Browsing by Subject "REMOVAL"

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  • Paajanen, Johanna; Weintraub, Saara; Lönnrot, Satu; Heikkilä, Mikko; Vehkamäki, Marko; Kemell, Marianna; Hatanpää, Timo; Ritala, Mikko; Koivula, Risto (2021)
    Nanoscale SnO2 has many important properties ranging from sorption of metal ions to gas sensing. Using a novel electroblowing method followed by calcination, we synthesized SnO2 and composite SnO2/SiO2 submicron fibers with a Sn : Si molar ratio of 3 : 1. Different calcination temperatures and heating rates produced fibers with varying structures and morphologies. In all the fibers SnO2 was detected by XRD indicating the SnO2/SiO2 fibers to be composite instead of complete mixtures. We studied the Co2+ separation ability of the fibers, since Co-60 is a problematic contaminant in nuclear power plant wastewaters. Both SnO2 and SnO2/SiO2 fibers had an excellent Co2+ uptake with their highest uptake/K-d values being 99.82%/281 000 mL g(-1) and 99.79%/234 000 mL g(-1), respectively. Compared to the bare SnO2 fibers, the SiO2 component improved the elasticity and mechanical strength of the composite fibers which is advantageous in dynamic column operation.
  • Xu, Junhua; Virolainen, Sami; Zhang, Wenzhong; Kuva, Jukka; Sainio, Tuomo; Koivula, Risto (2018)
    Recycled Nd and Dy from the end-of-life NdFeB permanent magnet is an important supplement for the increasing demand of rare-earth elements. Thus, there is an urgent need to develop an environmentally friendly recycling method. Amorphous zirconium phosphate exhibits selective separation properties towards the ternary Co-Nd-Dy system, however, its powdery form limits development of scaled-up applications. We present an efficient amorphous ZrP/Polyacrylonitrile (am-ZrP/PAN) composite ion exchanger for uptake and separation of Nd, Dy and Co. The am-ZrP/PAN composite was synthesized and its structural, morphologic and acidic properties were investigated by various methods. X-ray tomography revealed rather evenly distributed am-ZrP in the PAN polymer matrix. The selectivity and ion-exchange kinetics of the am-ZrP/PAN composite were determined in relation to the individual elements. Due to dimethylformide (DMF) intercalation into the interlayer of ZrP, the uptake of Co, Nd and Dy increased 50% compared with that of the pristine am-ZrP. Column separation of Co, Nd and Dy from the Co-Nd-Dy ternary system was assessed by varying the feed concentration, loading degree, temperature, running speed and elution agent (HNO3) concentration. Finally, gradient elution was employed for Co, Nd and Dy separation from a simulated ternary leachate. Fractions with 87.9% pure Co, 96.4% pure Nd and 40% pure Dy were collected through a single-column operation.
  • Manner, Suvi; Goeres, Darla M.; Skogman, Malena; Vuorela, Pia; Fallarero, Adyary (2017)
    Biofilm formation leads to the failure of antimicrobial therapy. Thus, biofilm prevention is a desirable goal of antimicrobial research. In this study, the efficacy of antibiotics (doxycycline, oxacillin and rifampicin) in preventing Staphylococcus aureus biofilms was investigated using Microtiter Well Plates (MWP) and Drip Flow Reactors (DFR), two models characterized by the absence and the presence of a continuous flow of nutrients, respectively. Planktonic culture of S. aureus was exposed to antibiotics for one hour followed by 24 hours incubation with fresh nutrients in MWP or continuous flow of nutrients in DFR. The DFR grown biofilms were significantly more tolerant to the antibiotics than those grown in MWP without the continuous flow. The differences in log reductions (LR) between the two models could not be attributed to differences in the cell density, the planktonic inoculum concentration or the surface-area-to-volume ratios. However, eliminating the flow in the DFR significantly restored the antibiotic susceptibility. These findings demonstrate the importance of considering differences between experimental conditions in different model systems, particularly the flow of nutrients, when performing anti-biofilm efficacy evaluations. Biofilm antibiotic efficacy studies should be assessed using various models and more importantly, in a model mimicking conditions of its clinical application.
  • Kakaei Lafdani, Elham; Saarela, Taija; Laurén, Ari; Pumpanen, Jukka; Palviainen, Marjo (2020)
    Biochar can be an effective sorbent material for removal of nutrients from water due to its high specific surface area, porous structure, and high cation and anion exchange capacity. The aim of this study was to test a biochar reactor and to evaluate its efficiency in runoff water purification and consecutive nutrient recycling in clear-cut peatland forests. The goodness of the method was tested in a meso-scale (water volume thousands of liters) reactor experiment by circulating runoff water through wood biochar-filled columns and by determining water nutrient concentrations in the column inlet and outlet. The pseudo-first and second order kinetic models were fitted to the experimental data and the adsorption rate (K-dd) and maximum adsorption capacity (Q(max)) of the biochar reactor were quantified. The concentration of total nitrogen (TN) decreased by 58% during the 8-week experiment; the majority of TN adsorption occurred within the first 3 days. In addition, NO3-N and NH4-N concentrations decreased below the detection limit in 5 days after the beginning of the experiment. The maximum adsorption capacity of the biochar reactor varied between 0.03-0.04 mg g(-1) biochar for NH4-N, and was equal to 0.02 mg g(-1) biochar for TN. The results demonstrated that the biochar reactor was not able to adsorb TN when the water TN concentration was below 0.4 mg L-1. These results suggest that a biochar reactor can be a useful and effective method for runoff water purification in clear-cut forests and further development and testing is warranted. Unlike traditional water protection methods in peatland forestry, the biochar reactor can effectively remove NO3-N from water. This makes the biochar reactor a promising water protection tool to be tested in sites where there is the risk of a high rate of nutrient export after forest harvesting or drainage.
  • Venäläinen, Salla H.; Hartikainen, Helinä (2017)
    We carried out an adsorption experiment to investigate the ability of anionic nanofibrillated cellulose (NFC) to retain metal and SO42- ions from authentic highly acidic (pH 3.2) mining water. Anionic NFC gels of different consistencies (1.1%, 1.4-% and 1.8-% w/w) were allowed to react for 10 min with mining water, after which NFC-induced changes in the metal and SO42- concentrations of the mining water were determined. The sorption capacities of the NFC gels were calculated as the difference between the element concentrations in the untreated and NFC-treated mining water samples. All the NFCs efficiently co-adsorbed both metals and SO42-. The retention of metals was concluded to take place through formation of metal-ligand complexes. The reaction between the NFC ligand and the polyvalent cations renders the cellulose nanofibrils positively charged and, thus, able to retain SO42- electrostatically. Adsorption capacity of the NFC gels substantially increased upon decreasing DM content as a result of the dilution-induced weakening of the mutual interactions between individual cellulose nanofibrils. This outcome reveals that the dilution of the NFC gel not only increases its purification capacity but also reduces the demand for cellulosic raw material. These results suggest that anionic NFC made of renewable materials serves as an environmentally sound and multifunctional purification agent for acidic multimetal mining waters or AMDs of high ionic strength. Unlike industrial minerals traditionally used to precipitate valuable metals from acidic mining effluents before their permanent disposal from the material cycle, NFC neither requires mining of unrenewable raw materials nor produces inorganic sludges. (C) 2017 Elsevier B.V. All rights reserved.
  • Ojanen, Paavo; Minkkinen, Kari (2020)
    Peat soils drained for agriculture and forestry are important sources of carbon dioxide and nitrous oxide. Rewetting effectively reduces these emissions. However, rewetting also increases methane emissions from the soil and, on forestry-drained peatlands, decreases the carbon storage of trees. To analyze the effect of peatland rewetting on the climate, we built radiative forcing scenarios for tropical peat soils, temperate and boreal agricultural peat soils, and temperate and boreal forestry-drained peat soils. The effect of tree and wood product carbon storage in boreal forestry-drained peatlands was also estimated as a case study for Finland. Rewetting of tropical peat soils resulted in immediate cooling. In temperate and boreal agricultural peat soils, the warming effect of methane emissions offsets a major part of the cooling for the first decades after rewetting. In temperate and boreal forestry-drained peat soils, the effect of rewetting was mostly warming for the first decades. In addition, the decrease in tree and wood product carbon storage further delayed the onset of the cooling effect for decades. Global rewetting resulted in increasing climate cooling, reaching -70 mW (m(2)Earth)(-1)in 100 years. Tropical peat soils (9.6 million ha) accounted for approximately two thirds and temperate and boreal agricultural peat soils (13.0 million ha) for one third of the cooling. Forestry-drained peat soils (10.6 million ha) had a negligible effect. We conclude that peatland rewetting is beneficial and important for mitigating climate change, but abandoning tree stands may instead be the best option concerning forestry-drained peatlands.
  • Lynch, Fiona; Santana-Sanchez, Anita; Jämsä, Mikael; Sivonen, Anna Kaarina; Aro, Eva-Mari; Allahverdiyeva, Yagut (2015)
    The value and efficiency of microalgal biofuel production can be improved in an integrated system using waste streams as feed-stock, with fuel-rich biomass and treated wastewater being key end-products. We have evaluated seven native cyanobacterial isolates and one native green alga for their nutrient removal, biomass accumulation and lipid production capacities. All native isolates were successfully grown on synthetic wastewater mimicking secondary treated municipal wastewater (without organic carbon). Complete phosphate removal was achieved by the native green alga, isolated from Tvarminne (SW Finland). Optimisation of the C:N ratio available to this strain was achieved by addition of 3% CO2 and resulted in complete ammonium removal in synthetic wastewater. The native green alga demonstrated similar nutrient removal rates and even stronger growth in screened municipal wastewater, which had double the ammonium concentration of the synthetic media and also contained organic carbon. Sequencing of the genes coding for 18S small rRNA subunit and the ITS1 spacer region of this alga placed it in the Scenedesmaceae family. The lipid content of native isolates was evaluated using BODIPY (505/515) staining combined with high-throughput flow cytometry, where the native green alga demonstrated significantly greater neutral lipid accumulation than the cyanobacteria under the conditions studied. (C) 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
  • Prieto-Borja, Laura; Perez-Tanoira, Ramon; Levano-Linares, Dennis-Cesar; Celdran, Angel; Mahillo-Fernandez, Ignacio; Esteban, Jaime (2016)
    Background: The use of drains in patients undergoing abdominal surgery has been a subject of debate for several decades. In this paper, the usefulness of quantitative cultures of sonicated abdominal drains for diagnosing surgical site of infection (SSI) and the association between culture results with patient outcome is evaluated. Methods: Forty-five abdominal drainage tubes from 35 patients who underwent abdominal surgery were studied. Samples were sonicated for 5 min, the sonicate was centrifuged, and the sediment was cultured on different media. Total bacterial counts were adjusted to the actual surface of the drainage tubing. Clinical information of the patients was reviewed retrospectively. Results: A relation was observed between SSI and the use of drains for more than 3 d (p = 0.0216). The presence of a suspected pathogen was related to the prevalence of SSI (p = 0.035), complications (p = 0.013), and greater leukocyte count (p = 0.048 Mann Whitney test), as well as to the use of drains for more than 3 d (p = 0.0386) and to the serous appearance of the exudates at the point of insertion of the drain (p = 0.0399). The sonication procedure showed a sensitivity of 50%, specificity of 84.2%, positive predictive value of 72.72%, and negative predictive value of 66.67% in the diagnosis of SSI. The most commonly isolated group of organisms was coagulase-negative staphylococci, being present in 18 patients (51.43%) who, however, were not associated with SSI. One or two organisms considered as pathogens were detected in 11 patients (31.43%). The more common pathogens detected were Enterobacteriae spp. (nine patients): Enterobacter aerogenes (2), Enterobacter cloacae (1), Escherichia coli (4), Klebsiella pneumoniae (1), Morganella morganii (1); and Pseudomonas aeruginosa (five patients). Candida spp. and Enterococcus spp. were detected in one patient each one. Conclusions: The detection and quantification of organisms not present in skin microbiota after drain sonication is helpful in the diagnosis of SSI and it is associated with a worse outcome in patients. Duration of use of drainage tubes is an independent risk factor for the development of SSI.
  • Niinikoski-Fusswinkel, Paula; Purkamo, Lotta; Karhu, Juha (2020)
    This study examines the effect of poly-aluminium chloride (PACl) pre-treatment on the biological purification process taking place during managed aquifer recharge (MAR). PACl treatment is used in waste and surface water treatment to remove organic material. PACl can decrease the organic carbon contents of water significantly. However, aluminium is toxic to microbes, which may be detrimental when the PACl treatment is followed by infiltration into an aquifer (MAR). In this study the effect of pre-treatment with PACl on the water purification process in MAR was examined, by using sediment from a MAR site in four test columns. Two columns were filled with PACl-treated water, and the remaining ones with river water without PACl. The residence time of water in the columns was raised from direct sampling gradually to 64 days. Among the parameters monitored were the pH of the water, microbial activity and the decomposition of dissolved organic carbon (DOC). The results showed active decomposition in all columns. Decomposition of organic matter, and the amount of living/active microbial cells, was marginally higher in the untreated water, which could imply a better functioning MAR system. However, this may also be due to higher DOC starting concentration.
  • Kanerva, Anna-Maria; Hokkanen, Tatu; Lehikoinen, Aleksi; Norrdahl, Kai; Suhonen, Jukka (2020)
    Migration has evolved to tackle temporal changes in availability of resources. Climate change has been shown to affect the migration dates of species, which raises the question of whether the variation in the timing of migration is climate or resource dependent? The relative importance of temperature and availability of food as drivers of migration behaviour during both spring and autumn seasons has been poorly studied. Here, we investigated these patterns in frugivorous and granivorous birds (hereafter frugivorous) that are assumed to postpone their autumn migration when there is plenty of food available, which may also advance upcoming spring migration. On the other hand, especially spring migration dates have been negatively connected with increasing temperatures. We tested whether the autumn and spring migration dates of eleven common frugivorous birds depended on the crop size of trees or ambient temperatures using 29 years of data in Finland. The increased crop sizes of trees delayed autumn migration dates; whereas, autumn temperature did not show a significant connection. We also observed a temporal trend towards later departure. Increasing temperature and crop sizes advanced spring arrival dates. Our results support the hypothesis that the timing of autumn migration in the frugivorous birds depends on the availability of food and is weakly connected with the variation in temperature. Importantly, crop size can have carry-over effects and affect the timing of spring arrival possibly because birds have overwintered closer to the breeding grounds after an abundant crop year.
  • Krüger, Heidi; Väänänen, Veli-Matti; Holopainen, Sari; Nummi, Petri (2018)
    European populations of many ground-nesting farmland birds have declined in recent decades. Increases in predator populations and nest predation may play an important role in this decline, along with habitat loss. However, the role of various predators has often remained unclear. We conducted a study with artificial nests and wildlife cameras (n=104) in agricultural landscapes during 2015-2016 in South Finland. Our trials formed a 400-m wide gradient from forest to field. The aim of our study was to monitor nest survival and nest predators in a spatial and temporal scale. We tested the effect of distance to the forest and nest visibility to nest predation. During an 8-day period, 39.4% of the artificial nests were predated. Fifty percent of the predators were birds, 40% mammals, and 10% remained unknown. The three dominant predators of our artificial nests were the raccoon dog (Nyctereutes procyonoides) with 11 nests and the hooded crow (Corvus corone cornix) and the magpie (Pica pica) with 10 depredated nests each. Our analysis indicates that avian predators preyed upon nests in open fields further away from the forest edge, whereas mammalian predation concentrated closer to the forest edge. Predation occurred more likely at the beginning of the survey and nest survival increased as days passed. Our study highlights the efficiency of using wildlife camera traps in nest predation studies. We also suggest that the ongoing expansion of alien predators across Europe may have a greater impact on ground-nesting bird populations than previously anticipated.
  • Dyer, Alan; Hriljac, Joe; Evans, Nick; Stokes, Ian; Rand, Peter; Kellet, Simon; Harjula, Risto; Moller, Teresia; Maher, Zoe; Heatlie-Branson, Ross; Austin, Jonathan; Williamson-Owens, Scott; Higgins-Bos, Manon; Smith, Kurt; O'Brien, Luke; Smith, Nick; Bryan, Nick (2018)
    Mud Hills clinoptilolite has been used in an effluent treatment plant (SIXEP) at the Sellafield nuclear reprocessing site. This material has been used to remove Cs-134/137 and Sr-90 successfully from effluents for 3 decades. Samples of the zeolite have been tested in column experiments to determine their ability to remove radioactive Cs+ and Sr2+ ions under increasing concentrations of competing ions, Ca2+, Mg2+, Na+ and K+. These ions caused increased elution of Cs+ and Sr2+. Ca2+, Mg2+ and K+ were more effective competitors than Na+. For Na+, it was found that if concentration was reduced, then column performance recovered rapidly.