In this study, we investigated the microbiological quality of the small urban Zenne River which flows through the city of Brussels (Belgium). The abundances of faecal indicator bacteria (FIB) (Escherichia coli and intestinal enterococci) revealed high levels of faecal contamination of the Zenne River, especially in Brussels area and downstream from this area where FIB were in the range of what is usually observed in secondary treated wastewaters. The origin of this faecal contamination is mainly attributed to the effluents of the two wastewater treatment plants (WWTPs) located along the river in Brussels. Comparison of the present situation with the 1990s situation (before the implementation of Brussels WWTPs) showed a sharp improvement of the river microbiological quality. This improvement should however be regarded with care as it was also observed that, during rain events, combined sewer overflows (CSO) outfalls were responsible of a strong increase of faecal contamination in the river downstream from Brussels, and such CSO occur frequently in Brussels. Altogether, these results document the variations of the microbiological quality of a sewage-polluted urban river in relation with long-term changes (implementation of WWTP) and the short-term disturbances (CSO).

In the Mezquital valley, untreated wastewater (45 m³ s⁻¹) from Mexico City is used for the irrigation of around 900 km²of agricultural soil. High concentrations of metals including methylmercury (3.8 ± 2.5 ng l⁻¹) and lead (0.16 ± 0.05 mg l⁻¹) were measured in anoxic wastewater canals. Downstream, dissolved, and particulate polymetallic (Hg, Pb, Cr…) concentrations decreased by factors 10 to 1,000 in the Tula River (which received a mix of fresh and wastewater) due to the dilution and oxidation of surface water, and to the decrease of contaminants concentration in wastewater downstream irrigated soils. However, dissolved and particulate methylmercury concentrations (0.06 to 0.33 ng l⁻¹and 1.6 to 4.5 μg kg⁻¹, respectively) remained elevated in comparison to other natural hydrosystems. The monitoring of an irrigation event and the distribution of metals in a soil profile irrigated for more than 80 years showed that metals were retained in the draining tilled layer. The oxic conditions and slightly acidic pH (~6.5) in this layer were found favorable for metal adsorption and co-precipitation with redox-sensitive elements (Fe, Mn) and suggestively for mercury demethylation. In the downstream Tula River and groundwater, almost all metallic concentrations remained below guideline thresholds. Only, dissolved As and Pb concentrations remained two to five times above thresholds for drinking water, highlighting a potential health risk for approximately 500,000 people who use groundwater as water supply.

This paper presents a study of the combined process of adsorption and biodegradation in solid biologically activated carbon (AC) for the removal of salicylic acid aimed at determining the influence of the presence of biofilm on the process. Adsorption on AC and biodegradation of free cell cultures were studied separately so as to compare their performance with that of the combined biosorption system. The formation of bacterial biofilm on the surface of the carbon was investigated. The study was carried out using a range of synthetic solutions containing between 15 and 500 mg/L salicylic acid simulating an industrial effluent from the pharmaceutical industry. An individual bacterium, Pseudomonas putida (DSM 4478), was used to study the differentiated effects. Filtrasorb 400 and GAC 830 ACs were used in the adsorption processes and Filtrasorb 400 in the biofilm formation and combined biosorption processes. As regards, combined adsorption/biodegradation results indicated that the bioactivated carbon system outperformed the combination of conventional AC and biological water treatment processes when working with high pollutant concentrations.

The thiol-ene-based P(Penta3MP4/PEGDA/AAc) hydrogels were prepared by UV curing technique, then characterized and used as adsorbents for the investigation of the effect of process parameters such as pH of solution, contact time, and initial concentration of solution, on the removal of Ag(I) from aqueous solution. The results indicate that the adsorption of Ag(I) ions from aqueous solutions is strongly dependent on pH under experimental conditions. Both Langmuir and Freundlich isotherm models were applied to experimental data, and the results show that the adsorption process is well fitted to the Langmuir isotherm model. Selectivity, reusability, and applicability of hydrogels to radiographic film waste were investigated.

Anthropogenic activities such as industry, agriculture, and daily life are related to metal pollution of the environment. Places known of the highest impact are fishponds where intensive fish farming is believed to input a significant amount of various elements to water. Additionally, many studies suspect wetland hunting activity of water lead pollution. The present paper aims to check if hunting is a significant source of lead (Pb) in water as well as to study the temporal trends of numerous parameters (pH, SEC, Cd, Cu, Zn, Ca, Mg, Na, K, NH4+, HCO₃⁻, SO₄²⁻, Cl⁻, NO₃⁻, F⁻) in ponds (n = 48) and inflow (n = 24) waters near Zator in southern Poland, Europe. Most concentrations were measured with ion chromatography and electrothermal atomic absorption spectrometry. Lead concentrations in pond waters were low and found not to be linked with hunting activity, as well as they did not differ from the ones found in the inflow water. Moreover, it could be stated that activities led on ponds did not enrich rivers in the studied ions and elements.

The disposal of cyanogenic residues from the processing of cassava, during the flour production in certain regions of the Brazilian northeastern, has been a cause of concern in recent years, since this practice may lead to environmental imbalances. The results obtained in this work show a possible impact caused by the release of this kind of waste into water bodies, as well as its potential use as biofertilizer, mainly due to its high nutrient content. Humic substances (HS) from water and soil showed high interaction with cyanide ions (CN⁻), being the main responsible for the bioavailability of these ions into the environment. Furthermore, studies in microcosms propose viable and low-cost alternatives to decrease the levels of CN⁻ions in the liquid waste (called “manipueira”), as well as its potential use as biofertilizer.

In this study, the potential effects of three modified industrial by-products—modified low-grade phosphate rock with soda dregs (MP), modified flue gasses desulfurization residue (MF), and a mixture of MF and phosphoric acid (MFP)—were evaluated in the remediation of heavy metal-contaminated agricultural soil at four different treatment levels. The effects of the amendments on the extractability and phytoavailability of soil heavy metals were tested using a standardized sequential extraction test and a pakchoi pot experiment. The impacts of the three amendments on soil quality was investigated, including changes of soil pH, availability of K, Ca, Mg, Si and P, and the effects on pakchoi growth. The addition of these amendments resulted in a significant decrease of labile fraction of the heavy metals in soil (p < 0.05) and a marked decrease in heavy metal uptake by pakchoi (p < 0.05) in the pot experiment. All the amendments improved soil quality as measured by neutralization of soil acidity, increased content of mineral nutrients of soil (specifically, available K, Ca, Mg, Si, and/or P), and enhanced pakchoi growth when compared to the controls. Significant correlations (positive/negative) were observed among these factors, indicating multiple effects of the amendments on the remediation process. The increased soil pH and elevated mineral nutrients contributed to the stabilization of heavy metals, and the remediated soil conditions resulted in improved growth of pakchoi. These results suggest that all three of the modified industrial by-products could be used for the remediation and restoration of heavy metal-contaminated agricultural soil.

The role of the hyporheic zone in mercury (Hg) cycling has received limited attention despite the biogeochemically active nature of this zone and, thus, its potential to influence Hg behavior in streams. An assessment of Hg geochemistry in the hyporheic zone of a coarse-grained island in the Coast Fork Willamette River in Oregon, USA, illustrates the spatially dynamic nature of this region of the stream channel for Hg mobilization and attenuation. Hyporheic flow through the island was evident from the water-table geometry and supported by hyporheic-zone chemistry distinct from that of the bounding groundwater system. Redox-indicator species changed abruptly along a transect through the hyporheic zone, indicating a biogeochemically reactive stream/hyporheic-zone continuum. Dissolved organic carbon (DOC), total Hg, and methylmercury (MeHg) concentrations increased in the upgradient portion of the hyporheic zone and decreased in the downgradient region. Total Hg (collected in 2002 and 2003) and MeHg (collected in 2003) were correlated with DOC in hyporheic-zone samples: r ² = 0.63 (total Hg-DOC, 2002), 0.73 (total Hg-DOC, 2003), and 0.94 (MeHg-DOC, 2003). Weaker Hg/DOC association in late summer 2002 than in early summer 2003 may reflect seasonal differences in DOC reactivity. Observed correlations between DOC and both total Hg and MeHg reflect the importance of DOC for Hg mobilization, transport, and fate in this hyporheic zone. Correlations with DOC provide a framework for conceptualizing and quantifying Hg and MeHg dynamics in this region of the stream channel, and provide a refined conceptual model of the role hyporheic zones may play in aquatic ecosystems.

The aim of this study is to develop a new method for the preconcentration of copper via a dispersive liquid–liquid microextraction method using 4-phenyl-3-thiosemicarbazide as a ligand and determination with FAAS in different sample types such as plants, soils and natural waters such as seawater. Optimum experimental conditions were determined, and the applicability of the proposed dispersive liquid–liquid microextraction method was investigated. In the first step of the work, the parameters that affect complex formation and extraction, such as volume of extractant/disperser solvent, pH and concentration of the chelating agent, NaCl and surfactant, were optimised. The interference effects from potential concomitants on the determination of the Cu(II) ion were investigated in synthetic mixtures that contain high levels of these ions. These results showed the analytical applicability of the proposed method in different kinds of samples. Under the optimal conditions, the calibration curve was linear over the range 2–600 μg L⁻¹of copper, and the detection limit was 0.69 μg L⁻¹in the original solution (3 Sb/m). The accuracy of the developed method was checked by analysing certified reference materials (QCS-19 (high purity standard), LGC 6156 (harbour sediment) and NBS 1572 (citrus leaves)). Results obtained were in agreement with certified values with a t test showing that no significant differences at the 95 % confidence interval levels were found. The proposed method was applied to seawater, river water, and plant and soil samples. The recovery values for spiked water samples were between 99.7 and 117.3 %.

Micrometer-size poly(vinyl phosphonic acid) (p(VPA)) hydrogel was synthesized by employing UV irradiation of an emulsion containing vinyl phosphonic acid (VPA) and crosslinker, prepared using lecithin as surfactant and gasoline as solvent. The p(VPA) microgels were employed in absorption of UO₂²⁺ions from aqueous environments and have very high and fast absorption capacity. In about 20 min, 670 mg UO₂²⁺ions were absorbed per gram of p(VPA) microgel from the prepared UO₂²⁺ion solution, and the absorption capacity increased up to 900 mg at pH 6. Various parameters affecting UO₂²⁺absorption characteristics of p(VPA) were investigated. It was found that the Langmuir isotherm fitted the absorption characteristics of p(VPA) better than the Freundlich isotherm. Moreover, magnetic ferrite can be prepared within p(VPA) and used as a magnetically responsive p(VPA) microgel composite for externally controlled absorption of UO₂²⁺ions with little decrease in the absorption capacity of the p(VPA) microgel.