Drinking water network is vulnerable to toxic chemicals. Anomaly detection-based event detection can provide reliable indication of contamination by analyzing the real-time water quality data, collected by online-distributed sensors in water network. This article reviews the water quality event detection methodologies based on the correlation of water quality parameters and contaminants. Further, we review how to reduce the impact of contamination in water distribution network, including sensor placement optimization and contamination source determination.

The results of a comparative study of chromium removal from model systems and wastewater by activated carbon AG-5 are reported. The process of chromium adsorption from laboratory solution was studied at different activated carbon dosages. The results obtained by neutron activation analysis (NAA) and atomic absorption spectrometry (AAS) showed that about 85 % of chromium was removed from model systems and only 4 % from wastewater. The NAA data point to an increase of Fe, Ni, and Cu content in activated carbon after wastewater treatment, which is indicative of competitive adsorption.

With more and more emerging organic contaminants (EOCs) detected in the soil and groundwater, researches on interactions between these pollutants and soils or aquifer materials have attracted greater concerns. In this study, the removal of chlorpheniramine maleate (CP), an antihistamine drug used to treat rhinitis and urticaria, by birnessite, which is a common layered manganese oxide, in aqueous solution was investigated by batch studies, X-ray diffraction (XRD) and Fourier transform infrared (FTIR) analyses, and molecular simulations. The quantum mechanics simulation showed that the final energy of the interaction between CP and the (010) edge surfaces under a strong alkaline condition was much smaller than that under a neutral to slightly alkaline condition. A higher CP adsorption were achieved from neutral to weak alkaline solution, as the broken bond effect of birnessite was strongly influenced by solution pH by protonation and deprotonation of birnessite edges.

Titanate whiskers were prepared by hydrothermal method starting from hydrous metatitanic acid and potassium hydroxide. The titanate whiskers were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, inductively coupled plasma, and N₂ adsorption/desorption techniques. When the concentrations of potassium hydroxide ranged from 6 to 12 mol L⁻¹, titanate whiskers were formed by bundling layer-structured nanoribbons. The titanate whiskers were certified with the formula of H₂ ₋ ₓKₓTi₃O₇ · nH₂O (x = 0.6, n = 3.8–4.0). After hydrochloric acid treatment, the potassium content and the layer distance decreased due to the replacement of potassium ions by protons. The maximum adsorption capacities of titanate whiskers for Cu(II), Pb(II), and Cr(III) ions were 142.0, 395.7, and 97.0 mg g⁻¹ when their initial concentrations were 150, 300, and 80 mg L⁻¹, respectively. The adsorption equilibriums were almost established in 30 min. The adsorption of Cu(II), Pb(II), and Cr(III) ions on titanate whiskers followed the pseudo-second-order adsorption kinetics. The Langmuir adsorption isotherms well fitted the adsorption equilibriums of Cu(II) and Pb(II) ions while the Freundlich adsorption isotherm well fitted the adsorption equilibrium of Cr(III) ions.

Amorphous tin(IV) hydrogen phosphate immobilized on silica (ATHPS) was investigated as an adsorbent for the removal of Pb(II), Cu(II), and Zn(II) from aqueous solutions to determine its applicability in remediation of heavy-metal contaminated saline water. The effect of pH, contact time, initial concentration of heavy metal ions, and salinity on adsorption was studied using a batch method. Equilibrium data were interpreted in terms of Langmuir, Freundlich, and Dubinin–Radushkevich isotherm models. The Freundlich model provided the best fit to the equilibrium data. The selectivity sequence can be given as Pb(II) > Cu(II) > Zn(II). The kinetic data correspond well to the pseudo-second-order and Elovich models. The thermodynamic parameters (i.e., ΔG ⁰, ΔH ⁰, ΔS ⁰) were evaluated to predict the nature of adsorption process. The negative ΔG ⁰ values at various treatment temperatures for each ion indicate that the adsorption processes are spontaneous and endothermic in nature. The ATHPS material can be regenerated, and the adsorption capacity in model seawater is acceptable, although a higher ionic strength can inhibit adsorption. These results show the great potential of ATHPS in removing cationic heavy metal ions from saline water.

TiO₂-mediated photodegradation is widely reported to degrade recalcitrant pollutants such as nitrophenolics. This paper investigated the TiO₂-mediated photodegradation of trinitrophenol (TNP) in aqueous solution irradiated by an artificial light source. About 28.4 % TNP degradation was attained over 450 min from an initial TNP concentration of 1,000 mg L⁻¹. Ionic chromatographic analysis further revealed the evolution of nitrite and nitrate anions and an unknown intermediate X during the photodegradation process. The trends of nitrite and nitrate anions indicate that the photodegradation process produced nitrite at first, which subsequently turned to nitrate in the presence of oxygen. The removal rate of COD was far slower than that of TNP, inferring the photodegradation reaction gradually mineralized the parent pollutants. The photodegradation of TNP could not proceed under anaerobic condition, presumably a result of oxygen deficiency that disabled the denitration process. Because of the volumetric loss of the test solution, follow-up irradiations were performed after addition of supplementary water. This follow-up irradiation period revealed that direct photolysis, i.e., irradiation in the absence of TiO₂photocatalysts, could not photodegrade TNP but gradually diminish the component X.

The contamination of hazardous metal(loid) is one of the serious environmental and human health risks. This study isolated a total of 40 cadmium (Cd)- and arsenic (As)-resistant bacterial isolates from coastal sediments by pour plate technique using tryptic soy agar supplemented with Cd or As (50 mg l⁻¹) for use as metal(loid) bioremediation agents. Out of 40, 4 isolates, RCd3, RCd6, RAs7, and RAs10, showed a relatively higher growth rate in Cd- or As-supplemented culture media which were selected for further study. The selected isolates showed a high minimum inhibitory concentration (60–400 mg l⁻¹for Cd and 400–2200 mg l⁻¹for As), which demonstrated their remarkable Cd and As resistance capabilities. The metal(loid) removal efficiencies (0.032–0.268 μg Cd h⁻¹ mg⁻¹and 0.0003–0.0172 μg As h⁻¹ mg⁻¹[wet weight cell]) of selected isolates indicated their greater magnitude in absorbing Cd compared to As from water. Phylogenetic analysis of the 16S rDNA sequences revealed that isolates RCd3, RCd6, RAs7, and RAs10 were closely related to Acinetobacter brisouii, Pseudomonas abietaniphila, Exiguobacterium aestuarii, and Planococcus rifietoensis, respectively. Because of high Cd and As resistance and removal efficiency, the selected isolates can survive in a high metal(loid)-contaminated environment and could be a potential tool for bioremediation of high metal(loid)-contaminated effluents to protect the aquatic environment.

A column experiment was conducted to evaluate the effectiveness of nanoscale zerovalent iron (nZVI) for the in situ immobilization of Pb and Zn in an acidic soil. The impact of nZVI on soil was evaluated by monitoring the physicochemical characteristics of the leachates and their ecotoxicological effects on three species, Vibrio fischeri, Artemia franciscana, and Caenorhabditis elegans. Treatment with nZVI resulted in more effective Pb immobilization in comparison to Zn and reduced the leachability by 98 and 72 %, respectively; the immobilization was stable throughout the experiment. Leachates from nZVI-treated soils showed lower toxicity than leachates from untreated ones. The highest toxicity in treated soils was observed in the first leachate, which presented high values of electrical conductivity due to the leachability of soil ions and those provided by the commercial nanoparticle suspension (Na and Fe). V. fischeri and C. elegans were more sensitive to leachates from nZVI-treated soils polluted with Zn than those from soils polluted with Pb; A. franciscana showed the opposite trend.

The present study deals with the synthesis and subsequent application of Fe₃O₄@n-SiO₂nanoparticles for the removal of Cr(VI) from aqueous solutions. Rice husk, an agrowaste material, was used as a precursor for the synthesis of nanoparticles of silica. Synthesized nanoparticles were characterized by XRD and SEM to investigate their specific characteristics. Fe₃O₄@n-SiO₂nanoparticles were used as adsorbent for the removal of Cr(VI) from their aqueous solutions. The effects of various important parameters, such as initial Cr(VI) concentration, adsorbent dose, temperature, and pH, on the removal of Cr(VI) were analyzed and studied. A pH of 2.0 was found to be optimum for the higher removal of Cr(VI) ions. It was observed that removal (%) decreased by increasing initial Cr(VI) concentration from 1.36 × 10⁻²to 2.4 × 10⁻² M. The process of removal was found to be endothermic, and the removal increased with the rise in temperature from 25 to 45 °C. The kinetic data was better fitted in pseudo-second-order model in comparison to pseudo-first-order model. Langmuir and Freundlich adsorption capacities were determined and found to be 3.78 and 1.89 mg/g, respectively, at optimum conditions. The values of ΔG⁰were found to be negative at all temperatures, which confirm the feasibility of the process, while a positive value of ΔH⁰indicates the endothermic nature of the adsorption process. The present study revealed that Fe₃O₄@n-SiO₂nanoparticles can be used as an alternate for the costly adsorbents, and the outcome of this study may be helpful in designing treatment plants for treatment of Cr(VI)-rich effluents.

The present study reports the remediation of radiocesium-137 (¹³⁷Cs) using napiergrass in Cs-contaminated soils of Fukushima Prefecture. Two field experiments were performed to examine the remediation effects in two different land-use soils (lowland and upland soils) using two different cutting frequencies (cut once or twice a year). Plant growth in the upland soil was significantly greater than that in the lowland soil. The¹³⁷Cs concentration (Bq kg⁻¹dry weight basis) in the aboveground parts and total Cs-removal ratio (CR) in the upland soil were also significantly higher than those in the lowland soil. In the lowland soil, cutting twice a year [at 12 and 24 weeks after transplanting (WAT)] was more effective for CR (P < 0.01) than cutting once a year (18 WAT); however, there was no significant difference of CR related to cutting difference in the upland soil as a result of the shading effect on the plants at second cutting. In the present study, aboveground dry matter weight was highly correlated with CR in both fields. Given the possibility to increase plant number per unit of land to increase aboveground biomass per unit of land, the potential Cs remediation effect could be much greater in a wide range of Cs-contaminated soils than the potential of napiergrass for Cs uptake demonstrated in the present study.