Operating cost reduction of UF membrane filtration process for drinking water treatment attributed to chemical cleaning optimization.

This study investigated the cost and CO2 emission reduced as a result of optimizing operating conditions for chemical cleaning in a membrane filtration process used for water treatment. A new protocol was proposed and operating conditions for chemical cleaning of a pilot-scale membrane filtration process were optimized. The critical flux for irreversibility was identified as the permeate flux using a modified flux-step method, and was 100 l m-2 h-1, 20 l m-2 h-1 higher than the vendor recommended permeate flux. NaOCl, which is also the vendor recommended chemical, was selected as the optimal chemical reagent following an examination of the permeability restoration ratios and nature of the irreversible foulants. The optimized operating conditions of enhanced flux maintenance (EFM), determined using response surface methodology (RSM) were: 6.3 d interval, 500 ppm concentration, and 76 min duration, which represented an increase of 4.3 d, 300 ppm, and 36 min, respectively, as opposed to the vendor recommended conditions. As a result, the total operating cost and CO2 emission were $0.1187/m3 and 112.75 g CO2/m3, respectively, and 26.5% lesser compared to the operating cost and CO2 emission based on vendor recommended conditions. This study found that the reductions in operating cost and CO2 emission using the optimization process were excellent.

Identification of multi-concentration aromatic fragrances with electronic nose technology using a support vector machine.

Due to the concentration effect, there is a major challenge for the electronic nose system to identify different odor samples with multiple concentrations. The development of artificial intelligence provides new ways to solve such problems. This article attempts to use support vector machine (SVM) technology to distinguish four fragrance samples with three concentrations, including roman chamomile, jasmine, lavender, and orange. The responses of these samples were collected by an 11-sensor electronic nose. After baseline correction, data smoothing, and removal of non-responsive sensors, the signals of 8 sensors were used for subsequent model analysis. Due to the concentration effect, when the primary signal intensities were used as features, the electronic nose cannot distinguish between different aroma types (accuracy less than 50%). When the normalized maximum signal intensity Xmr was used, the accuracy of the model was greatly improved. Graphic analysis and PCA showed that the normalized feature effectively eliminates the concentration effect, and appropriately reducing some sensors can enhance the ability to distinguish odors. The SVM correctly classified all 14 aromas when feeding 8 sets of data to train the radial kernel C-classification SVM. This showed that the cross-interference of the sensors was reduced, and the resolving power of the electronic nose was enhanced after the feature reduction.

Characterization of marine dissolved organic matter and its effect on ozonation.

As the marine industry develops, the importance of seawater treatment process is increasing. To treat seawater, oxidation processes have primarily been used, such as ballast water treatment systems, aquaculture farm operations, aquarium management, and seawater desalination. However, dissolved organic matter in seawater, whose characteristics vary spatially and seasonally, affects the efficiency of oxidation processes. Therefore, in this study, seawater samples were acquired from various locations in the Republic of Korea to understand the spatio-temporal patterns of marine dissolved organic matter. It was reported that the characterization of marine dissolved organic matter using liquid chromatography-organic carbon detector and excitation-emission matrix-parallel factor modeling. Furthermore, the effects of marine dissolved organic matter were evaluated on ozonation, an oxidation process. The results demonstrate that marine dissolved organic matter varies in its aquagenic, pedogenic, and intermediate characteristics based on region and season. These variations affect ozonation by influencing the consumption of oxidants (e.g., bromine). As a result, it was concluded that characterizing marine dissolved organic matter can help improve the effectiveness of oxidation processes, particularly ozonation.

Characteristics of intracellular algogenic organic matter and its reactivity with hydroxyl radicals.

The aim of this study was to investigate the reactivity of intracellular algogenic organic matter (IOM) with hydroxyl radicals (·OH), a key reaction species in advanced oxidation processes. IOM was extracted from two green algae, Chlamydomonas reinhardtii and Scenedesmus sp., and two blue-green algae, Anabaena sp. and Microcystis aeruginosa using a freeze-thaw method. The second-order rate constants of the extracted IOM with ·OH were determined as 7.95 × 108 MC-1 s-1 (Chlamydomonas reinhardtii), 6.71 × 108 MC-1 s-1 (Scenedesmus sp.), 4.02 × 108 MC-1 s-1 (Anabaena sp.), and 4.45 × 108 MC-1 s-1 (Microcystis aeruginosa). These rate constants were significantly higher than values reported for dissolved organic matter in various water sources. This implies that IOM formation during algal bloom season could change the ·OH water matrix demand and adversely affect the performance of advanced oxidation processes. To investigate the physical and chemical composition characteristics of IOM and their relationship to the rate constants determined for the reaction between IOM and ·OH, liquid chromatography-organic carbon detection (LC-OCD) and fluorescence excitation-emission matrix & parallel factor analysis (FEEM-PARAFAC) were used. The IOM mainly consisted of low molecular weight (LMW) matter and protein-related compounds, as evidenced LMW neutrals (38-65%), biopolymers (7-19%), and tryptophan-like compounds (74-94%). Based on the composition characteristics of IOM, it was concluded that the molecular weight and the presence of nitrogen-containing compounds are influential parameters for determining the reactivity of IOM with ·OH.

Characteristics and fate of natural organic matter during UV oxidation processes.

Advanced oxidation processes (AOPs) are widely used in water treatments. During oxidation processes, natural organic matter (NOM) is modified and broken down into smaller compounds that affect the characteristics of the oxidized NOM by AOPs. In this study, NOM was characterized and monitored in the UV/hydrogen peroxide (H2O2) and UV/persulfate (PS) processes using a liquid chromatography-organic carbon detector (LC-OCD) technique, and a combination of excitation-emission matrices (EEM) and parallel factor analysis (PARAFAC). The percentages of mineralization of NOM in the UV/H2O2 and UV/PS processes were 20.5 and 83.3%, respectively, with a 10 mM oxidant dose and a contact time of 174 s (UV dose: approximately 30,000 mJ). Low-pressure, Hg UV lamp (254 nm) was applied in this experiment. The steady-state concentration of SO4- was 38-fold higher than that of OH at an oxidant dose of 10 mM. With para-chlorobenzoic acid (pCBA) as a radical probe compound, we experimentally determined the rate constants of Suwannee River NOM (SRNOM) with OH (kOH/NOM = 3.3 × 108 M-1s-1) and SO4- (kSO4-/NOM = 4.55 × 106 M-1s-1). The hydroxyl radical and sulfate radical showed different mineralization pathways of NOM, which have been verified by the use of LC-OCD and EEM/PARAFAC. Consequently, higher steady-state concentrations of SO4-, and different reaction preferences of OH and SO4- with the NOM constituent had an effect on the mineralization efficiency.

Estrogen enhances angiogenesis through a pathway involving platelet-activating factor-mediated nuclear factor-kappaB activation.

In this study, we investigated the molecular events involved in estrogen-induced angiogenesis. Treatment of the human endometrial adenocarcinoma cells, HEC-1A, with estrogen up-regulated mRNA expression and protein synthesis of various angiogenic factors such as tumor necrosis factor-alpha, interleukin-1, basic fibroblast growth factor, and vascular endothelial growth factor. The estrogen-dependent induction of the expression was blocked by the platelet-activating factor (PAF) antagonists, WEB 2170. Estrogen treatment caused the activation of nuclear factor (NF)-kappaB in HEC-1A cells and was also blocked by PAF antagonist. Inhibitors of NF-kappaB activation inhibited estrogen-induced mRNA expression and protein synthesis of the angiogenic factors. Estrogen led to a pronounced angiogenesis as assessed by a mouse Matrigel model in vivo and endothelial cell sprouting in vitro. PAF antagonists or NF-kappaB inhibitors significantly inhibited this estrogen-dependent angiogenesis. Estrogen caused phospholipase A2 (PLA2) gene and protein expression. Estrogen-induced vascular endothelial growth factor mRNA expression and sprouting were significantly inhibited by PLA2 inhibitors, suggesting PLA2 expression is the upstream pathway in the estrogen-induced angiogenesis. Taken together, these results suggest that estrogen induces the production of angiogenic factors via a mechanism involving PAF-mediated NF-kappaB activation.

Nuclear factor kappaB dependency of platelet-activating factor-induced angiogenesis.

This study investigated the mechanisms of platelet-activating factor (PAF)-induced angiogenesis in a mouse model of Matrigel implantation. PAF induced a dose- and time-dependent angiogenic response. Inhibitors of nuclear factor (NF) kappaB expression or action, including antisense oligonucleotides to the p65 subunit of NFkappaB (p65 antisense) and antioxidants such as alpha-tocopherol and N-acetyl-L-cysteine, significantly reduced PAF-induced angiogenesis. In human umbilical vein endothelial cells, PAF-induced mRNA expression and protein synthesis of various NFkappaB-dependent angiogenic factors, such as tumor necrosis factor-alpha, interleukin-1alpha, basic fibroblast growth factor, and vascular endothelial growth factor (VEGF). The PAF-induced expression of the above mentioned factors was inhibited by p65 antisense or antioxidants. A significant inhibition of the angiogenic effect of PAF was achieved by anti-VEGF antibodies or soluble VEGF receptors such as KDR and flt-1 but not by antibodies against tumor necrosis factor-alpha, interleukin-1alpha, or basic fibroblast growth factor. These data indicate that PAF enhances angiogenesis through inducing NFkappaB activation, which in turn promotes the production of angiogenic factors such as VEGF.