The potential of ferrihydrite-modified diatomite as a phosphorus co-precipitant was investigated at a laboratory scale. Ferrihydrite-modified diatomite was demonstrated to effectively remove phosphorus from lake water as well as strongly bind phosphorus in sediment under anoxic conditions. Phosphorus removal from the lake water proceeded primarily through phosphorus adsorption onto ferrihydrite-modified diatomite and further phosphorus consumption by stimulated diatom growth. A total phosphorus removal efficiency of 85% was achieved when lake water was dosed with 250 mg/L ferrihydrite-modified diatomite; the residual total phosphorus concentration was 17.0 µg/L, which falls within the range for oligotrophic phosphorus levels. During a 30-day anoxic incubation period, total phosphorus concentrations in lake water treated with 400, 500, or 600 mg/L of ferrihydrite-modified diatomite slightly decreased and maximum total phosphorus concentrations remained below 15 µg/L. Addition of ferrihydrite-modified diatomite resulted in a marked increase in the iron-bound phosphorus fraction, a pronounced decrease in labile phosphorus and organic-bound phosphorus fractions, and stable aluminum-bound phosphorus, calcium-bound phosphorus, and residual phosphorus fractions in the anoxic sediments. Comparable iron-bound phosphorus concentration in the sediment treated by 400 mg/L of ferrihydrite-modified diatomite relative to that of the sediment treated by the combination of 400 mg/L of ferrihydrite-modified diatomite and alum solution at the concentration less than 532 mg/L indicated that ferrihydrite-modified diatomite exhibited a stable phosphorus-binding capacity when dosed at a similar amount. Ferrihydrite-modified diatomite had the potential to be used as an effective phosphorus co-precipitant.

Fe3+ and Ce3+ codoped titanium dioxide films with high photocatalytic activity were successfully obtained via the improved sol–gel process. The as-prepared specimens were characterized using X-ray diffraction (XRD), high-resolution field emission scanning electron microscopy (FE-SEM), X-ray energy dispersive spectroscopy, Brunauer–Emmett–Teller (BET) surface area, X-ray photoelectron spectroscopy, photoluminescence (PL) spectra, and UV–Vis diffuse reflectance spectroscopy. The photocatalytic activities of the films were evaluated by degradation of various organic dyes in aqueous solutions. The results of XRD, FE-SEM, and BET analyses indicated that the TiO2 film had nanostructure. With the codoping of Fe3+ and Ce3+, TiO2 photocatalysts with smaller crystal size, larger surface area, and larger pore volume were obtained. Moreover, codoped ions could obviously not only suppress the formation of brookite phase but also inhibit the transformation of anatase to rutile at high temperature. Compared with pure TiO2 film, Fe3+ doped or Ce3+ doped TiO2 film, the Fe3+/Ce3+ codoped TiO2 film exhibited excellent photocatalytic activity. It is believed that the surface microstructure of the films and the doping methods of the ions are responsible for improving the photocatalytic activity.

Differences in the culturable fractions of total and metal-tolerant bacteria inhabiting bulk soil of a metal-mine spoil heap and the rhizosphere of silver birch (Betula pendula) or bushgrass (Calamagrostis epigejos), completed with changes in total microbial community structure in the soil, were assessed by MIDI-FAME (fatty acid methyl ester) profiling of whole-cell fatty acids. In addition, the abundance of metal-tolerant populations among the culturable bacterial communities and their identity and the metal-tolerance patterns were determined. The high proportions of Cu- and Zn-tolerant bacteria that ranged from 60.6% to 94.8% were ascertained in the heap sites. Within 31 bacterial isolates obtained, 24 strains were Gram-positive and Arthrobacter, Bacillus, Rathayibacter, Brochothrix, and Staphylococcus represented those identified. Minimum inhibitory concentration (MIC) data indicated that several strains developed multi-metal tolerance, and the highest tolerance to Cu (10 mM) and Zn (12 mM) was found for Pseudomonas putida TP3 and three isolated strains (BS3, TP12, and SL16), respectively. The analysis of FAME profiles obtained from the culturable bacterial communities showed that Gram-positive bacteria predominated in bulk soil of all heap sites. In contrast, the rhizosphere communities showed a lower proportion of the Gram-positive group, especially for silver birch. For the total microbial community, mostly Gram-negative bacteria (e.g., Pseudomonas) inhabited the heap sites. The results suggest that the quantitative and qualitative development of heterotrophic microbiota in the soil of the metal-mine spoil heap seems to be site-dependent (i.e., rhizosphere vs. bulk soil), according to differences in the site characteristics (e.g., enrichment of nutrients and total metal concentrations) and impact of plant species.

In this study, seven types of first-order and one-variable grey differential equation model (abbreviated as GM (1, 1) model) were used to predict hourly particulate matter (PM) including PM10 and PM2.5 concentrations in Banciao City of Taiwan. Their prediction performance was also compared. The results indicated that the minimum mean absolute percentage error (MAPE), mean squared error (MSE), root mean squared error (RMSE), and maximum correlation coefficient (R) was 14.10%, 25.62, 5.06, and 0.96, respectively, when predicting PM10. When predicting PM2.5, the minimum MAPE, MSE, RMSE, and maximum R value of 15.24%, 11.57, 3.40, and 0.93, respectively, could be achieved. All statistical values revealed that the predicting performance of GM (1, 1, x (0)), GM (1, 1, a), and GM (1, 1, b) outperformed other GM (1, 1) models. According to the results, it revealed that GM (1, 1) GM (1, 1) was an efficiently early warning tool for providing PM information to the inhabitants.

The effects of application of biosolids, at four rates, to an alkaline (pH 8.4), neutral (pH 7.0) and acidic (pH 4.0) soil on concentrations of Cu, Zn, Pb, Cd and dissolved organic C in soil solution were measured over a 170-day period in a laboratory incubation study using Rhizon pore water samplers. Applications of biosolids decreased solution pH in the alkaline soil, increased it in the acidic soil and had little effect in the neutral soil. In general, increasing application rates of biosolids progressively increased EC and concentrations of dissolved organic C (DOC), Cu, Zn, and to a lesser extent Cd and Pb, in soil solution. Concentrations of DOC and concentrations of solution Cu, Zn, and to a lesser extent solution Cd and Pb, decreased over the incubation period. In all three soils, concentrations of solution Cu and Zn were closely positively correlated with DOC concentrations and similar positive but weaker correlations were found for solution Cd and Pb. For the alkaline and neutral soils, concentrations of solution Cu, Zn, Cd and Pb were generally negatively correlated with solution pH but for the acidic soil, positive correlations for Cu and Zn were recorded. The percentage reduction in solution Cu and Zn, between 0 and 170 days incubation, increased with increasing rates of biosolids in the acid soil (where biosolids applications increased pH) but the reverse was the case for the alkaline soil (where pH fell following biosolids applications). Greatest percentage reduction in soluble Cu and Zn occurred in the neutral soil which had the greatest BET surface area, clay and organic matter contents and therefore the greatest capacity to adsorb heavy metal cations. It was concluded that solution pH, dissolved organic C and the intrinsic capacity of the soil to remove metals from solution, were the main factors interacting to regulate heavy metal cation solubility in the biosolids-amended soils.

The influence of the operational variables on the Anammox process has been generally researched considering each variable separately. However, the optimization of the process also requires the identification of the more significant variables and their possible interactions. Response surface models were successfully applied to evaluate the performance of the Anammox process in a deammonification system (i.e., one-stage biofilm Anammox process) taking into account the combined effects caused by two sets of three variables. Specific Anammox activity was measured by a manometric method and used as the response variable. The obtained models pointed out that the significant variables were the temperature, the value of pH, and the ratio between the unionized species of the substrates (free ammonia and free nitrous acid (FA/FNA)). There were interactions among them caused by chemical equilibriums. Total nitrogen concentration and ammonium concentration were found to be not significant in the tested range. According to the models, the optimum values of temperature, pH, and free ammonia to free nitrous acid ratio within the test ranges were, respectively, 30°C, 7.0, and 0.3. Further research at higher temperatures and lower values of pH and FA/FNA ratios would be necessary in order to find the absolute optimum conditions for the process. The obtained model can be also useful in order to develop control strategies that take into account the significant variables and their optimum ranges. A strategy to control deammonification reactors has been proposed, according to the results of the modeling.

This study examined a comparative degradation of various chlorinated phenolic compounds including phenol, 4-chlorophenol (4-CP), 2,6-dichlorophenol (2,6-DCP), 2,4,6-trichlorophenol (2,4,6-TCP), 2,3,4,6-tetrachlorophenol (2,3,4,6-TeCP), and pentachlorophenol (PCP) using 28, 580, and 1,000 kHz ultrasonic reactors. The concentration of hydrogen peroxide was also determined in order to investigate the efficacy of different sonochemical reactors for hydroxyl radical production. Clearly, it was observed that the 580 kHz sonochemical reactor had maximum efficacy for hydroxyl radical production. The degradation of all the compounds followed the order; 580 kHz (91–93%) > 1,000 kHz (84–86%) > 28 kHz (17–34%) with an initial concentration of 2.5 mg L−1 at a reaction time of 40 min with ultrasonic power of 200 ± 3 W and aqueous temperature of 20 ± 1°C in each experiment. Overall, the degradation of those phenolic compounds followed the order, PCP > 2,3,4,6-TeCP > 2,4,6-TCP > 2,6-DCP > 4-CP > phenol at various frequencies in the presence/absence of a radical scavenger (tert-butyl alcohol). It was revealed that the correlations between the compound degradation rates and the physicochemical parameters, R 2 = 0.99 for octanol–water partition coefficient, R 2 = 0.95 for water solubility, R 2 = 0.94 for vapor pressure, and R 2 = 0.88 for Henry’s law constant, excluding PCP, were very good in the entire range of each parameter.

Total topsoil 50th percentile Cu, Pb and Zn concentrations (n = 491) in the Sydney estuary catchment were 23 μg g−1, 60 μg g−1 and 108 μg g−1, respectively. Nine percent, 6% and 25% of samples were above soil quality guidelines, respectively and mean enrichment was 14, 35 and 29 times above background, respectively. Soils in the south-eastern region of the catchment exhibited highest metal concentrations. The close relationship between soil metal and road network distributions and outcomes of vehicular emissions modelling, strongly suggested vehicular traffic was the primary source of metals to catchment soils. Catchment soil and road dust probably make an important contribution to contamination of the adjacent estuary. The concentration of soil metals followed the land use trend: industrial > urban > undeveloped areas. A high proportion (mean 45%, 62% and 42%, for Cu, Pb and Zn, respectively) of metals in the soils may be bioavailable.

In recent years, Microcystis bloom occurs frequently and causes a wide range of social, environmental, and economic problems. In this study, dose-dependent inhibitory effect of cinnamaldehyde on the growth of Microcystis aeruginosa was investigated. It was found that cinnamaldehyde with the concentration more than 0.6 mM showed algicide activity against M. aeruginosa. When M. aeruginosa was exposed to 0.6 mM cinnamaldehyde, considerable reactive oxygen species (ROS) were generated followed by lipid peroxidation and decrease in the content of both chlorophyll a and soluble protein. Although superoxide dismutase had made response to the stress caused by cinnamaldehyde, activity increasing after a time of lag could not prevent the lysis of M. aeruginosa cells. Interestingly, the addition of antioxidants glutathione and L-ascorbic acid (Vc) could prevent the lysis of M. aeruginosa cells. All the results suggested that cinnamaldehyde induced the death of M. aeruginosa cells via inducing ROS burst. Further understanding of the mechanism of cinnamaldehyde-induced M. aeruginosa cell death would contribute to the control of cyanobacteria pollution.

The present investigation was carried out to evaluate the detoxification potential of Pseudomonas fluorescens SM1 strain immobilized in calcium alginate beads for some major toxicants of Indian water bodies. The toxicants selected in this study were benzene hexachloride, mancozeb, 2,4-dichloro-phenoxyacetic acid (pesticides); phenol, catechol, cresol (phenolics); and Cd++, Cr(VI), Cu++ and Ni++ (heavy metals), which were taken as mixtures up to a concentration of roughly twice that usually found in highly polluted sites. Allium cepa phytotoxicity test, Ames fluctuation test and plasmid nicking assay were employed to estimate the phytotoxicity and genotoxicity of the model water containing the test toxicants under different combinations before and after exposure to our bioremediation-cum-detoxification system. The IC50 of the model water containing all the test toxicants, treated with the immobilized SM1 cells, was recorded to be 0.7× compared to 0.06× for the same but untreated water sample, enhancing the IC50 value by 12-fold. The IC25 of the test heavy metal mixture only could enhance from 0.07 to 1.30× (18-fold). The IC25 of the test pesticide mixture alone was increased from 0.07 to 1.71× (24-fold). The IC25 values for the mixture of test phenolics were 0.07× and 2.18× under the pre- and post-treatment conditions, respectively, exhibiting a 31-fold increase. A mutational induction (Mi) corresponding to the 0.5 value in the Ames fluctuation test was used to evaluate the mutagenicity of the test model water containing all the toxicants before and after exposure to the immobilized SM1 cell system. The Mi (0.5) value with the TA98 tester strain was estimated to be 0.08× for the untreated and 0.6× for the treated model water, whereas the same index was calculated to be 0.48× and 1.8×, respectively, for the TA100 strain. A remarkable improvement in the quality of the test water as a result of exposure to this bioremediating system was observed in terms of the absence of the linear form of the plasmid contrary to the visible linearization with the untreated model water. In view of the above findings, it is quite clear that the test of P. fluorescens SM1 strain immobilized in the calcium alginate beads could be used as an efficient system of bioremediation and for water decontamination strategies owing to its remarkable detoxification potential.