Water samples collected in 1995 and 2007 from the Shinano and Agano rivers were examined to determine the types and concentrations of pesticides and their effects on tap water in typical rice production areas of Japan. Tap water originating from the Shinano River was also sampled in 2007, in Niigata City, Japan. Pesticides were present in the river and tap water throughout the year. Comparison of 13 pesticides common to both 1995 and 2007 series revealed that the frequency of individual pesticide occurrence and concentrations were decreasing. Riverine pesticides were classified into five groups according to the period of their appearance and changes in concentration. Pesticides were detected at the time of application to, and drainage from, paddy fields. Pesticide concentrations in tap water showed notable decline following rapid sand-filtration combined with granular activated carbon. The detection index (DI) for tap water and Shinano River water did not exceed a value of 1. Herbicides contributed most to the DI.

Polybrominated diphenyl ethers (PBDEs) are a class of global flame retardants whose residues have markedly increased in fish and human tissues during the last decade. They belong to persistent and toxic contaminants which need more attention and toxicological study as their degradation in the environment is not well understood. This study characterizes 2,2′,4,4′-tetrabromodiphenyl ether (BDE-47) bioconcentration, elimination and biotransformation in juvenile turbot Psetta maxima, in order to evaluate the risk of its bioaccumulation in the marine environment. During this study, juvenile turbot were exposed to environmentally relevant BDE-47 concentrations from 0.001 to 1 μg/L for 16 days via aqueous exposure. This study found that juvenile turbot bioconcentrated and biotransformed BDE-47. There was no difference in standard length or weight between control and exposed fish. Uptake and elimination of BDE-47 by the turbot during exposure were examined in controlled laboratory experiments. Bioconcentration of BDE-47 was similar in fish from all treatment groups. Bioconcentration was rapid and increased with exposure time, since the bioconcentration factor (BCF) was higher. However, elimination was slower in comparison and low elimination was detected after 10 days in clean water. BDE-47 concentration in water influences the BCF. Half-life ranged between 37 and 108 days and theoretical times t₉₀could range from 120 to 358 days. The present study demonstrates a stepwise debromination of BDE-47 to BDE-28.

Treatment of reverse osmosis concentrate (ROC) has been complicated in terms of feasibility, cost, and most importantly, efficiency in removing contaminants. While adsorbents such as activated carbon, coal, and fly ash can remove organics, they may not be effective in removing nutrient salts that cause algae growth. Moreover, with regards to physical treatment, removing contaminants using adsorbents may not be appropriate, as toxic and non-biodegradable pollutants are not transformed or degraded into non-toxic forms. In this study, a series of processes involving adsorption using activated carbon and oxidation by hydroxyl and sulfate radicals were assessed as a means of treating ROC. The method includes treating water containing organics with an adsorbent, and adding nano-sized zero-valent iron (nZVI) to the water in the presence of oxygen, followed by the addition of persulfate, where the water is oxidized with reactive oxygen species (e.g., hydroxyl radical, peroxide, superoxide anion) produced by the addition of ZVI and persulfate radicals generated from persulfate activated by the addition of nZVI. Removal of non-biodegradable organics (as well as nitrogen and phosphorous) and nutrient salts not readily removed by conventional treatment methods can be effectively accomplished through the physical removal method described, using activated carbon, and by a chemical removal method using radical oxidation.

Zn⁰-activated persulfate as a novel and potential approach to the degradation of azo dyes has hardly been reported. In this study, the effects of initial pH, persulfate concentration, Zn⁰ dosage, and temperature on the decomposition of Congo red (CR), an azo dye, were investigated. The results demonstrated that Zn⁰-activated persulfate could effectively mineralize CR. At the initial pH 5.5 and 25 °C, chemical oxygen demand (COD) and total organic carbon (TOC) in the solution with 95 mg/L CR decreased by approximately 87 and 60 %, respectively, within 3 h. The optimum dosages of persulfate and Zn⁰ were approximately 95 mg/L and 2 g/L, respectively. The highest decolorization efficiency of CR was realized at the initial pH 5.5. Both ·OH and SO₄ ⁻· contributed to the degradation of CR, and the spectra of free radicals showed that SO₄ ⁻· was gradually converted to ·OH with pH increasing from weak acidic to neutral condition.

This paper reports on the effect of activating agents such as the impregnation ratio of phosphoric acid (1:1–1:5) at constant activation temperature on the performance of porous activated carbon from waste residues (maize tassel). The variation in the impregnation ratio of the produced activated carbon (AC) from 1:1 to 1:5 enabled the preparation of a high surface area (1,263 m²/g) and a large pore volume (1.592 cm³/g) of AC produced from maize tassel (MT) using a convectional chemical activating agent (phosphoric acid). Impregnation ratios (IR) of the precursors were varied between 1:1 and 1:5 in which it was found that the ratio of 1:4 was optimal based on the high surface area, while 1:5 has the optimal pore volume value for the produced activated carbon.

This study evaluated the effect of the soil solution ionic strength (IS) on the adsorption of Zn, Cu, Cd, Pb, As, and P on aluminum mining by-product (AMB), as well as performed the toxicity characteristic leaching procedure test (TCLP) followed by semi-total digestion in order to evaluate whether the adsorbed elements can cause environmental health risks. We measured adsorption by reacting the adsorbent with Zn, Cu, Cd, Pb, As, and P solutions in low IS (47 mmol L⁻¹) and high IS (470 mmol L⁻¹). Subsequent cation and anion desorption was evaluated by adding electrolyte solutions to the remaining adsorption residue. After the desorption experiment, we performed the TCLP test followed by semi-total digestion. Changing the IS interfered on Zn, Cd, Cu, and As adsorption, while no effect was observed for Pb and P. Increasing IS decreased the desorbed amounts of Cd, Zn, Cu, and As. Among the studied elements, Cd and Zn were noteworthy for having adsorbed the least and desorbed the most. Disposal of the AMB after being used as adsorbent of Cd, Pb, and As has to be carefully made as it may present their contents above the concentration causing toxicity.

The main objective of this study was to evaluate the degradation of a ternary mixture of n-hexane, benzene, and methanol fed to two Trickle Bed Air Biofilters (TBABs) designated as “A” and “B”. Both TBABs were loaded with pelletized diatomaceous earth support media and run at an empty bed residence time (EBRT) of 120 s. TBABs “A” and “B” were operated at pH 4 and fed with n-hexane:benzene:methanol (CH:CB:CM) concentrations ratios of 1:3:10 and 1:3:6.6, respectively under different loading rates. The influent total loading rates varied from 39.2 to 117.7 g/m³h and from 32 to 96.4 g/m³h for TBABs “A” and “B”, respectively. In both TBABs, methanol and benzene were the most eliminated volatile organic compounds (VOCs), while the removal of n-hexane was controlled by the VOCs ratios. Higher removal efficiencies were obtained for the VOCs ratio of 1:3:6.6 corresponding to a total VOCs load of 96.4 g/m³h. The addition of VOCs mixture to the TBABs resulted in change of the fungi community within the TBABs as compared to the fungi community when the TBABs were previously receiving only n-hexane as a sole substrate.

The main goal of this study was to explore the suitability and performance of bicomponent polymer membranes based on acrylonitrile copolymers-polyvinyl alcohol (PVA) mixtures and small quantities of anion (Purolite A100) or cation exchange resin (Purolite C150), prepared by phase inversion. Membranes were used for copper removal from synthetic wastewater solutions. A three detachable cylindrical compartment electrodialysis cell without recirculation of the electrolytes and synthetic solutions of various concentrations, similar to a copper electrowinning electrolyte, were used. The electrodialysis unit operates under galvanostatic control. The effect of pH on electrodialysis separation of Cu²⁺and on the solution conductivity has been also investigated. The laboratory electrodialysis cell performance was evaluated in terms of percent of extraction (pe) and current efficiency (ce). Experimental results showed that the ionic transfer in electrodialysis cell was especially affected by concentration. The highest values for the pe (>81 %) and the ce (>25 %) of copper ions were obtained at maximum concentration in copper ions (3 g/L), indicating a better performance of the ion extraction. The transport of copper ions was also correlated with flux data. The ion exchange membranes were characterized using FT-IR spectroscopy, ESEM, and electrochemical impedance spectroscopy.

The effects of urbanization on runoff pollutant concentrations and pollutant loading were studied in three urban catchments of varying imperviousness and land use type in the city of Lahti, Finland. Imperviousness of the catchments were 19 % (“Low”), 62 % (“Intermediate”) and 89 % (“High”). During the 2-year study period, runoff quantity was measured continuously and samples were taken for water quality analysis. Besides imperviousness, land use type strongly affected pollutant concentrations: differences in total phosphorus (tot-P), Al, Cr, Zn and Pb concentrations were observed especially between the city centre catchments (High and Intermediate) and the residential catchment (Low), while total suspended solids (TSS), total nitrogen (tot-N), Mn, Co, Ni and Cu concentrations increased with increasing imperviousness. As for pollutant loads, imperviousness was strongly related to TSS, tot-P, Al, Mn, Zn, Cr, Co, Ni and Cu export. The effects of urbanization on runoff quality were season dependent: urbanization increased runoff volumes and, hence, pollutant loads, especially during warm seasons. Still, highest pollutant export in the catchments occurred during spring. Nevertheless, the warm period produced comparable loads to spring at the city centre catchments. Pollutant concentrations, especially in the city centre catchments, exceeded thresholds set for surface waters, indicating a need for runoff treatment in water quality protection.

This paper presents a comprehensive analysis of the pollutant emissions and intensity from Canada’s power stations. An analysis of National Pollutant Release Inventory (NPRI) and site generation data shows significant variability with the dominant emissions pathway being point-source air emissions. In general, power stations are a very small fraction of Canada’s direct facility and estimated diffuse emissions, as well as showing significant variability of pollutant intensities per megawatt or megawatt hour of capacity or generation. The evidence also suggests that increased scale does not lead to a lower pollutant intensity, and that transfers and disposal pollutant loads are substantial, often representing most of the total reported pollutants. Overall, this study provides a valuable insight into the current status of pollutant intensities from Canada’s power stations, possible improvements to the NPRI and a valuable benchmark for future studies and international comparisons.