Nano-silver is increasingly used in consumer products from washing machines and refrigerators to devices marketed for the disinfection of drinking water or recreational water. The nano-silver in these products may be released, ending up in surface water bodies which may be used as drinking water sources. Little information is available about the stability of the nano-silver in sources of drinking water, its fate during drinking water disinfection processes, and its interaction with disinfection agents and disinfection by-products (DBPs). This study aims to investigate the stability of nano-silver in drinking water sources and in the finished drinking water when chlorine and chloramines are used for disinfection and to observe changes in the composition of DBPs formed when nano-silver is present in the source water. A dispersion of nano-silver particles (10 nm; PVP-coated) was used to spike untreated Ottawa River water, treated Ottawa River water, organic-free water, and a groundwater at concentrations of 5 mg/L. The diluted dispersions were kept under stirred and non-stirred conditions for up to 9 months and analyzed weekly using UV absorption to assess the stability of the nano-silver particles. In a separate experiment, Ottawa River water containing nano-silver particles (at 0.1 and 1 mg/L concentration, respectively) was disinfected by adding sodium hypochlorite (a chlorinating agent) in sufficient amounts to maintain a free chlorine residual of approximately 0.4 mg/L after 24 h. The disinfected drinking water was then quenched with ascorbic acid and analyzed for 34 neutral DBPs (trihalomethanes, haloacetonitriles, haloacetaldehydes, 1,1 dichloro-2-propanone, 1,1,1 trichloro-2-propanone, chloropicrin, and cyanogen chloride). The results were compared to the profile of DBPs obtained under the same conditions in the absence of nano-silver and in the presence of an equivalent concentration of Ag⁺ ions (as AgNO₃). The stability of the nano-silver dispersions in untreated Ottawa River water, with a dissolved organic carbon concentration of 6 mg/L, was significantly higher than the stability of the nano-silver dispersions in distilled, organic-free water. Nano-silver particles suspended in the groundwater agglomerated and were quickly and quantitatively removed from the solution. Our data confirm previous observations that natural dissolved organic matter stabilizes nano-silver particles, while the high-ionic strength of groundwater appears to favor their agglomeration and precipitation. As expected, nano-silver was not stable in Ottawa River water through the chlorination process, but survived for many days when added to the Ottawa River water after treatment with chlorine or chloramines. Stirring appeared to have minimal effect on nano-silver stability in untreated and treated Ottawa River water. The profile of DBPs formed in the presence of nAg differed significantly from the profile of DBPs formed in the absence of nAg only at the 1 mg/L nAg concentration. The differences observed consisted mainly in reduced formation of some brominated DBPs and a small increase in the formation of cyanogen chloride. The reduced formation of brominated congeners may be explained by the decrease in available bromide due to the presence of Ag⁺ ions. It should be noted that a concentration of 1 mg/L is significantly higher than nAg concentrations that would be expected to be present in surface waters, but these results could be significant for the disinfection of some wastewaters with comparably high nano-silver concentrations.

Two new photoactive materials compatible with environmentally friendly solvents (water and methanol) have been synthesized and characterized. They are comprised of a porous matrix of polystyrene and divinylbenzene with bound Rose Bengal and additional pendant groups added to increase the hydrophilicity (ethylenediamine and γ-gluconolactone). The new polymers are efficient photocatalysts capable of generating singlet oxygen after irradiation with visible light. Photochemical oxygenations of 9,10-anthracenedipropionic acid and 2-furoic acid have been carried out. The measured conversions indicate that the new supported photosensitizers are more effective than the parent hydrophobic polymer.

The degradation of methylparaben (MeP) in water was investigated using a pulsed corona discharge generated in oxygen, above the liquid. A comparison was made between results obtained in semi-batch corona (SBC) configuration (stationary solution, continuous gas flow) and results obtained in a semi-batch corona with recirculation combined with ozonation (SBCR + O₃), where the liquid is continuously circulated between a solution reservoir and the plasma reactor and the effluent gas containing ozone is bubbled through the solution in the reservoir. It was found that MeP was completely degraded after 10–15 min of treatment in both configurations. Oxidation by ozone alone, in the absence of plasma, was a slower process. The energy efficiency for MeP removal (Y MₑP) and for mineralization (Y TOC) was significantly higher in the SBCR + O₃ configuration (Y MₑP = 7.1 g/kWh at 90 % MeP removal and Y TOC = 0.41 g/kWh at 50 % total organic carbon (TOC) removal) than in the SBC configuration (Y MₑP = 0.6 g/kWh at 90 % MeP removal and Y TOC = 0.11 g/kWh at 50 % TOC removal).

In situ metal stabilisation by amendments has been demonstrated as an appealing low-cost remediation strategy for contaminated soil. This study investigated the short-term leaching behaviour and long-term stability of As and Cu in soil amended with coal fly ash and/or green waste compost. Locally abundant inorganic (limestone and bentonite) and carbonaceous (lignite) resources were also studied for comparison. Column leaching experiments revealed that coal fly ash outperformed limestone and bentonite amendments for As stabilisation. It also maintained the As stability under continuous leaching of acidic solution, which was potentially attributed to high-affinity adsorption, co-precipitation, and pozzolanic reaction of coal fly ash. However, Cu leaching in the column experiments could not be mitigated by any of these inorganic amendments, suggesting the need for co-addition of carbonaceous materials that provides strong chelation with oxygen-containing functional groups for Cu stabilisation. Green waste compost suppressed the Cu leaching more effectively than lignite due to the difference in chemical composition and dissolved organic matter. After 9-month soil incubation, coal fly ash was able to minimise the concentrations of As and Cu in the soil solution without the addition of carbonaceous materials. Nevertheless, leachability tests suggested that the provision of green waste compost and lignite augmented the simultaneous reduction of As and Cu leachability in a fairly aggressive leaching environment. These results highlight the importance of assessing stability and remobilisation of sequestered metals under varying environmental conditions for ensuring a plausible and enduring soil stabilisation.

Seventeen organochlorine pesticides (OCPs) were investigated in the water and sediments from a waterbird-inhabited lake (Yangchaihu Lake) to evaluate their current pollution levels and potential risks. The concentrations of total OCPs in water and sediments were 10.12–59.75 ng/l and 4.25–27.35 ng/g dry weight, respectively. Hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) were the most abundant OCPs, while HCB and cyclodiene pesticides were detected with low levels. Levels of ∑OCPs (sum of 17 OCPs) at sites highly influenced by waterbirds were significantly higher than the sites with no significant waterbird populations (one-way ANOVA, P < 0.05), suggesting that bird activities were one reason for concentration distribution of these pollutants. Compositional and source analyses of OCPs in water and sediments indicated that there might be fresh introduction of lindane and heptachlor. The partitions of most OCPs were not in equilibrium between water and sediments. The results of an ecological risk assessment showed that residue levels of DDTs in the studied area might pose adverse effects on ecosystems.

The aim of this study was to evaluate the antimutagenic and antigenotoxic potential of grape juice concentrate in rodent organs exposed to cadmium chloride intoxication. A total of 15 Wistar rats were distributed into three groups (n = 5), as follows: control group (CTRL; nontreated group), cadmium group (Cd), and cadmium-grape juice group (Cd + GJ). Exposed animals received intraperitoneal injection of cadmium chloride (1.2 mg/kg body weight) diluted in water and, after 15 days, Cd + GJ group received grape juice concentrate for 15 days, by gavage (0.8 mL, 1.18 mg of polyphenols kg⁻¹ day⁻¹). Grape juice concentrate was able to decrease genotoxic effects induced by cadmium in peripheral blood and liver cells as depicted by single cell gel (comet) and micronucleus assays. A decrease for anti-8-hydroxy-20-deoxyguanosine (8OHdG) expression in hepatocytes of animals exposed to cadmium and treated with grape juice concentrate was also detected. Higher CuZn-SOD activity was observed in liver cells of the Cd + GJ group. No remarkable differences were seen regarding Mn-SOD activity among groups. Taken together, our results demonstrate that grape juice concentrate was able to exert antimutagenic and antigenotoxic activities in blood and liver cells of rats exposed to cadmium.

The electrochemical degradation of the nonsteroidal anti-inflammatory drug ketoprofen in tap water has been studied using electro-Fenton (EF) and anodic oxidation (AO) processes with platinium (Pt) and boron-doped diamond (BDD) anodes and carbon felt cathode. Fast degradation of the parent drug molecule and its degradation intermediates leading to complete mineralization was achieved by BDD/carbon felt, Pt/carbon felt, and AO with BDD anode. The obtained results showed that oxidative degradation rate of ketoprofen and mineralization of its aqueous solution increased by increasing applied current. Degradation kinetics fitted well to a pseudo-first-order reaction. Absolute rate constant of the oxidation of ketoprofen by electrochemically generated hydroxyl radicals was determined to be (2.8 ± 0.1) × 10⁹ M⁻¹ s⁻¹by using competition kinetic method. Several reaction intermediates such as 3-hydroxybenzoic acid, pyrogallol, catechol, benzophenone, benzoic acid, and hydroquinone were identified by high-performance liquid chromatography (HPLC) analyses. The formation, identification, and evolution of short-chain aliphatic carboxylic acids like formic, acetic, oxalic, glycolic, and glyoxylic acids were monitored with ion exclusion chromatography. Based on the identified aromatic/cyclic intermediates and carboxylic acids as end products before mineralization, a plausible mineralization pathway was proposed. The evolution of the toxicity during treatments was also monitored using Microtox method, showing a faster detoxification with higher applied current values.

As pollution becomes one of the biggest environmental challenges of the twenty-first century, pollution of water threatens the very existence of humanity, making immediate action a priority. The most persistent and hazardous pollutants come from industrial and agricultural activities; therefore, effective treatment of this wastewater prior to discharge into the natural environment is the solution. Advanced oxidation processes (AOPs) have caused increased interest due to their ability to degrade hazardous substances in contrast to other methods, which mainly only transfer pollution from wastewater to sludge, a membrane filter, or an adsorbent. Among a great variety of different AOPs, a group of electrochemical advanced oxidation processes (EAOPs), including electro-Fenton, is emerging as an environmental-friendly and effective treatment process for the destruction of persistent hazardous contaminants. The only concern that slows down a large-scale implementation is energy consumption and related investment and operational costs. A combination of EAOPs with biological treatment is an interesting solution. In such a synergetic way, removal efficiency is maximized, while minimizing operational costs. The goal of this review is to present cutting-edge research for treatment of three common and problematic pollutants and effluents: dyes and textile wastewater, olive processing wastewater, and pharmaceuticals and hospital wastewater. Each of these types is regarded in terms of recent scientific research on individual electrochemical, individual biological and a combined synergetic treatment.

Heavy metal contamination of water bodies and groundwater is a major concern of the modern world. Rhizofiltration—the use of plant root system to remove/extract pollutants from wastewater—has proven advantages over conventional methods of treatment. However, commercialization of this in situ remediation technology requires a better understanding of plant–metal interactions especially on the ability of different plant species to accumulate metals at different parts of the plant system which is critical for the successful remediation of contaminated medium. Many aquatic and terrestrial plants have been reported to accumulate heavy metals when grown hydroponically. Therefore, a batch experiment with different concentrations of lead and a nutrient film technique (NFT) experiment with recycling of wastewater were employed in this study in order to investigate the rhizofiltration of lead-containing wastewater using Plectranthus amboinicus, an aromatic medicinal plant. Results show that P. amboinicus is tolerant to a wide range of lead concentrations and nutrient deficiency. The plant accumulates considerable amount of lead, particularly in the roots, and translocation to the stem and leaf was limited, indicating that the use of leaves/above-ground parts of the plant for medicinal purposes is not hindered by its ability to remove lead from the soil or water. The study also suggests that the plant can be considered for the clean-up of lead-contaminated wastewater in combination with safe biomass disposal alternatives.

This work evaluates the treatment of wastewater from a personal care products factory by a full-scale side-stream membrane bioreactor (MBR) intermittently fed. The wastewater contained particulate and soluble chemical oxygen demand (COD) which is partially removed by physicochemical pretreatment. Steady removal efficiencies above 98 % were achieved for BOD5, COD and suspended solids. Fats, oils and grease present in the raw wastewater were also successfully removed. The MBR was operated at an average permeate flux of 12 L/m2 · h (LMH) working at a transmembrane pressure of 272 ± 97 mbar. The soluble microbial products concentration remained fairly stable at 175 ± 25 and 85 ± 15 mg/L for proteins and carbohydrates, respectively. This maintained the filtration characteristics of the mixed liquor unaltered over a long-term basis, which was evidenced by a constant permeability of 43 ± 19 LMH/bar. Most of the trace organics detected in the wastewater were completely removed and only some fragrances were detected in the permeate at trace concentrations.