The aim of the present study was to evaluate the influence of the recirculation rate on the efficiency of a 1,000-L pilot anaerobic sequencing batch biofilm reactor (ASBBR) treating effluent from a small dairy plant over a long-term period (570 days). Three operational conditions were studied, in which recirculation rates were varied, resulting in upflow velocities of 0.2, 3.8, and 6.4 m h⁻¹and the cycle time of 48 h. The biomass was immobilized on plastic supports containing polyurethane foam. The organic loading rate varied according to the operations occurring in the dairy plant. After system stability had been verified, temporal profiles of the substrate and metabolite concentrations were obtained, allowing kinetic parameter inference. Sludge samples from the inoculum and from the reactor were analyzed through microscopic examination, molecular biology analyses, and specific methanogenic activity assays. The average efficiencies of organic matter removal were 82 ± 11, 84 ± 9, and 87 ± 9 % at velocities of 0.2, 3.8, and 6.4 m h⁻¹, respectively. Microscopic examinations indicated that the fluorescent microorganisms decreased throughout the experiment, and they were not detected in the last condition. Homoacetogenesis was inferred as a possible pathway for H₂removal and for maintenance of the methanogenic process. Specific methanogenic activity increased throughout the monitoring period. It was possible to conclude that the ASBBR was efficient, robust, and reliable in treating dairy effluents under the conditions used.

Phosphorus (P) is widely known as a limiting nutrient of water eutrophication for inland freshwater ecosystems. Owing to the complexity of P chemistry, remote sensing detection of total phosphorus (TP) concentrations currently remains limited especially for optically complex turbid inland waters. To address this need, a new TP remote sensing algorithm is developed based on prior water optical classification and the use of support vector regression (SVR) machine. The in situ observed datasets, used in this study, were collected at specific times during 2009 ~ 2011, covering a total of 232 stations from eight cruises in Lakes Taihu, Chaohu, Dianchi, and Three Gorges reservoir of China. Three types of waters were first classified by using a recently developed NTD675 (Normalized Trough Depth of spectral reflectance at 675 nm) water classification method. Then, spectral regions sensitive specifically to each water type were explored and expressed via several band ratios and used for retrieval algorithm development. The established type-specific SVR algorithms yield relatively high predictive accuracies. Specifically, the mean absolute percentage errors (MAPE) produced with the independent validation samples were achieved at 32.7, 23.2, and 14.1 % for type 1, type 2, and type 3 waters, respectively. Such water type-specific SVR algorithms are more accurate for the classified waters than an aggregated SVR algorithm for the nonclassified water and also superior to commonly used statistical algorithms. Moreover, application of the developed algorithms with HJ1A/HSI image data demonstrates that the algorithms have a large potential for remote sensing estimation of TP concentrations in optically complex turbid inland waters.

In this research, different inlet concentrations of n-hexane vapor (1–11 g m⁻³) corresponds to the inlet loading rates of 9–598 g m⁻³ h⁻¹at different temperatures (35–45 °C) were eliminated from air under continuous and intermittent loading (10-h feeding per day) in a biofilter packed with compost and lava rock. Loading type had minor effect on the n-hexane removal at 35 °C and the removal efficiency (RE) was in the range of 70 to 100 % at an inlet concentration of 11 gm⁻³. On the contrary, RE dropped significantly to 25 % at 40 °C under intermittent loading while it was 77 % under continuous loading with the inlet concentration of 9 g m⁻³and empty bed residence time (EBRT) of 2 min. Increasing the temperature to 45 °C significantly reduced the RE at both types of loading at both EBRTs of 2 and 1.3 min; however, intermittent loading was led to a slightly greater removal. According to transient-state experiment under intermittent loading at EBRT of 2 min, the biochemical reaction became the dominant mechanism, after an initial short period, every day to remove n-hexane rather than adsorption on bed. Kinetic modeling showed that the biodegradation rates changed linearly with increase in the logarithmic mean n-hexane concentration during intermittent loading at different temperatures while the order of reaction was higher at continuous loading.

The purpose of the present study was to evaluate the effect of planting trees (Pinus pinaster or Eucalyptus globulus) and amending with wastes (sewage sludges and paper mill residues) on the nutrient content of mine soils and under field conditions. The studied soils were located in a settling pond and a mine tailing within a former copper mine. The soil samples were analyzed for several physico-chemical characteristics and the concentration of nutrients. The untreated settling pond soil had levels of N and K adequate only for the growth of eucalyptuses and pines, and moreover, the concentration of Ca and P were undetectable. The untreated mine tailing soil presented the same condition, also with adequate levels of Ca and Mg for eucalyptuses and pines. Planting these trees increased the concentration of Mg in the settling pond up to adequate levels only for such trees. Amending with wastes increased the phytoavailable concentration of all nutrients up to adequate levels for most plant species. In conclusion, it is recommended to amend mine soils with wastes rich in nutrients and re-amend after some time because they raise them up to adequate levels for most plants but are depleted over time. It is possible to increase the concentration of all nutrients in mine soils by adding organic wastes, even to values adequate for most plant species.

Humic acid (HA) is ubiquitous in groundwater, and poses great influence on the biogeochemical controls on, as well as treatment of, contaminants. This study deals with the adsorption of HA on a bimetallic iron system, Cu/Fe, and its influence on the reduction of nitrobenzene in synthetic groundwater. The adsorption kinetics, isotherms, and enthalpy of HA on bimetallic Cu/Fe particles are investigated. Compared with the adsorption of HA on Fe⁰particles, the adsorption on Cu/Fe is faster than that on Fe⁰. The adsorption isotherms of HA at different pH values and temperatures show that the adsorption is always greater on Cu/Fe than on Fe⁰, and increases when the pH decreases and temperature increases. Moreover, the influences of pH and temperature on adsorption by Cu/Fe are less than those observed in adsorption on Fe⁰. The adsorption enthalpy on Cu/Fe is lower than that on Fe⁰, and both adsorptions are spontaneous and endothermic. Characterization of the corrosion products by SEM-EDX, XRD, and XPS reveals the appearance of maghemite (γ-Fe₂O₃) and magnetite (Fe₃O₄) on Cu/Fe with HA adsorption, which were more crystalline than those of Fe⁰, indicating that bimetallic Cu/Fe facilitated the formation of crystalline corrosion products. The adsorption of HA accelerates the release of iron ions but suppresses the reduction of nitrobenzene. Compared with Fe⁰, Cu/Fe accelerates the adsorption of HA and Cu/Fe increases the reduction of nitrobenzene. The suppression on nitrobenzene reduction increased with the increase in HA concentration.

Chemical stabilization is a cost-effective, environmentally friendly, in situ remediation technology based on the application of organic and/or inorganic amendments to reduce soil metal bioavailability. Our objective was to assess the early short-term effects of organic amendments (sheep manure—SHEEP, poultry litter—POULTRY, cow slurry—COW, paper mill sludge mixed with poultry litter—PAPER), in sterilized and non-sterilized form, on the microbial and chemical properties, as well as on the phytotoxicity, of a Cd, Pb and Zn contaminated soil. Our results provide useful information regarding (1) the effectiveness of amendments for chemical stabilization of mine soil and (2) the impact of microbial populations present in the amendments on soil native microbial communities. Microbial populations present in the amendments did not substantially modify soil microbial functional diversity, as reflected by Biolog EcoPlates™ data, except for PAPER-amended soils. We observed a good correlation between lettuce root elongation (phytotoxicity bioassay) and Cd, Pb, and Zn CaCl₂-extractable concentrations in soil. SHEEP and PAPER amendments were particularly effective at increasing soil pH and reducing metal bioavailability and phytotoxicity, while POULTRY and COW led to higher values of soil microbial properties (respiration and functional diversity). Beneficial effects observed under POULTRY at the beginning of the experiment, due to the presence of easily degradable organic matter, were partially lost over time. Our results emphasize the importance of the early monitoring of soil properties (microbial and chemical) and phytotoxicity to properly identify bottlenecks during amendment selection for chemical stabilization, in terms of reduction in metal bioavailability and improvement in soil health.

In recent years, there has been the phenomena of spruce dieback in Europe. Significant areas of spruce low mortality now cover both sides of the Polish southern border. We evaluated ecochemical parameters influencing the heavy dieback occurring in mature spruce stands in the Polish Carpathian Mountains. Dolomite, magnesite and serpentinite fertilizers were applied to experimental plots located in 100-year-old stands in the autumn of 2008. The experimental plots were located in the mid-elevational forest zone (900–950 m) on two nappes of the flysch Carpathians: Magura (Ujsoły Forest District) and Silesian (Wisła Forest District). The saturation of the studied soils demonstrates moderate resilience of soils in Wisła Forest District in relation to acid load and high flexibility of the Ujsoły soils. After application of the fertilizers, an increase of Mg, Ca and Mb was noted in the soil solution, determined in the overlaying highly acidic organic horizons through the ion-exchange buffering mechanism of highly protonated functional groups with high buffering capacity. Magnesium concentration increased following fertilization, presenting a potential improvement of forest growth capacity without the hazard of adverse side effects of liming. Aluminium stress in old spruce is unlikely, while trees in the control plots in Wisła Forest District may already be sensitive to aluminium stress. Serpentinite fertilization improved the supply of soils in magnesium without causing significant changes in the pH of the soil. Such changes in the pH were found in dolomite and magnesite fertilizer.

In order to develop an effective and economical method for removing U(VI) from the low concentration radioactive wastewater with the U(VI) concentration of less than 1 mg L⁻¹, the biomass of Aspergillus niger was prepared and modified with ethylenediamine, and the biosorption of uranium from the low concentration radioactive wastewater by the unmodified and the modified biomasses was investigated in a batch system. The modified biomass exhibited the adsorption efficiency of 99.25 % for uranium under the optimum conditions that pH was 5.0, the contact time was 150 min, and the biosorbent dose was 0.2 g L⁻¹. The adsorption fitted well to Langmuir isotherm, and the maximum sorption capacity of the modified biomass for U(VI) was determined to be 6.789 mg g⁻¹which increased by 36.45 % compared with the unmodified biomass. The adsorption kinetics was better depicted by pseudo-second-order kinetic model. The Gibbs free energy change (ΔG⁰), enthalpy change (ΔH⁰), and entropy change (ΔS⁰) showed that the process of U(VI) adsorption was spontaneous, endothermic, and feasible. The changes in the groups, morphology, and the presence of U(VI) on the surface of the adsorbents which were characterized by FT-IR, SEM, and EDS, demonstrated that the U(VI) was successfully adsorbed onto the modified biomass. Moreover, the UO₂²⁺absorbed on the modified biomass can be released by 0.1 mol L⁻¹HNO₃with high desorption efficiency of 99.21 %. The results show that the modified biomass can remove U(VI) from low concentration radioactive wastewater more effectively than the unmodified biomass.

Storm runoff is a major vector for transporting urban contaminants, especially metals, and continues to be a leading cause of urban waterways degradation. Stormwater treatment systems in New Zealand and Australia are primarily designed to remove total suspended solids and heavy metals to low levels, principally through bioinfiltration. In Christchurch, the second largest city in New Zealand, more than two thirds of the water, including stormwater, infrastructure is currently being rebuilt following the devastating 2010–2011 earthquakes. Despite increased use of bioinfiltration systems for this purpose, there is a dearth of knowledge about their treatment performance or water quality dynamics. This paper reports enhanced treatment efficacy in bioinfiltration stormwater systems by including an alkaline waste product, mussel shells, in the substrates. Experimental systems with mussel shells significantly increased the metal removal efficacy, hardness, and pH, which also have implications for reducing the potential ecotoxicological effects of stormwater. Mussel shell systems resulted in lower dissolved metal fractions in the treated effluent because metals shifted to the particulate states facilitated by hardness buffering. This resulted in greater metal removal afforded by increased filtration. Using locally available waste products can reduce the amount and transport impacts of waste going to landfills and offset costs associated with the construction of stormwater treatment systems, while concurrently improving stormwater treatment. The long-term capacity of such systems to enhance metal removal using waste mussel shells should be examined by monitoring larger pilot-scale systems in situ under different seasonal events.

Chromium(III) oxide is an amphoteric, dark green solid. This most stable dye is widely used in construction and ceramic industries as well as in painting. In this study, the attempt is made to determine flocculating properties of exopolysaccharide (EPS) synthesized by the bacteria Sinorhizobium meliloti 1021, which would increase the efficiency of chromium(III) oxide removal from sewages and wastewaters. The conditions under which EPS is the most effective destabilizing component of chromium(III) oxide suspension have been determined too. In order to characterize the structure of electric double layer formed at the solid/supporting electrolyte (EPS) solution interface, electrokinetic potential measurements and potentiometric titration were performed. The EPS amount adsorbed on the chromium(III) oxide surface as a solution pH function was also measured. Moreover, the stability of Cr₂O₃suspension in the absence and presence of S. meliloti 1021 EPS was estimated. The pooled analysis of all obtained results showed that EPS causes chromium(III) oxide suspension destabilization in the whole examined pH range. The largest change in the system stability before and after the polymer addition was observed at pH 9. It is probable that under these conditions bridging flocculation occurs in the examined system.