen(II)salzlösung im Vergleich zum "ferrite process" effektiver hergestellt werden kann. Die Reaktionszeiten sind kürzer, die Temperatur kann niedriger gewählt werden, und es ist keine zusätzliche Oxidation mit Luft erforderlich. Bei der Fällung von Schwermetallen mit diesem künstlich hergestellten Magnetitschlamm aus einem Galvanikabwassr zeigten sich eine bessere Elimination und kleinere Schlammvolumina gegenüber der NaOH-Fällung. So wurden nach Filtration in der überstehenden Lösung nur noch gelöste bzw. kolloidale Nickel- und Kupferverbindungen nachgewiesen. Die Gehalte der übrigen Metalle lagen unter der Nachweisgrenze. Mit Natronlauge wurden auch nach 120 min Fällungszeit keine Nickelgehalte unter 0.5 mg/L erreicht. Dagegen fiel der Nickelgehalt im Überstand nach der Magnetitfällung schon nach 20 min unter 0.5 mg/L. Der Kupfergehalt betrug nach einer 20minütigen Fällung mit Natronlauge 64 µg/L. Bei der Magnetitfällung wurden nach 20 min 34 µg/L erreicht. Diese Ergebnisse sind nicht nur auf eine Sorption von Metallen am Magnetit, sondern auch auf Koagulationseffekte des Magnetitschlamms mit den feindispersen Metallhydroxiden zurückzuführen. Da der Magnetitschlamm als frisch gefälltes Hydrolyseprodukt gute Sorptions- und Flockungseigenschaften aufweist und der Fällungs-pH-Wert niedriger gewählt werden kann, würde sein Einsatz in der HGMS (high gradient magnetic separation) anstelle von Magnetitpulver das Verfahren bezüglich der Metallelimination effizienter machen.The separation of heavy metals from wastewater may be improved by precipitation/flocculation with iron- or aluminium salts. Often, the resulting products are voluminous, water-containing, amorphous hydroxides which show only limited flocculation properties and may possibly pose problems with the technical separation from the aqueous phase. The application of magnetite could be advantageous because magnetite is ferromagnetic and can be separated very quickly in a magnetic field. First of all, a simple preparation method for magnetite was studied. Pure magnetite could be prepared by mixing an iron(II) salt solution with an equivalent amount of sodium hydroxide at room temperature without oxidation by air. The required reaction time was only 3 hours. For the precipitation of heavy metals from an electroplating wastewater, a better metal elimination and smaller sludge volumes resulted with that artificially produced magnetite in comparison with a precipitation by NaOH. Thereby not only the adsorption of metals was established but also coagulation effects of the magnetite sludge with small metal hydroxide particles. By means of the experimental results, sorption of nickel and chromium was compiled as function of pH and precipitation time. Because freshly precipitated magnetite shows very good sorption and flocculation properties, and pH of precipitation may be lower, its use in high gradient magnetic separation (HGMS) could be more effective for metal elimination than magnetite powder

Quantitative NMR as a Versatile Tool for the Reference Material Preparation

The assessment of primary calibrator purity is critical for establishing traceability to the International System of Units (SI). Recently, quantitative nuclear magnetic resonance (qNMR) has been used as a purity determination method for reference material development, and many related measurement techniques have been designed to acquire accurate and reliable results. This review introduces the recent advances in these techniques (including multidimensional methods), focusing on the application of qNMR to reference material preparation

Augmented Categorial Grammar with Its Computational Implementation

A grammatical system called Augmented Categorial Grammar (ACG) is proposed to construct a computationally tractable categorial grammar that can adequately treat some syntactic and semantic problems involving grammatical relations, semantic roles, control, and unbounded dependency in English and to use it in our subsequent work as a basic framework for developing situation semantics for natural languages. ACG is claimed to be a monostratal context-free grammar compatible with some current versions of phrase structure grammars. An implementation for a parsing system is presented to test the computational tractability of ACG. Its program is written in Prolog

Quadratic symmetry of modified q-Euler polynomials

Abstract We use the p-adic q-integral and group action to count the number of the generating functions of modified q-Euler polynomials in a prescribed set. Some generating function yields modified q-Euler polynomials with the isotropy group D4 $D_{4}$ and some gives Euler polynomials with the isotropy group V4 $V_{4}$

Non-volatile logic-in-memory ternary content addressable memory circuit with floating gate field effect transistor

Due to the limitations of the currently widely used von Neumann architecture-based computing system, research on various devices and circuit systems suitable for logic-in-memory computing applications has been conducted. In this work, the silicon-based floating gate memory cell transistor structure, which has been attracting attention as a memory to replace the dynamic random access memory or NAND Flash technology, was newly recalled, and its applicability to logic-in-memory application was confirmed. This floating gate field effect transistor (FGFET) has the advantage that the compatibility of the existing silicon-based complementary metal–oxide–semiconductor (CMOS) process is far superior to that of logic-in-memory application devices to which materials with new memory characteristics are applied. At the 32 nm technology node, which is the front node to which the planar MOSFET structure is applied, an analysis environment that can simultaneously analyze the device and circuit of the FGFET was established. For a seamless connection between FGFET-based devices and circuit analysis, the compact model of the FGFET was developed, which is applied to logic-in-memory ternary content addressable memory (TCAM) circuit design. It was verified that the two types of logic-in-memory TCAM circuits to which FGFETs are applied are superior to a conventional CMOS FET-based TCAM circuit in the number of devices used (=circuit area) and power/energy efficiency

Analysis of Logic-in-Memory Full Adder Circuit With Floating Gate Field Effect Transistor (FGFET)

The high data throughput and high energy efficiency required recently are increasingly difficult to implement due to the von Neumann bottleneck. As a way to overcome this, Logic-in-Memory (LiM) technology has recently been receiving a lot of attention. In particular, since the addition function is important to solve high data throughput in applications such as artificial intelligence, the results of applying various fine-grain LiM application devices to full adder circuit design are being announced. In this paper, a Floating Gate Field Effect Transistor (FGFET), which has a structure similar to a floating gate memory cell transistor that has been widely used in the past and is highly applicable to mass production, was applied to the LiM application circuit design. Prior to application to circuit design, the FGFET characteristics were confirmed using a well-calibrated technology computer-aided design (TCAD) simulation at the 32nm technology node, and a compact model was developed to describe them. Afterwards, the delay and power consumption were evaluated with three different types of FGFET-based full adder circuits, and benchmarked with conventional CMOS (complementary metal-oxide-semiconductor)-based conventional full adder circuits