Sericite, a mica-based natural clay was employed in the remediation of waters contaminated with two important heavy metal toxic ions, viz. Cd(II) and Mn(II), under batch and column experimentation. The batch reactor studies were intended to study various physicochemical parameters, viz. effect of sorptive pH, concentration, contact time, and background electrolyte concentrations which helped to deduce the mechanism involved at the solid/solution interface. The percent uptake of Cd(II) and Mn(II) was increased with increasing of the sorptive pH, and almost 100 % of these cations were removed at pH 10. Equilibrium-state sorption data was modeled and fitted well to the Langmuir and Freundlich adsorption isotherms. The kinetic data followed the pseudo-first-order and pseudo-second-order kinetic models. Increasing the background electrolyte concentrations by 100 times caused significant decrease of the uptake of Cd(II) and Mn(II) ions, which inferred that these metal cations were less adsorbed specifically and predominantly attached with relatively weak electrostatic attraction onto the solid surface. Additionally, the fixed-bed column reactor operations were also performed to assess the suitability of sericite in the attenuation of Cd(II) and Mn(II) from aqueous solutions under dynamic conditions. The breakthrough data obtained were successfully utilized to fit into a nonlinear fitting of Thomas equation. The results showed that the naturally and abundantly available sericite could be a potential natural material in the remediation of aquatic environment contaminated with Cd(II) and Mn(II).

Cloud point extraction (CPE) factors, namely Triton X-114 (TX-114) concentration, pH, ionic strength, incubation time, and temperature, were optimized for the separation of nano-sized copper(II) oxide (nCuO) in aqueous matrices. The kinetics of phase transfer was studied using UV–visible spectroscopy. From the highest separation rate, the most favorable conditions were observed with 0.2 % w/v of TX-114, pH = 9.0, ionic strength of 10 mM NaCl, and incubation at 40 °C for 60 min, yielding an extraction efficiency of 89.2 ± 3.9 % and a preconcentration factor of 86. The aggregate size distribution confirmed the formation of very large nCuO–micelle assemblies (11.9 μm) under these conditions. The surface charge of nCuO was also diminished effectively. An extraction efficiency of 91 % was achieved with a mixture of TX-100 and TX-114 containing 30 wt.% of TX-100. Natural organic and particulate matters, represented by humic acid (30 mg/L) and micron-sized silica particles (50 mg/L), respectively, did not significantly reduce the CPE efficiency (<10 %). The recovery of copper(II) ions (20 mg/L) in the presence of humic acid was low (3–10 %). The spiked natural water samples were analyzed either directly or after CPE by inductively coupled plasma mass spectrometry following acid digestion/microwave irradiation. The results indicated the influence of matrix effects and their reduction by CPE. A delay between spiking nCuO and CPE may also influence the recovery of nCuO due to aggregation and dissolution. A detection limit of 0.04 μg Cu/L was achieved for nCuO.

Fast-growing metal-accumulating woody plants are considered potential candidates for phytoextraction of metals. Shuikoushan mining, one of the biggest Pb and Zn production bases in China, presents an important source of the pollution of environment during the last 100 years. Over 150 km²of fertile soil have been contaminated by the dust, slag, and tailings from this mining. The goal of the present work has been to determine the content of Pb, Zn, Cd, and Cu in wild woody plants (18 species) naturally growing in this area. Two hundred five plant and soil samples from 11 contaminated sites were collected and analyzed. In addition, to assess the ability of multi-metal accumulation of these trees, we proposed a predictive comprehensive bio-concentration index (CBCI) based on fuzzy synthetic assessment. Our data suggest some adult trees could also accumulate a large amount of metals. Pb concentrations in leaves of Paulownia fortunei (Seem.) Hemsl. (1,179 mg/kg) exceeded the hyperaccumulation threshold (1,000 mg/kg). Elevated Pb concentrations (973.38 mg/kg) were also found in the leaves of Broussonetia papyrifera (L.) Vent., with a Pb bio-concentration factor of up to 0.701. Endemic species, Zenia insignis Chun exhibited huge potential for Zn and Cd phytoextraction, with the highest concentrations of Zn (1,968 mg/kg) and Cd (44.40 mg/kg), characteristic root nodules, and fast growth rates in poor soils. As for multi-metal accumulation ability, native species B. papyrifera was calculated to have the most exceptional ability to accumulate various metals simultaneously (CBCI 2.93), followed by Amorpha fruticosa L. (CBCI 2.72) and Lagerstroemia indica L. (CBCI 2.53). A trend of increasing metal from trunks to leaves (trunks < branches < leaves) and towards fine roots has been shown by metal partitioning between tissues. The proposed CBCI would allow for the selection of suitable trees for phytoremediation in the future.

River eutrophication could drastically influence the phosphorus (P) in the water and sediment. To understand the biogenic-P species, distribution and bioconversion, five sediment samples were collected from an artificial river, and analyzed by phosphorus-31 nuclear magnetic resonance (³¹P-NMR). The P pollution in the water and sediment were both severe. The average concentrations of total P (TP) and solution reactive phosphorus in the water were 3.0 and 2.6 mg L⁻¹, respectively, which surpass grade V of the national quality standard (China) and should not be used for any purpose. The river sediments accumulated significant inorganic phosphorus (Pi) and organic phosphorus (Po); in the P fractionation, the rank order of the P fractions was as follows: Ca-P > NaOH-Pi > Res-P > KCl-P > NaOH-Po, with average relative proportions of 25.1:16.8:6.6:1.7:1:0. Six P compounds were detected in the NaOH-EDTA extract by³¹P-NMR. Mono-P (8.96–29.58 %) was the dominant forms of biogenic-P, and other smaller fractions of biogenic-P were also observed, including pyro-P (0.22–0.86 %), DNA-P (0.75–2.03 %), phon-P (0–1.57 %), and lipids-P (0–2.66 %). The TP and biogenic-P decreased along the direction of flows, with their average relative proportions 7.97:1.20:1.49:1.00:1.00 and 40.87:2.34:3.46:1.60:1 from the upstream to downstream, respectively. The concentration and species of Po in NaOH-Po were lower than found in³¹P-NMR analysis in this research. Thus, the use of 0.25 M NaOH and 50 mM EDTA extracts and solution³¹P-NMR analysis was a more accurate method for quantifying biogenic-P in the river sediments than P fractionation.

Tordon is a widely used herbicide formulation of 2,4-dichlorophenoxyacetic acid (2,4-D) and 4-amino-3,5,6-trichloropicolinic acid (picloram), and it is considered a toxic herbicide. The purposes of this work were to assess the feasibility of a microbial consortium inoculated in a lab-scale compartmentalized biobarrier, to remove these herbicides, and isolate, identify, and evaluate their predominant microbial constituents. Volumetric loading rates of herbicides ranging from 31.2 to 143.9 g m⁻³ day⁻¹, for 2,4-D, and 12.8 to 59.3 g m⁻³ day⁻¹for picloram were probed; however, the top operational limit of the biobarrier, detected by a decay in the removal efficiency, was not reached. At the highest loading rates probed, high average removal efficiencies of 2,4-D, 99.56 ± 0.44; picloram, 94.58 ± 2.62; and chemical oxygen demand (COD), 89.42 ± 3.68, were obtained. It was found that the lab-scale biofilm reactor efficiently removed both herbicides at dilution rates ranging from 0.92 to 4.23 day⁻¹, corresponding to hydraulic retention times from 1.087 to 0.236 days. On the other hand, few microbial strains able to degrade picloram are reported in the literature. In this work, three of the nine bacterial strains isolated cometabolically degrade picloram. They were identified as Hydrocarboniphaga sp., Tsukamurella sp., and Cupriavidus sp.

This study investigated potential nitrogen fixation, net nitrification, and denitrification responses to short-term crude oil exposure that simulated oil exposure in Juncus roemerianus salt marsh sediments previously impacted following the Deepwater Horizon accident. Temperature as well as crude oil amount and type affected the nitrogen cycling rates. Total nitrogen fixation rates increased 44 and 194 % at 30 °C in 4,000 mg kg⁻¹ tar ball and 10,000 mg kg⁻¹ moderately weathered crude oil treatments, respectively; however, there was no difference from the controls at 10 and 20 °C. Net nitrification rates showed production at 20 °C and consumption at 10 and 30 °C in all oil treatments and controls. Potential denitrification rates were higher than controls in the 10 and 30 ºC treatments but responded differently to the oil type and amount. The highest rates of potential denitrification (12.7 ± 1.0 nmol N g⁻¹ wet h⁻¹) were observed in the highly weathered 4,000 mg kg⁻¹ oil treatment at 30 °C, suggesting increased rates of denitrification during the warmer summer months. These results indicate that the impacts on nitrogen cycling from a recurring oil spill could depend on the time of the year as well as the amount and type of oil contaminating the marsh. The study provides evidence for impact on nitrogen cycling in coastal marshes that are vulnerable to repeated hydrocarbon exposure.

The impact of suspended particles on the bioavailability of pollutants has long been a controversial topic. In this study, adsorption of pentachlorophenol (PCP) onto a natural suspended particulate matter (SPM) and multi-walled carbon nanotubes (MWCNTs) was studied. Facilitated transports of PCP into carp by SPM and MWCNTs were evaluated by bioaccumulation tests exposing carp (Carassius auratus red var.) to PCP-contaminated water in the presence of SPM and MWCNTs, respectively. Desorption of PCP on SPM and MWCNTs in simulated digested fluids was also investigated. The results demonstrate that MWCNTs (KF = 7.99 × 10⁴) had a significantly stronger adsorption capacity for PCP than the SPM (KF = 19.0). The presence of SPM and MWCNTs both improved PCP accumulation in the carp during the 21 days of exposure, and the 21 days PCP concentration in the carp was enhanced by 25.9 and 12.8 % than that without particles, respectively. The enhancement in bioaccumulation by MWCNTs was less than that by the SPM. Considerably more PCP was accumulated in the viscera of the fish (BCF = 519495 for SPM and 148955 for MWCNTs), and the difference in PCP concentrations between different tissues became greater with particles. PCP desorption in the simulated digestive fluids was faster than that in the background solution. Compared to MWCNTs-bound PCP, more SPM-bound PCP was desorbed, and KFof desorption for SPM was at least 4 orders of magnitude higher than that for MWCNTs, which can explain the greater enhancement in bioaccumulation in the presence of SPM. Particle-bound pollutants might pose more risk than pollutants alone.

Extracellular polymeric substances (EPS) are an extracellular matrix found in sludge which plays a crucial role in flocculation by interacting with the organic solids. Therefore, to enhance pretreatment of sludge, EPS have to be removed. In this study, EPS were removed with a chemical extractant, NaOH, to enhance the bacterial pretreatment. A lysozyme secreting bacterial consortium was isolated from the waste activated sludge (WAS). The result of density gradient gel electrophoresis (DGGE) analysis revealed that the isolated consortium consists of two strains. The two novel strains isolated were named as Jerish03 (NCBI accession number KC597266) and Jerish 04 (NCBI accession number KC597267) and they belong to the genus Bacillus. Pretreatment with these novel strains enhances the efficiency of the aerobic digestion of sludge. Sludge treated with the lysozyme secreting bacterial consortium produced 29 % and 28.5 % increase in suspended solids (SS) reduction and chemical oxygen demand (COD) removal compared to the raw activated sludge (without pretreatment) during aerobic digestion. It is specified that these two novel strains had a high potential to enhance WAS degradation efficiency in aerobic digestion.

The application of advanced oxidation process (AOP) in the treatment of wastewater contaminated with oil was investigated in this study. The AOP investigated is the homogeneous photo-Fenton (UV/H₂O₂/Fe⁺²) process. The reaction is influenced by the input concentration of hydrogen peroxide H₂O₂, amount of the iron catalyst Fe⁺², pH, temperature, irradiation time, and concentration of oil in the wastewater. The removal efficiency for the used system at the optimal operational parameters (H₂O₂ = 400 mg/L, Fe⁺² = 40 mg/L, pH = 3, irradiation time = 150 min, and temperature = 30 °C) for 1,000 mg/L oil load was found to be 72 %. The study examined the implementation of artificial neural network (ANN) for the prediction and simulation of oil degradation in aqueous solution by photo-Fenton process. The multilayered feed-forward networks were trained by using a backpropagation algorithm; a three-layer network with 22 neurons in the hidden layer gave optimal results. The results show that the ANN model can predict the experimental results with high correlation coefficient (R² = 0.9949). The sensitivity analysis showed that all studied variables (H₂O₂, Fe⁺², pH, irradiation time, temperature, and oil concentration) have strong effect on the oil degradation. The pH was found to be the most influential parameter with relative importance of 20.6 %.