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The objective of this work was to investigate electrochemical removal of nitrate from a high salinity waste stream generated by Donnan dialysis. Donnan dialysis for nitrate removal is a promising technique. It produces a distinctive composition of a high salinity waste stream of NaCl or Na2SO4 that requires a viable disposal method. The waste stream has the full anionic composition of contaminated groundwater, but the only cation is sodium. Experiments were conducted in a batch system setup. A copper cathode was chosen over brass, aluminum and graphite cathodes. A dimensionally stable anode (DSA), Ti/PbO2, was selected over a Ti/Pt anode. Electrochemical denitrification of high salinity Donnan dialysis nitrate wastes was successfully achieved, with different behavior exhibited in high salinity NaCl solution than in high salinity Na2SO4 solution. NaCl inhibited nitrate removal at high salinities while Na2SO4 did not. The maximum removals after 4 h operation in the high salinity wastes were 69 and 87% for the NaCl and Na2SO4 solutions respectively. [ABSTRACT FROM AUTHOR]

This paper aims to assess the performance of a distributed hydrological model for simulating the transport of various heavy metals in rivers, to enhance and support environmental monitoring strategies for rivers in developing countries. In this context, we evaluated the performance of the Geophysical flow Circulation (GeoCIRC) model based on Object-Oriented Design (OOD) for the simulation of contamination from multiple heavy metals (Pb, Hg, Cr, and Zn) in Harrach River in Algeria. The results of the case study were in good agreement with the observations. Methodology for the assessment of data quality control and the improvement of monitoring procedures was proposed by using the hydrological model to simulate different scenarios. The GeoCIRC-model-based OOD allowed the prediction of the concentrations of heavy metals with minimal input data. Also, various heavy metals could be numerically treated simultaneously because the OOD increases the model's flexibility to allow the handling of many transportable materials. Therefore, the GeoCIRC model is a powerful tool for the monitoring of environmental contamination in rivers by various heavy metals. [ABSTRACT FROM AUTHOR]

Total phosphorus (TP) standards for lakes differ from those for rivers in GB3838-2002. This disjunction may lead to the failure of lake-water quality improvement plans that control nutrient inputs from inflow rivers. With monthly monitoring data for the period 2009-2015, Northwest Lake Taihu was regarded as a case study and the BATHTUB model was utilised to simulate the correspondence between concentrations of TP in the lake and in its inflow rivers. A control plan for TP in Northwest Lake Taihu's inflow rivers is proposed. To guarantee the fulfillment of the control goals of TP in the lake, concentration of TP in the inflow rivers of North Zone, Zhushan Bay, Meiliang Bay and Gonghu Bay should be reduced by 50%, 58%, 18% and 11%, respectively, and TP flux loads should be maintained under 227.35, 173.39, 113.69 and 90.62 ta-1, respectively. Meanwhile, total TP influxes from Northwest Lake Taihu should be maintained under 604.63 ta-1. A control plan that is more restrictive than GB3838-2002 should be proposed to address the TP pollution of the lake. This research provides the foundation for quantifying reduction of the nutrient loading from the catchment and for maintaining Lake Taihu and other typical eutrophic lakes. [ABSTRACT FROM AUTHOR]

This study was conducted to assess the levels of toxic metals like arsenic (As), chromium (Cr), cadmium (Cd), and lead (Pb) in water and sediments of the Pasur River in Bangladesh. The ranges of Cr, As, Cd, Pb in water were 25.76-77.39, 2.76-16.73, 0.42-2.98 and 12.69-42.67 μg/L and in sediments were 20.67-83.70, 3.15-19.97, 0.39-3.17 and 7.34-55.32 mg/kg. The level of studied metals in water samples exceeded the safe limits of drinking water, indicating that water from this river is not safe for drinking and cooking. Certain indices, including pollution load index (PLI) and contamination factor (Cif ) were used to assess the ecological risk. The PLI indicated progressive deterioration of sediments by the studied metals. Potential ecological risks of metals in sediment indicated low to considerable risk. However, the Cif values of Cd ranged from 0.86 to 8.37 revealed that the examined sediments were strongly impacted by Cd. Considering the severity of potential ecological risk (PER) for single metal (Eri ), the descending order of contaminants was Cd >Pb> As> Cr. According the results, some treatment scheme must formulate and implement by the researchers and related management organizations to save the Pasur River from metals contamination. [ABSTRACT FROM AUTHOR]

Four conventional activated sludge sewage treatment plants (STPs) in Southern India were chosen to investigate the occurrence of major ions and trace metals in dissolved fraction of the wastewater. Samples were collected from inlet and outlet of STPs during the pre-monsoon and monsoon seasons. Except for a few elements (Mn, Mo and Ni), the concentrations of the rest increased at the outlet of STPs, suggesting that there is an addition of these elements during the treatment process. The increase in concentrations at the STP outlet ranged from 1.25 times for Mn to 3,254 times for Ag during the pre-monsoon. In the monsoon, the increase ranged from 1.75 (Fe) to 1,510 (Ag). This suggests that there is a substantial anthropogenic input of these elements as they pass through the treatment process. Removal rates of elements in STPs also varied. 59% of Mn was removed during the treatment process during pre-monsoon as compared to 67% removal during monsoon. [ABSTRACT FROM AUTHOR]

The black-odor mechanism of Yitong River was analyzed based on survey and monitoring results. We found that organic matter is the main pollution source of Yitong River and its tributaries. A black-odor evaluation model that can describe the pollution of the Yitong River water system was developed, and this model has the parameters I = 0.21 [CODCr] + 0.18 [DO] -- 0.36[NH3-N] + 0.91. The model performance was satisfactory with a black-odor defining accuracy of 69%. Moreover, we found that CODCr, NH3-N, and DO are the influential factors of the Yitong River black-odor water body and that their threshold values when the water body transitioned to black odor were 109.2, 1.90, and 7.50 mg·L-1, respectively. We found that most of the Yitong River was polluted by six heavy metals, namely, As, Cd, Cr, Cu, Pb, and Zn. We used the Nemerow method to calculate the heavy metal pollution degree of each sampling point and found that 60% of the points were seriously polluted. Furthermore, we drew the heavy metal pollution distribution map of the Yitong River. Finally, we proposed an effective measure called new-type multistep constructed wetland to improve the water quality of Yitong River. [ABSTRACT FROM AUTHOR]

Payatas landfill in Quezon City, Philippines, releases leachate to the Marikina River through a creek. Multivariate statistical techniques were applied to study temporal and spatial variations in water quality of a segment of the Marikina River. The data set included 12 physico-chemical parameters for five monitoring stations over a year. Cluster analysis grouped the monitoring stations into four clusters and identified January-May as dry season and June-September as wet season. Principal components analysis showed that three latent factors are responsible for the data set explaining 83% of its total variance. The chemical oxygen demand, biochemical oxygen demand, total dissolved solids, Cl- and PO43- are influenced by anthropogenic impact/eutrophication pollution from point sources. Total suspended solids, turbidity and SO42- are influenced by rain and soil erosion. The highest state of pollution is at the Payatas creek outfall from March to May, whereas at downstream stations it is in May. The current study indicates that the river monitoring requires only four stations, nine water quality parameters and testing over three specific months of the year. The findings of this study imply that Payatas landfill requires a proper leachate collection and treatment system to reduce its impact on the Marikina River. [ABSTRACT FROM AUTHOR]

Prediction of the pollutant mixing zone (PMZ) near the discharge outfall in Huangshaxi shows large error when using the methods based on the constant lateral diffusion assumption. The discrepancy is due to the lack of consideration of the diffusion coefficient variation. The variable lateral diffusion coefficient is proposed to be a function of the longitudinal distance from the outfall. Analytical solution of the two-dimensional advection-diffusion equation of a pollutant is derived and discussed. Formulas to characterize the geometry of the PMZ are derived based on this solution, and a standard curve describing the boundary of the PMZ is obtained by proper choices of the normalization scales. The change of PMZ topology due to the variable diffusion coefficient is then discussed using these formulas. The criterion of assuming the lateral diffusion coefficient to be constant without large error in PMZ geometry is found. It is also demonstrated how to use these analytical formulas in the inverse problems including estimating the lateral diffusion coefficient in rivers by convenient measurements, and determining the maximum allowable discharge load based on the limitations of the geometrical scales of the PMZ. Finally, applications of the obtained formulas to onsite PMZ measurements in Huangshaxi present excellent agreement. [ABSTRACT FROM AUTHOR]

In this paper, a new methodology is proposed for waste load allocation in river systems using the decision support system (DSS) for the graph model for conflict resolution II (GMCRII), multi-criteria decision making (MCDM) analysis and the Multi-Objective Particle Swarm Optimization (MOPSO) algorithm. Minimization of total treatment and penalty costs and minimization of biological oxygen demand violation of standards at the check point are considered as the main objectives of this study. At first, the water quality along the river was simulated using the Streeter-Phelps (S-P) equation coupled with the MOPSO model. Thereby a trade-off curve between the objectives is obtained and a set of non-dominated solutions is selected. In the next step, the best alternative is chosen using MCDM techniques and the GMCRII DSS package and non-cooperative stability definitions. The applicability and efficiency of the methodology are examined in a real-world case study of the Sefidrud River in the northern part of Iran. [ABSTRACT FROM AUTHOR]

Water transparency is an important ecological indicator for shallow lakes. The largest shallow lake, Poyang Lake, as well as the most typical river-connected lake in China was selected as the research area. In view of the complicated water-sediment conditions induced by its frequent water exchange with external rivers, the dominant factors driving water transparency were determined against the field investigated data from 2003 to 2013 and a specific driving function was established. A numerical model coupling suspended sediment, Chl-a and chemical oxygen demand was developed and validated, and the spatial water transparency distributions under three typical current structures in Poyang Lake, Gravity-style, Jacking-style and Backflow-style, were quantitatively estimated. The following results stood out: water transparency in the lake varied distinctly with the current status; Backflow-style current was basically characterized by the lowest water transparency, while that under Jacking-style was the highest due to the lower sediment carrying capacity. In some outlying regions in the lake, where the water current is hardly influenced by the mainstream, the water transparency was always kept at a stable level. [ABSTRACT FROM AUTHOR]

River classification is a very useful tool for rivermanagement yet still a difficult task. This paper proposed a new decision classifier (DCF) to classify rivers for Chinese river management based on existing classification systems. Aimed at river function management, the DCF with the five-layers frame was developed on reach level in a spatially nested pattern that fromtop to bottomare natural province, basin, valley, reach, habitat and microhabitat. Five indexes (artificial degree, closeness, sinuosity, bed material texture, geomorphic units (GUs)) were selected and organized into the DCF according to the importance of the influence on river structure from macro to micro, large to small and top to bottom, because they represent main aspects of river structures and are easy to obtain. In addition, the closeness index is another good connector between valley level and reach level, and the GUs index links reach level to habitat level. The overall procedure to use DCF includes primary indoor classification and field validation. Remote sensing, geographical information system and global positioning system technologies were adopted in the process to dramatically reduce workload, especially fieldwork. Finally, the approach was applied to the Yongding river as a good example, and 17 river styles were identified. [ABSTRACT FROM AUTHOR]

To assess the effects of Fe(III) and anthropogenic ligands on the bioavailability of Ni, Cu, Zn, and Pb, concentrations of bioavailable metals were measured by the DGT (diffusive gradients in thin films) method in some urban rivers, and were compared with concentrations calculated by a chemical equilibrium model (WHAM 7.0). Assuming that dissolved Fe(III) (<0.45 µm membrane filtered) was in equilibrium with colloidal iron oxide, the WHAM 7.0 model estimated that bioavailable concentrations of Ni, Cu, and Zn were slightly higher than the corresponding values estimated assuming that dissolved Fe(III) was absent. In contrast, lower levels of free Pb were predicted by the WHAM 7.0 model when dissolved Fe(III) was included. Estimates showed that most of the dissolved Pb was present as colloidal iron-Pb complex. Ethylene-diamine-tetra-acetic acid (EDTA) concentrations at sampling sites were predicted from the relationship between EDTA and the calculated bioavailable concentration of Zn. When both colloidal iron and predicted EDTA concentrations were included in the WHAM 7.0 calculations, dissolved metals showed a strong tendency to form EDTA complexes, in the order Ni>Cu >Zn>Pb. With the inclusion of EDTA, bioavailable concentrations of Ni, Cu, and Zn predicted by WHAM 7.0 were different from those predicted considering only humic substances and colloidal iron. [ABSTRACT FROM AUTHOR]

In this study, the dynamic adsorption of methylene blue dye onto CuO-acid modified sepiolite was investigated. Meanwhile, the equilibrium and kinetic data of the adsorption process were studied to understand the adsorption mechanism. Furthermore, a high-temperature gas stream was applied to regenerate the adsorbent. The results showed that the Langmuir isotherm model was applied to describe the adsorption process. The positive value of enthalpy change indicated that the adsorption process was endothermic in nature. In the dynamic adsorption process, the best adsorption performance was achieved when the ratio of column height to diameter was 2.56 and the treatment capacity was 6 BV/h. The optimal scenario for regeneration experiments was the regeneration temperature of 550-650 °C, the space velocity of 100 min-1 and the regeneration time of 10 min. The effective adsorption of CuO-acid modified sepiolite was kept for 12 cycles of adsorption and regeneration. [ABSTRACT FROM AUTHOR]

Human adenovirus (HAdV) infections can occur throughout the year. Cases of HAdV-associated respiratory disease have been more common in the late winter, spring, and early summer. In this study, to provide viral pollution data for further epidemiological studies and governmental actions, the presence of HAdV in the aquatic environment was quantitatively surveyed in the summer. This study was conducted to compare the efficiencies of nested-PCR (polymerase chain reaction) and qPCR (quantitative PCR) for detecting HAdV in environmental waters. A total of 73 water samples were collected from Puzi River in Taiwan and subjected to virus concentration methods. In the results, qPCR had much better efficiency for specifying the pathogen in river sample. HAdV41 was detected most frequently in the river water sample (10.9%). The estimated HAdV concentrations ranged between 6.75 × 10² and 2.04 × 109 genome copies/L. Significant difference was also found in heterotrophic plate counts, conductivity, water temperature, and water turbidity between presence/absence of HAdV. HAdV in the Puzi River may pose a significant health risk. [ABSTRACT FROM AUTHOR]

Transit data analysis and artificial neural networks (ANNs) have proven to be a useful tool for characterizing and modelling non-linear hydrological processes. In this paper, these methods have been used to characterize and to predict the discharge of Lor River (North Western Spain), 1, 2 and 3 days ahead. Transit data analyses show a coefficient of correlation of 0.53 for a lag between precipitation and discharge of 1 day. On the other hand, temperature and discharge has a negative coefficient of correlation (-0.43) for a delay of 19 days. The ANNs developed provide a good result for the validation period, with R2 between 0.92 and 0.80. Furthermore, these prediction models have been tested with discharge data from a period 16 years later. Results of this testing period also show a good correlation, with R2 between 0.91 and 0.64. Overall, results indicate that ANNs are a good tool to predict river discharge with a small number of input variables. [ABSTRACT FROM AUTHOR]

This study is focused on isolation of Ni(II), Cu(II) and Cr(VI) resistant bacteria to assess their exopolysaccharide (EPS) production and related bioremoval capacities. Mixed cultures had higher heavy metal removal capacity in media with molasses (MAS) than the control cultures lacking this carbon (AS) containing 50 mg/l of heavy metal. The yields were 32%, 75.7%, and 51.1% in MAS, while the corresponding values were 29%, 55.1%, and 34.5% in AS, respectively. Purification of the strains 1, 5 and 6 present in the mixed cultures decreased the bioremoval capacities of the mixed culture samples, although these strains produced higher EPS amounts in MAS agar. Strain 5 had the highest Cu(II) (69.1%) and Cr(VI) (43.1%) removal rates at 25 mg/l initial concentration of each pollutant with EPS amounts of 0.74 g/l and 1.05 g/l, respectively. This strain was identified as Stenotrophomonas maltophilia. The presented data show that especially mixed and also pure cultures of bacterial strains isolated from Ankara Stream could be assessed as potential bioremoval agents in the treatment of Cu(II) or Cr(VI) containing wastewaters. [ABSTRACT FROM AUTHOR]

Stream ecosystems may suffer from the effects of multiple stressors. Planning restoration actions without knowing the relative weight of each stressor might lead to disproportionately costly or ecologically meaningless measures. This is particularly relevant under the EU Water Framework Directive where economic considerations play a role in justifying exemptions from the overarching aim of the directive of achieving the good ecological status in all the EU water bodies by 2015. In this study, we correlated the status of macroinvertebrate assemblages with many environmental variables at 120 monitoring stations (surveyed in 2009-2011) in the streams of Lombardy, Italy. We used a combination of regression techniques to disentangle the effects of the different stressors. Furthermore, different profiles of ecological quality were associated with the dominant stressors. Finally, examples are given about how these study findings provide elements to identify restoration scenarios that maximize the effectiveness/cost ratio. [ABSTRACT FROM AUTHOR]

Using a Guelph Permeameter, the soil water infiltration processes were analyzed in the Babao River of the Qilian Mountain in China. The results showed that the average soil initial infiltration and the steady infiltration rates in the upstream reaches of the Babao River are 1.93 and 0.99 cm/min, whereas those of the middle area are 0.48 cm/min and 0.21 cm/min, respectively. The infiltration processes can be divided into three stages: the rapidly changing stage (0-10 min), the slowly changing stage (10-30 min) and the stabilization stage (after 30 min). We used field data collected from lawn soils and evaluated the performances of the infiltration models of Philip, Kostiakov and Horton with the sum of squared error, the root mean square error, the coefficient of determination, the mean error, the model efficiency and Willmott's index of agreement. The results indicated that the Kostiakov model was most suitable for studying the infiltration process in the alpine lawn soils. [ABSTRACT FROM AUTHOR]