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Two solvent extraction systems for V (V) and Cr (VI) separation in leaching solution were investigated in order to select the suitable separation method for the disposing of chromium-bearing vanadium slag. The best/suitable system was determined by extraction yield (EV，%) and the separation factor of V(V) and Cr(VI) (βV/Cr). On the condition of 1:1 molar ratio of H+ to vanadium (V), the EV values were 99.8% and 95.1%, while the βV/Cr values were 546.58 and 29.53 using the two different systems, respectively. The extraction reactions for system 1 were determined by the slope method, and the chemical equilibrium constants were obtained.

This work aimed to determine the effect of organic foulants and fouling behavior on separation of multi-ions for nanofiltration (NF) membrane. Three model organic foulants (bovine serum albumin, lysozyme, and humic acid) were selected and studied in depth. The rejections of mono- and di-anions by virgin membrane varied with different organic foulants because of foulant-enhanced co-ion competition. Subsequent multi-ions separations by fouled membranes were different due to the zeta potential and structure of the fouling cake. In contrast to the single protein system, Cl− and rejection was reduced by HA fouled membrane. However, with added proteins in the HA solution, mixed systems experienced decreasing Cl− rejection and increasing rejection. In addition, solution chemistry (solution pH, ionic strength, and Ca2+) had marked effect on the cake layer composition, likely due to the changing interaction between foulant and foulant, as well as between foulant and NF membrane. The suitable foulant cake s...

The fouling behavior of nanofiltration (NF) membranes by proteins bovine serum album (BSA), lysozyme (LYS), and humic acids (HA), as well as their mixtures was studied in a cross flow bench-scale cell. The similarities and differences of the effects of pH on single and mixed organic foulant systems were compared by analyzing the size distribution and zeta potential of foulants in the feed, and in conjunction with the characterization of fouled NF membranes, respectively. Results showed that the fouling behaviors of both single and the mixed systems were significantly correlative with solution pH, moreover BSA/LYS combined with HA appeared more aggravated fouling behavior than single foulant within the test pH range. For solution pH, this can affect interactions of foulants–foulants and foulants–membrane by changing zeta potential of them. Also, therefore, zeta potential value could be used to predict the fouling behavior of NF. Considering the experimental results, more severe fouling behavior by ...

Coking wastewater is one of the most toxic industrial effluents since it contains high concentration of toxic organic compounds. Biological treatments are widely applied in coking wastewater treatment, pollutants can be degraded completely due to the synergistic effect of the community composition. In this study, the community structure and degradation of organic compounds of a full-scale coking wastewater treatment plant with anaerobic, anoxic, and oxic process (A1/A2/O) were studied. GC-MS results showed that phenols, indole, quinoline and pyridine, accounting for 61.70, 13.63, 7.71 and, 2.30%, respectively, were the main organic pollutants in the raw coking wastewater. Those pollutants were degraded gradually during the A1/A2/O bioprocess, respectively. High throughput pyrosequencing was applied to investigate the bacterial community, the sequences could be affiliated to 21 phylogenetic groups, including Proteobacteria, Chloroflexi, Bacteroidetes, Planctomycetes, Synergistetes, Chlorobi, Acidobacteria, Nitrospira, Firmicutes, and Actinobacteria. Diversity and richness indexes, venn analysis and principal component analysis indicated that the diversity and abundance of species in three samples were different. The abundance of the phylum Proteobacteria accounted for 84.64% (A1), 62.73% (A2), and 83.24% (O) of the total reads, respectively. The corresponding most dominant orders in three samples were Pseudomonadales (A1), Syntrophobacterales (A2), and Burkholderiales (O), respectively. While genus Pseudomonas, Desulfoglaeba, and Diaphorobacter was the dominant bacterium in three samples, respectively.

High levels of heavy metals in Panax notoginseng (Sanchi), a valued traditional Chinese medicine, have drawn increasing concern regarding the safe usage of Sanchi preparations. Here, we measured the concentrations of six heavy metals in Sanchi samples from 20 major plantations, investigated the pharmaceutical processes and usages of Sanchi preparations, and assessed the associated potential health risks to consumers. The average concentrations of chromium (Cr), copper (Cu), nickel (Ni), zinc (Zn), lead (Pb), and arsenic (As) in the Sanchi samples were 2.7, 3.7, 6.2, 22.1, 2.0, and 1.4 mg/kg, respectively. The hazard quotients (HQs) for these six single metals and the hazard index (HI) of these metals’ combination were all far less than 1, indicating the absence of a non-carcinogenic health hazard to consumers. The carcinogenic risk of As was 2.1 × 10−6, which is higher than the allowable level suggested by the U.S. Environmental Protection Agency but less than the level suggested by the World Heal...

In this study, anaerobic granular sludge with sulphate-reducing bacteria (SRB) was applied to treat Cu 2+-, -containing wastewater in an expanded granular sludge bed reactor. The migration and enrichment of copper in anaerobic granular sludge were envaluated. By analysing the sludge with X-ray diffraction, copper was determined to be present as covellite (CuS) in the sludge. Observations at the microscopic level showed that CuS precipitates were absorbed onto granules and gradually migrated from the outer to the interior layer of the granule over time and finally accumulated in the core of the granular sludge. Because of the migration of the CuS precipitates and the protection of the extracellular polymeric substances matrix, SRB were able to tolerate copper concentrations up to 10 mg/L. A copper removal efficiency of about 96% was observed at a steady state for 3 months, and copper was enriched in the granular sludge.

In this study, an ordered mesoporous carbon (OMC) was synthesized and investigated as electrodes for capacitive deionization (CDI). The influence of working parameters on salt removal was studied and the electrosorption isotherm and kinetics were investigated. It was found that the electrosorption process fitted both Langmuir isotherm and Freundlich isotherm, and followed pseudo-first-order kinetics. The maximum electrosorptive capacity was 10.1 mg/g at the optimized applied voltage of 1.2 V and flow rate of 40 ml/min. In order to investigate the effect of surface groups on CDI efficiency, OMC was modified by H2O2 solution or thermal treatment under N2 atmosphere, without significantly changing its textural properties. X-ray photoelectron spectroscopy measurements showed that the amount of surface oxygen-containing groups was decreased and increased by the thermal and chemical treatments, respectively. CDI experiments revealed that OMC modified by H2O2 solution performed better than original OMC, ...

Chromium, copper, zinc, cadmium, mercury, and lead are frequently found at high concentrations simultaneously in the soils of contaminated sites. Greater-than-additive and less-than-additive interactions have been found between pairs of these metals of concern. We performed a target-organ toxicity dose (TTD) approach and a weight-of-evidence (WOE) analysis to estimate the potential cumulative health risks of multiple metals accounting for joint toxic effects. As a case study, dietary exposure via consumption of locally planted rice and vegetables was assessed along with the associated combined health risk of the six metals for inhabitants in the vicinity of an industrial zone in southern Jiangsu, China. The Hazard Index (HI) values of each endpoint for neurological, renal, cardiovascular, hematological, testicular, and hepatic effects were 0.61, 0.54, 0.12, 0.48, 0.05, and 0.12, respectively, all less than 1. Interactions between Cd and Pb were greater than additive for testicular effects with re...

Dietary consumption of fish is the greatest contributor to dioxin exposure of the general population in Japan. Unlike with other routes of exposure to dioxins, exposure via foodstuffs does not necessarily occur from local sources. Clarifying the distribution of fish from the catch area to local markets helps to control dioxin exposure from the head of the distribution chain down. We analyzed the data from 30 major central wholesale fish markets to determine both the market share of fish by catch area and the market share of major fish types in fish consumption markets. Probabilistic estimation of dietary exposure of the general population to dioxins in fish was conducted in seven regions in Japan. Probabilistic density functions (PDFs) were assigned to express the variability of data from monitoring of dioxin levels in fish by catch area or by fish type. From histograms of dioxin levels in fish by catch area, the mean and 5th to 95th percentile range of dietary exposure to dioxins in the region w...