Laboratory snow melting experiments were conducted with actual late-winter snow samples, collected just before the final snowmelt, in two similar northern Swedish cities, Luleå and Umeå, to investigate releases of the selected heavy metals (HM) (Cu, Pb, Zn, and Cd) and 16 USEPA PAHs from melting snow. Metal concentrations were determined in three fractions: total, dissolved, and truly dissolved (defined as the fraction passing through a 3-kMWCO ultrafilter). Total HM concentrations in snowmelt were rather high at both sites and reflected the accumulation of pollutants in the roadside snowbanks over a period of about 5 months: Cd = 0.43, Cu = 303, Pb = 41.9, Zn = 817 (μg/l), and TSS = 2000 (mg/l) in Luleå samples and Cd = 1.87, Cu = 905, Pb = 165, Zn = 3150 (μg/l), and TSS = 4800 (mg/l) in Umeå samples. The difference between metal and TSS concentrations at the two sites of similar characteristics was attributed to a smaller volume snowbank in Umeå. The dissolved HM concentrations represented relatively small fractions of the total concentrations (0.3–6.9% in Luleå and 0.01–3.1% in Umeå). The truly dissolved fraction represented 71–90% of the dissolved fraction in Luleå and 74–98% in Umeå. At both sites, the dissolved fractions exhibited preferential elution from the laboratory snow piles. The PAHs studied (16 US EPA PAHs) were mostly particulate bound, with only 5–12% of the total burden contributed by the meltwater, and most dissolved concentrations below the reporting limits. PAH concentrations in the Luleå samples were about one-third to one-fourth of those in Umeå. In general, the releases of PAHs from the snowbank were delayed, compared with releases of meltwater, and showed similar release patterns as TSS.

Phosphorus-rich sludge is one of most suitable raw materials for phosphorus recovery as slow release fertilizers by struvite crystallization. However, alginic acid as a surrogate for extracellular polymeric substances in the sludge has been proved to adversely inhibit struvite crystallization. To quantitatively evaluate the inhibitory effect, the study aimed to investigate the influence of the concentration of alginic acid (0–250 mg/L), reactant concentration (2.5–3.5 mmol/L), pH (8.0–9.5), and ionic strength (0.01–0.2 mol/L NaCl), on the inhibition of the growth rate of struvite crystals, which was accurately determined by constant composition technique. The results indicated that the growth rate of struvite crystals substantially decreased with increasing the concentration of alginic acid, thereby adversely affecting the quantity and quality of struvite crystals. Moreover, as reactant concentration or pH increased, the growth rate of struvite crystals showed a considerable increase, whereas the weaker inhibitory effect of alginic acid was observed. Conversely, the increase of ionic strength drastically reduced the growth rate of struvite crystals, but moderately enhanced the inhibitory effect. Our study provides an effective theoretical foundation for deriving high-quality struvite crystals as slow release fertilizers from the phosphorus-rich sludge commonly containing a considerable number of organic pollutants.

The aim of the present experimental study was to perform a technical-economic evaluation of a combined treatment system, consisting of coagulation-flocculation or rapid sand filtration as pre-treatment followed by column adsorption, for reducing the arsenic concentration from approximately 1 mg/L to below the limit set for groundwater remediation and drinking water, i.e., 0.01 mg/L, according to the legislation in force. A wide number of operating conditions were experimentally evaluated in the different tests. In the coagulation-flocculation study, it was initially investigated if the iron contained in a mining drainage co-mixed with the groundwater would be able to achieve a better As content reduction by adsorption/precipitation, thus avoiding fresh coagulant addition. Then, different polyelectrolyte dosages were tested varying the mixing ratio. None of the tested conditions allowed to improve the arsenic removal so significantly to warrant the consequent incremental costs. Therefore, the optimal condition was considered any mixing with a different liquid stream and any polyelectrolyte dosage. The iron content naturally present in the groundwater and contact with air was capable alone of reducing As concentration of about 80%. Sand filtration reached approximately the same removal efficiency (about 80%) at the lower surface loading rate among the values tested. Between coagulation and sand filtration, in terms of costs, the latter showed to be more convenient than coagulation-flocculation, at the same removal efficiency: therefore, it was considered the optimal pre-treatment. The following adsorption column plant was capable of further reducing As concentration up to the required value of 0.01 mg/L. Among the two iron-based commercial adsorbents applied in the adsorption column tests, the hybrid media consisting of an exchange resin with iron oxides showed to be preferable under the selected operating conditions: it offered higher adsorption capacity at breakthrough and, after exhaustion, could be regenerated for a number of cycles. The influent pH showed to have a great influence on the duration of the adsorbent media, and values around neutrality were considered preferable. The estimated cost of the full treatment was computed to be about 0.50 €/m³ of purified water. Therefore, the capacity of achieving the required remediation goal, the limited cost, and simplicity of operation make the proposed combined treatment being potentially suitable for real application.

Nanomaterial applications are a fast-developing field. In spite of their powerful advantages, many open questions regarding how these small-sized chemicals may influence the environment and human health. However, scarce reports are available on the potential hazards of combined nanoparticles, taken into consideration that nickel oxide (NiO) and cobalt (II, III) oxide (Co₃O₄) nanoparticles (NPs) are already used together in many applications. Hence, the present work was designed to study the probable changes in some biological, hematological, and serum biochemical variables throughout 2 weeks following an oral administration of 0.5 g and 1.0 g of NiO-NPs or/and Co₃O₄-NPs per kilogram body weight of rats. As compared with the controls, the exposure to NiO-NPs or Co₃O₄-NPs solely caused significant elevations in the relative weights of brain (RBW), kidney (RKW) and liver (RLW), water consumption (WC), red blood cells (RBCs) count, hemoglobin (Hb) content, packed cell volume (PCV), and serum levels of low-density lipoprotein cholesterol (LDL-C), glucose, creatinine, urea, and uric acid as well as serum activities of aspartate and alanine aminotransferases (ASAT and ALAT). In addition, remarkable declines in the total body weight (TBW), feed consumption (FC), white blood cells (WBCs) count, serum levels of total protein (TP), albumin, albumin/globulin ratio, total cholesterol (TC), triglycerides (TG), and high-density lipoprotein cholesterol (HDL-C) were caused by administration of NiO-NPs or Co₃O₄-NPs, separately. On contrary, the co-administration of NiO-NPs and Co₃O₄-NPs together caused less noticeable changes in most of studied variables as compared with those administered NiO-NPs or Co₃O₄-NPs, individually. In conclusion, the exposure to a combination of NiO-NPs and Co₃O₄-NPs suppressed the adverse effects of the individual NPs on the studied variables.

Concerns regarding disinfection by-product (DBP) formation during drinking water treatment have led water utilities to apply treatment processes to reduce the concentration of DBP precursor natural organic matter (NOM). However, these processes often do not remove bromide, leading to high bromide to dissolved organic carbon (DOC) ratios after treatment, which can increase the formation of more toxic brominated DBPs. In the current study, we investigated the formation and effect of DBPs in a matrix of synthetic water samples containing different concentrations of bromide and DOC after disinfection with chlorine. Trihalomethanes and haloacetic acids were analysed by chemical analysis, while effect was evaluated using in vitro bioassays indicative of the oxidative stress response and bacterial toxicity. While the addition of increasing bromide concentrations did not alter the sum molar concentration of DBPs formed, the speciation changed, with greater bromine incorporation with an increasing Br:DOC ratio. However, the observed effect did not correlate with the Br:DOC ratio, but instead, effect increased with increasing DOC concentration. Water samples with low DOC and high bromide did not exceed the available oxidative stress response effect-based trigger value (EBT), while all samples with high DOC, irrespective of the bromide concentration, exceeded the EBT. This suggests that treatment processes that remove NOM can improve drinking water quality, even if they are unable to remove bromide. Further, iceberg modelling showed that detected DBPs only explained a small fraction of the oxidative stress response, supporting the application of both chemical analysis and bioanalysis for monitoring DBP formation.

In this study, the removal of ciprofloxacin hydrochloride (a fluoroquinolone antibiotic) by using various effective adsorbents such as activated carbon, montmorillonite, modified montmorillonite (commercial name Cloisite 20A), and alumina was investigated. Adsorption experiments were performed to determine and compare the adsorption capacities of these adsorbents. The adsorption capacities of adsorbents were examined at different initial concentrations of ciprofloxacin hydrochloride. Activated carbon was found to be having the best adsorption capacity for the removal of ciprofloxacin hydrochloride. For the solution having an initial ciprofloxacin hydrochloride concentration of 4 ppm, the adsorption capacities of adsorbents were obtained as 1.86 mg g⁻¹ for activated carbon, 1.67 mg g⁻¹ for modified montmorillonite, 1.15 mg g⁻¹ for alumina, and 0.60 mg g⁻¹ for montmorillonite. And also, about 92% of the ciprofloxacin hydrochloride was removed from the water using the activated carbon. In addition, Langmuir, Freundlich, and Temkin isotherm models were employed to express the adsorption process. For all adsorbents, Freundlich isotherm model provided best fitting to the experimental data because of very high values of R² (> 0.99). Kinetic models of pseudo-first order, pseudo-second order, Elovich, and Weber-Morris intraparticle diffusion model were utilized to evaluate the experimental adsorption data. Adsorption kinetics data were well represented by pseudo-second order kinetic model with values of R² (> 0.999).

The aim of this study was to evaluate the acute and chronic effects caused by exposure to the 2,4 dichlorophenoxyacetic acid (2,4-D)-based commercial herbicide Amina Zamba® on Physalaemus albonotatus tadpoles from Gosner stage 25. The lethal concentration (LC50) was determined after exposure to different concentrations of Amina Zamba® (350 to 2400 mg/L) at 96 h. Sublethal effects were evaluated after chronic exposure to four fractions of the LC50₉₆ₕ obtained (12.5, 25, 50, and 75% of LC50₉₆ₕ) and a control. The biological responses analyzed included survival, growth and development, morphological abnormalities, and histological changes in the liver. The LC50 values of Amina Zamba® at 48, 72, and 96 h were 1040.2, 754.2, and 350 mg/L, respectively. The chronic exposure to the herbicide altered the survival of exposed tadpoles and caused several morphological abnormalities and liver histological alterations, mainly at the highest concentrations tested. Oral disc malformations and intestinal abnormalities were the most frequent abnormalities in all treated tadpoles. Histological alterations observed in the liver structure included hepatocyte vacuolization, enlargement of sinusoids, dilation of blood vessels, and a significant increase in the number of melanomacrophages in tadpoles exposed to 25, 50, and 75% LC50₉₆ₕ with respect to control (P < 0.05). Furthermore, the treated tadpoles showed an accelerated development rate, reaching Gosner stages 38 and 42 before controls. These results demonstrate that the chronic exposure to this commercial formulation affects the survival, accelerates metamorphosis, and induces morphological abnormalities and liver damage in P. albonotatus tadpoles.

This study investigated a small waterway that had been impacted by upwelling groundwater due to recent geological strata fracturing caused by subsidence activity from longwall coal mining. Documents from the coal mine report that subsidence has undermined and fractured the stream channel for more than 10 years prior to this study. Mine documents also report many years of variably degraded water quality (salinity, elevated metals) in the reaches affected by fracturing. In this study, water quality of the stream was monitored over an 11-month period with water flow dominated by ground water upwelling through fractures in the creek channel. The upwelling water caused extensive modifications to the creek’s surface water quality relative to unmined reference sites. The mean electrical conductivity increased by seven times from 230 μS/cm at reference sites to 1833 μS/cm below the upwelling. Dissolved oxygen in the upwelling groundwater was extremely low (2.7% saturation) and was mildly acidic (5.8 pH). Alterations to the ionic composition included sevenfold increases in magnesium, sodium, and chloride concentrations. Heavy metals iron and manganese increased by more than ten times, with nickel by more than 60 times compared to the reference sites. The alteration to ionic composition was inferred to be saline groundwater intrusion. The ecological impacts of such large modifications to surface stream water quality would be hazardous for integrity of downstream aquatic ecosystems.

Membrane filtration techniques are distinguished among methods for wastewater treatment and fully correspond to the requirements of the green concept of chemistry and production. The limiting factor for greater application of these methods is the phenomenon of fouling and the decline of the permeate flux. In this study, polynomial neural network based on group method data handling (GMDH) algorithm was applied to predict the performance of the complexation-microfiltration process for the removal of Pb(II), Zn(II), and Cd(II) from synthetic wastewater. The influence of working parameters such as pH, initial concentration of metal ions, type of complexing agent, and pressure on flux was experimentally determined. The data obtained were used as input parameters for the GMDH model as well as for the multiple linear regression (MLR) model. Root mean square error (RMSE), mean absolute error (MAE), and mean absolute percent error (MAPE) were used for evaluation purposes. Results showed that the developed model has excellent performance in flux prediction with R² of 0.9648.

Huge amounts of natural bischofite (MgCl₂∙6H₂O) resulting from the mining process of salt lakes often cannot be utilized effectively and are discarded; techniques for reutilization of the discarded bischofite as magnesium resources are limited. The nano-magnesium hydroxide (nano-Mg(OH)₂) synthesized from natural bischofite was firstly used as catalyst for ozonation of antibiotics including sulfathiazole (ST), ofloxacin (OFL), and tetracycline (TC). Rapid ozonation of ST, OFL, and TC was achieved using nano-Mg(OH)₂ as catalyst. The removal rate constant of OFL in the catalytic ozonation treatment (kOFL = 0.512 min⁻¹) was nearly 2.1 times higher than the single ozonation (kOFL = 0.249 min⁻¹). The removal rate constant of ST and TC increased by 23.5% and 32.8% from 0.298 min⁻¹ and 0.384 min⁻¹ to 0.368 min⁻¹ and 0.510 min⁻¹, respectively, when the catalyst was added into the reaction system. The removal rate constant of ST sharply increased from 0.259 to 0.604 min⁻¹ when the reaction temperature increased from 15 to 35 °C while those of OFL and TC changes slightly. The removal efficiency sharply decreased when the initial concentration of ST, OFL, and TC increased from 10 to 500 mg L⁻¹. Both anions and cations could inhibit the removal of ST, OFL, and TC at relatively higher concentrations. The prepared nano-Mg(OH)₂ catalyst could maintain its catalytic activity in the repeated use process. High removal efficiency of typical antibiotics and heavy metals free indicated that nano-Mg(OH)₂ from natural bischofite is a promising ozonation catalyst in terms of antibiotics removal.