Wastewater treatment plants elevating microplastic abundances, ecological risks, and loads in Japanese rivers: a source-to-sink perspective.

Little were certain about how wastewater treatment plants (WWTPs) affected the Japanese riverine microplastic contamination. This study explored the influences of WWTPs on microplastic pollution, assessed ecological risks, and looked at the sources-to-sinks phenomenon (WWTPs-to-rivers-to-marine) in riverine settings in Japan's Yamaguchi prefecture. Fifty surface water samples from the five selected rivers (Koya, Saba, Shimaji, and Fushino, Nishiki) and 11 effluent samples from WWTPs in the rivers' catchment were examined.

Abundance, characteristics, and ecological risks of microplastics in the riverbed sediments around Dhaka city.

Microplastic (MP) pollution has become an escalating problem in Bangladesh due to its rapid urbanization, economic growth, and excessive use of plastics; however, data on MP pollution from fresh water resources in this country are limited. This study investigated microplastics pollution in riverbed sediments in the peripheral rivers of Dhaka, the capital of Bangladesh. Twenty-eight sediment samples were collected from the selected stations of the Buriganga, Turag, and Balu Rivers.

Microplastics in the sediments of small-scale Japanese rivers: Abundance and distribution, characterization, sources-to-sink, and ecological risks.

Microplastic pollution in small-scale river sediments remains mostly unknown. This study explored microplastics in the sediments of four small-scale Japanese rivers in Yamaguchi Prefecture: the Awano, Ayaragi, Asa, and Majime. Sediment samples (n = 23) were collected from the selected stations.

Assessing small-scale freshwater microplastics pollution, land-use, source-to-sink conduits, and pollution risks: Perspectives from Japanese rivers polluted with microplastics.

Rivers are vital for understanding freshwater microplastics pollution, along with the conduits from land-sources to marine-sinks. In this study, we investigated microplastics in the small-scale Awano and Ayaragi rivers, which flow into the Sea of Japan (SJ), and the Asa and Majime rivers, which flow into the Seto Inland Sea (SIS) in Yamaguchi Prefecture, Japan. Surface water samples were collected from 29 stations.

Fish habitat evaluation based on width-to-depth ratio and eco-environmental diversity index in small rivers.

We estimated the performance of river fish habitat evaluation using width-to-depth ratio (WDR) in comparison with eco-environmental diversity (EED) to propose an inexpensive and easy-to-use habitat evaluation procedure, which is applicable to small river construction works. WDR calculation costs less than that of EED. For verification, 25 stations in eight rivers were selected and fish were captured using electrofishing.

Influence of water-film-forming-unit on the enhanced removal of carbon dioxide from mixed gas using water absorption apparatus.

This research uses tap water to absorb carbon dioxide from mixed gas (N and CO) in an absorption apparatus coupled with a water-film-forming-unit (WFFU). The objective is to assess the benefits of using a WFFU to enhance CO removal efficiency at low pressure conditions. Based on our results, the WFFU significantly improves CO capture at 0.

Response surface method for modeling the removal of carbon dioxide from a simulated gas using water absorption enhanced with a liquid-film-forming device.

This paper presents the results from using a physical absorption process to absorb gaseous CO mixed with N using water by producing tiny bubbles via a liquid-film-forming device (LFFD) that improves the solubility of CO in water. The influence of various parameters-pressure, initial CO concentration, gas-to-liquid ratios, and temperature-on the CO removal efficiency and its absorption rate in water were investigated and estimated thoroughly by statistical polynomial models obtained by the utilization of the response surface method (RSM) with a central composite design (CCD). Based on the analysis, a high efficiency of CO capture can be reached in conditions such as low pressure, high CO concentration at the inlet, low gas/liquid ratio, and low temperature.

Synergistic effect of pressurized carbon dioxide and sodium hypochlorite on the inactivation of Enterococcus sp. in seawater.

This study investigated the effect of combined treatments using pressurized carbon dioxide (PCD) and sodium hypochlorite (NaOCl) on the inactivation of Enterococcus sp. in artificial seawater. Bacterial inactivation was conducted in a liquid-film-forming apparatus with various pressure conditions, CO supply rates, and chlorine dosages.

Effects of pressure and pressure cycling on disinfection of Enterococcus sp. in seawater using pressurized carbon dioxide with different content rates.

Interest is growing in a disinfection technique for water treatment without disinfection byproducts. This study presents the result of using a liquid-film-forming apparatus at less than 1.0 MPa for disinfection of seawater.

Effect of different carbon sources on the biological phosphorus removal by a sequencing batch reactor using pressurized pure oxygen.

The effect of different carbon source on the efficiency of enhanced biological phosphorus removal (EBPR) from synthetic wastewater with acetate and two ratios of acetate/starch as a carbon source was investigated. Three pressurized pure oxygen sequencing batch reactor (POSBR) experiments were operated. The reactors (POSBR1, POSBR2 and POSBR3) were developed and studied at different carbon source ratios of 100% acetate, 75% acetate plus 25% starch and 50% acetate plus 50% starch, respectively.

Delignification of disposable wooden chopsticks waste for fermentative hydrogen production by an enriched culture from a hot spring.

Hydrogen (H2) production from lignocellulosic materials may be enhanced by removing lignin and increasing the porosity of the material prior to enzymatic hydrolysis. Alkaline pretreatment conditions, used to delignify disposable wooden chopsticks (DWC) waste, were investigated. The effects of NaOH concentration, temperature and retention time were examined and it was found that retention time had no effect on lignin removal or carbohydrate released in enzymatic hydrolysate.

Inactivation effect of pressurized carbon dioxide on bacteriophage Qβ and ΦX174 as a novel disinfectant for water treatment.

The inactivation effects of pressurized CO2 against bacteriophage Qβ and ΦX174 were investigated under the pressure of 0.3-0.9 MPa, initial concentration of 10(7)-10(9) PFU/mL, and temperature of 17.

Potential bioremediation of mercury-contaminated substrate using filamentous fungi isolated from forest soil.

The use of filamentous fungi in bioremediation of heavy metal contamination has been developed recently. This research aims to observe the capability of filamentous fungi isolated from forest soil for bioremediation of mercury contamination in a substrate. Six fungal strains were selected based on their capability to grow in 25 mg/L Hg(2+)-contaminated potato dextrose agar plates.

Potable water scarcity: options and issues in the coastal areas of Bangladesh.

In the coastal areas of Bangladesh, scarcity of drinking water is acute as freshwater aquifers are not available at suitable depths and surface water is highly saline. Households are mainly dependent on rainwater harvesting, pond sand filters and pond water for drinking purposes. Thus, individuals in these areas often suffer from waterborne diseases.

Comparison of disinfection effect of pressurized gases of CO2, N2O, and N2 on Escherichia coli.

Based on the production of gas bubbles with the support of a liquid film-forming apparatus, a device inducing contact between gas and water was used to inactivate pathogens for water disinfection. In this study, the inactivation effect of CO2 against Escherichia coli was investigated and compared with the effects of N2O and N2 under the same pressure (0.3-0.

Excited-state intramolecular proton transfer and charge transfer in 2-(2'-hydroxyphenyl)benzimidazole crystals studied by polymorphs-selected electronic spectroscopy.

Crystal structures of polymorphs of 2-(2'-hydroxyphenyl)benzimidazole (HPBI), Forms α and β, are analyzed by X-ray crystallography. The fluorescence excitation (FE) and fluorescence spectra of the polymorphs are separately observed at temperatures 77-298 K. It has been found that the electronic spectra of the two crystal forms are significantly different from each other.

Thermal luminescence spectra of polyamides and their Maillard reaction with reducing sugars.

Thermal luminescence (TL) spectra of polyamides were measured with a Fourier-transform chemiluminescence spectrometer to elucidate the emission mechanism. A TL band of ε-polylysine with a peak at 542 nm observed at 403 K was assigned to the emission due to the interaction of the -CO-NH- group with oxygen molecules by comparison with nylon-6, polyglycine, and polyalanine. When the sample was kept at 453 K, the intensity of the TL band decreased and the wavelength of the peak shifted to 602 nm, which was assigned to the emission due to the interaction of the NH2 group on the side chain with oxygen molecules by comparison with monomeric lysine.

Infrared and electronic spectra of radicals produced from 2-naphthol and carbazole by UV-induced hydrogen-atom eliminations.

The photoreaction mechanisms of 2-naphthol and carbazole in low-temperature argon matrices have been investigated by infrared and electronic absorption spectroscopy with aids of density-functional-theory (DFT) and time-dependent DFT (TD-DFT) calculations. When the matrix samples were irradiated upon UV light, 2-naphthoxyl and N-carbazolyl radicals were produced by the elimination of the H atom in the O-H group of 2-naphthol and in the N-H group of carbazole, respectively. The observed IR and electronic absorption spectra of the radicals were reproduced satisfactorily by the quantum chemical calculations.

Characterization of polyhydroxyalkanoates (PHAs) biosynthesis by isolated Novosphingobium sp. THA_AIK7 using crude glycerol.

Biodiesel-contaminated wastewater was used to screen for PHAs-producing bacteria by using crude glycerol as the sole carbon source. A gram-negative THA_AIK7 isolate was chosen as a potential PHAs producer. The 16S rRNA phylogeny indicated that THA_AIK7 isolate is a member of Novosphingobium genus which is supported by a bootstrap percentage of 100% with Novosphingobium capsulatum.

Bacteriological assessment of drinking water supply options in coastal areas of Bangladesh.

This study was conducted to assess the bacteriological quality of alternative drinking water supply options in southwest coastal areas of Bangladesh. A total of 90 water samples were collected during both dry and wet seasons from household based rainwater harvesting systems (RWHSS), community based rain water harvesting systems (CRWHSs), pond-sand filters (PSFs) and ponds. The samples were evaluated for faecal coliform, Escherichia coli and Heterotrophic Plate Count, as well as Vibrio cholerae, Salmonella spp.

Hydrogen-atom tunneling in isomerization around the C-O bond of 2-chloro-6-fluorophenol in low-temperature argon matrixes.

Infrared spectra of 2-chloro-6-fluorophenol in argon matrixes at 20 K revealed the presence of a "Cl-type" isomer, which has the OH···Cl hydrogen bond, but no "F-type" isomer with OH···F bonding, in striking contrast to the existence of both isomers in the gas and liquid phases at room temperature. This finding suggests that the F-type isomer changes to the more stable Cl-type one by hydrogen-atom tunneling in the matrixes. Similar experiments on the OD···X analog species were performed to confirm the tunneling isomerization, resulting in an O-D stretching band of the F-type isomer appearing as well as that of the Cl type, like the spectra reported in the gas and liquid phases.

Inactivation of Escherichia coli and bacteriophage T4 by high levels of dissolved CO2.

Little information is available regarding the effectiveness of water disinfection by CO(2) at low pressure. The aim of this study was to evaluate the use of high levels of dissolved CO(2) at 0.3-0.

Electronic spectra of two long-lived photoproducts: double-proton transfer in 7-hydroxyquinoline dimer in a 2-methyltetrahydrofuran glass matrix.

Photoreactions of 7-hydroxyquinoline (7-HQ) in low-temperature (77-100 K) 2-methyltetrahydrofuran glass matrices are investigated using electronic spectroscopy. We have observed fluorescence excitation and fluorescence spectra of two long-lived species generated by irradiation of UV light (230-400 nm). The dominant species responsible for the fluorescence spectrum between 470 and 600 nm was assigned to the S(1)-->S(0) (pipi*) transition of the keto form of cyclic 7-HQ dimer [(7-HQ)(2)] produced by excited-state double-proton transfer, the corresponding S(1)-S(0) fluorescence excitation spectrum of which was detected between 360 and 510 nm.

Removal of sulphur dioxide using palygorskite in a fixed bed adsorber.

This work describes the use of a novel palygorskite, a type of magnesium aluminium silicate clay possessing a high specific surface area and pore surface activity, as a low cost and highly efficient adsorbent for sulphur dioxide (SO2) removal. Dynamic adsorption in a fixed bed adsorber showed that palygorskite pretreated with sodium hydroxide had a higher adsorption capacity at 10% breakthrough than either raw material or that pretreated with acid. The SO2 adsorption capacity increased with increasing inlet SO2 concentration and decreased with increasing temperature.

Photoinduced hydrogen-atom eliminations of 6-hydroxyquinoline and 7-hydroxyquinoline studied by low-temperature matrix-isolation infrared spectroscopy and density-functional-theory calculations.

Photoreaction mechanisms of 6-hydroxyquinoline (6-HQ) and 7-hydroxyquinoline (7-HQ) in low-temperature argon matrixes have been investigated by Fourier transform infrared (IR) spectroscopy and density-functional-theory (DFT) calculations. A comparison of the observed IR spectra of reactants with the corresponding calculated spectral patterns obtained by the DFT method led to the conclusion that the hydrogen atoms in the O-H group of 6-HQ and in that of 7-HQ are selectively located at the outer position against the quinoline ring. When the matrix samples were irradiated upon UV light around 300 nm, IR spectra of unknown chemical species were observed; they were assigned to the photoreaction intermediates, quinolinoxyl radicals and ketene compounds, produced by eliminations of a hydrogen atom and a hydrogen molecule, respectively.