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Kaja Orupõld received her PhD at the University of Tartu, Estonia in environmental chemistry. She has worked as a lecture and a researcher at the University of Tartu, Estonia, in short term as a visiting researcher at the Lund University, Sweden. Presently, Kaja Orupõld is associate professor in environmental chemistry and ecotoxicology. She runs also the laboratory of Bio-and Environmental Chemistry at the Chair of Environmental Protection and Landscape Management of Estonian University of Life Sciences. Main research interests include anaerobic digestion of organic wastes, characterization of compost and waste for stability as well as mobility and bioavailability of hazardous substances in the environment.
Waste banknote paper is a residue from the banking industry that cannot be recycled due to the presence of ink, microbial load and special coating that provides protection against humidity. As a result, waste banknote paper ends up being burned or buried, which brings environmental impacts, mainly caused by the presence of heavy metals in its composition. To minimize the environmental impacts that come from the disposal of waste banknote paper, this study proposes to produce value-added products (bioethanol and biogas) from waste banknote paper. For this, the effect of ink and pretreatment conditions on bioethanol and biomethane yields were analyzed. Waste banknote paper provided by the Central Bank of Iran was used. The raw material with ink (WPB) and without ink (WPD) was pretreated using sulfuric acid at different concentrations (1%, 2%, 3%, and 4%) and the nitrogen explosive decompression (NED) at different temperatures (150 °C, 170 °C, 190 °C, and 200 °C). The results show that the use of NED pretreatment in WPD resulted in the highest glucose concentration of all studies (13 ± 0.19 g/L). The acid pretreatment for WPB showed a correlation with the acid concentration. The highest ethanol concentration was obtained from the fermentation using WPD pretreated with NED (6.36 ± 0.72 g/L). The maximum methane yields varied between 136 ± 5 mol/kg TS (2% acid WPB) and 294 ± 4 mol/kg TS (3% acid WPD). Our results show that the presence of ink reduces bioethanol and biogas yields and that the chemical-free NED pretreatment is more advantageous for bioethanol and biogas production than the acid pretreatment method. Waste banknote paper without ink is a suitable feedstock for sustainable biorefinery processes.
Omid Yazdani Aghmashhadi; Lisandra Rocha-Meneses; Nemailla Bonturi; Kaja Orupõld; Ghasem Asadpour; Esmaeil Rasooly Garmaroody; Majid Zabihzadeh; Timo Kikas. Effect of Ink and Pretreatment Conditions on Bioethanol and Biomethane Yields from Waste Banknote Paper. Polymers 2021, 13, 239 .
AMA StyleOmid Yazdani Aghmashhadi, Lisandra Rocha-Meneses, Nemailla Bonturi, Kaja Orupõld, Ghasem Asadpour, Esmaeil Rasooly Garmaroody, Majid Zabihzadeh, Timo Kikas. Effect of Ink and Pretreatment Conditions on Bioethanol and Biomethane Yields from Waste Banknote Paper. Polymers. 2021; 13 (2):239.
Chicago/Turabian StyleOmid Yazdani Aghmashhadi; Lisandra Rocha-Meneses; Nemailla Bonturi; Kaja Orupõld; Ghasem Asadpour; Esmaeil Rasooly Garmaroody; Majid Zabihzadeh; Timo Kikas. 2021. "Effect of Ink and Pretreatment Conditions on Bioethanol and Biomethane Yields from Waste Banknote Paper." Polymers 13, no. 2: 239.
Results from an investigation of the mechanical size reduction with the Szego Mill™ as a pretreatment method for lignocellulosic biomass are presented. Pretreatment is a highly expensive and energy-consuming step in lignocellulosic biomass processing. Therefore, it is vital to study and optimize different pretreatment methods to find a most efficient production process. The biomass was milled with the Szego Mill™ using three different approaches: dry milling, wet milling and for the first time nitrogen assisted wet milling was tested. Bioethanol and biogas production were studied, but also fibre analysis and SEM (scanning electron microscope) analysis were carried out to characterize the effect of different milling approaches. In addition, two different process flows were used to evaluate the efficiency of downstream processing steps. The results show that pretreatment of barely straw with the Szego Mill™ enabled obtaining glucose concentrations of up to 7 g L−1 in the hydrolysis mixture, which yields at hydrolysis efficiency of 18%. The final ethanol concentrations from 3.4 to 6.7 g L−1 were obtained. The lowest glucose and ethanol concentrations were measured when the biomass was dry milled, the highest when nitrogen assisted wet milling was used. Milling also resulted in an 6–11% of increase in methane production rate during anaerobic digestion of straw.
Merlin Raud; Kaja Orupõld; Lisandra Rocha-Meneses; Vahur Rooni; Olev Träss; Timo Kikas. Biomass Pretreatment with the Szego Mill™ for Bioethanol and Biogas Production. Processes 2020, 8, 1327 .
AMA StyleMerlin Raud, Kaja Orupõld, Lisandra Rocha-Meneses, Vahur Rooni, Olev Träss, Timo Kikas. Biomass Pretreatment with the Szego Mill™ for Bioethanol and Biogas Production. Processes. 2020; 8 (10):1327.
Chicago/Turabian StyleMerlin Raud; Kaja Orupõld; Lisandra Rocha-Meneses; Vahur Rooni; Olev Träss; Timo Kikas. 2020. "Biomass Pretreatment with the Szego Mill™ for Bioethanol and Biogas Production." Processes 8, no. 10: 1327.
The main components of landfill gas are methane and carbon dioxide. Emissions of methane, a strong greenhouse gas, can be minimized by in situ oxidation in the bioactive cover layer. Typically, organic-rich porous materials such as compost are used for this process. In this study, the material for a biocover was obtained from the same landfill by landfill mining. The objective was to study the spatial distribution of gases and the efficiency of methane degradation in the biocover. The methane and carbon dioxide emissions were measured at 29 measuring points six times on the surface and once at a depth of 0.5 m. The highest values of both gases from the surface were recorded in July 2015: 1.0% for CO2 and 2.1% for CH4. Deeper in the cover layer, higher values of methane concentration were recorded. The results showed that (a) methane from the waste deposit was entering the biocover, (b) the migration of methane to the atmosphere was low, (c) fluctuations in the composition of gases are seasonal, and (d) the trend in the concentration of CH4 over time was an overall decrease. The described cover design reduces the CH4 emissions in landfills using elements of circular economy—instead of wasting natural soils and synthetic liners for the construction of the final cover layer, functional waste-derived materials can be used.
Kaur-Mikk Pehme; Kaja Orupõld; Valdo Kuusemets; Ottar Tamm; Yahya Jani; Toomas Tamm; Mait Kriipsalu. Field Study on the Efficiency of a Methane Degradation Layer Composed of Fine Fraction Soil from Landfill Mining. Sustainability 2020, 12, 6209 .
AMA StyleKaur-Mikk Pehme, Kaja Orupõld, Valdo Kuusemets, Ottar Tamm, Yahya Jani, Toomas Tamm, Mait Kriipsalu. Field Study on the Efficiency of a Methane Degradation Layer Composed of Fine Fraction Soil from Landfill Mining. Sustainability. 2020; 12 (15):6209.
Chicago/Turabian StyleKaur-Mikk Pehme; Kaja Orupõld; Valdo Kuusemets; Ottar Tamm; Yahya Jani; Toomas Tamm; Mait Kriipsalu. 2020. "Field Study on the Efficiency of a Methane Degradation Layer Composed of Fine Fraction Soil from Landfill Mining." Sustainability 12, no. 15: 6209.
Cellulosic biomass has been widely used as a feedstock for biofuel applications due to its low-cost, renewability and abundance. However, the production of liquid biofuels is still costly and inefficient mainly due to the recalcitrant structure of lignocellulosic biomass. It requires expensive pretreatment methods to break down the plant cell wall, and efficient enzymes capable of hydrolysing cellulose into glucose. One possible solution to make bioethanol production cost-effective and, at the same time, increase the energy output from the biomass is genetic engineering. Genetic modification has been reported as an effective strategy to increase productivity, biomass yields and specific traits of various agricultural plants. This paper provides an overview of the potential of cereal-based agricultural waste as a feedstock for bioethanol production. It focuses on the progress of different techniques used in genetic modification (transgenesis, cisgenesis mutagenesis and conventional breeding) to genetically engineer plant cell wall. Utilization of genetic modification of cereal plants is proposed as a solution to high costs and low yields of bioethanol production from cereal-based agricultural waste.
Lisandra Rocha-Meneses; Jorge A. Ferreira; Maryam Mushtaq; Sajjad Karimi; Kaja Orupõld; Timo Kikas. Genetic modification of cereal plants: A strategy to enhance bioethanol yields from agricultural waste. Industrial Crops and Products 2020, 150, 112408 .
AMA StyleLisandra Rocha-Meneses, Jorge A. Ferreira, Maryam Mushtaq, Sajjad Karimi, Kaja Orupõld, Timo Kikas. Genetic modification of cereal plants: A strategy to enhance bioethanol yields from agricultural waste. Industrial Crops and Products. 2020; 150 ():112408.
Chicago/Turabian StyleLisandra Rocha-Meneses; Jorge A. Ferreira; Maryam Mushtaq; Sajjad Karimi; Kaja Orupõld; Timo Kikas. 2020. "Genetic modification of cereal plants: A strategy to enhance bioethanol yields from agricultural waste." Industrial Crops and Products 150, no. : 112408.
This study investigates the potential of different stages of the bioethanol production process (pretreatment, hydrolysis, and distillation) for bioethanol and biomethane production, and studies the critical steps for the liquid and the solid fractions to be separated and discarded to improve the efficiency of the production chain. For this, Napier grass (a fast-growing grass) from Effurun town of Delta State in Nigeria was used and the novel pretreatment method, nitrogen explosive decompression (NED), was applied at different temperatures. The results show that the lowest glucose (13.7 g/L) and ethanol titers (8.4 g/L) were gained at 150 °C. The highest glucose recovery (31.3 g/L) was obtained at 200 °C and the maximum ethanol production (10.3 g/L) at 170 °C. Methane yields are higher in samples pretreated at lower temperatures. The maximum methane yields were reported in samples from the solid fraction of post-pretreatment (pretreated at 150 °C, 1.13 mol CH4/100 g) and solid fraction of the post-hydrolysis stage (pretreated at 150 °C, 1.00 mol CH4/100 g). The lowest biomethane production was noted in samples from the liquid fraction of post-pretreatment broth (between 0.14 mol CH4/100 g and 0.24 mol CH4/100 g). From the process point of view, samples from liquid fraction of post-pretreatment broth should be separated and discarded from the bioethanol production process, since they do not add value to the production chain. The results suggest that bioethanol and biomethane concentrations are influenced by the pretreatment temperature. Napier grass has potential for bioethanol and further biomethane production and it can be used as an alternative source of energy for the transportation sector in Nigeria and other countries rich in grasses and provide energy security to their population.
Lisandra Rocha-Meneses; Oghenetejiri Frances Otor; Nemailla Bonturi; Kaja Orupõld; Timo Kikas. Bioenergy Yields from Sequential Bioethanol and Biomethane Production: An Optimized Process Flow. Sustainability 2019, 12, 272 .
AMA StyleLisandra Rocha-Meneses, Oghenetejiri Frances Otor, Nemailla Bonturi, Kaja Orupõld, Timo Kikas. Bioenergy Yields from Sequential Bioethanol and Biomethane Production: An Optimized Process Flow. Sustainability. 2019; 12 (1):272.
Chicago/Turabian StyleLisandra Rocha-Meneses; Oghenetejiri Frances Otor; Nemailla Bonturi; Kaja Orupõld; Timo Kikas. 2019. "Bioenergy Yields from Sequential Bioethanol and Biomethane Production: An Optimized Process Flow." Sustainability 12, no. 1: 272.
Almost 500 municipal solid waste incineration plants in the EU, Norway and Switzerland generate about 17.6 Mt/a of incinerator bottom ash (IBA). IBA contains minerals and metals. Metals are mostly separated and sold to the scrap market and minerals are either disposed of in landfills or utilised in the construction sector. Since there is no uniform regulation for IBA utilisation at EU level, countries developed own rules with varying requirements for utilisation. As a result from a cooperation network between European experts an up-to-date overview of documents regulating IBA utilisation is presented. Furthermore, this work highlights the different requirements that have to be considered. Overall, 51 different parameters for the total content and 36 different parameters for the emission by leaching are defined. An analysis of the defined parameter reveals that leaching parameters are significantly more to be considered compared to total content parameters. In order to assess the leaching behaviour nine different leaching tests, including batch tests, up-flow percolation tests and one diffusion test (monolithic materials) are in place. A further discussion of leaching parameters showed that certain countries took over limit values initially defined for landfills for inert waste and adopted them for IBA utilisation. The overall utilisation rate of IBA in construction works is approximately 54 wt%. It is revealed that the rate of utilisation does not necessarily depend on how well regulated IBA utilisation is, but rather seems to be a result of political commitment for IBA recycling and economically interesting circumstances.
Dominik Blasenbauer; Florian Huber; Jakob Lederer; Margarida Quina; Denise Blanc-Biscarat; Anna Bogush; Elza Bontempi; Julien Blondeau; Josep Maria Chimenos; Helena Dahlbo; Johan Fagerqvist; Jessica Giro Paloma; Ole Hjelmar; Jiri Hyks; Jackie Keaney; Maria Lupsea-Toader; Catherine Joyce O'Caollai; Kaja Orupõld; Tadeusz Pająk; Franz-Georg Simon; Lenka Svecova; Michal Syc; Roy Ulvang; Kati Vaajasaari; Jo Van Caneghem; Andre van Zomeren; Saulius Vasarevičius; Krisztina Wégner; Johann Fellner. Legal situation and current practice of waste incineration bottom ash utilisation in Europe. Waste Management 2019, 102, 868 -883.
AMA StyleDominik Blasenbauer, Florian Huber, Jakob Lederer, Margarida Quina, Denise Blanc-Biscarat, Anna Bogush, Elza Bontempi, Julien Blondeau, Josep Maria Chimenos, Helena Dahlbo, Johan Fagerqvist, Jessica Giro Paloma, Ole Hjelmar, Jiri Hyks, Jackie Keaney, Maria Lupsea-Toader, Catherine Joyce O'Caollai, Kaja Orupõld, Tadeusz Pająk, Franz-Georg Simon, Lenka Svecova, Michal Syc, Roy Ulvang, Kati Vaajasaari, Jo Van Caneghem, Andre van Zomeren, Saulius Vasarevičius, Krisztina Wégner, Johann Fellner. Legal situation and current practice of waste incineration bottom ash utilisation in Europe. Waste Management. 2019; 102 ():868-883.
Chicago/Turabian StyleDominik Blasenbauer; Florian Huber; Jakob Lederer; Margarida Quina; Denise Blanc-Biscarat; Anna Bogush; Elza Bontempi; Julien Blondeau; Josep Maria Chimenos; Helena Dahlbo; Johan Fagerqvist; Jessica Giro Paloma; Ole Hjelmar; Jiri Hyks; Jackie Keaney; Maria Lupsea-Toader; Catherine Joyce O'Caollai; Kaja Orupõld; Tadeusz Pająk; Franz-Georg Simon; Lenka Svecova; Michal Syc; Roy Ulvang; Kati Vaajasaari; Jo Van Caneghem; Andre van Zomeren; Saulius Vasarevičius; Krisztina Wégner; Johann Fellner. 2019. "Legal situation and current practice of waste incineration bottom ash utilisation in Europe." Waste Management 102, no. : 868-883.
The production of second-generation ethanol using lignocellulosic feedstock is crucial in order to be able to meet the increasing fuel demands by the transportation sector. However, the technology still needs to overcome several bottlenecks before feasible commercialization can be realized. These include, for example, the development of cost-effective and environmentally friendly pretreatment strategies and valorization of the sidestream that is obtained following ethanol distillation. This work uses two chemical-free pretreatment methods—nitrogen explosive decompression (NED) and synthetic flue gas explosive decompression—to investigate the potential of a bioethanol production sidestream in terms of further anaerobic digestion. For this purpose, samples from different stages of the bioethanol production process (pretreatment, hydrolysis, and fermentation) and the bioethanol sidestream went through a separation process (involving solid–liquid separation), following which a biomethane potential (BMP) assay was carried out. The results show that both factors being studied in this article (involving the pretreatment method and the separation process) served to influence methane yields. Liquid fractions that were obtained during the process with NED gave rise to methane yields that were 8% to 12% higher than when synthetic flue gas was used; fermented and distillation sidestream gave rise to the highest methane yields (0.53 and 0.58 mol CH4/100 g respectively). The methane yields from the liquid fractions were between 60–88% lower than those that were obtained from solid fractions. Samples from the bioethanol sidestream (solid fraction) that were pretreated with NED had the highest methane yield (1.7 mol CH4/100 g). A solid–liquid separation step can be a promising strategy when it comes to improving the energy output from lignocellulosic biomass and the management of the ethanol distillation sidestream.
Lisandra Rocha-Meneses; Jorge A Ferreira; Nemailla Bonturi; Kaja Orupõld; Timo Kikas. Enhancing Bioenergy Yields from Sequential Bioethanol and Biomethane Production by Means of Solid–Liquid Separation of the Substrates. Energies 2019, 12, 3683 .
AMA StyleLisandra Rocha-Meneses, Jorge A Ferreira, Nemailla Bonturi, Kaja Orupõld, Timo Kikas. Enhancing Bioenergy Yields from Sequential Bioethanol and Biomethane Production by Means of Solid–Liquid Separation of the Substrates. Energies. 2019; 12 (19):3683.
Chicago/Turabian StyleLisandra Rocha-Meneses; Jorge A Ferreira; Nemailla Bonturi; Kaja Orupõld; Timo Kikas. 2019. "Enhancing Bioenergy Yields from Sequential Bioethanol and Biomethane Production by Means of Solid–Liquid Separation of the Substrates." Energies 12, no. 19: 3683.
Lignocellulosic biomass is emerging as an important feedstock for biofuel production. Bioethanol is one of the most common liquid biofuels in the transportation sector. However, its production process is still inefficient due to the large quantity of production waste that is left unused after the distillation process. In this paper, the biomethane potential of bioethanol production waste is analysed. The results are compared with the biomethane potential of samples from different stages of the bioethanol production process (pretreatment, hydrolysis and fermentation), and that of untreated biomass. In this study, barley straw is used as a biomass crop and N2 explosive decompression (NED) is applied as a pretreatment method. The results show that bioethanol production waste has higher methane yields (1.17 mol CH4/100 g) than raw barley straw (1.04 mol CH4/100 g). Production waste also has a higher degradation rate (0.252) than untreated material (0.138), and achieves 95% of the maximum methane yield much faster (7.8 days) than untreated samples (22 days). This shows that production waste can be used for further anaerobic digestion (AD) to add value to the bioethanol production chain. NED pretreatment is an effective method of pretreatment.
Lisandra Rocha-Meneses; Merlin Raud; Kaja Orupõld; Timo Kikas. Potential of bioethanol production waste for methane recovery. Energy 2019, 173, 133 -139.
AMA StyleLisandra Rocha-Meneses, Merlin Raud, Kaja Orupõld, Timo Kikas. Potential of bioethanol production waste for methane recovery. Energy. 2019; 173 ():133-139.
Chicago/Turabian StyleLisandra Rocha-Meneses; Merlin Raud; Kaja Orupõld; Timo Kikas. 2019. "Potential of bioethanol production waste for methane recovery." Energy 173, no. : 133-139.
The chemical composition of the test medium as well as the presence of algae (microcrustaceans’ food) affects the bioavailability and thus the toxicity of metal nanoparticles (NP) to freshwater microcrustaceans. This study evaluated the effect of the addition of algae (Rapidocelis subcapitata at 7.5 × 106 cells/mL) on the toxicity of CuO (primary size 22–25 nm) and ZnO NP (10–15 nm) to planktic Daphnia magna and benthic Heterocypris incongruens in artificial (mineral) and natural freshwater (lake water). The toxicity of ionic controls, CuSO4 and ZnSO4, was evaluated in parallel. When algae were added and the toxicity was tested in mineral medium, 48 h EC50 of CuO and ZnO NP to D. magna was ~2 mg metal/L and 6-day LC50 of H. incongruens was 1.1 mg metal/L for CuO and 0.36 mg metal/L for ZnO. The addition of algae to D. magna test medium mitigated the toxicity of CuO and ZnO NP 4–11-fold when the test was conducted in natural water but not in the artificial freshwater. The addition of algae mitigated the toxicity of CuSO4 (but not ZnSO4) to D. magna at least 3-fold, whatever the test medium. In the 6-day H. incongruens tests (all exposures included algae), only up to 2-fold differences in metal NP and salt toxicity between mineral and natural test media were observed. To add environmental relevance to NP hazard assessment for the freshwater ecosystem, toxicity tests could be conducted in natural water and organisms could be fed during the exposure.
Marge Muna; Irina Blinova; Anne Kahru; Ivana Vinković Vrček; Barbara Pem; Kaja Orupõld; Margit Heinlaan. Combined Effects of Test Media and Dietary Algae on the Toxicity of CuO and ZnO Nanoparticles to Freshwater Microcrustaceans Daphnia magna and Heterocypris incongruens: Food for Thought. Nanomaterials 2018, 9, 23 .
AMA StyleMarge Muna, Irina Blinova, Anne Kahru, Ivana Vinković Vrček, Barbara Pem, Kaja Orupõld, Margit Heinlaan. Combined Effects of Test Media and Dietary Algae on the Toxicity of CuO and ZnO Nanoparticles to Freshwater Microcrustaceans Daphnia magna and Heterocypris incongruens: Food for Thought. Nanomaterials. 2018; 9 (1):23.
Chicago/Turabian StyleMarge Muna; Irina Blinova; Anne Kahru; Ivana Vinković Vrček; Barbara Pem; Kaja Orupõld; Margit Heinlaan. 2018. "Combined Effects of Test Media and Dietary Algae on the Toxicity of CuO and ZnO Nanoparticles to Freshwater Microcrustaceans Daphnia magna and Heterocypris incongruens: Food for Thought." Nanomaterials 9, no. 1: 23.
Lignocellulosic biomass is an attractive feedstock for the production of liquid (eg. biofuel) or gaseous (eg. methane) fuels for the transportation sector. The bioethanol production process still produces a large quantity of production waste following the distillation process. Stillage consists mostly of lignin, hemicellulose, extractives, and yeast and therefore does not have any commercial value. The conversion of bioethanol production waste into gaseous biofuels like biogas or biomethane is a promising solution when it comes to transforming stillage into value-added products, enhancing the value of the biomass, and as a strategy for achieving zero-waste societies. This study aims to investigate the potential of bioethanol production waste for biomethane production. The results are compared with samples from different stages of the bioethanol production process. Milled barley straw (Hordeum vulgare) was used as a feedstock to produce energy in the form of methane, and the flue gas pre-treatment method (with and without bubbling) was applied. The results show that the methane production yield of bioethanol production waste, which has been pretreated with flue gas without bubbling is 5% higher than that of untreated substrate, and can achieve 94% of the methane production of fermented samples. Bioethanol production waste from substrates, which have been pretreated with flue gas with bubbling have a methane production level that is 29% higher than that of untreated materials. The results suggest that methane yields are influenced by the bubbling process. It is reasonable to use bioethanol production waste for the production of energy in the form of methane and to increase the energy output from the biomass.
Lisandra Rocha-Meneses; Anastasia Ivanova; Guilherme Atouguia; Isaac Ávila; Merlin Raud; Kaja Orupõld; Timo Kikas. The effect of flue gas explosive decompression pretreatment on methane recovery from bioethanol production waste. Industrial Crops and Products 2018, 127, 66 -72.
AMA StyleLisandra Rocha-Meneses, Anastasia Ivanova, Guilherme Atouguia, Isaac Ávila, Merlin Raud, Kaja Orupõld, Timo Kikas. The effect of flue gas explosive decompression pretreatment on methane recovery from bioethanol production waste. Industrial Crops and Products. 2018; 127 ():66-72.
Chicago/Turabian StyleLisandra Rocha-Meneses; Anastasia Ivanova; Guilherme Atouguia; Isaac Ávila; Merlin Raud; Kaja Orupõld; Timo Kikas. 2018. "The effect of flue gas explosive decompression pretreatment on methane recovery from bioethanol production waste." Industrial Crops and Products 127, no. : 66-72.
Application of efficient antimicrobial surfaces has been estimated to decrease both, the healthcare-associated infections and the spread of antibiotic-resistant bacteria. In this paper, we prepared ZnO and ZnO/Ag nanoparticle covered surfaces and evaluated their antimicrobial efficacy towards a Gram-negative bacterial model (Escherichia coli), a Gram-positive bacterial model (Staphylococcus aureus) and a fungal model (Candida albicans) in the dark and under UVA illumination. The surfaces were prepared by spin coating aliquots of ZnO and ZnO/Ag nanoparticle suspensions onto glass substrates. Surfaces contained 2 or 20 μg Zn/cm2 and 0–0.02 μg Ag/cm2. No significant antimicrobial activity of the surfaces, except of those with the highest Ag or Zn content was observed in the dark. On the other hand, UVA illuminated surfaces containing 20 μg Zn/cm2 and 2 μg Zn plus 0.02 μg Ag/cm2 caused >3 log decrease in the viable counts of E. coli and S. aureus in 30 min. As proven by brilliant blue FCF dye degradation and elemental analysis of the surfaces, this remarkable antimicrobial activity was a combined result of photocatalytic effect and release of Zn and Ag ions from surfaces. Surfaces retained significant antibacterial and photocatalytic properties after several usage cycles. Compared to bacteria, yeast C. albicans was significantly less sensitive to the prepared surfaces and only about 1 log reduction of viable count was observed after 60 min UVA illumination. In conclusion, the developed ZnO/Ag surfaces exhibit not only high antibacterial activity but also some antifungal activity.
Meeri Visnapuu; Merilin Rosenberg; Egle Truska; Ergo Nõmmiste; Andris Šutka; Anne Kahru; Mihkel Rähn; Heiki Vija; Kaja Orupõld; Vambola Kisand; Angela Ivask. UVA-induced antimicrobial activity of ZnO/Ag nanocomposite covered surfaces. Colloids and Surfaces B: Biointerfaces 2018, 169, 222 -232.
AMA StyleMeeri Visnapuu, Merilin Rosenberg, Egle Truska, Ergo Nõmmiste, Andris Šutka, Anne Kahru, Mihkel Rähn, Heiki Vija, Kaja Orupõld, Vambola Kisand, Angela Ivask. UVA-induced antimicrobial activity of ZnO/Ag nanocomposite covered surfaces. Colloids and Surfaces B: Biointerfaces. 2018; 169 ():222-232.
Chicago/Turabian StyleMeeri Visnapuu; Merilin Rosenberg; Egle Truska; Ergo Nõmmiste; Andris Šutka; Anne Kahru; Mihkel Rähn; Heiki Vija; Kaja Orupõld; Vambola Kisand; Angela Ivask. 2018. "UVA-induced antimicrobial activity of ZnO/Ag nanocomposite covered surfaces." Colloids and Surfaces B: Biointerfaces 169, no. : 222-232.
In common sense, a landfill is a place where the life cycle of products ends. Landfill mining (LFM) mostly deals with former dumpsites and derived material may have a significant importance for the circular economy. Deliverables of recently applied LFM projects in Sweden and Estonia have revealed the potential and problems for material recovery. There are 75–100 thousand old landfills and dumps in the Baltic Sea Region, and they pose environmental risks to soil, water and air by pollution released from leachate and greenhouse gas emissions. Excavation of landfills is potential solution for solving these problems, and at the same time, there are perspectives to recover valuable lands and materials, save expenses for final coverage of the landfills and aftercare control. The research project “Closing the Life Cycle of Landfills—Landfill Mining in the Baltic Sea Region for Future” included investigation at four case studies in Estonia and Sweden: Kudjape, Torma, Högbytorp and Vika landfills. Added value of this research project is characterization of waste fine fraction material, determination of concentration for most critical and rare earth elements. The main results showed that both, coarse and fine, fractions of waste might have certain opportunities of recovery.
Marika Hogland; Dace Āriņa; Mait Kriipsalu; Yahya Jani; Fabio Kaczala; André Luís De Sá Salomão; Kaja Orupõld; Kaur-Mikk Pehme; Vita Rudovica; Gintaras Denafas; Juris Burlakovs; Zane Vincēviča-Gaile; William Hogland. Remarks on four novel landfill mining case studies in Estonia and Sweden. Journal of Material Cycles and Waste Management 2017, 20, 1355 -1363.
AMA StyleMarika Hogland, Dace Āriņa, Mait Kriipsalu, Yahya Jani, Fabio Kaczala, André Luís De Sá Salomão, Kaja Orupõld, Kaur-Mikk Pehme, Vita Rudovica, Gintaras Denafas, Juris Burlakovs, Zane Vincēviča-Gaile, William Hogland. Remarks on four novel landfill mining case studies in Estonia and Sweden. Journal of Material Cycles and Waste Management. 2017; 20 (2):1355-1363.
Chicago/Turabian StyleMarika Hogland; Dace Āriņa; Mait Kriipsalu; Yahya Jani; Fabio Kaczala; André Luís De Sá Salomão; Kaja Orupõld; Kaur-Mikk Pehme; Vita Rudovica; Gintaras Denafas; Juris Burlakovs; Zane Vincēviča-Gaile; William Hogland. 2017. "Remarks on four novel landfill mining case studies in Estonia and Sweden." Journal of Material Cycles and Waste Management 20, no. 2: 1355-1363.
The fractionation of metals in the fine fraction (<10 mm) of excavated waste from an Estonian landfill was carried out to evaluate the metal (Pb and Cu) contents and their potential towards not only mobility but also possibilities of recovery/extraction. The fractionation followed the BCR (Community Bureau of Reference) sequential extraction, and the exchangeable (F1), reducible (F2), oxidizable (F3) and residual fractions were determined. The results showed that Pb was highly associated with the reducible (F2) and oxidizable (F3) fractions, suggesting the potential mobility of this metal mainly when in contact with oxygen, despite the low association with the exchangeable fraction (F1). Cu has also shown the potential for mobility when in contact with oxygen, since high associations with the oxidizable fraction (F3) were observed. On the other hand, the mobility of metals in excavated waste can be seen as beneficial considering the circular economy and recovery of such valuables back into the economy. To conclude, not only the total concentration of metals but also a better understanding of fractionation and in which form metals are bound is very important to bring information on how to manage the fine fraction from excavated waste both in terms of environmental impacts and also recovery of such valuables in the economy.
Fabio Kaczala; Kaja Orupõld; Anna Augustsson; Juris Burlakovs; Marika Hogland; Amit Bhatnagar; William Hogland. Fractionation of Pb and Cu in the fine fraction (<10 mm) of waste excavated from a municipal landfill. Waste Management & Research: The Journal for a Sustainable Circular Economy 2017, 35, 1175 -1182.
AMA StyleFabio Kaczala, Kaja Orupõld, Anna Augustsson, Juris Burlakovs, Marika Hogland, Amit Bhatnagar, William Hogland. Fractionation of Pb and Cu in the fine fraction (<10 mm) of waste excavated from a municipal landfill. Waste Management & Research: The Journal for a Sustainable Circular Economy. 2017; 35 (11):1175-1182.
Chicago/Turabian StyleFabio Kaczala; Kaja Orupõld; Anna Augustsson; Juris Burlakovs; Marika Hogland; Amit Bhatnagar; William Hogland. 2017. "Fractionation of Pb and Cu in the fine fraction (<10 mm) of waste excavated from a municipal landfill." Waste Management & Research: The Journal for a Sustainable Circular Economy 35, no. 11: 1175-1182.
Silver nanoparticles (AgNPs) are highly toxic to aquatic organisms, however, there is no consensus whether the toxicity is caused solely by released Ag-ions or also by reactive oxygen species (ROS). Here, the effects of protein-coated AgNPs (14.6 nm, Collargol) were studied on viability, oxidative stress and gene expression levels in wild type strains (CU427 and CU428) of ciliate Tetrahymena thermophila. Viability-based 24 h EC values of AgNPs were relatively high and significantly different for the two strains: ∼100 mg/L and ∼75 mg/L for CU427 and CU428, respectively. Similarly, the expression profiles of oxidative stress (OS) related genes in the two strains were different. However, even though some OS related genes were overexpressed in AgNP-exposed ciliates, intracellular ROS level was not elevated, possibly due to efficient cellular antioxidant defence mechanisms. Compared to OS related genes, metallothionein genes were upregulated at a considerably higher level (36 versus 5000-fold) suggesting that Ag-ion mediated toxicity mechanism prevailed over OS related pathway. Also, comparison between Ag-ions released from AgNPs at EC concentration and the respective EC values of AgNO indicated that Ag-ions played a major role in the toxicity of AgNPs in T. thermophila. The study highlights the importance of combining physiological assays with gene expression analysis in elucidating the mechanisms of action of NPs to reveal subtle cellular responses that may not be detectable in bioassays. In addition, our data filled the gaps on the toxicity of AgNPs for environmentally relevant and abundant organisms. The parallel study of two wild type strains allowed us to draw conclusions on strain to strain variability in susceptibility to AgNPs.
Katre Juganson; Monika Mortimer; Angela Ivask; Sandra Pucciarelli; Cristina Miceli; Kaja Orupõld; Anne Kahru. Mechanisms of toxic action of silver nanoparticles in the protozoan Tetrahymena thermophila : From gene expression to phenotypic events. Environmental Pollution 2017, 225, 481 -489.
AMA StyleKatre Juganson, Monika Mortimer, Angela Ivask, Sandra Pucciarelli, Cristina Miceli, Kaja Orupõld, Anne Kahru. Mechanisms of toxic action of silver nanoparticles in the protozoan Tetrahymena thermophila : From gene expression to phenotypic events. Environmental Pollution. 2017; 225 ():481-489.
Chicago/Turabian StyleKatre Juganson; Monika Mortimer; Angela Ivask; Sandra Pucciarelli; Cristina Miceli; Kaja Orupõld; Anne Kahru. 2017. "Mechanisms of toxic action of silver nanoparticles in the protozoan Tetrahymena thermophila : From gene expression to phenotypic events." Environmental Pollution 225, no. : 481-489.
Juris Burlakovs; Fabio Kaczala; Zane Vincevica-Gaile; Vita Rudovica; Kaja Orupõld; Mara Stapkevica; Amit Bhatnagar; Mait Kriipsalu; Marika Hogland; Maris Klavins; William Hogland. Mobility of Metals and Valorization of Sorted Fine Fraction of Waste After Landfill Excavation. Waste and Biomass Valorization 2016, 7, 593 -602.
AMA StyleJuris Burlakovs, Fabio Kaczala, Zane Vincevica-Gaile, Vita Rudovica, Kaja Orupõld, Mara Stapkevica, Amit Bhatnagar, Mait Kriipsalu, Marika Hogland, Maris Klavins, William Hogland. Mobility of Metals and Valorization of Sorted Fine Fraction of Waste After Landfill Excavation. Waste and Biomass Valorization. 2016; 7 (3):593-602.
Chicago/Turabian StyleJuris Burlakovs; Fabio Kaczala; Zane Vincevica-Gaile; Vita Rudovica; Kaja Orupõld; Mara Stapkevica; Amit Bhatnagar; Mait Kriipsalu; Marika Hogland; Maris Klavins; William Hogland. 2016. "Mobility of Metals and Valorization of Sorted Fine Fraction of Waste After Landfill Excavation." Waste and Biomass Valorization 7, no. 3: 593-602.
Leaching of fine fraction (<10 mm) obtained from landfill mining activities in an Estonian landfill was done. On-site excavation was carried out in four test pits (TP1, TP2, TP3, TP4) that were further divided in four layers (L 1, L 2, L 3, L 4). Total chemical oxygen demand (CODt), dissolved chemical oxygen demand (CODd), total organic carbon (TOC), dissolved organic carbon (DOC) and metals (Zn, Cu, Pb and Cd) were analyzed. The results showed that approximately 70 % of CODt were in particulate/colloidal state. The TOC released ranged between 2326 and 3530-mg/kg dry matter for test pits suggesting spatial differences in the studied landfill. DOC ranged between 365–874 and 317–940 mg/kg for different test pits and sampling layers, respectively. Low average leaching rates of metals were observed (0.2–1.5 %). Pb had a significantly higher average leaching rate (1.0 %) compared to Zn (0.70 %) and Cu (0.35 %). The potential use of CODt as a surrogate indicator of TOC, DOC and Zn on the basis of high correlation coefficients was observed. To conclude, the implementation of adequate strategies to manage fine-grained fractions obtained from excavated waste relies on physico-chemical characterization of both the fine fractions itself and the leachate generated during storage and use.
Fabio Kaczala; Mohammad Hadi Mehdinejad; Allar Lääne; Kaja Orupõld; Amit Bhatnagar; Mait Kriipsalu; William Hogland. Leaching characteristics of the fine fraction from an excavated landfill: physico-chemical characterization. Journal of Material Cycles and Waste Management 2015, 19, 294 -304.
AMA StyleFabio Kaczala, Mohammad Hadi Mehdinejad, Allar Lääne, Kaja Orupõld, Amit Bhatnagar, Mait Kriipsalu, William Hogland. Leaching characteristics of the fine fraction from an excavated landfill: physico-chemical characterization. Journal of Material Cycles and Waste Management. 2015; 19 (1):294-304.
Chicago/Turabian StyleFabio Kaczala; Mohammad Hadi Mehdinejad; Allar Lääne; Kaja Orupõld; Amit Bhatnagar; Mait Kriipsalu; William Hogland. 2015. "Leaching characteristics of the fine fraction from an excavated landfill: physico-chemical characterization." Journal of Material Cycles and Waste Management 19, no. 1: 294-304.
Landfill mining applied in reclamation at the territories of old dump sites and landfills is a known approach tended to global economic and environmental benefits as recovery of metals and energy is an important challenge. The aim of this study was to analyse the concentration of several metallic elements (Ca, Cu, Cr, Fe, K, Mn, Pb, Zn) in the fine fraction of waste derived in the landfill and to compare the results of measurements obtained by field-portable equipment with the data gained by advanced analytical tools. Atomic absorption spectrometry (AAS) and inductively coupled plasma mass spectrometry (ICP-MS) were used for the quantitative detection of metallic elements at the laboratory; whereas field-portable X-ray fluorescence spectrometry (FPXRF) was applied for rapid sample characterisation in the field (on-site). Wet digestion of samples (fine fraction of waste at landfill) was done prior analytical procedures at the laboratory conditions, but FPXRF analysis was performed using raw solid samples of waste fine fraction derived in the Kudjape Landfill in Estonia. Although the use of AAS and ICP-MS for the measurements of metals achieves more precise results, it was concluded that precision and accuracy of the measurements obtained by FPXRF is acceptable for fast approximate evaluation of quantities of metallic elements in fine fraction samples excavated from the waste at landfills. Precision and accuracy of the results provided by express method is acceptable for quick analysis or screening of the concentration of major and trace metallic elements in field projects; however, data correction can be applied by calculating moisture and organic matter content dependent on sample matrix as well as special attention must be paid on sample selection and homogenisation and number of analysed samples.
Juris Burlakovs; Fabio Kaczala; Kaja Orupõld; Amit Bhatnagar; Zane Vincevica-Gaile; Vita Rudovica; Mait Kriipsalu; Marika Hogland; Mara Stapkevica; William Hogland; Maris Klavins. Field-portable X-ray fluorescence spectrometry as rapid measurement tool for landfill mining operations: comparison of field data vs. laboratory analysis. International Journal of Environmental Analytical Chemistry 2015, 95, 609 -617.
AMA StyleJuris Burlakovs, Fabio Kaczala, Kaja Orupõld, Amit Bhatnagar, Zane Vincevica-Gaile, Vita Rudovica, Mait Kriipsalu, Marika Hogland, Mara Stapkevica, William Hogland, Maris Klavins. Field-portable X-ray fluorescence spectrometry as rapid measurement tool for landfill mining operations: comparison of field data vs. laboratory analysis. International Journal of Environmental Analytical Chemistry. 2015; 95 (7):609-617.
Chicago/Turabian StyleJuris Burlakovs; Fabio Kaczala; Kaja Orupõld; Amit Bhatnagar; Zane Vincevica-Gaile; Vita Rudovica; Mait Kriipsalu; Marika Hogland; Mara Stapkevica; William Hogland; Maris Klavins. 2015. "Field-portable X-ray fluorescence spectrometry as rapid measurement tool for landfill mining operations: comparison of field data vs. laboratory analysis." International Journal of Environmental Analytical Chemistry 95, no. 7: 609-617.
The effects of bulk- and nano-sized CuO and ZnO particles on biogas and methane production during anaerobic digestion of cattle manure were studied for a period of 14 days at 36 °C using the ISO 13641-2 guidelines. Biogas production was severely affected at concentrations of bulk and nanoparticles over 120 and 15 mg/L for CuO and 240 and 120 mg/L for ZnO, respectively. EC50 concentrations for methane inhibition were estimated to be 129 mg Cu/L for bulk CuO, 10.7 mg Cu/L for nano CuO, 101 mg Zn/L for bulk ZnO and 57.4 mg Zn/L for nano ZnO. The solubility of CuO nanoparticles in the reaction mixture was observed after 14 days of incubation and was significantly higher than the levels observed for ZnO. These results are of significant importance, as it is the first time that the effects of metal oxide particle size on biogas and methane production have been studied.
Mario Luna-Delrisco; Kaja Orupõld; Henri-Charles Dubourguier. Particle-size effect of CuO and ZnO on biogas and methane production during anaerobic digestion. Journal of Hazardous Materials 2011, 189, 603 -608.
AMA StyleMario Luna-Delrisco, Kaja Orupõld, Henri-Charles Dubourguier. Particle-size effect of CuO and ZnO on biogas and methane production during anaerobic digestion. Journal of Hazardous Materials. 2011; 189 (1-2):603-608.
Chicago/Turabian StyleMario Luna-Delrisco; Kaja Orupõld; Henri-Charles Dubourguier. 2011. "Particle-size effect of CuO and ZnO on biogas and methane production during anaerobic digestion." Journal of Hazardous Materials 189, no. 1-2: 603-608.
The bio-oxidation of phenol, catechol, resorcinol, m-cresol and 5-methylresorcinol on activated sludge was investigated by oxygen uptake measurements. In addition, the degradation of acetate with the same microbial population was studied. The substrate-dependent oxygen uptake data were analysed on the basis of the Michaelis-Menten kinetics. The extant kinetic parameters, the maximum rates of oxygen consumption and half-saturation constants for the processes with different substrates were determined. The simple respirometric approach also made it possible to determine the short-term oxygen demands of the substrates which formed 23-38% of the theoretical oxygen demand of the studied compounds.
Kaja Orupõld; Aleksei Maširin; Toomas Tenno. Estimation of biodegradation parameters of phenolic compounds on activated sludge by respirometry. Chemosphere 2001, 44, 1273 -1280.
AMA StyleKaja Orupõld, Aleksei Maširin, Toomas Tenno. Estimation of biodegradation parameters of phenolic compounds on activated sludge by respirometry. Chemosphere. 2001; 44 (5):1273-1280.
Chicago/Turabian StyleKaja Orupõld; Aleksei Maširin; Toomas Tenno. 2001. "Estimation of biodegradation parameters of phenolic compounds on activated sludge by respirometry." Chemosphere 44, no. 5: 1273-1280.
Kaja Orupõld; Aleksei Mashirin; Toomas Tenno. Amperometric phenol sensor with immobilized bacteria. Electroanalysis 1995, 7, 904 -906.
AMA StyleKaja Orupõld, Aleksei Mashirin, Toomas Tenno. Amperometric phenol sensor with immobilized bacteria. Electroanalysis. 1995; 7 (9):904-906.
Chicago/Turabian StyleKaja Orupõld; Aleksei Mashirin; Toomas Tenno. 1995. "Amperometric phenol sensor with immobilized bacteria." Electroanalysis 7, no. 9: 904-906.