This work has evaluated the efficiency of two coagulants, aluminum sulfate (AS) and polyaluminum chloride (PACl), combined with the adsorption process using powdered activated carbon (PAC) on the removal of diclofenac (DCF), sulfamethoxazole (SMX), ethinylestradiol (EE2), estradiol (E2), estrone (E1), estriol (E3), and bisphenol-A (BPA) from low- and high-turbidity waters. The results have shown that the concomitant application of PAC and either coagulant has worsened the removal efficiency for all pharmaceuticals and endocrine disruptors tested, which might have occurred due to the covering of adsorption sites by aluminum hydroxide particles. In this configuration (coagulation in the presence of PAC, 10 mg L⁻¹), the best removal efficiency (∼40 %) was obtained for E1 and EE2 when AS was used as coagulant in contact times that varied from 13.5 to 23.5 min. When the coagulant was the PACl, contact times were lower (8.5 to 13.5 min) and the highest removal efficiency was observed for EE2 (∼52 %). When PAC was added as a pre-treatment (before addition of coagulant), the removal efficiency was greatly increased for all microcontaminants and the application of 2.5 mg L⁻¹of PAC with 120 min of contact led to removal efficiencies varying from 30 to 99.9 %.

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 article, Pilot-Scale Test for a Phosphate Treatment Using Sulfate-Coated Zeolite at a Sewage Disposal Facility by Jae-Woo Choi, Kyu-Sang Kwon, Soonjae Lee, Byungryul An, Seok-Won Hong, Sang-Hyup Lee, is replete with some fundamental scientific flaws which have the potential to misinform readers. This comment seek to correct these flaws.

Cyanobacterial toxins have caused worldwide concern because of their lethal effects, which has led to intensive search of cost-effective removal techniques. With the application of a Box–Behnken experimental design combined with response surface methodology, the adsorption process of the potent and commonly occurring microcystin-LR (MC-LR) onto nano-sized montmorillonite (NMMT) K10 was investigated through the HPLC-UV system. The quadratic statistical model was established to predict the interactive effects of pH (1–12), NMMT K10 dose (1–10 mg mL⁻¹), and MC-LR initial concentration (100–1,000 μg L⁻¹) on MC-LR adsorption and to optimize the controlling parameters. The MC-LR adsorption by NMMT K10 was pH dependent and was found to reach a maximum at pH 2.96 with a removal peak of 186.37 μg g⁻¹. The range of optimal pH for MC-LR adsorption was 2.96–3.48, and higher adsorption capacities were achieved with increasing adsorbent dose and MC-LR initial concentration. Sorption kinetics revealed that the sorption process of MC-LR on NMMT K10 was rapid (short equilibrium time) and involved several kinetic stages. The Langmuir isotherm model predicted that the theoretical maximum adsorption capacity at pH 3 was 285.20 μg g⁻¹. Alkali eluting media (0.1 M NaOH) showed the highest desorption percentage (75.3 %) during regeneration studies. The high Brunauer–Emmett–Teller (BET) specific surface area (204.65 m² g⁻¹) of NMMT K10 was also characterized. NMMT K10 was determined to be an effective and economic adsorbent for MC-LR removal on a large scale.

Evaluation of variation in the concentration of heavy metal provides vital information about the spatial behavior of the metals affecting the air quality. In the present study, lichen samples of the species Pyxine subcinerea Stirton were collected in the Rudraprayag valley to investigate the metal profile that bioaccumulated in lichens. Multivariate statistical analysis was carried out to elucidate possible contribution of various sources of pollution including anthropogenic sources on heavy metal profile of lichens. Cluster analysis successfully grouped geogenic and anthropogenic inputs represented by Al and Mn and Cu, Cd, Pb, and Zn, respectively. Principal component analysis also segregated sites based on the origin (major contributors).

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.

Concentration of methylmercury (MeHg) in different habitats and associated food chains may vary because of habitat characteristics that determine methylation and MeHg transfer. We examined MeHg levels in primary consumers from littoral, pelagial and profundal habitats of a boreal humic lake, and measured total mercury (TotHg) and MeHg in surface sediments at increasing depths. MeHg concentrations in primary consumers increased from profundal to littoral, a pattern which was mirrored by the surface sediment concentrations. Methylation potential (expressed as the ratio of MeHg to TotHg) was lower in profundal than in littoral sediments, suggesting that littoral sediments have higher net methylation rates. No specific MeHg-enriched entrance point in the littoral food chain was identified, however. High MeHg concentrations in littoral primary consumers and sediments suggest that shallow lake sediments are important for MeHg transfer to the aquatic food web in boreal humic lakes. Lake morphometry, most specifically the fraction of littoral, is hence likely to add to differences in MeHg bioaccumulation rates in lake food webs.

Vanadium (V) is an essential trace element for certain biological enzymatic reactions but becomes toxic at higher concentrations. The impact of V at concentrations of 0 − 500 mg/kg V(V) spiked in soils on soil enzymatic activities, and microbial diversity was investigated in soybean pot experiments. The results from sequential extraction of soil V indicated increasing V mobilizable fractions with increase of soil V concentrations. The soil sulfatase activity decreased drastically from 2.35 − 5.55 to 0.30 − 0.88 μmol methylumbelliferon (MUB)/[h g soil] with increasing soil V loading at different vegetative stages. Surprisingly, the activity of soil phenol oxidase increased from 0 − 0.73 to 3.74 − 7.61 μmol L-3,4-dihydroxyphenylalanine (DOPA)/[h g soil] with increasing soil V concentrations at different vegetative stages probably due to oxidation stress caused by V in soils. These observations were not affected by the presence of soybean plants. In comparison, soil phosphatase, protease, and ß-glucosidase showed no significant reaction to V concentrations in soil. Both fungal and bacterial communities changed significantly at different levels of V treatments. Accordingly, V may pose a threat to some biologically mediated functions in soils even at low bioavailable amounts.

Management strategies that prevent the onset of nuisance and noxious cyanobacteria blooms are needed to preserve the integrity and safety of freshwater resource uses. Scientifically defensible data are needed regarding efficacy of proactive approaches in order to assist water resource managers in making informed decisions. As phosphorus availability has been indicated as a crucial aspect of cyanobacteria presence/dominance in freshwater systems, the integration of novel technologies to inactivate phosphorus is a critical component to achieve improved water quality. Phoslock (Phoslock Water Solutions, Ltd.) phosphorus locking technology is composed of the element lanthanum in a bentonite clay matrix that has a high specificity to bind and inactivate soluble reactive phosphorus. This research evaluated the phosphorus binding efficiency of Phoslock in aqueous and sediment matrices and the consequent impact on algae assemblage composition and water quality parameters. Laguna Niguel Lake in California afforded an opportunity to evaluate the operational effectiveness of Phoslock in a system historically plagued by high phosphorus concentrations, potentially toxic cyanobacteria (Aphanizomenonflos-aquae dominant), and lake closures. Phoslock was able to rapidly (<2 weeks) and significantly (p < 0.0005) decrease total (>80 %) and free reactive (>95 %) phosphorus in the water column and shift potentially releasable sediment phosphorus fractions to residual forms after treatment. Despite documented cyanobacteria blooms and high pretreatment cell densities, cyanobacteria levels remained below or near detection limits and only comprised a small fraction of the algae assemblage following Phoslock application. This study provides water resource managers an information on operational implementation and efficacy of a phosphorus binding technology.

Stabilization of sewage sludge (SS) prior to its land disposal may help control the mobility of SS-borne contaminants, particularly potentially toxic metals. We examined the effects of stabilized SS application on soil properties, biomass production, and phytoavailability of Cu and Zn to plants grown in two contrasting soils, Entisol and Aridisol. Stabilized SS mixtures were created by mixing SS in a 3-to-1 ratio with bentonite (B), sugar beet factory lime (SL), brick factory fly ash (BFA), rice straw (RS), water hyacinth (WH), and 50:50 mixture of RS and SL. Mixtures were applied at 50 Mg ha⁻¹, and Sorghum vulgare L. and Eurica sativa were grown in a pot experiment. All the amendments increased plant availability and uptake of both Cu and Zn compared to the unamended control. The application of stabilized SS increased dry plant biomass significantly and decreased DTPA-extractable elements compared to the non-stabilized SS treatment. We conclude that of the six amendments studied, especially sugar beet factory lime (SL) and bentonite (B), are promising for the stabilization of metal-contaminated biosolids and should be tested under field conditions.