INTRODUCTION: In this work, we report in situ studies of UV photoelectrocatalytic discoloration of a dye (indigo carmine) by a TiO2 thin film in a microreactor to demonstrate the driving force of the applied electrode potential and the dye flow rate toward dye discoloration kinetics. METHODS: TiO2 65-nm-thick thin films were deposited by PVD magnetron sputtering technique on a conducting glass substrate of fluorinated tin oxide. A microreactor to measure the discoloration rate, the electrode potential, and the photocurrent in situ, was developed. The dye solutions, before and after measurements in the microreactor, were analyzed by Raman spectroscopy. RESULTS: The annealed TiO2 thin films had anatase structure with preferential orientation (101). The discoloration rate of the dye increased with the applied potential to TiO2 electrode. Further, acceleration of the photocatalytic reaction was achieved by utilizing dye flow recirculation to the microreactor. In both cases the photoelectrochemical/photocatalytic discoloration kinetics of the dye follows the Langmuir–Hinshelwood model, with first-order kinetics. CONCLUSIONS: The feasibility of dye discoloration on TiO2 thin film electrodes, prepared by magnetron sputtering using a flow microreactor system, has been clearly demonstrated. The discoloration rate is enhanced by applying a positive potential (E AP) and/or increasing the flow rate. The fastest discoloration and shortest irradiation time (50 min) produced 80% discoloration with an external anodic potential of 0.931 V and a flow rate of 12.2 mL min−1.

INTRODUCTION: While the literature is replete with studies of the toxic potency of pentachlorophenol (PCP), site-specific criteria for native aquatic species that can be used in ecological risk assessments has been lacking and application of toxicity information for non-native species is controversial. MATERIALS AND METHODS: In the present study, acute and chronic toxicities of PCP to six aquatic species native to the Yangtze River were determined. The HC5 and HC50 (hazardous concentration for 5% and 50% of species) were derived from dose–response curves for these native aquatic species and were then compared with those derived for non-native species. RESULTS: The acute toxicity values for the native species ranged from 8.8 × 10−2 mg l−1 (Plagiognathops microlepis) to 1.1 mg l−1 (Soirodela polyrhiza), while chronic toxicity values based on no observed effect concentrations (NOECs) ranged from 0.01 mg l−1 (Macrobrachium superbum) to 0.25 mg l−1 (Soirodela polyrhiza). Native aquatic benthos was more sensitive to acute PCP exposure than non-native species. There was no significant difference in NOECs derived from native fish species and those based on non-native fish species. The median acute HC5 and HC50 derived from the toxicity data of native taxa were both less than those derived from non-native taxa. There was no significant difference between chronic HC5s derived from the two sets of taxa. However, the median chronic HC50 derived from native taxa was less than that derived from non-native taxa. CONCLUSION: The study upon which we report here provides site-specific toxicity information developed for native species which can be used for the protection of local aquatic life from a common contaminant, PCP.

PURPOSE: To examine (1) the effect of organic (poultry manure) and inorganic (residue mud and phosphogypsum) amendments on nutrient leaching losses from residue sand and (2) whether amendments improve the growth of plants in residue sand. METHODS: Leaching columns were established using residue sand. The phosphogypsum-treated surface layer (0–15 cm) was amended with poultry manure and/or bauxite residue mud and the subsurface layer (15–45 cm) was either left untreated or amended with phosphogypsum. RESULTS: Much of the Na+, K+, Cl− and SO 4 2− was lost during the first four leachings. Additions of phosphogypsum to both surface and subsurface layers resulted in partial neutralization of soluble alkalinity. Mean pH of leachates ranged from 8.0 to 8.4, the major cation leached was Na+ and the major balancing anion was SO 4 2− . Where gypsum was not applied to the subsurface, mean pH of leachates was 10.0–10.9, the main cation leached was still Na+ and the main balancing anions were a combination of SO 4 2− and HCO 3 − /CO 3 2− . At the end of the experiment, concentrations of exchangeable Na+ in the subsurface layers were similar regardless of whether gypsum had been applied to that layer or not. Yields of Acacia saligna were promoted by additions of poultry manure to the surface layer but unaffected by gypsum incorporation into the subsurface layer. CONCLUSIONS: Lack of reaction of phosphogypsum with the subsurface layer is unlikely to be a major factor limiting revegetation of residue sand since in the absence of phosphogypsum the excess Na+ leaches with the residual alkalinity (HCO 3 − /CO 3 2− ) rather than SO 4 2− .

PURPOSE: Biosorption is an emerging, eco-friendly and economical method for treating the wastewater effluents. Compared to many other biological materials, algae biomass proved to be the better biosorbent due to the presence of cell wall polymers in them. METHODS: Algal biomasses namely Enteromorpha flexuosa and Gracilaria corticata were dried, crushed and used as biosorbents. Ponceau S, a diazo dye was used as a model adsorbate for the biosorption studies. The biosorbents were characterized by Scanning Electron Microscopy, FT-IR and zero point charge. Batch studies were performed by varying pH, biosorbent dosage and initial dye concentrations. Adsorption isotherms, kinetic and thermodynamic analyses were carried out. The effect of electrolytes was also studied. Batch desorption studies were also carried out using various reagents. RESULTS: Isotherm data were tested with Langmuir and Freundlich isotherm models and the results suggested that the Freundlich isotherm fitted the data well. Kinetic studies were performed with varying initial dye concentrations and the data were incorporated with pseudo first-order and pseudo second-order kinetic equations and was found that the studied biosorption processes followed pseudo second-order kinetic equation. Thermodynamic parameters were evaluated at three different temperatures 293 K, 300 K and 313 K. About 95% of the dye could be desorbed from both the biosorbents. CONCLUSION: Both the algal biomasses had heterogeneous surfaces and followed pseudo second-order chemical kinetics. Thermodynamic parameters proved that the biosorption by both the biomasses were spontaneous, feasible and endothermic processes. Desorption studies proved the worth of the algal biomasses as biosorbents in industrial level.

INTRODUCTION: The recognition that industrial activity plays an essential role in a sustainable society is now widespread. To understand the causal relationship between industrial pollution abatement expenditure and industrial system cleaning level in China is of considerable importance, especially under extremely rapid industrial growth and serious pressure of industrial pollutants abatement context. STUDY METHODS: We use composite index assessment method and regression analysis in this paper. We establish the mathematical model between composite industrial cleaner index and investment intensity for industrial pollutants abatement, and analyze the effects of industrial pollutants treatment and discharge indicators on composite industrial cleaner index in China. RESULTS AND DISCUSSION: Results show that: (1) There is significant nonlinear relationship between composite industrial cleaner index and investment intensity for industrial pollutants abatement. (2) From single indicator perspective, the effect of investment intensity on pollutants treatment indicators is positively, on the contrary, the effect of investment intensity on pollutants discharge indicators is negatively; (3) From decomposition cleaner index perspective, the effect of pollutants discharge level (process control) is higher than pollutants treatment capacity (end-of-pipe) on composite industrial cleaner index; (4) There is threshold between investment intensity and composite cleaner industrial index, it is a crucial reference scale for industrial environmental management in selected period.

PURPOSE: Tannins and dyes pose major threat to the environment by generating huge pollution problem. Biodegradation of wattle extract, chrome tannin and dye compounds using suitable fungal culture namely Aspergillus niger, Penicillium sp. were carried out. In addition to these, ozone treatment was carried out to get higher degradation rate. RESULTS: The results were monitored by carrying out chemical oxygen demand (COD), total organic carbon (TOC), and UV–Vis analysis. The results showed that wattle extract (vegetable tannin) gave better biodegradation rate than dye and chromium compounds. Biodegradation plus ozone showed degradation rates of 92–95%, 94–95%, and 85–87% for the wattle extract, dyes, chromium compounds, respectively. UV–Vis showed that there were no peaks observed for biodegraded samples indicating better degradation rates as compared to the control samples. FT-IR spectra analysis suggested that the formation of flavanoid derivatives, chromic oxide and NH2 compounds during degradation of wattle extract, chromium and dye compounds, respectively, at the peaks of 1,601–1,629 cm−1, 1,647 cm−1, and 1,610–1,680 cm−1. CONCLUSION: The present investigation shows that combination of biodegradation with ozone is the effective method for the removal of dyes and tannins. The biodegradation of the said compounds in combination with ozonation showed better rate of degradation than by chemical methods. The combination of biodegradation with ozone helps to reduce pollution problems in terms of COD, TOC, total dissolved solids and total suspended solids.

PURPOSE: The aim of this paper was to develop a new recreational water quality index (RWQI) as a tool to ensure the health of swimmers and to take practical decisions. METHODS: RWQI was elaborated with epidemiological data, and we carried out an exhaustive study of the different guidelines for recreational waters proposed by different organisations around the world. Different parameters were chosen, considering, as a priority, the swimmer’s contact and the possibility of ingestion of water during the recreational activity. Furthermore, rating curves were established for pH, chemical oxygen demand, nitrate, phosphate, detergents, enterococci, total coliforms, faecal coliforms and Escherichia coli. RESULTS AND CONCLUSIONS: The index was applied to the data set on water quality of the Potrero de los Funes River (San Luis, Argentina), generated during 2 years (2009–2010). Following the RWQI values classification, most of the Potrero de los Funes water samples fell in the good quality range during the study period.

INTRODUCTION: This study relates to use of zerovalent iron to generate hydroxyl free radicals and undergo subsequent oxidation to destroy 4-nonylphenol (NP) by mild process in aqueous solution and activation of oxygen gas (O2) at room temperature. This technology is based on a novel oxidative mechanism mediated by zerovalent iron rather than commonly used reduction mechanism. MATERIALS AND METHODS: A laboratory scale device consisting of a 250 ml pyrex serum vials fixed to a Vortex agitator was used. Different amounts of zerovalent iron powder (ZVI; 1, 10, and 30 g/l) at pH 4 and room temperature with bubbling of oxygen gas were investigated. RESULTS AND CONCLUSION: Experiments showed an observed degradation rate k (obs) directly proportional to the amount of iron. 4-Nonylphenol degradation reactions demonstrated first-order kinetics with a half-life of about 10.5 ± 0.5 and 3.5 ± 0.2 min when experiments were conducted at [ZVI] = 1 and 30 g/l respectively. Three analytical techniques were employed to monitor 4-nonylphenol degradation and mineralization: (1) spectrofluorimetry; (2) high-performance liquid chromatography; (3) total organic carbon meter (TOC meter). Results showed a complete disappearance of 4-nonylphenol after 20 min of contact with ZVI. The intermediate by-products of the reaction were not identified but the disappearance of NP was monitored by the three above-mentioned techniques.

INTRODUCTION AND METHODS: This study investigated the remediation of cadmium-polluted soil using a combination of stainless steel slag and ammonium humate. These remedial agents were added to an artificially polluted garden soil to inhabit cadmium toxicity in soil by changing the physical and chemical properties of soil in a pot experiment. RESULTS AND CONCLUSIONS: The results showed that the co-application of ammonium humate and stainless steel slag significantly decreased the total and available soil cadmium concentrations, with maximum decreases of 16.30% and 58.04%, respectively. The co-application of an adequate dose of these remedial agents can significantly increase soil pH. The soil organic matter and cation exchange capacity, as well as the amount of soil aggregates, were also significantly increased by the addition ammonium humate, but not stainless steel slag.

Manure products fermented underground in cow horns and commonly used as field spray (preparation 500) in the biodynamic farming system, were characterized for molecular composition by solid-state nuclear magnetic resonance [13 C cross-polarization magic-angle-spinning NMR (13 C-CPMAS-NMR)] spectroscopy and offline tetramethylammonium hydroxide thermochemolysis gas chromatography-mass spectrometry. Both thermochemolysis and NMR spectroscopy revealed a complex molecular structure, with lignin aromatic derivatives, polysaccharides, and alkyl compounds as the predominant components. CPMAS-NMR spectra of biodynamic preparations showed a carbon distribution with an overall low hydrophobic character and significant contribution of lignocellulosic derivatives. The results of thermochemolysis confirmed the characteristic highlighted by NMR spectroscopy, revealing a molecular composition based on alkyl components of plant and microbial origin and the stable incorporation of lignin derivatives. The presence of biolabile components and of undecomposed lignin compounds in the preparation 500 should be accounted to its particularly slow maturation process, as compared to common composting procedures. Our results provide, for the first time, a scientific characterization of an essential product in biodynamic agriculture, and show that biodynamic products appear to be enriched of biolabile components and, therefore, potentially conducive to plant growth stimulation.