Consuming drinking water contaminated with As(V) represents a hazard to human health. Adsorption of As(V) onto bone char (BC) has been studied previously, but a detailed study is required for applying BC to remove arsenate present in drinking water. The effect of the operating conditions, water matrix, and presence of fluoride onto the adsorption capacity of BC toward As(V) were thoroughly investigated. The XRD examination confirmed the presence of hydroxyapatite in BC, and the TEM examination of BC showed the random piling of the layers of hydroxyapatite. The BC adsorption capacity was contrasted with that of reagent-grade hydroxyapatite, and it was found that the BC capacity was mainly attributed to its hydroxyapatite content. The BC capacity is augmented by diminishing the solution pH because of the rise of the electrostatic attraction between the arsenate in water and the positive charge of the BC surface. The adsorption capacity was improved by incrementing the temperature so that the adsorption of As(V) was endothermic. The adsorption mechanism of As(V) on BC comprised electrostatic attraction and ion exchange. The simultaneous elimination of fluoride and arsenate in drinking water samples in San Luis Potosí, SLP, México, revealed that both pollutants could be effectively removed by adsorption on BC, and the presence of As(V) did not affect the adsorption capacity of BC toward fluoride. In contrast, the capacity of BC for adsorbing As(V) was enhanced in the drinking water compared with that of deionized water, and this synergistic behavior was due to a screening effect.

Climate scenarios for future global warming expect the enhancement of the hydrological cycle during the twenty-first century. In particular, accurate simulation of water content in the soil depends not only on the correct determination of the percentages of each component in the water balance but also on the measured biophysical properties of the soil available. One of the greatest man-made environmental disasters in history is the destruction of the Aral Sea which is heavily polluted. Possible scenarios have been formulated, to transfer water from the Siberian rivers to Central Asia and to limit the unsustainable extension of irrigation in this region. A new scenario proposed in this paper is partly based on the use of Caspian water evaporators located on the eastern coast of the Caspian Sea. The implementation of this scenario allows the rescue of the Aral Sea and the normalization of water balance in Central Asia. The results of the calculations show that the Aral Sea can be restored over the next 90–240 years depending on these versions. If the anthropogenic outflow of river water is further reduced by 10%, the Aral Sea will be restored for about 90 years. Finally, possible versions of the water recovery scenario are discussed and evaluated and compared with other examples such as Lake Eyre in Australia, Lake Sevan in Armenia, and Lake Chad in central Africa.

Pollution of the potentially toxic elements (PTEs) is a major concern in the metal ore-mining environment. Active polymetallic industries and mines cause great continuous devastation of both terrestrial and aquatic environments on a local and regional scale. This study investigated the pollution of surface water and groundwater in the area containing six large-scale iron ore mines, which have been in operation for more than a few decades. In order to assess the PTEs pollution, the spatial and temporal distributions of 13 different PTEs (Al, As, Co, Li, Mn, Mo, Ni, Pb, Rb, Se, Si, Sr, and Zn) were measured in 42 water samples collected from the multi-aquifer system including three distinct aquifers (upper alluvial aquifer (UAA), lower alluvial aquifer (LAA), and hard-rock aquifer (HRA)) of the Gohar-Zamin mining area in Iran. The highest concentrations of total dissolved solids (TDS = 164,000 mg/l) and PTEs were measured in HRA. Three trends were identified between the PTE concentration and increasing of TDS based on Spearman correlation analysis: (1) an increasing trend for Al, Co, Li, Mn, Rb, Se, Sr, and Ni; there were strong positive correlations in HRA between TDS and Mn (0.83), Al (0.65), Co (0.74), Li (0.90), Ni (0.83), Rb (0.91), Se (0.82), and Sr (0.84), suggesting a common origin for these elements; (2) no obvious trend for As and Mo, no correlation was founded between As and Mo with other PTEs and TDS, indicating a natural geogenic origin and mutual dependencies of these elements; and (3) a decreasing trend for Si, Zn, and Pb; TDS had a significantly negative correlation with the PTEs and attributing to different chemical properties of infiltrated groundwater. In the principal component analysis (PCA), the first PC that covers 85.09% of the total observed variance is mainly attributed the groundwater salinization. This component is composed of Al, Co, Li, Mn, Rb, Se, Sr, and Ni. The second PC contains elements As and Mo. This PC explain 14.4% of total variance and may be referred to natural origin of PTEs. Si, Zn, and Pb are in the third principal component and cover 9.64% of the variance of the data. Third PC have been attributed to lithogenic and/or primary water chemistry factors. The PTE pollution were evaluated based on heavy metal evaluation index (HEI), heavy metal pollution index (HPI), and degree of contamination (Cd). The results indicated that all of the groundwater samples collected from HRA had HEI, HPI, and Cd values greater than 21, 264, and 14 (highly pollution limits of indices), respectively, and were classified as highly polluted groundwater. HPI values within the UAA, LAA, and salt playa (SP) were lower than the critical level of 100, suggesting a threshold for the drinking water pollution. Moreover, HEI and Cd with values of less than 10 and 7 suggested low-level pollution in UAA, LAA, and SP. However, the contaminated level of PTEs exceeded the WHO standard for drinking water in HRA only. Since groundwater in HRA is a brine with the high values of PTEs, pumping of this water out to the surrounding natural environment may cause harmful impacts on the environment and perhaps living species in Bahram-e-Goor protected area. Graphical abstract

The widespread use of diesel/biodiesel blends as a transportation fuel can increase the risk of groundwater contamination, which requires remediation actions. Two pilot-field experiments were conducted to assess and compare their potential to treat groundwater contaminated with B20 (20% biodiesel and 80% diesel, v/v), using combined iron and sulfate biostimulation (CISB) and a modified Fenton system (MFS). A low-cost and sustainable product recovered from acid mine drainage was used to stimulate both iron- and sulfate-reducing conditions. The modified Fenton system was composed of magnesium peroxide to promote the slow release of hydrogen peroxide by magnesium peroxide decomposition. Fe₂O₃ recovered from acid mine drainage was used as catalyst for modified Fenton reaction. Both technologies demonstrated to efficiently degrade B20-blend aromatic hydrocarbons. However, the application of MFS maintained BTEX dissolved concentrations below the detection limit (1 μg L⁻¹) over 22 months, while in CISB, the dissolved concentrations of BTEX compounds were > 50 μg L⁻¹ after 8.4 months. Additionally, total PAH dissolved concentrations in MFS experiment were lower than those observed for the CISB plot. In MFS, microbial growth was inhibited as opposed to CISB in which microbial growth enhanced up to 3 orders of magnitude. Therefore, though MFS was more efficient to meet remediation goals relative to CISB approach, if the site requires complete restoration, less aggressive technologies such as CISB should be considered. This novel pilot study presents chemical and biological technologies that can potentially be applied to remediate diesel/biodiesel blends in groundwater.

Chemcatcher® and POCIS passive sampling devices are widely used for monitoring polar organic pollutants in water. Chemcatcher® uses a bound Horizon Atlantic™ HLB-L sorbent disk as receiving phase, whilst the POCIS uses the same material in the form of loose powder. Both devices (n = 3) were deployed for 21 days in the final effluent at three wastewater treatment plants in South Wales, UK. Following deployment, sampler extracts were analysed using liquid chromatography time-of-flight mass spectrometry. Compounds were identified using an in-house database of pharmaceuticals using a metabolomics workflow. Sixty-eight compounds were identified in all samplers. For the POCIS, substantial losses of sorbent (11–51%) were found during deployment and subsequent laboratory analysis, necessitating the use of a recovery factor. Percentage relative standard deviations varied (with 10 compounds exceeding 30% in both samplers) between individual compounds and between samplers deployed at the three sites. The relative performance of the two devices was evaluated using the mass of analyte sequestered, measured as an integrated peak area. The ratio of the uptake of the pharmaceuticals for the POCIS versus Chemcatcher® was lower (1.84x) than would be expected on the basis of the ratio of active sampling areas (3.01x) of the two devices. The lower than predicted uptake may be attributable to the loose sorbent material moving inside the POCIS when deployed in the field in the vertical plane. In order to overcome this, it is recommended to deploy the POCIS horizontally inside the deployment cage.

Lead is a toxic metal, and its characterization in contaminated soils is crucial to the success of a remediation, especially for the soil washing, one of most commonly used technologies. In this study, we propose a convenient approach that combines sedimentary hydro-classification with semi-quantitative powder X-ray diffraction analysis for characterizing the Pb-bearing minerals in soils. The approach was applied to two samples (YYm and YYu-1) collected from a closed Cu–Pb–Zn mine in the Tohoku region of Japan. The samples were taken from adjacent areas but had different appearances (YYm was a gray soil and YYu-1 was a creamy colored soil). The coarser YYm fractions had higher Pb contents than the finer YYm fractions, but the finer YYu-1 fractions (diameters < 32 μm) had higher Pb contents than the coarser YYu-1 fractions. The semi-quantitative powder X-ray diffraction analysis showed that the main Pb-containing minerals in the YYm and YYu-1 samples were galena and plumbojarosite, respectively. Tessier sequential extractions were also performed, and 1 M sodium acetate leached 21% and 65% of the Pb from the YYm and YYu-1 samples, respectively. This suggested that most of the Pb in the YYu-1 sample was ion-exchangeable and was more easily leached compared with that in the YYm sample. The findings indicate that it is important to accurately characterize the Pb-bearing minerals (especially naturally occurring Pb) present in contaminated soils before selecting appropriate remediation techniques and conditions.

Different studies have shown that livestock manure has a high potential for fertilization in plant growth and crop yield. However, the main challenge of using animal manure as fertilizer is to increase the risk of endocrine-disrupting compounds (EDCs) pollution in soil and water. Because of their adverse effects, these compounds have gained more concern. Farmland applied with manure is considered the primary source of estrogens in the environment. To manage the pollution of EDCs, manure management approaches such as aerobic composting should be utilized to degrade and remove these pollutants. Composting has attracted attention because of its rapid reaction scale and strong degradation ability against the steroidal compounds. However, estrogen removal via traditional composting needs to be improved, as the steroidal compounds that remained in the composted manure could be quickly discharged to the environment because their biodegradation rate is lower than their discharge rate. For that reason, more advanced approaches, such as inoculation with microorganisms, should be involved. Also, applying adsorbent materials such as biochar (BC) and humic acid (HA) should be considered. In the light of the modern studies, affording an overall vision and perspectives about the fate of estrogens during composting is highly valuable. This review was designed to explore the sources, properties, occurrence, half-life, degradation, and transformation of estrogens during animal manure composting. Besides, the efficiency of estrogens degrading microorganisms and adsorbent additives was also reviewed. The eventual remarks were mentioned, and their prospects were discussed.

High levels of heavy metals in soil pose considerable threats to the ecosystem. The in situ remediation technology is obtaining increasing global concerns as a sustainable remediation strategy. In this study, the hydroxyapatite/calcium silicate hydrate (HAP/CSH) was recovered from waste water to evaluate the effects on heavy metal immobilization by coupling with biochar. Five mixtures of HAP/CSH and biochar with different weight ratios (10:0, 0:10, 1:9, 2:8, 4:6 w/w) were prepared to remediate two heavy metal–contaminated soils planted with water spinach (Ipomoea aquatica Forsk.). The mixture of HAP/CSH and biochar in the ratio of 4:6 shows the best immobilization effect assessed by toxicity characteristic extraction procedure (TCLP) and BCR sequence extraction procedure. After remediation, the immobilization efficiency decreased 83%, and content of heavy metals in plants decreased 72.8%. The conversion efficiency of heavy metal residual fraction was 3.95 times higher than that of the control group. At the same time, soil pH, water-soluble organic carbon (WSOC), and soil microbial biomass (SMB) all showed an increasing trend, indicating the improvement of soil conditions. The combined application of HAP/C-S-H and biochar changed soil bacterial community structure, leading to an increase in soil bacterial diversity. The results of redundancy analysis (RDA) suggested that pH and the concentration of heavy metals were the main factors affecting microbial community. Therefore, the mixture of HAP/C-S-H and biochar can be considered as an effective, feasible, and environmentally friendly amendment for the remediation of Cd-contaminated soil and multi-metal–contaminated soil.

The water quality of Lake Mariut has been deteriorated for about 5 decades due to continuous discharge of agricultural, municipal, and industrial wastes from Alexandria City and the adjacent land. During the past two decades, some steps were taken for rehabilitation of the lake through primary treatment of the discharged wastes and insulation of the polluted wastewater of QD from the water body in the main basin of the lake. Several parameters of water quality at the surface and near bottom were measured at twelve locations during winter (January) and summer (August) of 2013 and 2014. The present study revealed that the lake water appeared to be well aerated but still containing high concentrations of N and P and suffering hyper-eutrophic conditions. The water quality index (WQI) reflected medium condition in the lake and bad condition in the diverted drains. The P-budget calculation displayed that TP input into the LMMB from UDᵤₛ and resuspension process from sediments exceeded the output by out flowing at UDdₛ and settling.

Pharmaceutical compounds are considered as emerging contaminants in the aquatic environments that are not easily eliminated by conventional treatment processes. In the present study, the photocatalytic oxidation of acetaminophen and codeine medicines under UV and solar irradiation was investigated in the aqueous solutions using a novel synthesized zeolite from stone cutting sludge as a support for TiO₂ and ZnO. The effect of photocatalyst synthesis conditions including catalyst dose, mixing time, calcination time, and temperature on the efficiency of the pharmaceutical removal were optimized using Taguchi process optimization method. The prepared photocatalysts were characterized using X-ray diffractometer, field emission scanning electron microscopy, energy-dispersive X-ray, the BET surface area, and the Fourier transformation infrared. The results indicated that the performance of ZnO-zeolite for the removal of acetaminophen-codeine under UV and solar radiation with 58.7% and 45.7% was better than that of TiO₂-zeolite with 44.3% and 39.2% efficiency, respectively. Removal efficiency under UV and solar radiation was comparable, suggesting that sunlight could be a promising source for treatment of contaminated water by acetaminophen and codeine using photocatalytic degradation. Regeneration of the prepared photocatalysts after 4 cycles revealed a slight decrease in their efficiency. Overall, photocatalytic degradation of the medicines in the water and wastewater using the ZnO-zeolite and TiO₂-zeolite could be developed as an efficient treatment process.