Since usual processes involve water as absorbent, they appear not always really efficient for the treatment of hydrophobic volatile organic compound (VOC). Recently, absorption and biodegradation coupling in a two-phase partitioning bioreactor (TPPB) proved to be a promising technology for hydrophobic compound treatment. The choice of the organic phase, the non-aqueous phase liquid (NAPL) is based on various parameters involved in both steps of the process, hydrophobic VOC absorption in a gas–liquid contactor, and biodegradation in the TPPB. VOC solubility and diffusivity in the selected NAPL, as well as NAPL viscosity, seems to be the main parameters during the absorption step, while biocompatibility, namely the absence of toxic effect of the NAPL towards microorganisms, non-biodegradability and VOC partition coefficient between NAPL and water were revealed as the key factors during the biodegradation step. The screening of the various NAPL available in the literature highlighted two families of compounds matching the required conditions for the proposed integrated process, silicone oils and ionic liquids.

Volcanic rock is a potential adsorbent for metallic ions from wastewater. This study determined the capacity of Gisenyi volcanic rock found in Northern Rwanda to adsorb Cd, Cu, Pb and Zn using laboratory scale batch experiments under a variety of experimental conditions (initial metal concentration varied from 1 to 50 mg/L, adsorbent dosage 4 g/L, solid/liquid ratio of 1:250, contact time 120 h, particle size 250–900 μm). The adsorbent had a surface area of 3 m2/g. The adsorption process was optimal at near-neutral pH 6. The maximal adsorption capacity was 6.23, 10.87, 9.52 and 4.46 mg/g for Cd, Cu, Pb and Zn, respectively. The adsorption process proceeded via a fast initial metal uptake during the first 6 h, followed by slow uptake and equilibrium after 24 h. Data fitted well the pseudo second-order kinetic model. Equilibrium experiments showed that the adsorbent has a high affinity for Cu and Pb followed by Cd and Zn. Furthermore, the rock is a stable sorbent that can be reused in multiple sorption–desorption–regeneration cycles. Therefore, the Gisenyi volcanic rock was found to be a promising adsorbent for heavy metal removal from industrial wastewater contaminated with heavy metals.

Stem cuttings with homogenous diameter of Populus x euramericana (clone I-214) and Salix fragilis L. were grown in growth chamber in water culture method. After 45 days, the plants were treated with 10−7 and 10−5 M cadmium (Cd). As these species have different phytoextraction potentials, there is a need to analyze the level of Cd uptake, its translocation into aboveground organs, and changes in leaf structure. We analyzed micromorphological leaf characteristics: a fresh mass of the root, stem, and leaf, as well as a Cd concentration within them. Besides, we compared 23 micromorphological leaf blade quantitative traits of poplar and willow and monitored the structural changes induced by the intoxication of stem cuttings. Percent of Cd accumulation and translocation in plant organs varied between species. It depended on the level of Cd applied. When compared to the poplar clone, S. fragilis had a smaller leaf area and epidermal cells, thicker palisade tissue, smaller lumen of main vein vessels, and a higher percentage of main vein xylem. S. fragilis had more distinctive xeromorphic characteristics in the lamina structure. Increased concentrations of Cd led to significant structural changes, mainly in the main vein. When searching for valid parameters in assessing plant to be utilized in phytoremediation, it is necessary to take into consideration the interrelation of a large number of micromorphological parameters together with physiological and biochemical characteristics.

The application of poly(acrylamide-co-sodium methacrylate) (AAm/SMA) hydrogel for the removal of Pb²⁺ ions from aqueous solutions has been investigated using batch adsorption technique. The extent of adsorption was investigated as a function of pH, adsorbent dose, and temperature. The Fourier transform infrared (FTIR) spectra showed that –NH₂ and –COOH groups are involved in Pb²⁺ ion adsorption. The obtained results were analyzed by pseudo-first-order, pseudo-second–order, and intraparticle diffusion models using both linear and nonlinear methods. It was found that the Pb²⁺ ion adsorption followed pseudo-first-order kinetics. Nonlinear regression analysis of six isotherms, Langmuir, Freundlich, Redlich-Peterson, Toth, Dubinin-Radushkevich, and Sips, have been applied to the sorption data, while the best interpretation was given by Redlich-Peterson. Based on the separation factor, R L, the Pb²⁺ ion adsorption is favorable, while the negative values of ∆G indicates that the Pb²⁺ ion adsorption on the investigated hydrogel is spontaneous.

Poultry litter leachate (PLL) is known to contain a variety of contaminants including endocrine disrupting compounds (EDCs). This study analyzed the presence of steroids and contaminants in samples of poultry litter from a broiler poultry operation in Maryland, USA. Litter samples were homogenized, hydrated, incubated for two time periods (4 and 24 h) at two temperatures (20°C and 37°C), filtered, and analyzed for steroids and anthropogenic contaminants. In addition, duplicate samples were spiked with 17‐β estradiol (E2) and testosterone (T), and β-glucuronidase and aryl sulfatase, to measure steroid recovery and the presence of conjugates, respectively. A steroid recovery rate of 71 and 73% was obtained from E2 and T spiked samples, respectively. Increased incubation duration demonstrated an increased trend in E2 and a decreased trend in androgen (T and/or dihydrotestosterone [DHT]) concentrations, regardless of temperature. In contrast, increased incubation temperature displayed different trends in E2 and androgen concentrations. High temperature with a 4-h incubation resulted in an increased trend in androgen with no effect on E2. However, after 24 h of incubation at high temperature, an increased trend in E2 was observed with no effect on androgen. The presence of de-conjugating enzymes resulted in a greatly increased trend in T concentrations with a slight increased trend of E2 concentrations. Trace amounts of several metals and anthropogenic compounds were detected. Arsenic, barium, endosulfan, and bis (2-ethylhexyl) phthalate were detected at quantifiable levels. This study demonstrates that PLL contains potential EDCs and contaminants that can be toxic to, and bioaccumulate in, aquatic fauna. Determination of EDC concentrations in environmental samples is important to elucidate potential detrimental effects of agricultural runoff on aquatic wildlife.

The Loxahatchee National Wildlife Refuge (Refuge) developed as a system with waters low in nutrients. Today, the Refuge wetlands are impacted by inflows containing elevated nutrient concentrations originating from agricultural sources flowing into canals surrounding the west side and from urban and horticultural areas flowing into canals surrounding the eastern side of the Refuge. We analyzed water quality sampled at 40 sites divided into eastern and western areas and four zones in the Refuge. We defined four zones as the canals surrounding the Refuge marsh, the perimeter zone, the transition zone, and the interior zone. The canal receiving agricultural inflows had greater alkalinity and conductivity (SpC), Si and SO4 but lower turbidity and total suspended solids than the canal receiving urban and horticultural inflows. Alkalinity, total dissolved solids (TDS), SpC, Ca, Cl, and SO4 concentrations were greater in the perimeter than in transition and interior zones. Alkalinity and SpC values and SO4 concentrations were greater in the transition than in interior zone. Alkalinity, SpC, and TDS values and Ca, SO4, and Cl concentrations correlated in negative curvilinear relationships with distance from the canal (r 2 = 0.78, 0.70, 0.61, 0.78, 0.64, 0.57, respectively). Analysis of multiple water quality parameters may reveal the complexity of interactions that might be overlooked in a simple single parameter analysis. These data show an impact of canal water containing high nutrient concentrations on water quality flowing from the canal towards the Refuge interior.

Four devices developed for measuring settling velocity distributions of combined sewer overflow (CSO) solids were applied to dry and wet weather flow samples from an urban area serviced by combined sewers (Welland, ON, Canada). The settling column-based methods (the Aston, Brombach and US Environmental Protection Agency columns) produced comparable results indicating minimal differences in settleability of dry and wet weather samples. The elutriation apparatus, which assessed settling velocities in a flowing medium, indicated higher settleabilities than the column methods. This was attributed to enhanced opportunities for particle coalescence in the flowing medium, which should better approximate actual sedimentation conditions. While the elutriation apparatus also indicated larger differences in settleabilities between dry and wet weather samples than the column methods, this difference was not statistically significant. Experimental distributions of particle settling velocities were approximated by a mathematical function, which was then used to estimate partial settling of total suspended solids (TSS) with settling velocities smaller than the clarifier overflow rate. The TSS removal target of 50%, which is applicable to CSOs in Ontario, could be met for overflow rates ranging from 4.7 to 6.8 m/h, for dry and wet weather flows, respectively, based on the average settling velocities measured. Experimental data collected in the study indicate that the design of CSO storage and settling facilities is affected, among other factors, by both the apparatus used to assess CSO settleability and the inter-event variability of CSO settling characteristics.

The concentrations of heavy metals in water, sediments, soil, roots, and shoots of five aquatic macrophytes species (Oenanthe sp., Juncus sp., Typha sp., Callitriche sp.1, and Callitriche sp.2) collected from a detention pond receiving stormwater runoff coming from a highway were measured to ascertain whether plants organs are characterized by differential accumulations and to evaluate the potential of the plant species as bioindicators of heavy metal pollution in urban stormwater runoff. Heavy metals considered for water and sediment analysis were Cd, Cr, Cu, Ni, Pb, Zn, and As. Heavy metals considered for plant and soil analysis were Cd, Ni, and Zn. The metal concentrations in water, sediments, plants, and corresponding soil showed that the studied site is contaminated by heavy metals, probably due to the road traffic. Results also showed that plant roots had higher metal content than aboveground tissues. The floating plants displayed higher metal accumulation than the three other rooted plants. Heavy metal concentrations measured in the organs of the rooted plants increased when metal concentrations measured in the soil increased. The highest metal bioconcentration factors (BCF) were obtained for cadmium and nickel accumulation by Typha sp. (BCF = 1.3 and 0.8, respectively) and zinc accumulation by Juncus sp. (BCF = 4.8). Our results underline the potential use of such plant species for heavy metal biomonitoring in water, sediments, and soil.

Reclamation of land disturbed due to mining in arid and semiarid environments occurs across the globe. Large-scale surface mines provide unique opportunities to examine the reclamation process across a landscape. The objectives of this research were to (1) measure infiltration rates in reclaimed surface coal mines and (2) determine the effects of soil properties on ground cover on infiltration rates of surface coal mines. In this study, reclaimed land 10–15 and 20–25 years old, and native reference site (undisturbed) were investigated at two large surface coal mines in Wyoming, USA. Infiltration rates were measured using double-ring infiltrometer method. The soil properties including bulk density, pH, carbonate content, organic carbon content, aggregate stability, electrical conductivity, and soil texture were analyzed using standard methods. The ground cover was estimated visually. Statistical analysis was conducted to determine if any correlations between infiltration rate and soil properties and ground cover exist. Results suggest that at Mine 1, infiltration rates on reclaimed land were found to be significantly higher in the 20–25-year-old reclamation than the 10–15-year-old reclamation and the native site. At Mine 2, the native site had significantly higher infiltration than 20–25-year-old reclamation, which in turn had significantly higher infiltration rates than the 10–15-year-old reclaimed site. Along with infiltration, soil characteristics were examined. Overall, the findings of this study suggest soil texture and plant cover play an important role in controlling infiltration rates in reclaimed surface coal mines.

Utilization of industrial solid wastes for the treatment of wastewater from another industry could help environmental pollution abatement, in solving both solid waste disposal as well as liquid waste problems. Red mud (RM) is a waste product in the production of alumina and it poses serious pollution hazard. The present paper focuses on the possibility of utilization of RM as an adsorbent for removal of Remazol Brilliant Blue dye (RBB), a reactive dye from dye-contaminated water. Adsorption of RBB, from dye-contaminated water was studied by adsorption on powdered sulfuric acid-treated RM. The effect of initial dye concentration, contact time, initial pH, and adsorbent dosage were studied. Langmuir isotherm model has been found to represent the equilibrium data for RBB–RM adsorption system better than Freundlich model. The adsorption capacity of RM was found to be 27.8 mg dye/g of adsorbent at 40 °C. Thermodynamic analysis showed that adsorption of RBB on acid-treated RM is an endothermic reaction with ∆H ⁰ of 28.38 kJ/mol. The adsorption kinetics is represented by second-order kinetic model and the kinetic constant was estimated to be 0.0105 ± 0.005 g/mg min. Validity of intra-particle diffusion kinetic model suggested that among the mass transfer processes during the dye adsorption process, pore diffusion is the controlling step and not the film diffusion. The process can serve dual purposes of utilization of an industrial solid waste and the treatment of liquid waste.