Direct ultrafiltration and its combination with pretreatment by coagulation/flocculation/sedimentation using Moringa oleifera as coagulant to treat dairy industry wastewater were investigated. A single-channel tubular ceramic membrane with an average porosity of 0.1 μm was used at transmembrane pressures of 1, 2, and 3 bars, using the cross-flow filtration principle in a membrane filtration unit. Process efficiency was evaluated in terms of chemical oxygen demand (COD), apparent color, and turbidity removal, along with major requirements such as average permeate flux, percentage of fouling, and contribution of different resistances (resistances in series model) to the total resistance of the membrane. The highest removals for the evaluated parameters occurred in the combined coagulation/flocculation/sedimentation/ultrafiltration process. At a pressure of 2 bar, the removal of turbidity and apparent color was 99.9 % and that of COD was 98.5 %. For the combined process, the lowest percentage of fouling was 59.8 %, which occurred at 1 bar. The fraction of resistance due to fouling, which may indicate irreversible damage of the membrane, was lower in the process of coagulation/flocculation/sedimentation using M. oleifera as coagulant followed by ultrafiltration than in the process that treated dairy wastewater with direct ultrafiltration for all pressures. © 2013 Springer Science+Business Media Dordrecht.

Nitrate addition stimulated sulfide oxidation by increasing the activity of nitrate-reducing sulfide-oxidizing bacteria (NR-SOB), decreasing the concentration of dissolved H2S in the water phase and, consequently, its release to the atmosphere of a pilot-scale anaerobic bioreactor. The effect of four different concentrations of nitrate (0.12, 0.24, 0.50, and 1.00 mM) was investigated for a period of 3 days in relation to sulfide concentration in two bioreactors set up at Guadalete wastewater treatment plant (Jerez de la Frontera, Spain). Physicochemical variables were measured in water and air, and the activity of bacteria implicated in the sulfur and nitrogen cycles was analyzed in the biofilms and in the water phase of the bioreactors. Biofilms were a net source of sulfide for the water and gas phases (7.22±5.3 μmol S-1) in the absence of nitrate dosing. Addition of nitrate resulted in a quick (within 3 h) decrease of sulfide both in the water and atmospheric phases. Sulfide elimination efficiency in the water phase increased with nitrate concentrations following the Michaelis-Menten kinetics (Ks=0.63 mM NO3-). The end of nitrate addition resulted in a recovery or increase of initial net sulfide production in about 3 h. Addition of nitrate increased the activity of NR-SOB and decreased the activity of sulfate-reducing bacteria. Results confirmed the role of NR-SOB on hydrogen sulfide consumption coupled with nitrate reduction and sulfate recycling, revealing Sulfurimonas denitrificans and Paracoccus denitrificans as NR-SOB of great importance in this process. © Springer Science+Business Media Dordrecht 2013.

We studied the isotopic composition of organic matter in the sediments of eight mountain lakes located in the Tatra Mountains (Western Carpathians, Poland). The sediments of the lakes were fine and course detritus gyttja, mud, and sand. The total organic carbon content varied from 0.5 to 53 %. The C/N ratio indicated that in-lake primary production is the major source of the organic matter in the lakes located above the treeline, whereas terrestrial plant fragments are the major organic compounds in the sediments of dystrophic forest lakes. We also found that a clear trend of isotopic curves toward lower values of δ ¹³C and δ ¹⁵N (both ~3 ‰) began in the 1960s. This trend is a sign of the deposition of greater amounts of NO ₓ from the combustion of fossil fuels, mainly by vehicle engines. The combustion of fossil fuels in electric plants and other factories had a smaller influence on the isotopic composition. This trend has been weaker since the 1990s. Animal and human wastes from pastures and tourism had a surprisingly minor effect on lake environments. These data are contrary to previous data regarding lake biota and suggest the high sensitivity of living organisms to organic pollution.

The potential risk of surface and groundwater contamination by the heavy metals and radionuclides leached from uranium waste-rock piles (UWRP) is a major environmental concern in the uranium-mining district of Northern Saskatchewan, Canada. The main objective of this study was to evaluate the nickel and uranium leaching behaviour in the UWRP lithological materials. In addition to the chemical characterization, these selected UWRP geomedia samples were also subjected to the sequential extraction procedure, availability test to quantify leaching potential and cumulative leaching test (CLT). Sequential extractions results demonstrated substantial observed differences in the Ni and U distribution patterns among various operationally defined geochemical fractions. A large fraction of total Ni concentration was associated with non-labile residual fraction while U was mainly present in the labile fractions. The observed labile Ni and U concentrations also remained relatively high in the gneissic basement materials and underlying organic-rich lake sediment. In case of basement materials, both Ni and U concentrations in solution with the first CLT fraction exceeds their maximum permissible levels in both surface and groundwater. Leaching test results confirmed that Ni and U leachability depends on their total content distribution in various solid phase fractions, and several geochemical processes are controlling the solubility of Ni and U geochemical phases in the UWRP. Our experimental data suggest the potential for a long-term risk to surface and groundwater contamination from these UWRP.

Accumulation of metals in aquatic organisms is influenced by several factors, including the presence of other metals; therefore, there is a need to study the effects of mixtures of other metals on the accumulation of a particular metal on the organisms. In this study, the capacity for nickel (Ni) regulation by the juvenile decapod crustacean Penaeus vannamei was analyzed. The effects of both solely Ni exposure and in the presence of other metals such as zinc (Zn), lead (Pb), and cadmium (Cd) in a mixture were analyzed to determine any possible synergism. A previous study revealed that a metal mixture of Zn, Cd, and Pb without Ni induces a higher metal uptake in P. vannamei for all three metals, but in this study, no effect was observed for Ni. The results showed no change in the regulatory capacitance for Ni, even in the presence of other metals. The observed capacity of P. vannamei to regulate body concentrations of nickel prevents its use as a suitable biomonitor for this metal.

The photocatalytic degradation effectiveness of six selected typical phytotoxic substances (ferulic, benzoic, gallic, salicylic, tannic, and acetic acid) by two levels of 10 nm TiO₂ (11 and 22 g/m²) immobilized on tiles under 254 nm of UV light irradiation was investigated. The results showed that the immobilized nano-TiO₂ significantly degraded all phytotoxic substances dissolved in distilled water, and the cumulative degradation rates of ferulic, benzoic, gallic, salicylic, tannic, and acetic acid reached 22.2, 33.6, 48.2, 56.9, 57.5, and 76.0 % after 6 h of treatment, respectively. Furthermore, the cumulative degradation rates of six phytotoxic substances by immobilized nano-TiO₂ were different remarkably, i.e., salicylic acid > benzoic acid, gallic acid > ferulic acid, acetic acid > tannic acid. The maximal photocatalytic degradation efficiencies of all phytotoxic substances appeared at the first 2 h in the three experiments. During the 6-h treatment period, the photocatalytic degradation efficiency of all phytotoxic substances decreased gradually. There was no significant difference in the photocatalytic degradation of benzoic acid and ferulic acid between the two levels of immobilized nano-TiO₂ treatments, whereas a significant difference was found in the photocatalytic degradation of salicylic acid, gallic acid, tannic acid, and acetic acid. In a word, nano-TiO₂ photocatalysis is an effective method to degrade phytotoxic substances. And the photocatalytic degradation effectiveness of six typical phytotoxic substances may be related to their structures.

The congener-specific degradation pattern of polychlorinated biphenyls (PCBs) in Aroclor 1254 was investigated using a novel bacterial strain, Stenotrophomonas sp. JSG1, and it was accelerated by the surfactant, β-cyclodextrin. In addition, 4-chorobenzoic acid (CBA) degradation was also confirmed by the estimation of CBA depletion rate, microbial growth, and release of free chloride ion in mineral medium. Metal ions such as Ni²⁺, Hg²⁺ Ba²⁺, Cu²⁺, and NaCl (>4 %) were found greatly influencing the PCB degradation. However, Ca²⁺, Mg²⁺, Fe²⁺, and Mn²⁺ have not shown any impact on biodegradation. The bphC gene, which encodes an extradiol aromatic ring cleavage dioxygenase was successfully amplified and cloned. Phylogeny-based pairwise alignment of nucleotide sequences suggested that the cloned gene belongs to the extradiol dioxygenase family, but it showed high diversity to the traditional bphC gene. Results of the present investigation revealed that the Stenotrophomonas sp. JSG1 is an effective novel bacterium, which can be used in the PCB remediation studies.

Boric acid-treated and sulfur ion-doped multi-modified TiO₂ films with high photocatalytic activities were prepared on soda–lime glass (Na₂O · CaO · 6SiO₂) substrates via the sol–gel method. The as-prepared specimens were characterized using high-resolution field emission scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, photoluminescence spectra, UV–vis diffuse reflectance spectroscopy, and Brunauer–Emmett–Teller surface area. The photocatalytic activities of the films were evaluated by degradation of organic dyes in aqueous solutions. Compared with boric acid treatment and sulfur surface doping, the integration of both methods gave the best results. It is believed that high photocatalytic activity is correlated with the microstructure of the TiO₂ film.

Three pot experiments were carried out to evaluate the phytoextraction efficiency of cadmium (Cd) by an amaranth (Amaranthus hypochondriacus L.). To enhance phytoremediation potential, this study examined the effect of fertilization, repeated harvests, and growth time on the efficiency of Cd removal from soil. The result showed that fertilizing with NPK increased dry biomass by a factor of 4.2, resulting in a large increment of Cd accumulation. Repeated harvests had a significant effect on the plant biomass and thus on overall Cd removal and an optimal cutting position influenced the amount of Cd extracted from soils. Plant growth time was found to significantly affect the amount of Cd extracted by A. hypochondriacus. This study indicates that A. hypochondriacus has great phytoremediation potential in Cd-contaminated soil. For best practice, the recommendation is to maximize the phytoextraction efficiency of A. hypochondriacus by repeated harvests, harvesting at the squaring stage (soon after the flower begins to appear), and apply NPK compound fertilizer as base application.

This paper investigates the electrochemical treatment of polychlorinated biphenyl (PCB) contaminated soils. The research was performed within a project co-funded by the European Regional Development Fund and for the experimental part; artificially contaminated soil with PCB was used. Two reactors of different sizes were used; the smaller designed in a Ph.D. research and the larger in a research project co-funded by the European Regional Development Fund. Specific voltage, current density, redox potential, time and pH values were considered throughout the tests. The initial PCB concentration in the test soil (3.571 mg/kgdw) exceeds the intervention threshold for sensitive use according to Romanian regulations (1 mg/kgdw). Three different tests were performed: within the first one (T1) the soil was polluted with insulating oil; within the other two tests (T2 and T3) the soil was contaminated with capacitor oil. The initial PCB concentrations within the three tests (as a sum of all PCB concentrations) were: 4.4461 mg/kgdw within T1, and 3.5710 mg/kgdw within both T2 and T3. The study showed that the electrochemical treatment could achieve up to 87 % remediation efficiency for PCB polluted soils. Therefore, this treatment is relevant and a potential solution for the remediation of PCB polluted soils.