Catalytic ozonation process (COP) is a promising advanced oxidation process for petrochemical wastewater (PCW) treatment. However, the lack of economical and effective catalysts limits its application. Manganese sand ore (MSO) was utilized as a heterogeneous catalyst for ozonation of organic contaminants in PCW in this study. The calcined MSO-assisted COP (cMSO-COP) of aniline exhibited greater degradation than natural MSO-assisted COP or single ozonation process (SOP). The cMSO significantly promoted hydroxyl radical-mediated oxidation, decreased the ozonation activation energy by about 20 %, and doubled the reaction rates in comparison with SOP. The cMSO-COP increased the chemical oxygen demand (COD) removal of PCW twofold relative to SOP. The number of polar organic contaminants decreased by 50 % after cMSO-COP treatment. This study demonstrated the potential use of cMSO for efficient ozonation of petrochemical-derived contaminants at low cost.

The soil remediation field is still in development in Brazil. Currently, it is not known how many contaminated sites exist across the country; however, due to the country’s large size and its extensive urbanization and industrialization, it can be postulated that the number of contaminated sites must be very high. To remediate these sites, new sustainable technologies should be identified and evaluated. A technology that was born in the 1990s in the USA, and has been fairly investigated, is the use of nanoparticles (NPs) to degrade contaminants in soils and groundwater. This study aims to present a bibliographic review of nanotechnology application to remediation of soils and groundwater, as well as assess the potential of conducting research in this field in Brazil. This paper first presents an overview of the number of contaminated areas identified in the USA and Europe. The basic concepts of nanomaterials followed by classification, synthesis, and characterization of nanomaterials are explained. The main types of contaminants for which the technique was already applied as well as the chemical reactions between them and NPs are presented. The issues related to delivery and migration of NPs in the porous media is discussed. Concerns regarding the toxicity of nanomaterials are discussed. The in situ applications of nanomaterials for contaminated site remediation are presented. It is concluded that the issues involving remediation of soils and groundwater are site specific and it is not possible to directly transfer knowledge gained from sedimentary soils of temperate climates for residual soils found in tropical and subtropical climate regions. The research on nanotechnology for site remediation in Brazil has just begun, and more efforts are required from the technical and academic professionals to develop nanotechnology as practical technology for the remediation of contaminated sites.

Relative displacement of bromide (Br⁻) and coliphage P22 was analyzed in surface water and vadose zone solution from a 3-ha surface flow constructed wetland. In the vadose zone, water samples at 0.3-, 0.76-, 1.5-, and 3-m depth were collected to quantify Br⁻ and P22 simultaneously added into the wetland influent for a transport study. When P22 was detected, Br⁻ arrived earlier to the monitoring depths than the phage suggesting that preferential flow facilitated P22 displacement in the vadose zone. Concentrations for both tracers indicated that bacteriophage removal through the vadose zone profile was exceeding 99.21 % of the peak concentration observed in surface water samples. For transport parameter estimation, the temporal moment method (MOM) was used to calculate convective velocity (v) and longitudinal dispersion coefficient (D) from the outlet Br⁻ breakthrough curve. The transport parameters were estimated to be 55.7 m day⁻¹ and 1652 m² day⁻¹ for v and D, respectively. For P22 simulation, a first-order removal coefficient of 0.3 day⁻¹ (R ² = 0.943) was assessed. The observed results suggest that this method can be applied for solute transport simulation in constructed wetlands.

The search for new bacterial consortia capable of removing PAH from the environment is associated with the need to employ novel, simple, and economically efficient detection methods. A fluorimetric method (FL) as well as high voltage electrochemiluminescence (ECL) on a modified surface of an aluminum electrode were used in order to determine the changes in the concentrations of PAH in the studied aqueous solutions. The ECL signal (the spectrum and emission intensity for a given wavelength) was determined with the use of an apparatus operating in single photon counting mode. The dependency of ECL and FL intensity on the concentration of naphthalene, phenanthrene, and pyrene was linear in the studied concentration range. The biodegradation kinetics of the particular PAH compounds was determined on the basis of the obtained spectroscopic determinations. It has been established that the half-life of naphthalene, phenanthrene, and pyrene at initial concentrations of 50 mg/l (beyond the solubility limit) reached 41, 75, and 130 h, accordingly. Additionally, the possibility of using ECL for rapid determination of the soluble fraction of PAH directly in the aqueous medium has been confirmed. Metagenomic analysis of the gene encoding 16S rRNA was conducted on the basis of V4 hypervariable region of the 16S rRNA gene and allowed to identify 198 species of bacteria that create the S4consortium. The consortium was dominated by Gammaproteobacteria (78.82 %), Flavobacteria (9.25 %), Betaproteobacteria (7.68 %), Sphingobacteria (3.76 %), Alphaproteobacteria (0.42 %), Clostridia (0.04 %), and Bacilli (0.03 %).

Soil metal contamination represents serious threats to plant ecosystem sustainability. Knowledge of metal distribution in plants and the effects of long-term exposure to high levels of metals on cytological stability in Deschampsia cespitosa and Populus tremuloides population is limited. The objective of the present study was to determine how D. cespitosa and P. tremuloides plants cope with soil metal contamination. The effects of high copper (Cu) and nickel (Ni) soil concentrations on cytological stability were also analyzed. The results provide strong evidence that D. cespitosa plants cope with metal contaminations by accumulating them in their root system with limited translocation to their aerial plant parts. Metal bioaccumulation factors were high with values of 5.53 (Cu), 35.19 (Fe), 151.21 (Mg), 24.38 (Ni), and 27.42 (Zn). On the other hand, the bioaccumulation factors in P. tremuloides were 0.42 (Cu), 1.67 (Fe), 4.77 (Mg), 0.94 (Ni), and 5.53 (Zn). The translocation factors (TFs) from roots to leaves for poplar (P. tremuloides) were high for Ni (8.38) and low for Cu (0.71). Cytological analysis clearly showed that long exposure of roots to high levels of metal contamination lead to significant mitotic disruption. Overall, 100 % of the plants from metal-contaminated sites showed a high level of mixoploidy compared to 17 % from the reference sites. Lagging chromosomes in mitotic anaphase were observed in most of the plants from metal-contaminated sites. These mitotic abnormalities appear to have no detectable effects on plant growth and survival.

The paper presents the results of antimony removal from the Dúbrava water resource using a pilot plant system capable of taking samples from different heights of adsorption materials. The adsorbents GEH, CFH12, CFH18, and Bayoxide E33 and two experimental stainless columns with bleeder valves located at heights of 20, 45, and 70 cm of the adsorption media and 91 cm (GEH), 94 cm (CFH18), 87 cm (CFH12), and 87 cm (Bayoxide E33) filter media high were used. The results of the experiments show that the most suitable material for removing antimony from water is GEH. For an antimony concentration of 78.4–108.0 μg/L in raw water and a filtration rate of 5.6–5.9 m/h, the limit concentration of 5 μg/L at the outlet of the 70-cm high adsorption media was reached at the bed volume 1788. In a case when the media height was 91 cm, the antimony concentration in the treated water would reach the limit value of 5 μg/L after a 672-h operation of the stainless column at the bed volume 4256. Under these conditions, the adsorption capacity was calculated at 184 μg/g. The adsorption capacities and bed volumes of the other adsorbents were lower in comparison to GEH.

Deterioration of natural water resources due to runoff from agricultural land is a major problem in the US Great Plains. Changes in earth climate can create heavy storms and alter precipitation patterns which would affect the element concentrations in runoff. A 2-year study (dry and wet years) was conducted to assess the impact of annual precipitation on element concentrations in runoff from soils and element loadings to Salt Creek in the Roca watershed, NE. Both dissolved and sediment-associated forms of five elements (Al, Fe, Mn, Cu, and Zn) were determined in runoff. The amount of dissolved element in runoff during the wet year was greater than the dry year. Except for Zn, the total amount of element associated with sediment was greater than that found in dissolved form. The Mehlich3 extraction was applied to determine the reactive fraction of element in sediment. A small fraction of element associated with sediment was in reactive form, ranging from 1 to 33 % of the total element content. The sum of both the reactive fraction of element in sediment and amount of element dissolved in water were used to calculate the total bioactive element concentration (BEC) in runoff. During the dry year, the total BEC in runoff was 424, 349, 387, 5.2, and 26.8 μg/L for Al, Fe, Mn, Cu, and Zn, respectively. The corresponding total BEC during the wet year was 622, 479, 114, 3.7, and 19.8 μg/L for Al, Fe, Mn, Cu, and Zn, respectively. Further, the bioactive element loading (BEL) into Salt Creek was greater during the wet year than the dry year. Aluminum, Fe, and Mn contributed to the greatest BEL into the surface water body while Zn and Cu had the least contribution. We concluded that greater precipitation during the wet year would increase the negative impact of runoff from soils and BEL to surface water systems in the US Great Plains.

The directive 2008/105/EC suggests the use of sediment or biota matrix for long-term monitoring of specific priority pollutants that tend to accumulate. But, the intermittent nature of flow in the majority of the Mediterranean rivers results in large variability of biological communities and especially fish, making advantageous the examination of pollution trend in sediment matrix and not in living organisms (biota). In this study, sediment environmental quality standards (EQSs) and sediment quality indicators (SQIs) were used to assess pollution by heavy metals (cadmium, nickel, lead, mercury, arsenic, chromium, copper, and zinc) and polycyclic aromatic hydrocarbons (PAHs) in Evrotas River, South Greece, monitored seasonally for 2 years (2009–2010) in five sampling sites. The results showed that, based on SQIs (geoaccumulation index (Igeo), enrichment factor (EF), and modified degree of contamination (mCd)), sediments of the Evrotas River can be classified as “low polluted,” with some exceptions of “extreme pollution.” EQS assessment revealed heavy metal pollution ranging from “low” to “medium high.” Furthermore, based on the Hakanson’s ecological risk index (RI) method, heavy metal potential risk was classified from “low” to “extreme.” Cadmium showed the highest RI values, while mercury reached “moderate” pollution level. The average ΣPAH concentration (24.4 ng g⁻¹) was lower than both the reported EQSs and the values found in literature for unpolluted or moderately polluted river sediments. Increased heavy metal and PAH concentrations were found in sites where mixing of freshwater with reclaimed water occurred. EQSs are suggested to be supplemented with the RI or EF index that consider the natural background to assist a first ecorisk assessment and should be foreseen by 2008/105/EC directive. Sediments can be considered as a valuable matrix in assessing the spatial and temporal trends of several contaminants and should be included in the monitoring program of temporary river management plans. Special attention should be given when defining reference sites and the sampling period. Decreasing flow period at the beginning of the spring prevailed in order to diminish any disturbance by flash flood events.

In this study, nanosized zero-valent iron-reduced graphene oxide (nZVI-rGO)-activated persulfate (PS) was used to investigate the generation of reactive oxygen species (ROS) for the degradation of trichloroethylene (TCE) in the aqueous solution. More than 98 % of TCE was degraded within 2 min under experimental conditions. The generation of ·OH increased when the pH was shifted toward the basic region while ·SO₄⁻ radicals’ intensity increased in the acidic pH. Different scenarios have been observed in ·O₂⁻ generation in the neutral and strong basic pH and decreased in acidic or slightly basic pH. In addition, the intensity of ·OH was increased with the addition of HCO₃⁻ (10 mM) and NO₃⁻ (100 mM) but decreased in the presence of Cl⁻ (10 and 100 mM), HCO₃⁻ (100 mM), and NO₃⁻ (10 mM). The degradation of anisole, probe for both ·OH and ·SO₄⁻, was slightly enhanced by 10 mM NO₃⁻ anions but decreased in 100 mM salt solution. ·O₂⁻ intensity was increased while HCO₃⁻ (10 and 100 mM) and NO₃⁻ (100 mM) anions were used. nZVI-rGO-activated PS process could remove TCE in aqueous effectively, and the ROS generation and intensity were influenced by solution pH values and anions.

Identification of a suitable overlay and index method to map vulnerable zones for pollution in weathered rock aquifers was carried out in this study. DRASTIC and four models derived from it, namely Pesticide DRASTIC, modified DRASTIC, modified Pesticide DRASTIC and Susceptibility Index (SI) were compared by applying them to a weathered rock aquifer in southern India. The results were validated with the measured geochemical data. This study also introduces the use of temporal variation in the groundwater level and nitrate concentration in groundwater as input and for validation respectively to obtain more reliable and meaningful results. Sensitivity analysis of the vulnerability index maps highlight the importance of one parameter over another for a given hydrogeological setting, which will help to plan the field investigations based on the most or the least influential parameter. It is recommended to use modified Pesticide DRASTIC for weathered rock regions with irrigation practises and shallow aquifers (<20 m bgl). The crucial input due to land use should not be neglected and to be considered in any hydrogeological setting. It is better to estimate the specific vulnerability wherever possible rather than the intrinsic vulnerability as overlay and index methods are more suited for this purpose. It is also necessary to consider the maximum and minimum values of input parameters measured during a normal year in the models used for decision making.