The storage of coal combustion residue (CCR) in surface water impoundments may have an impact on nearby water quality and aquatic ecosystems. CCR contains leachable trace elements that can enter nearby waters through spills and monitored discharge. It is important, therefore, to understand their environmental fate in affected systems. This experiment examined trace element leachability into freshwater from fly ash (FA), the most common form of CCR. The effects on water quality of FA derived from both high and low sulfur coal sources as well as the influences of two different emergent macrophytes, Juncus effusus and Eleocharis quadrangulata, were evaluated in wetland microcosms. FA leachate dosings increased water electric conductivity (EC), altered pH, and, most notably, elevated the concentrations of boron (B), molybdenum (Mo), and manganese (Mn). The presence of either macrophyte species helped reduce elevated EC, and B, Mo, and Mn concentrations over time, relative to microcosms containing no plants. B and Mo appeared to bioaccumulate in the plant tissue from the water when elevated by FA dosing, while Mn was not higher in plants dosed with FA leachates. The results of this study indicate that emergent macrophytes could help ameliorate downstream water contamination from CCR storage facilities and could potentially be utilized in wetland filtration systems to treat CCR wastewater before discharge. Additionally, measuring elevated B and Mo in aquatic plants may have potential as a monitoring tool for downstream CCR contamination.

An aerobic denitrification system, initially bioaugmented with Pseudomonas strain T13, was established to treat coal-based ethylene glycol industry wastewater, which contained 3219 ± 86 mg/L total nitrogen (TN) and 1978 ± 14 mg/L NO₃ ⁻-N. In the current study, a stable denitrification efficiency of 53.7 ± 4.7% and nitrite removal efficiency of 40.1 ± 2.7% were achieved at different diluted influent concentrations. Toxicity evaluation showed that a lower toxicity of effluent was achieved when industry wastewater was treated by stuffing biofilm communities compared to suspended communities. Relatively high TN removal (~50%) and chemical oxygen demand removal percentages (>65%) were obtained when the influent concentration was controlled at below 50% of the raw industry wastewater. However, a further increased concentration led to a 20–30% decrease in nitrate and nitrite removal. Microbial network evaluation showed that a reduction in Pseudomonas abundance was induced during the succession of the microbial community. The napA gene analysis indicated that the decrease in nitrate and nitrite removal happened when abundance of Pseudomonas was reduced to less than 10% of the overall stuffing biofilm communities. Meanwhile, other denitrifying bacteria, such as Paracoccus, Brevundimonas, and Brucella, were subsequently enriched through symbiosis in the whole microbial network.

The aim of this study was to investigate phosphate removal using crushed concrete granules (CCGs). The CCGs were thermally treated at different temperatures (300, 500, 700, and 900 °C) for 3 h under anoxic conditions. The results showed that CCGs thermally treated at 700 °C (700TT-CCGs) were the most effective for the removal of phosphate. The equilibrium adsorption data fitted well the Langmuir isotherm model with a maximum phosphate adsorption capacity of 21.522 mg/g, higher than that of granular adsorbents in the literature. In pH experiments, phosphate adsorption by 700TT-CCGs decreased as initial pH increased from 3 to 5, but sharply increased above pH 5 (final pH 9.1), which was favorable for the formation of calcium phosphate precipitate. The effect of competing anions on phosphate adsorption follows the order: HCO₃⁻ > SO₄²⁻ > NO₃⁻, which is consistent with the reverse order of the shared charge. Column experiments showed no breakthrough of phosphate in the column packed with half 700TT-CCGs and half sand for over 300 h. This study demonstrates that CCGs can be used for phosphate removal from aqueous solution after thermal treatment, which is a simple and cheap way to improve the phosphate removal capacity of CCGs.

Increased Cd concentrations in the environment impair plant growth, but plants properly supplied with S may develop greater tolerance to the damage caused by Cd and be used in the remediation of contaminated environments. The aim of this study was to evaluate the Cd-phytoextraction potential of Panicum maximum cv. Tanzania grown with S rates and to identify alterations in the concentrations of nutrients and amino acids and in the activity of some antioxidant enzymes under Cd stress conditions. Combinations of five S rates (0.1, 1.0, 1.9, 2.8, and 3.7 mmol L⁻¹) and five Cd rates (0.0, 0.5, 1.0, 1.5, and 2.0 mmol L⁻¹) in a nutrient solution were provided in two plant growth periods. Concentrations of N, P, and Zn increased, while K, Fe, and Mn decreased with exposure to Cd. The concentration of Ca decreased as the S supply was increased. Isoleucine, leucine, proline, and valine concentrations increased with exposure to Cd and with higher levels of S. The APX activity was higher at the highest Cd exposure level. Activity and number of SOD and GR isoforms in the roots and of CAT in the shoots of the regrown plant decreased at the highest level of contamination by Cd, which was lessened by the supply of greater S rates. Tanzania guinea grass grown with an adequate supply of S has the potential for phytoextraction of Cd-contaminated environments.

Air sparging (AS) is one of the most efficient techniques for remediating saturated soils and groundwater contaminated with volatile organic compounds. Most studies have focused on how the subsurface conditions control the AS process; however, the “side-effects” of AS that feed back to subsurface environment have not been well addressed. This paper studied the perturbation of porous media induced by AS and the consequent multi-parameter changes with the support of Miller soil box and resistivity test, and Darcy experiment and tracer breakthrough test. The Miller soil box test shows that the resistivity response can be credibly used as a non-intrusive method to indicate the porosity change, and that the porosity-resistivity data can be well fitted using Archie equation (R ² > 0.98). Based upon the electricity measurement and above quantitive relationship, it was found that the porosity increased near the air injection point and decreased near the upper boundary of the column due to the upward-transport of particles during air sparging. The changes in porosity were found to be directly proportional to the air injection rate, and the maximum absolute variation of porosity was up to 0.104 at the air flow rate of 20 ml/min, while it did not change in the absence of AS. Both the hydraulic conductivity and dispersion coefficient increased after AS perturbation as the preferential flow pathway formed. The two parameters changed from 3.40 m/d and 0.110 to 6.13 m/d and 0.288, respectively, at 20 ml/min. This work provides useful insight into the changes in flow and transport properties of porous media induced by AS, which then help to understand the instability of air flow and the parameter-uncertainty analysis in related AS model.

Drought is a serious concern in many parts of the world, including in California, where paucity of available irrigation water has impaired crop production and soil health through salt accumulation. With extending water and salinity crises, there is a need for advanced salt and vegetation management. To develop more efficient management solutions, Slingram electromagnetic investigations and stochastic and statistical analyses were performed for determining optimal vegetable yields in a salt-affected farmland. The Slingram results were evaluated using multi-linear regression analyses, and the yield and salinity were characterized for central tendency, variance, distributions and symmetry. The yields of two studied vegetable crops, lettuce and tomato, increased with decreasing salinity load. The average lettuce and tomato yield potentials were 55 and 75%, respectively. The minimum yield potential for tomato was 9.5 times higher than that for lettuce. The mode value for conductivity (ECₑ) was 650 mS m⁻¹, which corresponded to 50% yield loss. The yield loss was <10% in locations with ECₑ < 250 mS m⁻¹. In zones with ECₑ > 850 mS m⁻¹, the yield reductions for lettuce and tomato reached up to 96 and 60%, respectively. About 57 and 82% of the field area could be limited to 20% yield potentials for tomato and lettuce, respectively. Lettuce had a higher cost benefit than tomato albeit with a greater yield potential of the latter crop. By delineating the spatial contours of salt-induced yield variability, vegetables can be grown in segmented soil zones based on salinity levels.

The soil saltiness in the Brazilian semiarid environment is a common problem caused by incorrect agricultural practices, allied to the local weather and soil condition. The use of phosphogypsum (PG) to recover these soils still is a concern since this material has in its composition natural radionuclides. An experiment was conducted to study the use of phosphogypsum to reduce the salinity and evaluate the bioavailability of radionuclides on the Brazilian semiarid region soils. The radionuclide content of phosphogypsum samples were previously analyzed by gamma spectrometry. Three differents doses of phosphogypsum were mixed with samples of surface soil in the greenhouse, and after a reaction time and irrigation, controlled soil samples + phosphogypsum underwent simple extractions based on the sequential extraction method by Tessier et al. Ra isotopes and ²¹⁰Pb in the extracted fractions were analyzed by counting alpha and beta. The higher concentration of Ra isotopes and ²¹⁰Pb were associated to residual fraction, followed by exchangeable fraction due to the low levels of carbonates, organic matter, and manganese and iron oxides. The use of phosphogypsum studied did not contribute to increase the ²²⁶Ra activity on the analyzed soils. ²²⁶Ra levels in phosphogypsum were lower than those recommended by the USEPA to allow the use of phosphogypsum in agricultural soils, but can contribute to the accumulation of ²²⁸Ra and ²¹⁰Pb. The phosphogypsum Imbituba promoted a satisfactory reduction of electrical conductivity in the soils, which indicates the possibility of recovery of these soils.

The presence of synthetic dyes in effluents leads to an environmental imbalance characterized by a decrease in photosynthetic activity and, therefore, a reduction of available oxygen, which affects all living aquatic species. To reduce this problem, a combination adsorption and biodegradation treatment strategy is proposed. In this work, Red 40 dye was adsorbed onto a low-cost waste product, followed by degradation by Trametes versicolor under solid state fermentation conditions. The principal aim of this research was to establish the best fermentation conditions using a kinetic evaluation of both degradation and laccase enzyme activity. The process was scaled-up using a rotating drum bioreactor. The best process conditions were a carbon:nitrogen ratio of 30:1, a moisture percentage of 75%, and an inductor concentration of 0.5 mM; the maximum dye degradation was 96.04%. Under these optimized conditions, the highest enzymatic activity was 8.49 U/gdₘ after 14 days of culture at the flask scale. Using a rotating drum bioreactor, 630 mg of azo dye was degraded after 30 days of culture. Red 40 dye degradation was confirmed using infrared spectroscopy Fourier transform infrared spectrometer and HPLC-MS techniques. The results show that the degradation percentage has a direct relation with laccase activity, and the obtained efficiency in the rotating drum bioreactor confirms the potential of this methodology for implementation at the industrial level.

A comparative study between conventional methods (EPA 3050B and ISO 11466.3) of metal extraction and a simple low-cost method, using aqua regia, was carried out in this work. Six elements (Mn, Cu, Zn, Pb, Ni, and Cd) were determined by flame atomic absorption spectrometry (FAAS) in a certified sample of sediment (CNS 392). Central composite design (CCD) and response surface methodology (RSM), as well as machine learning, were used to find the optimal conditions for metal extraction. The influence of the parameters—volume of nitric acid in aqua regia (v), time of extraction (t), and temperature (T)—on Mn, Cu, Zn, and Pb recoveries was investigated. The best condition for the recovery of all the metals was v = 2.5 mL of HNO₃, t = 2 h, and T = 90 °C. In comparison with the conventional methods, the aqua regia method was found to present better recovery values and lower standard deviations for all the metals studied.

Chicken feather, which is consisted of keratin, has always been abandoned as solid waste. The utilization technologies of waste keratin have been developed in electric zones and materials fields so far. Recently, numerous new types of adsorbents have been used for antibiotic removal. The chicken feather carbon is supposed to be a potential one. In this study, an activated feather carbon (AFC) was developed as the absorbent of amoxicillin (AMOX) in simulated wastewater. The micropore structures of AFC were detected by the scanning electron microscope (SEM). X-ray photoelectron spectrum (XPS) was recorded and analyzed. A BET surface area, as high as 1838.86 m²/g, was measured in this study. At the meantime, a rapid adsorption (5∼7 min) and high removal efficiency (99.63%) could be observed. The kinetics, isotherms, and thermodynamic studies indicated that the adsorption of AMOX by AFC was an exothermic physic-adsorption. The interaction between AMOX and AFC surface was supposed to be a multiple-layer adsorption process for it is well fitted with the Freundlich model. The adsorption behavior could be described by pseudo-second-order model almost perfectly in kinetic studies. In addition, effect of pH, ionic strength, and reusability properties were also discussed in this paper. The AFC was proved to be the most rapid, efficient, and economically absorbent for AMOX removal, which was effective enough under various temperatures and saline circumstances. It was also proved useful, convenient, and renewable in dealing with the tough antibiotic pollutant problems and rebuilding of antibiotic sewage treatment facilities.