Release of antibiotics into the environment, which often occurs downstream of wastewater treatment plants, poses a human health threat due to the potential development of bacterial antibiotic resistance. In this study, laboratory experiments were conducted to evaluate the performance of ball milled biochar on the removal of two sulfonamide antibiotics, sulfamethoxazole (SMX) and sulfapyridine (SPY) from water and wastewater. Aqueous batch sorption experiment using both pristine and ball milled biochar derived from bagasse (BG), bamboo (BB) and hickory chips (HC), made at three pyrolysis temperatures (300, 450, 600 °C), showed that ball milling greatly enhanced the SMX and SPY adsorption. The 450 °C ball milled HC biochar and BB biochar exhibited the best removal efficiency for SMX (83.3%) and SPY (89.6%), respectively. A range of functional groups were produced by ball milling, leading to the conclusion that the adsorption of sulfonamides on the biochars was controlled by multiple mechanisms including hydrophobic interaction, π–π interaction, hydrogen bonding, and electrostatic interaction. Due to the importance of electrostatic interaction, SMX and SPY adsorption was pH dependent. In laboratory water solutions, the Langmuir maximum adsorption capacities of SMX and SPY reached 100.3 mg/g and 57.9 mg/g, respectively. When tested in real wastewater solution, the 450 °C ball milled biochar still performed well, especially in the removal of SPY. The maximum adsorption capacities of SMX and SPY in wastewater were 25.7 mg/g and 58.6 mg/g, respectively. Thus, ball milled biochar has great potential for SMX and SPY removal from aqueous solutions including wastewater.

Effectiveness and mechanism of cadmium (Cd) sorption on original, acidified and ball milling nano-particle red muds were investigated using batch sorption experiments, sequential extraction analysis and X-ray absorption near edge structure (XANES) spectroscopy. The maximum sorption capacity of Cd was 0.16, 0.19, and 0.21mol/kg for the original, acidified, and nano-particle red muds at pH 6.5, respectively. Both acidification and ball-milling treatments significantly enhanced Cd sorption and facilitated transformation of Cd into less extractable fractions. The Cd LIII-edge XANES analysis indicated the formation of inner-sphere complexes of Cd similar to XCdOH (X represents surface groups on red mud) on the red mud surfaces although outer-sphere complexes of Cd were the primary species. This work shed light on the potential application of red mud to remediate Cd-contaminated soils and illustrated the promising tool of XANES spectroscopy for speciation of multicomponent systems of environmental relevance.

The most common lead (Pb) and zinc (Zn) ore minerals are galena (PbS) and sphalerite (ZnS). Milling and mining operations of these ores produce huge amounts of waste known as chat and tailings. Chat is composed of gravel, sand, and silt-sized rock materials, whereas tailings are often fine-grained and silt-sized particles with higher toxic element concentrations. Upon oxidation, tailings with high pyritic materials release Pb, Zn, Cadmium (Cd), and other elements associated with ores affecting plant productivity, the ecosystem, and human health. This article is an overview on utilizing the subsurface submergence technique for mitigating environmental impacts from abandoned mine waste materials. In the past, researchers have studied the influence of submergence on these elements; however, an emphasis on gathering a detailed understanding of such redox-based remediation processes is not that common. We reviewed literature that evaluated water chemistry, solid phases, and association of trace elements, and addressed utilization of surface amendments of mine tailings for predicting their interactions within sediments and overlying waters. Case studies specifically focused on mining of Pb and Zn, including a recent study conducted in the Tri-State mining district (Kansas, Missouri, and Oklahoma), are presented to add a more comprehensive understanding of biogeochemical transformations of trace elements present in mine waste materials under a long-term submergence. The purpose of this article is to present evidence on the viability of subsurface disposal of mine waste materials, in order to design effective remediation and mitigation strategies to protect human and environmental health in the global dimension.

From 1861 to the 1940s, gold was produced from 64 mining districts in Nova Scotia, where mercury amalgamation was the dominant method for the extraction of gold from ore until the 1880s. As a result, wastes (tailings) from the milling process were contaminated by mercury and were high in naturally occurring arsenic. In 2004 and 2005, sediments, water and mollusc tissues were collected from 29 sampling stations at nine former gold mining areas along the Atlantic coastline and were analysed for arsenic and mercury. The resulting data were compared with environmental quality guidelines. Samples indicated high potential risk of adverse effects in the intertidal environments of Seal Harbour, Wine Harbour and Harrigan Cove. Arsenic in Seal Harbour was bioavailable, resulting in high concentrations of arsenic in soft-shell clam tissues. Mercury concentrations in tissues were below guidelines. This paper presents results of the sampling programs and implications of these findings.

The adsorption of residue oil from palm oil mill effluent using natural zeolite was investigated in this study. The adsorption was performed in batch mode, and the effect of different operational parameters such as pH, dose of adsorbent, stirring rate, contact time and initial oil concentration were explored. It was found that the pH plays a major role in the adsorption process. Isotherm data best fitted with the Freundlich model, and kinetic data followed the pseudo-second-order kinetic model. The results obtained demonstrated that the oil removal efficiencies by natural zeolite were up to 70 % at a pH of 3.0 and 50 min of contact time. The adsorbent material also has been characterised by X-ray diffraction, X-ray fluorescence and scanning electron microscopy.

Past mining and processing of uranium ore at a former uranium mining site near Monument Valley, AZ has resulted in nitrate contamination of groundwater. The objective of this study was to investigate the potential of ethanol addition for enhancing the reduction of nitrate in groundwater. The results of two pilot-scale field tests showed that the concentration of nitrate decreased, while the concentration of nitrous oxide (a product of denitrification) increased. In addition, changes in aqueous concentrations of sulfate, iron, and manganese indicated that the ethanol amendment caused a change in prevailing redox conditions. The results of compound-specific stable isotope analysis for nitrate–nitrogen indicated that the nitrate concentration reductions were biologically mediated. Denitrification rate coefficients estimated for the pilot tests were approximately 50 times larger than resident-condition (non-enhanced) values obtained from prior characterization studies conducted at the site. The nitrate concentrations in the injection zone have remained at levels three orders of magnitude below the initial values for many months, indicating that the ethanol amendments had a long-term impact on the local subsurface environment.

Radionuclides were determined in streams and rivers receiving mine drainage from old uranium mines at the center of Portugal. Results showed enhanced radioactivity levels in some areas impacted by uranium mining and milling wastes, but levels were lower than several years ago due to current water treatment of mine drainage. In some areas, such as at the village of Cunha Baixa, water from wells was contaminated by acid mine drainage, and it is not suitable anymore for human consumption and irrigation of horticulture plots. In the present, villages and towns near those old uranium mines have tap water from public networks supplied from artificial lakes built in major rivers of the region. This tap water showed compliance with the recommended limits of total alpha and total beta radioactivity, and it is suitable for human consumption. Radiation exposure of the population was therefore controlled, but current water supply is much more costly than it was with local water sources.

Olive oil mill wastewater (OMW) generates a wide variety of pollutants depending on the production process and other factors such as olive varieties and cultivation system. Efforts to mitigate the impact of these effluents in the environment have been made by developing more efficient treatment systems in terms of removal of chemical oxygen demand (COD), color, organic compounds, and toxicity. This study is the first that reports the potential of a treatment of OMW by biocomposites of silica–alginate–fungi (Pleurotus sajor caju and Trametes versicolor). The treatment by biocomposites can be considered as a three-step process responsible for the removal of the compounds: (1) adsorption of reactants on the monolithic structure and diffusion to the biological active sites, (2) biodegradation by the fungi, and (3) diffusion of the products resulting from the biodegradation. Both treatments tested showed potential capacity to remove organic compounds, color, COD, and toxicity. The T. versicolor biocomposites were the most effective and responsible for the reduction in color (from 38.4 to 44.9 %), COD (from 42.8 to 63.8 %), and total phenolic content (from 85.3 to 88.7 %) after 29 days of treatment. The toxicity reduction on Portuguese OMW was minimal, but the use of composites on the Moroccan OMW caused a 9.5- to 19-fold reduction in toxicity. Furthermore, the biocomposites showed potential for re-utilization for more 29 days of treatment.