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Green iron tea nanoparticles (GT-Fe NPs) were used as persulfate(PS) activators to oxidize rhodamine B (RhB) in this study. Optimized oxidative degradation condition was 0.033 mM Fe, 5 mM PS at pH 3.0 and 298 K with an initial RhB content of 50 mg/L. After 120 min of RhB degradation utilizing GT-Fe NPs activated PS, 99% of RhB reduction was achieved, while 98% RhB reduction with PS activated by citric acid-Fe

Inductively coupled plasma mass spectrometry (ICP-MS) has been developed as an accurate and sensitive technique for multi-elemental or isotopic analysis. There are many circumstances in which the i...

The vegetation deterioration and pollution expansion from non-ferrous metal tailings pond have been found in many countries leading to water soil erosion and human health risk. Conventional ecological remediation technologies of mine tailings such as capping were costly and elusive. This study provided an economic and effective model as an alternative by substrate amelioration and vegetation restoration. A field experiment was carried out on a silver tailings pond in southwest China. Tailings substrate was ameliorated by adding organic matter (decomposed chicken manure, DCM), structural conditioner (polyacrylamide, PAM), water-retaining agent (acrylic acid-bentonite water-retaining agent, AAB), and heavy metal immobilizer (biofuel ash, BFA), which were optimized by laboratory experiment. Native heavy metal hyperaccumulator, Bidens pilosa, was colonized. Vegetation coverage and plant height of Bidens pilosa reached about 80% and over 30 cm respectively after 3 months, and the turbidity of tailings leaching solution decreased by 60%. The practice showed that the proportion of available heavy metals in tailings substrate was significantly lower than that in the soil surrounding mining area. Immobilization didn't have stabilization effect on Cd, Zn, and Pb, and As was only 0.002%, phytoremediation had stabilization effect of Cd, Zn, As, and Pb were 2.5-3.5%, 1-2%, 0.25-0.5%, and 0.25-0.75%. Phytoremediation was more effective significantly in controlling heavy metal pollution risk of tailings than immobilization. These results provided a new ecological remediation OSA-NHC model, meaning a combination of optimal substrate amelioration and native hyperaccumulator colonization, which could achieve vegetation restoration and augment heavy metal pollution control in non-ferrous metal tailings pond.

Oxidation of Cr(III) by birnessite (δ-MnO

This paper investigated the micron-scale activated carbon (MAC) immobilized diesel-oil-degrading bacteria (bio-MAC) used as remediation materials for the removal of diesel-oil-contaminated water. The high-efficiency indigenous diesel-oil-degrading bacteria were firstly screened and enriched, then the MAC was used as a diesel oil sorbent and biocarrier for the immobilization of degrading bacteria to prepare the bio-MAC material. The removal performance of the bio-MAC was evaluated via a comparison with the freely degrading bacteria and MAC. The SEM results demonstrated that the diesel-oil-degrading bacteria were effectively immobilized and grew well on the surfaces of MAC particles. The concentration of MAC significantly influenced the growth and activity (DHA and LPS) of immobilized bacteria, and the MAC addition of 3.0 g/L was proven to be an optimum amount for the preparation of bio-MAC. The high-throughput sequencing analysis further indicated that the bacteria immobilized on MAC showed higher abundance levels and diversities index values compared to freely suspended bacteria, such as Pseudomonas, Rhodococcus, Bacillus and Microbacterium. The FTIR spectroscopy results showed that the bio-MAC could effectively degrade the aliphatic hydrocarbons, alkenes and aromatic compounds of diesel oil to carboxylic acids, esters, alcohols and other metabolites. When the concentration of diesel oil was 1 g/L, the removal efficiency for the diesel oil of bio-MAC reached 86.35% after 15 days, while only 23.82% and 70.97% of the diesel oil was removed using the same amount of free bacteria and MAC, respectively. The prepared bio-MAC showed a synergic effect of adsorption and biodegradation and efficiently removed diesel oil from wastewater.

The effects of atmospheric precipitation on heavy metal accumulation and deactivation amendment in wheat surrounding a lead smelter were studied. The total precipitation amounts of Cd, Pb, and As in an in situ test were noticeably more than their amounts in an off-site test over the entire growing period of wheat. In the same soil-wheat system, the heavy metal concentrations of wheat leaves in the off-site test were significantly lower than those in the in situ test near the lead smelter. Specifically, Cd, Pb, and As were 53.1%, 89.2%, and 85.7% less, without the amendment of the heavy metal deactivator (HMD). Meanwhile, the deactivation effect improved in the off-site test, resulting in the respective Cd, Pb, and As decreases of 6.0%, 46.3%, and 22.1% more, compared with it in the in situ test. The changes in heavy metal concentrations of wheat grains were consistent with those of wheat leaves. The concentrations of Cd and Pb in the off-site test were 10.7% and 91.0% lower than the in situ values, without the amendment of the HMD, and deactivation effect also had enhanced, with Cd and Pb decreasing by 1.3% and 9.6% more. The heavy metal concentrations of wheat leaves in the indoor pot test were significantly lower than those in the in situ test, with Cd, Pb, and As 74.4%–87.3%, 95.6%–97.0%, and 86.2%–87.4% less, respectively. After repeated leaf-washing treatment, the effect of HMD amendment was further enhanced, with Cd, Pb, and As decreasing by 30.8%, 33.6%, and 34.7%, respectively. All tests conducted indicate atmospheric precipitation is the controlling pollution source. Deactivation amendment can reduce the heavy metal concentrations of wheat leaves and grains, even in the presence of precipitation contamination, although the presence of precipitation reduces the effect of HMD amendment. Repeated leaf-washing can enhance the effect of HMD amendment and decrease the accumulation of heavy metals from atmospheric precipitation in wheat.

Addition of activated carbon (AC) or biochar (BC) to sediment to reduce the chemical and biological availability of organic contaminants is a promising in-situ remediation technology. But concerns about leaving the adsorbed pollutants in place motivate research into sorbent recovery methods. This study explores the use of magnetic sorbents. A coal-based magnetic activated carbon (MAC) was identified as the strongest of four AC and BC derived magnetic sorbents for polycyclic aromatic hydrocarbons (PAHs) remediation. An 8.1% MAC amendment (w/w, equal to 5% AC content) was found to be as effective as 5% (w/w) pristine AC in reducing aqueous PAHs within three months by 98%. MAC recovery from sediment after three months was 77%, and incomplete MAC recovery had both, positive and negative effects. A slight rebound of aqueous PAH concentrations was observed following the MAC recovery, but aqueous PAH concentrations then dropped again after six months, likely due to the presence of the 23% unrecovered MAC. On the other hand, the 77% recovery of the 8.1% MAC dose was insufficient to reduce ecotoxic effects of fine grained AC or MAC amendment on the egestion rate, growth and reproduction of the AC sensitive species Lumbriculus variegatus.

This paper discusses the sorbent properties of magnetic activated carbons and biochars produced by wet impregnation with iron oxides. The sorbents had magnetic susceptibilities consistent with theoretical predictions for carbon-magnetite composites. The high BET surface areas of the activated carbons were preserved in the synthesis, and enhanced for one low surface area biochar by dissolving carbonates. Magnetization decreased the point of zero charge. Organic compound sorption correlated strongly with BET surface areas for the pristine and magnetized materials, while metal cation sorption did not show such a correlation. Strong sorption of the hydrophobic organic contaminant phenanthrene to the activated carbon or biochar surfaces was maintained following magnetite impregnation, while phenol sorption was diminished, probably due to enhanced carbon oxidation. Copper, zinc and lead sorption to the activated carbons and biochars was unchanged or slightly enhanced by the magnetization, and iron oxides also contributed to the composite metal sorption capacity. While a magnetic biochar with 219 ± 3.7 m(2)/g surface area nearly reached the very strong organic pollutant binding capacity of the two magnetic activated carbons, a magnetic biochar with 68 ± 2.8 m(2)/g surface area was the best metal sorbent. Magnetic biochars thus hold promise as more sustainable alternatives to coal-derived magnetic activated carbons.

Brownfield sites pollution and remediation is an urgent environmental issue worldwide. The screening and assessment of remedial alternatives is especially complex owing to its multiple criteria that involves technique, economy, and policy. To help the decision-makers selecting the remedial alternatives efficiently, the criteria framework conducted by the U.S. EPA is improved and a comprehensive method that integrates multiple criteria decision analysis (MCDA) with numerical simulation is conducted in this paper. The criteria framework is modified and classified into three categories: qualitative, semi-quantitative, and quantitative criteria, MCDA method, AHP-PROMETHEE (analytical hierarchy process-preference ranking organization method for enrichment evaluation) is used to determine the priority ranking of the remedial alternatives and the solute transport simulation is conducted to assess the remedial efficiency. A case study was present to demonstrate the screening method in a brownfield site in Cangzhou, northern China. The results show that the systematic method provides a reliable way to quantify the priority of the remedial alternatives.

The North China Plain (NCP) is one of the global hotspots of groundwater depletion, groundwater is almost the only source of water for agricultural, industrial and drinking water in this region. After long-term’s over-exploitation of deep groundwater, there appeared several deep groundwater depression cones, such as Cangzhou cone, Dezhou cone, Hengshui cone, Tianjin cone, etc., in which the Cangzhou cone is one of the typical cones for its special geography and hydrogeology conditions. In this study, the authors intended to analyze the evolution characteristics and influence factors of deep groundwater depression cone in Cangzhou region, especially the No. III aquifer depression cone, which is the main exploitation zone in this region. Analysis of the evolution of the groundwater depression cone of the No. III aquifer group in Cangzhou region showed that this process can be divided into four stages, namely, development, stable development, rapid expansion, and gradual recovery. The shape and evolution characteristics of the depression cone at different stages are described by analyzing the evolution of the −30, −40, and −50 contours of the groundwater table, for example the closed area of water table contour of −50 m has been enlarged from 95 km2 in 1985 to 6 528.5 km2 in 2005. The dominant factors that affect the evolution characteristics at different stages are proposed. The results showed that relatively long dry periods with less precipitation, special geological and hydrogeological conditions, and sharply increased water consumption for industrial and agricultural development are the main factors that cause the formation of deep groundwater depression cones. Meanwhile, an environmental response against groundwater exploitation is presented, and rational solutions are suggested to avert water crisis.

BACKGROUND In situ sorbent amendment for persistent organic pollutant sequestration in sediment has over the past 15 years steadily progressed from bench‐scale trials to full‐scale remediation applications. Hindering a wider technology uptake are, however, concerns about ecotoxic side‐effects of the most commonly used sorbent, activated carbon, on sensitive, sediment dwelling organisms like Lumbriculus variegatus. Using River Tyne sediment polluted with polycyclic aromatic hydrocarbons (PAHs) and L. variegatus as a case study, sorbent alternatives and magnetic sorbent‐recovery were investigated as potential engineering strategies to mitigate such ecotoxic side‐effects. The potential benefits of contacting the treated sediment with fresh River Tyne water, as would naturally occur over time in the intended applications, were studied. RESULTS Magnetic biochar was identified as an effective PAH sorbent with less ecotoxic side‐effects than magnetic activated carbon. After 85.1–100% magnetic recovery of this biochar, no ecotoxic side‐effects on L. variegatus were measurable in the treated sediment. Results show that ecotoxic effects of magnetic activated carbon can be alleviated through sorbent recovery. In contrast, contacting treated sediment repeatedly with River Tyne water had no measurable benefits. CONCLUSIONS Magnetic biochar is a promising sorbent material for the remediation of PAH polluted sediment. © 2017 The Authors. Journal of Chemical Technology & Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

A new composite adsorbent, zeolite-supported microscale zero-valent iron (Z-mZVI) was evaluated as a potential adsorbent for the removal of Cd

This paper introduced the first hand investigation results of the risk and treatment measures for the barrier lakes triggered by the earthquake of Wenchuan. Characteristics of 10 barrier lakes were investigated and analyzed; procedure and methods for barrier lake treatment were brought forward. The dams of the barrier lakes can be classified as two classes: block rock in the south and loose deposit in the north. All the barrier dams were stable at the time of investigation, but water drainage channel needed to be constructed and to be protected from blockage or collapse. After the rain season of 2008, some dams needed to be consolidated, and change the barrier lakes to reservoirs.

The paper aims to summarize the features of the Yellow River basin from viewpoints of physiographic conditions, climate, hydrography, economic development and water resources demand. The Yellow River basin is higher in the west and lower in the east, descending in three huge topographic steps. Most of the area belongs to the arid and semiarid continental monsoon climate zones and relatively dry. The main stream of the basin is 5,464 km long, and divided into upper, middle and lower reaches. The catchment area for upper reach is 38.6×10 km, and that for middle reach is the same, but lower reach very small (2.24×10 km). Both the upper and middle reaches are sections of rich water resources, but the middle reaches are also the main source for silt load. Economic development is presently unbalanced between upper-middle and middle-lower reaches. Based on these datasets, water demand for 2010 and 2020 is predicted.

Zeolite-supported microscale zero-valent iron (Z-mZVI) was synthesized and used to remove heavy metal cation (Cd 2+ ) and anion (Cr 6+ ) from aqueous solution. Transmission electron microscope (TEM) confirmed that mZVI (100–200 nm) has been successfully loaded and efficiently dispersed on zeolite. Atomic absorption Spectroscopy (AAS) revealed the amount of stabilized mZVI was about 1.3 wt.%. The synthesized Z-mZVI has much higher reduction ability and adsorption capacity for Cr 6+ and Cd 2+ compared to bare nanoscale zero-valent iron (nZVI) and zeolite. Above 77% Cr 6+ and 99% Cd 2+ were removed by Z-mZVI, while only 45% Cr 6+ and 9% Cd 2+ were removed by the same amount iron of nZVI, and 1% Cr 6+ and 39% Cd 2+ were removed by zeolite alone with an initial concentration of 20 mg/L Cr 6+ and 200 mg/L Cd 2+ . The removal of Cr 6+ by Z-mZVI follows the pseudo first-order kinetics model, and X-ray photoelectron spectroscopy (XPS) analysis confirmed that Cr 6+ was reduced to Cr 3+ and immobilized on the surface of Z-mZVI. The removal mechanisms for Cr 6+ include reduction, adsorption of Cr 3+ hydroxides and/or mixed Fe 3+ /Cr 3+ (oxy)hydroxides. The pseudo-second-order kinetic model indicated that chemical sorption might be rate-limiting in the sorption of Cd 2+ by Z-mZVI. This synthesized Z-mZVI has shown the potential as an efficient and promising reactive material for removing various heavy metals from wastewater or polluted groundwater.

Carbon nanotubes (CNTs), because of their wide application, will inevitably enter aquatic systems, but the fate and transport of their suspensions in the environment are largely unknown. Clay minerals are expected to interact with CNT suspensions, affecting their fate and bioavailability. This study investigated the influence of clay minerals (kaolinite and montmorillonite) on the stability of surfactant (SDBS, CTAB, and TX100) facilitated multiwalled CNT (MWCNT) suspensions. Adsorption of the surfactants by MWCNTs and clay minerals was also examined. This is a first study on the interaction between clay minerals and surfactant-CNT suspensions. Sorption of SDBS by clay minerals and MWCNTs followed the order MWCNTsmontmorillonite approximately kaolinite; but sorption of CTAB and TX100 followed the order montmorilloniteMWCNTskaolinite. For SDBS suspended MWCNTs, introduction of montmorillonite and kaolinite could not change their stability; for CTAB suspended MWCNTs, both montmorillonite and kaolinite greatly deposited the suspended MWCNTs; for TX100 suspended MWCNTs, montmorillonite could partially deposit the suspended MWCNTs, whereas kaolinite showed minimal effect. Two mechanisms of clay minerals affecting MWCNT suspensions are (1) removal of surfactants by clay minerals from solution and MWCNT surface and (2) bridging between clay mineral and MWCNTs by surfactant.