Marinos Stylianou - Profile on Academia.edu (original) (raw)

Papers by Marinos Stylianou

Removal of heavy metals from aqueous solutions by using natural minerals

Στη διατριβή μελετήθηκε η χρήση φυσικών ορυκτών για απομάκρυνση βαρέων μετάλλων (Pb2+, Cu2+, Cr3+... more Στη διατριβή μελετήθηκε η χρήση φυσικών ορυκτών για απομάκρυνση βαρέων μετάλλων (Pb2+, Cu2+, Cr3+, Zn2+ και Mn2+) με ιοντοεναλλαγή σε συστήματα συνεχούς έργου σταθερής και ρευστοποιημένης κλίνης και διαλείποντος έργου (batch). Χρησιμοποιήθηκαν τρία φυσικά ορυκτά: ζεόλιθος (κλινοπτιλόλιθος), μπεντονίτης και βερμικουλίτης. Στα πρώτα τρία κεφάλαια της διδακτορικής διατριβής γίνεται μια εκτενής βιβλιογραφική αναφορά σε σχέση με τη θεωρία των πυριτικών ορυκτών, τις εφαρμογές τους, αλλά και μια έρευνα αγοράς σε παγκόσμιο επίπεδο. Στη συνέχεια, γίνεται ανάλυση του φαινομένου της ιοντοεναλλαγής και της προσρόφησης και την εφαρμογή τους σε συστήματα διαλείποντος έργου (batch) αλλά και συνεχούς έργου σταθερών και ρευστοποιημένων κλινών. Επίσης, παρουσιάζονται τα διάφορα μοντέλα κινητικής και ισορροπίας που εφαρμόζονται στη βιβλιογραφία γι αυτά τα συστήματα. Στο τέταρτο κεφάλαιο, δίδεται ο χαρακτηρισμός των χρησιμοποιούμενων πυριτικών υλικών. Ο χαρακτηρισμός των πυριτικών ορυκτών επιτυγχάνεται...

In the present study, the ability of natural zeolite clinoptilolite and bentonite (clay) to remov... more In the present study, the ability of natural zeolite clinoptilolite and bentonite (clay) to remove Pb(II) from aqueous solutions has been investigated in batch reactors and maximum contact time of 120 min. Adsorption tests of Pb(II) carried out using a solution concentration of 1036 ppm at initial pH=4, and solid to liquid ratio of 2 g/100 mL. The effects of agitation speed (0, 100, 200, 500 rpm), temperature (28C, 45C, 60C) and particle size (2.5-5mm, dust) of the minerals were examined.

Metabolites

Carobs unique compositional and biological synthesis enables their characterization as functional... more Carobs unique compositional and biological synthesis enables their characterization as functional foods. In the present study, 76 samples derived from fruit and seeds of carobs, with origin from the countries of the Mediterranean region (Cyprus, Greece, Italy, Spain, Turkey, Jordan and Palestine) were analyzed for their nutritional composition, in order to identify potential markers for their provenance and address the carobs’ authenticity issue. Moisture, ash, fat, proteins, sugars (fructose, glucose, sucrose), dietary fibers and minerals (Ca, K, Mg, Na, P, Cu, Fe, Mn, Zn) were estimated following official methods. Due to the large number of data (76 samples × 17 parameters × 7 countries), chemometric techniques were employed to process them and extract conclusions. The samples of different geographical origin were discriminated with 79% success in total. The carobs from Cyprus, Italy and Spain were correctly classified without error. The main discriminators were found to be the di...

Desalination and Water Treatment, 2016

Bentonite is a clay mineral that is often used in ion exchange processes due to its high ion exch... more Bentonite is a clay mineral that is often used in ion exchange processes due to its high ion exchange capacity. In the present study, a commercially available in Greece market bentonite was obtained and characterized by using XRD, XRF, FTIR, BET and TG/DTA analysis. Monmorillonite was the main component of bentonite sample (~96%). Ion exchange equilibria of Zn 2+ , Cr 3+ and Mn 2+ on bentonite was examined by use of batch equilibrium isotherms, distribution coefficients and maximum exchange levels under the same normality for all metals (0.01 N) at 25±2 o C. The equilibrium isotherms for the metals studied exhibit a favorable-type isotherm. Selectivity series deduced from equilibrium isotherms are Cr 3+ >Zn 2+ >Mn 2+ , and the same occurs for maximum exchange levels (MELs). The Langmuir and Freundlich models were applied and fitted the equilibrium data for the metal ion uptake. The previous results can be applied in a wide range of environmental applications (e.g. in landfills, wastewater, etc.).

Jet A fuel recovery using micellar flooding: Design and implementation

Science of The Total Environment, 2016

Surfactants offer two mechanisms for recovering NAPLs: 1) to mobilize NAPL by reducing NAPL/water... more Surfactants offer two mechanisms for recovering NAPLs: 1) to mobilize NAPL by reducing NAPL/water interfacial tension, and; 2) to increase the NAPL's aqueous solubility-called solubilization-as an enhancement to pump & treat. The second approach has been well-studied and applied successfully in several pilot-scale and a few full-scale tests within the last 15years, known as Surfactant Enhanced Aquifer Remediation (SEAR). A useful source of information for this second approach is the "Surfactant-enhanced aquifer remediation (SEAR) design manual" from the U.S. Navy Facilities Engineering Command. Few attempts, however, have been made at recovering NAPLs using the mobilization approach presented in this paper. Now, a full-scale field implementation of the mobilization approach is planned to recover an LNAPL (Jet A fuel) from a surficial sand aquifer located in Denmark using a smaller amount of surfactant solution and fewer PVs of throughput compared with the SEAR approach. The approach will rely on mobilizing the LNAPL so that it is recovered ahead of the surfactant microemulsion, also known as a micellar flood. This paper will review the laboratory work performed as part of the design for a full-scale implementation of a micellar flood. Completed lab work includes screening of surfactants, phase behavior and detailed salinity scans of the most promising formulations, and generating a ternary diagram to be used for the numerical simulations of the field application. The site owners and regulators were able to make crucial decisions such as the anticipated field results based on this work.

Long-term environmental impact at an abandoned gold–silver enrichment plant: A case study in Mitsero, Cyprus

Engineering Geology, 2015

ABSTRACT The abandoned gold-silver enrichment plant of Mitsero village is located in Cyprus and i... more ABSTRACT The abandoned gold-silver enrichment plant of Mitsero village is located in Cyprus and is an example of the long-term environmental impact of mining activity when no rehabilitation measures are undertaken. We conducted a study at a plant that has been abandoned for 70 years to investigate potential environmental contamination and, if discovered, describe the extent of the contamination. Soil and water samples were collected from five potentially-polluted zones and the results are summarized as follows: soil pH of samples collected from inside the abandoned enrichment plant was low, around 3.4 to 5.4, while samples from the tailings were extremely low, ranging between 1.9 and 2.0. The tailing samples also exhibit high leachability of metals, particularly for Cu, Fe, Zn, Cr, Pb and Mn when subjected to the SPLP. Furthermore, the samples from the tailings also contain high cyanide levels of 25.05 mg/kg and 45.85 mg/kg, which are well-above allowable limits of 0.9 mg/kg (Canadian Environmental Quality Guidelines, 2007). It is particularly interesting that no arsenic leachability was measured for the tailings, although arsenic is present in these samples as determined by XRF analysis. Our results indicate that the low pH environment combined with high leachability of metals is reflected in the quality of water samples collected from the ephemeral stream: high levels of metals were detected in the water samples measured using ICP-OES. While the pH of the water samples was neutral (7.6), aqueous concentrations of Cu, Fe, Zn, As, Cr, Pb and Mn ranged between 173.95 μg/l and 3678.8 μg/l. Thus, our findings indicate that areas of the site contain significant concentrations of metals and cyanide, leading us to conclude that, in conjunction with the low soil pH in those same areas, the potential exists to form acidic runoff (regardless of the pH of the rain itself) capable of leaching metals, thus mobilizing the contaminants. That the contamination, particularly the presence of cyanide, is still found some 70 years after closure makes a compelling argument for remediation of such legacy sites.

Legacy Soil Contamination at Abandoned Mine Sites: Making a Case for Guidance on Soil Protection

Bulletin of Environmental Contamination and Toxicology, 2015

Within the European Union, guidance in the form of a uniform Soil Directive does not exist and me... more Within the European Union, guidance in the form of a uniform Soil Directive does not exist and member states are left to enact their own legislation governing historic soil contamination. Several historic or "legacy" sites exist in Cyprus - an EU member state with a long history of mining and a significant number of abandoned mining sites. The gold-silver enrichment plant of Mitsero village was abandoned 70 years ago, yet soil samples inside and outside the plant were extremely low in pH, exhibited high leachability of heavy metals and high cyanide levels. Water samples collected from an ephemeral stream located down-gradient of the site contained high levels of heavy metals. Two abandoned open-pit mines (Kokkinopezoula and Mathiatis) were investigated, where elevated metal content in soil samples from the surrounding streams and spoil heaps, and extremely low pH and high metal content in water samples from the mine crater were measured.

Journal of Physics and Chemistry of Solids, 2010

In the present paper three natural minerals used in many industrial and environmental application... more In the present paper three natural minerals used in many industrial and environmental applications namely zeolite clinoptilolite and the clays bentonite and vermiculite are studied by utilising ion exchange and adsorption. In particular, the Dubinin-Astakhov adsorption isotherm is used modified by introducing a solubility-normalized adsorption potential for studying the ion exchange process. The equation, is applied in experimental isotherms in order to determine adsorption energy and heterogeneity parameter for the ion exchange of Pb 2 + in the natural minerals. The results indicate that the modified Dubinin-Astakhov adsorption isotherm represents the experimental data well and at the same time provides the heterogeneity parameter of the materials, which is an important adsorbent physical parameter as well as the adsorption energy. In order to deepen the study and link the results to the pore structure BET analysis is presented as well.

Copper removal from sludge permeate with ultrafiltration membranes using zeolite, bentonite and vermiculite as adsorbents

Water science and technology : a journal of the International Association on Water Pollution Research, 2010

The aim of this work is to examine copper removal from sludge permeate with the use of low-cost m... more The aim of this work is to examine copper removal from sludge permeate with the use of low-cost minerals of Mediterranean origin combined with ultrafiltration membranes. The minerals used were zeolite (clinoptilolite), bentonite and vermiculite. Activated sludge was enriched with 0.01 N (317.7 ppm) of Cu(II). Fixed concentrations of minerals were added to sludge and the pH value was adjusted at 5.5. The mixture was agitated for 2 hours at 800 rpm at room temperature and was then filtered through a batch ultrafiltration system for 1 hour. This experiment was repeated, for comparison purposes, with sludge enriched with 0.01 N of Cu(II) with no mineral addition. The results showed that ultrafiltration membranes with no mineral addition were able to remove a significant amount of copper with removal efficiencies ranging from 59.4-78.3%. The addition of 10 g/l and 20 g/l of bentonite combined with ultrafiltration membranes resulted in removal efficiencies of 94.9% and 99.4% respectively ...

Journal of Hazardous Materials, 2007

This work deals with the removal of lead, copper and zinc from aqueous solutions by using natural... more This work deals with the removal of lead, copper and zinc from aqueous solutions by using natural zeolite (clinoptilolite). Fixed bed experiments were performed, using three different volumetric flow rates of 5, 7 and 10 bed volume/h, under a total normality of 0.01N, at initial pH of 4 and ambient temperature (25 • C). The removal efficiency increased when decreasing the flow rate and the following selectivity series was found: Pb 2+ > Zn 2+ ≥ Cu 2+ . Conductivity measurements showed that lead removal follows mainly ion exchange mechanism, while copper and zinc removal follows ion exchange and sorption mechanism as well.

Management of waste from electrical and electronic equipment: The case of television sets and refrigerators

Journal of Environmental Engineering and Science, 2008

Waste from electrical and electronic equipment (WEEE) constitutes one of the most complicated sol... more Waste from electrical and electronic equipment (WEEE) constitutes one of the most complicated solid waste streams, in terms of its composition, and, as a result, it is difficult to be effectively managed. Waste from electrical and electronic equipment recycling is an important subject not only from the point of waste management, but also from the recovery of valuable materials. Characterization of this waste stream is of paramount importance for developing a cost-effective and environmentally friendly recycling system. Selective disassembly, targeting on singling out hazardous and (or) valuable components, is an indispensable process in the practice of WEEE recycling. It is very costly to perform manual dismantling of those products, due to the fact that brown goods contain very low-grade precious metals and copper. This work focuses on two major types of WEEE, television sets and refrigerators, giving analytical information on specific recovery and recycling procedures for their ef...

Desalination, 2007

In the present study, the ability of natural zeolite clinoptilolite and bentonite (clay) to remov... more In the present study, the ability of natural zeolite clinoptilolite and bentonite (clay) to remove Pb(II) from aqueous solutions has been investigated in batch reactors with a maximum contact time of 120 min. Adsorption tests of Pb(II) were carried out using a solution concentration of 1,036 ppm at initial pH = 4, and solid to liquid ratio of 2 g/100 mL. The effects of agitation speed (0, 100, 200, 500 rpm), temperature (28°C, 45°C, 60°C) and particle size (2.5-5.0 mm, dust) of the minerals were examined. The effect of acidity of the aqueous solution was also examined. Bentonite was found to be more effective for the removal of Pb(II) than clinoptilolite, under the experimental conditions used. The removal of Pb(II) using bentonite reached 100% at ambient temperature and mild agitation (100 rpm), while it was approximately 90% at 60°C without agitation. On the other hand, the highest removal level reached by clinoptilolite was 55%. Clinoptilolite dust is found to be more efficient than granular clinoptilolite. Agitation and temperature affected the uptake of Pb(II), especially in the case of granular clinoptilolite (2.5-5.0 mm). Finally, it can be seen that acidity of the aqueous solution influences the removal of lead by the minerals. The adsorption of lead increases with an increase in pH of the solution from 1 to 4.

Desalination, 2008

Zeolites are naturally occurring minerals characterized by high cation exchange and adsorption ca... more Zeolites are naturally occurring minerals characterized by high cation exchange and adsorption capacity and, thus, are used for metal uptake from sewage sludge subjected to composting process. In the present paper, changes in the physicochemical characteristics of sewage sludge samples after composting were recorded and analysed. The composting process was carried out for 120 days in pilot bioreactors, which were filled with 20% w/w clinoptilolite and sludge. The experimental results indicated differences in the metal content of the initial sludge and essential changes in pH, %C org , % organic matter (OM), %N values and heavy metals content. Furthermore, the phytotoxicity tests that were performed showed that sludge samples affected seed germination and root elongation, but no phytotoxic effects were observed. According to the experimental results, it is concluded that the use of natural clinoptilolite leads to the improvement of the quality of the composted sewage sludge.

Desalination, 2007

In this paper, sludge samples that were collected from the municipal wastewater treatment plant i... more In this paper, sludge samples that were collected from the municipal wastewater treatment plant in Psittalia (Athens, Greece) were subjected to acid treatment using sulphuric acid. Furthermore, a sequential extraction scheme was applied in order to determine the chemical forms of Ni, Cu, total Cr, Pb and Zn in sewage sludge. The optimum combination was achieved through a variety of tests by applying a ratio of 1:5 of sludge quantity (g) per volume of acid (mL). The concentration of the acid used was in the range of 10-20% at two different temperatures (25-80°C) and the contact times ranged from 1 to 60 min. The optimum combination was achieved when the sludge samples were in contact with H 2 SO 4 (20%) for 30 min at 80°C, as these experimental conditions resulted in the highest heavy metal removal efficiency. In addition, the metal distribution in the residue was investigated and the heavy metal partitioning was found to be different after acid treatment.

Desalination, 2007

The ability of natural zeolite (clinoptilolite) and exfoliated vermiculite to remove copper from ... more The ability of natural zeolite (clinoptilolite) and exfoliated vermiculite to remove copper from aqueous solutions was studied in fixed bed column and batch reactors. The effect of agitation speed (0, 100, 200, 400 rpm), temperature (25, 45, 60°C), and particle size [2.5-5.0 mm, dust (<0.25 mm)] and solution pH (1.00-4.00) on the removal of heavy metals was studied. Fixed bed experiments were conducted, using three different volumetric flow rates of 5-7-10 BV (Bed Volumes)/h, under an initial normality of 0.01 N (317.7 mg/L), at initial pH of 4.00 and ambient temperature (25°C). Vermiculite was found to be more effective for the removal of copper in batch mode reactors under all the tested conditions, while the removal efficiency follows the order: vermiculite > clinoptilolite dust > clinoptilolite 2.5-5.0 mm. The removal of Cu(II) using vermiculite reached 67.6%, at ambient temperature and at the agitation speed of 400 rpm, while it was approximately 42.5% at 60°C with no agitation. The highest removal level in the case of clinoptilolite use reached the percentage of 37.3% at the temperature of 60°C without agitation; the same removal efficiency was obtained at ambient conditions with an agitation speed of 400 rpm. Clinoptilolite dust is found to be more efficient than granular clinoptilolite under all the conditions that were tested. Agitation and temperature also affect the uptake of the specific ions. Finally, the acidity of the aqueous solution influences the removal of copper by minerals. In column studies, the decrease of the flow rate resulted in the increase of the removal efficiency.

Waste management (New York, N.Y.), 2009

This article presents the methodology and the results of the performance testing of a prototype s... more This article presents the methodology and the results of the performance testing of a prototype system for the production of high quality compost from biodegradable household waste separated at the source. Selected households in three municipalities of the Attica Region in Greece constituted the users of the home composter. The results indicated the effective operational performance of the prototype household composter in practice (use of the system by the householders on a daily basis), as well as the high level of response of the householders in adopting the composting practice in their daily activities as common practice. The compost that was produced in the households was characterized by high quality, which is in accordance with the quality standards that are set for its use. In only a few cases (in the first cycle of the pilot implementation) the quality of the compost was not high due to the fact that some householders were not yet familiar with the use of the composter, but ...

Waste Management & Research, 2008

This paper refers to the management of the construction and demolition (C&D) waste since, accordi... more This paper refers to the management of the construction and demolition (C&D) waste since, according to the EU Waste Strategy, C&D waste is considered to be one of the priority waste streams and appropriate actions need to be taken with respect to its effective management. Initially, the paper presents the state-of-the-art of the problem of C&D waste, including the amount and composition of C&D waste in EU countries, differences in the characteristics of this waste stream depending on its origin, as well as collection and management practices that are applied. A methodology is described for the estimation of the quantities of the waste stream under examination, since in most cases quantitative primary data is not available. Next, the fundamentals for the development of an integrated scheme for the management of C&D waste are presented and discussed, such as appropriate demolition procedures and location of waste management (off-site waste management, on-site waste management, direct on-site recovery, centralized on-site recovery). Finally, taking into consideration all relevant parameters, alternative systems that could be applied for the management of the C&D waste are suggested.

Waste Management & Research, 2008

This study investigated the generation and management of demolition waste (DW) in Cyprus. A metho... more This study investigated the generation and management of demolition waste (DW) in Cyprus. A methodology has been developed and applied for the estimation of the quantities of the waste stream under examination, since quantitative primary data were not available. The existing situation relating to the practices applied for the management of DW was investigated and assessed. Furthermore, a multi-criteria analysis method (PROMETHEE II) was developed and applied in order to examine alternative systems that could be implemented for the management of the DW in the country. In particular, nine management systems (scenarios) were examined, evaluated and ranked according to their efficiency using seventeen individual criteria, divided into four groups (social-legislative, environmental, economic and technical). The ranking of the alternative waste management scenarios indicated that the optimum management system for possible implementation in the island included complete selective demolition procedures and transfer of mixed recyclable materials to the recycling centre and non-recyclable material to landfill.

International Journal of Chemical Reactor Engineering, 2010

The present study presents systematic experimental data on the fluidization of zeolite particles ... more The present study presents systematic experimental data on the fluidization of zeolite particles in water-solid fluidized beds. Four particle size groups, 90-180 µm, 180-250 µm, 250-315 µm and 315-500 µm and 22 different volumetric flow rates were used, corresponding to Rep of 0.012 to 1.452. All particle sizes showed smooth flow rate vs expanded bed height curves. As is proven, the Ergun equation is useful for determining the minimum fluidization velocity for the large particle sizes by using a fixed sphericity value of 0.354. For the fluidized bed regime (us>umf), the Ergun equation fails to represent the data as it results in fluctuating particle sphericity values, while the Richardson-Zaki model seems to correlate the data for the large particle sizes only. A new correlation is presented, connecting bed voidage to Rep for all particle sizes with an average relative error of 2.38±2.49% and the range is 0.02-9%.

Open Environmental Sciences, 2010

The aim of this study is to investigate ammonium removal from a wastewater resulted after homogen... more The aim of this study is to investigate ammonium removal from a wastewater resulted after homogenization and anaerobic digestion of a mixture of wastes and wastewater from animal processing units and sewage sludge, by using natural zeolite clinoptilolite. Batches as well as closed loop fixed bed system (CLFB) are studied, offering an alternative to conventional fixed bed systems. The experimental results showed that the optimum pH is in the vicinity of 6.48, where the achieved removal in the batch system reached 46%. The CLFB system, under the same experimental conditions and relative flow rate of 2.56 BV h -1 , reached a removal of 55%, which is almost 22% higher. In the CLFB the removal of ammonia could be further increased by diluting the initial solution by 1/8, reaching the level of 96%. The achieved zeolite loading, for all studied systems, is between 2.62 and 13 mg g -1 . This kind of operation is very useful for relatively high concentration and small volumes of wastewater and in systems that there is no need for continuous flow operation.

Removal of heavy metals from aqueous solutions by using natural minerals

Στη διατριβή μελετήθηκε η χρήση φυσικών ορυκτών για απομάκρυνση βαρέων μετάλλων (Pb2+, Cu2+, Cr3+... more Στη διατριβή μελετήθηκε η χρήση φυσικών ορυκτών για απομάκρυνση βαρέων μετάλλων (Pb2+, Cu2+, Cr3+, Zn2+ και Mn2+) με ιοντοεναλλαγή σε συστήματα συνεχούς έργου σταθερής και ρευστοποιημένης κλίνης και διαλείποντος έργου (batch). Χρησιμοποιήθηκαν τρία φυσικά ορυκτά: ζεόλιθος (κλινοπτιλόλιθος), μπεντονίτης και βερμικουλίτης. Στα πρώτα τρία κεφάλαια της διδακτορικής διατριβής γίνεται μια εκτενής βιβλιογραφική αναφορά σε σχέση με τη θεωρία των πυριτικών ορυκτών, τις εφαρμογές τους, αλλά και μια έρευνα αγοράς σε παγκόσμιο επίπεδο. Στη συνέχεια, γίνεται ανάλυση του φαινομένου της ιοντοεναλλαγής και της προσρόφησης και την εφαρμογή τους σε συστήματα διαλείποντος έργου (batch) αλλά και συνεχούς έργου σταθερών και ρευστοποιημένων κλινών. Επίσης, παρουσιάζονται τα διάφορα μοντέλα κινητικής και ισορροπίας που εφαρμόζονται στη βιβλιογραφία γι αυτά τα συστήματα. Στο τέταρτο κεφάλαιο, δίδεται ο χαρακτηρισμός των χρησιμοποιούμενων πυριτικών υλικών. Ο χαρακτηρισμός των πυριτικών ορυκτών επιτυγχάνεται...

In the present study, the ability of natural zeolite clinoptilolite and bentonite (clay) to remov... more In the present study, the ability of natural zeolite clinoptilolite and bentonite (clay) to remove Pb(II) from aqueous solutions has been investigated in batch reactors and maximum contact time of 120 min. Adsorption tests of Pb(II) carried out using a solution concentration of 1036 ppm at initial pH=4, and solid to liquid ratio of 2 g/100 mL. The effects of agitation speed (0, 100, 200, 500 rpm), temperature (28C, 45C, 60C) and particle size (2.5-5mm, dust) of the minerals were examined.

Metabolites

Carobs unique compositional and biological synthesis enables their characterization as functional... more Carobs unique compositional and biological synthesis enables their characterization as functional foods. In the present study, 76 samples derived from fruit and seeds of carobs, with origin from the countries of the Mediterranean region (Cyprus, Greece, Italy, Spain, Turkey, Jordan and Palestine) were analyzed for their nutritional composition, in order to identify potential markers for their provenance and address the carobs’ authenticity issue. Moisture, ash, fat, proteins, sugars (fructose, glucose, sucrose), dietary fibers and minerals (Ca, K, Mg, Na, P, Cu, Fe, Mn, Zn) were estimated following official methods. Due to the large number of data (76 samples × 17 parameters × 7 countries), chemometric techniques were employed to process them and extract conclusions. The samples of different geographical origin were discriminated with 79% success in total. The carobs from Cyprus, Italy and Spain were correctly classified without error. The main discriminators were found to be the di...

Desalination and Water Treatment, 2016

Bentonite is a clay mineral that is often used in ion exchange processes due to its high ion exch... more Bentonite is a clay mineral that is often used in ion exchange processes due to its high ion exchange capacity. In the present study, a commercially available in Greece market bentonite was obtained and characterized by using XRD, XRF, FTIR, BET and TG/DTA analysis. Monmorillonite was the main component of bentonite sample (~96%). Ion exchange equilibria of Zn 2+ , Cr 3+ and Mn 2+ on bentonite was examined by use of batch equilibrium isotherms, distribution coefficients and maximum exchange levels under the same normality for all metals (0.01 N) at 25±2 o C. The equilibrium isotherms for the metals studied exhibit a favorable-type isotherm. Selectivity series deduced from equilibrium isotherms are Cr 3+ >Zn 2+ >Mn 2+ , and the same occurs for maximum exchange levels (MELs). The Langmuir and Freundlich models were applied and fitted the equilibrium data for the metal ion uptake. The previous results can be applied in a wide range of environmental applications (e.g. in landfills, wastewater, etc.).

Jet A fuel recovery using micellar flooding: Design and implementation

Science of The Total Environment, 2016

Surfactants offer two mechanisms for recovering NAPLs: 1) to mobilize NAPL by reducing NAPL/water... more Surfactants offer two mechanisms for recovering NAPLs: 1) to mobilize NAPL by reducing NAPL/water interfacial tension, and; 2) to increase the NAPL&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s aqueous solubility-called solubilization-as an enhancement to pump &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp; treat. The second approach has been well-studied and applied successfully in several pilot-scale and a few full-scale tests within the last 15years, known as Surfactant Enhanced Aquifer Remediation (SEAR). A useful source of information for this second approach is the &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;Surfactant-enhanced aquifer remediation (SEAR) design manual&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; from the U.S. Navy Facilities Engineering Command. Few attempts, however, have been made at recovering NAPLs using the mobilization approach presented in this paper. Now, a full-scale field implementation of the mobilization approach is planned to recover an LNAPL (Jet A fuel) from a surficial sand aquifer located in Denmark using a smaller amount of surfactant solution and fewer PVs of throughput compared with the SEAR approach. The approach will rely on mobilizing the LNAPL so that it is recovered ahead of the surfactant microemulsion, also known as a micellar flood. This paper will review the laboratory work performed as part of the design for a full-scale implementation of a micellar flood. Completed lab work includes screening of surfactants, phase behavior and detailed salinity scans of the most promising formulations, and generating a ternary diagram to be used for the numerical simulations of the field application. The site owners and regulators were able to make crucial decisions such as the anticipated field results based on this work.

Long-term environmental impact at an abandoned gold–silver enrichment plant: A case study in Mitsero, Cyprus

Engineering Geology, 2015

ABSTRACT The abandoned gold-silver enrichment plant of Mitsero village is located in Cyprus and i... more ABSTRACT The abandoned gold-silver enrichment plant of Mitsero village is located in Cyprus and is an example of the long-term environmental impact of mining activity when no rehabilitation measures are undertaken. We conducted a study at a plant that has been abandoned for 70 years to investigate potential environmental contamination and, if discovered, describe the extent of the contamination. Soil and water samples were collected from five potentially-polluted zones and the results are summarized as follows: soil pH of samples collected from inside the abandoned enrichment plant was low, around 3.4 to 5.4, while samples from the tailings were extremely low, ranging between 1.9 and 2.0. The tailing samples also exhibit high leachability of metals, particularly for Cu, Fe, Zn, Cr, Pb and Mn when subjected to the SPLP. Furthermore, the samples from the tailings also contain high cyanide levels of 25.05 mg/kg and 45.85 mg/kg, which are well-above allowable limits of 0.9 mg/kg (Canadian Environmental Quality Guidelines, 2007). It is particularly interesting that no arsenic leachability was measured for the tailings, although arsenic is present in these samples as determined by XRF analysis. Our results indicate that the low pH environment combined with high leachability of metals is reflected in the quality of water samples collected from the ephemeral stream: high levels of metals were detected in the water samples measured using ICP-OES. While the pH of the water samples was neutral (7.6), aqueous concentrations of Cu, Fe, Zn, As, Cr, Pb and Mn ranged between 173.95 μg/l and 3678.8 μg/l. Thus, our findings indicate that areas of the site contain significant concentrations of metals and cyanide, leading us to conclude that, in conjunction with the low soil pH in those same areas, the potential exists to form acidic runoff (regardless of the pH of the rain itself) capable of leaching metals, thus mobilizing the contaminants. That the contamination, particularly the presence of cyanide, is still found some 70 years after closure makes a compelling argument for remediation of such legacy sites.

Legacy Soil Contamination at Abandoned Mine Sites: Making a Case for Guidance on Soil Protection

Bulletin of Environmental Contamination and Toxicology, 2015

Within the European Union, guidance in the form of a uniform Soil Directive does not exist and me... more Within the European Union, guidance in the form of a uniform Soil Directive does not exist and member states are left to enact their own legislation governing historic soil contamination. Several historic or &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot;legacy&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;quot; sites exist in Cyprus - an EU member state with a long history of mining and a significant number of abandoned mining sites. The gold-silver enrichment plant of Mitsero village was abandoned 70 years ago, yet soil samples inside and outside the plant were extremely low in pH, exhibited high leachability of heavy metals and high cyanide levels. Water samples collected from an ephemeral stream located down-gradient of the site contained high levels of heavy metals. Two abandoned open-pit mines (Kokkinopezoula and Mathiatis) were investigated, where elevated metal content in soil samples from the surrounding streams and spoil heaps, and extremely low pH and high metal content in water samples from the mine crater were measured.

Journal of Physics and Chemistry of Solids, 2010

In the present paper three natural minerals used in many industrial and environmental application... more In the present paper three natural minerals used in many industrial and environmental applications namely zeolite clinoptilolite and the clays bentonite and vermiculite are studied by utilising ion exchange and adsorption. In particular, the Dubinin-Astakhov adsorption isotherm is used modified by introducing a solubility-normalized adsorption potential for studying the ion exchange process. The equation, is applied in experimental isotherms in order to determine adsorption energy and heterogeneity parameter for the ion exchange of Pb 2 + in the natural minerals. The results indicate that the modified Dubinin-Astakhov adsorption isotherm represents the experimental data well and at the same time provides the heterogeneity parameter of the materials, which is an important adsorbent physical parameter as well as the adsorption energy. In order to deepen the study and link the results to the pore structure BET analysis is presented as well.

Copper removal from sludge permeate with ultrafiltration membranes using zeolite, bentonite and vermiculite as adsorbents

Water science and technology : a journal of the International Association on Water Pollution Research, 2010

The aim of this work is to examine copper removal from sludge permeate with the use of low-cost m... more The aim of this work is to examine copper removal from sludge permeate with the use of low-cost minerals of Mediterranean origin combined with ultrafiltration membranes. The minerals used were zeolite (clinoptilolite), bentonite and vermiculite. Activated sludge was enriched with 0.01 N (317.7 ppm) of Cu(II). Fixed concentrations of minerals were added to sludge and the pH value was adjusted at 5.5. The mixture was agitated for 2 hours at 800 rpm at room temperature and was then filtered through a batch ultrafiltration system for 1 hour. This experiment was repeated, for comparison purposes, with sludge enriched with 0.01 N of Cu(II) with no mineral addition. The results showed that ultrafiltration membranes with no mineral addition were able to remove a significant amount of copper with removal efficiencies ranging from 59.4-78.3%. The addition of 10 g/l and 20 g/l of bentonite combined with ultrafiltration membranes resulted in removal efficiencies of 94.9% and 99.4% respectively ...

Journal of Hazardous Materials, 2007

This work deals with the removal of lead, copper and zinc from aqueous solutions by using natural... more This work deals with the removal of lead, copper and zinc from aqueous solutions by using natural zeolite (clinoptilolite). Fixed bed experiments were performed, using three different volumetric flow rates of 5, 7 and 10 bed volume/h, under a total normality of 0.01N, at initial pH of 4 and ambient temperature (25 • C). The removal efficiency increased when decreasing the flow rate and the following selectivity series was found: Pb 2+ > Zn 2+ ≥ Cu 2+ . Conductivity measurements showed that lead removal follows mainly ion exchange mechanism, while copper and zinc removal follows ion exchange and sorption mechanism as well.

Management of waste from electrical and electronic equipment: The case of television sets and refrigerators

Journal of Environmental Engineering and Science, 2008

Waste from electrical and electronic equipment (WEEE) constitutes one of the most complicated sol... more Waste from electrical and electronic equipment (WEEE) constitutes one of the most complicated solid waste streams, in terms of its composition, and, as a result, it is difficult to be effectively managed. Waste from electrical and electronic equipment recycling is an important subject not only from the point of waste management, but also from the recovery of valuable materials. Characterization of this waste stream is of paramount importance for developing a cost-effective and environmentally friendly recycling system. Selective disassembly, targeting on singling out hazardous and (or) valuable components, is an indispensable process in the practice of WEEE recycling. It is very costly to perform manual dismantling of those products, due to the fact that brown goods contain very low-grade precious metals and copper. This work focuses on two major types of WEEE, television sets and refrigerators, giving analytical information on specific recovery and recycling procedures for their ef...

Desalination, 2007

In the present study, the ability of natural zeolite clinoptilolite and bentonite (clay) to remov... more In the present study, the ability of natural zeolite clinoptilolite and bentonite (clay) to remove Pb(II) from aqueous solutions has been investigated in batch reactors with a maximum contact time of 120 min. Adsorption tests of Pb(II) were carried out using a solution concentration of 1,036 ppm at initial pH = 4, and solid to liquid ratio of 2 g/100 mL. The effects of agitation speed (0, 100, 200, 500 rpm), temperature (28°C, 45°C, 60°C) and particle size (2.5-5.0 mm, dust) of the minerals were examined. The effect of acidity of the aqueous solution was also examined. Bentonite was found to be more effective for the removal of Pb(II) than clinoptilolite, under the experimental conditions used. The removal of Pb(II) using bentonite reached 100% at ambient temperature and mild agitation (100 rpm), while it was approximately 90% at 60°C without agitation. On the other hand, the highest removal level reached by clinoptilolite was 55%. Clinoptilolite dust is found to be more efficient than granular clinoptilolite. Agitation and temperature affected the uptake of Pb(II), especially in the case of granular clinoptilolite (2.5-5.0 mm). Finally, it can be seen that acidity of the aqueous solution influences the removal of lead by the minerals. The adsorption of lead increases with an increase in pH of the solution from 1 to 4.

Desalination, 2008

Zeolites are naturally occurring minerals characterized by high cation exchange and adsorption ca... more Zeolites are naturally occurring minerals characterized by high cation exchange and adsorption capacity and, thus, are used for metal uptake from sewage sludge subjected to composting process. In the present paper, changes in the physicochemical characteristics of sewage sludge samples after composting were recorded and analysed. The composting process was carried out for 120 days in pilot bioreactors, which were filled with 20% w/w clinoptilolite and sludge. The experimental results indicated differences in the metal content of the initial sludge and essential changes in pH, %C org , % organic matter (OM), %N values and heavy metals content. Furthermore, the phytotoxicity tests that were performed showed that sludge samples affected seed germination and root elongation, but no phytotoxic effects were observed. According to the experimental results, it is concluded that the use of natural clinoptilolite leads to the improvement of the quality of the composted sewage sludge.

Desalination, 2007

In this paper, sludge samples that were collected from the municipal wastewater treatment plant i... more In this paper, sludge samples that were collected from the municipal wastewater treatment plant in Psittalia (Athens, Greece) were subjected to acid treatment using sulphuric acid. Furthermore, a sequential extraction scheme was applied in order to determine the chemical forms of Ni, Cu, total Cr, Pb and Zn in sewage sludge. The optimum combination was achieved through a variety of tests by applying a ratio of 1:5 of sludge quantity (g) per volume of acid (mL). The concentration of the acid used was in the range of 10-20% at two different temperatures (25-80°C) and the contact times ranged from 1 to 60 min. The optimum combination was achieved when the sludge samples were in contact with H 2 SO 4 (20%) for 30 min at 80°C, as these experimental conditions resulted in the highest heavy metal removal efficiency. In addition, the metal distribution in the residue was investigated and the heavy metal partitioning was found to be different after acid treatment.

Desalination, 2007

The ability of natural zeolite (clinoptilolite) and exfoliated vermiculite to remove copper from ... more The ability of natural zeolite (clinoptilolite) and exfoliated vermiculite to remove copper from aqueous solutions was studied in fixed bed column and batch reactors. The effect of agitation speed (0, 100, 200, 400 rpm), temperature (25, 45, 60°C), and particle size [2.5-5.0 mm, dust (<0.25 mm)] and solution pH (1.00-4.00) on the removal of heavy metals was studied. Fixed bed experiments were conducted, using three different volumetric flow rates of 5-7-10 BV (Bed Volumes)/h, under an initial normality of 0.01 N (317.7 mg/L), at initial pH of 4.00 and ambient temperature (25°C). Vermiculite was found to be more effective for the removal of copper in batch mode reactors under all the tested conditions, while the removal efficiency follows the order: vermiculite > clinoptilolite dust > clinoptilolite 2.5-5.0 mm. The removal of Cu(II) using vermiculite reached 67.6%, at ambient temperature and at the agitation speed of 400 rpm, while it was approximately 42.5% at 60°C with no agitation. The highest removal level in the case of clinoptilolite use reached the percentage of 37.3% at the temperature of 60°C without agitation; the same removal efficiency was obtained at ambient conditions with an agitation speed of 400 rpm. Clinoptilolite dust is found to be more efficient than granular clinoptilolite under all the conditions that were tested. Agitation and temperature also affect the uptake of the specific ions. Finally, the acidity of the aqueous solution influences the removal of copper by minerals. In column studies, the decrease of the flow rate resulted in the increase of the removal efficiency.

Waste management (New York, N.Y.), 2009

This article presents the methodology and the results of the performance testing of a prototype s... more This article presents the methodology and the results of the performance testing of a prototype system for the production of high quality compost from biodegradable household waste separated at the source. Selected households in three municipalities of the Attica Region in Greece constituted the users of the home composter. The results indicated the effective operational performance of the prototype household composter in practice (use of the system by the householders on a daily basis), as well as the high level of response of the householders in adopting the composting practice in their daily activities as common practice. The compost that was produced in the households was characterized by high quality, which is in accordance with the quality standards that are set for its use. In only a few cases (in the first cycle of the pilot implementation) the quality of the compost was not high due to the fact that some householders were not yet familiar with the use of the composter, but ...

Waste Management & Research, 2008

This paper refers to the management of the construction and demolition (C&D) waste since, accordi... more This paper refers to the management of the construction and demolition (C&D) waste since, according to the EU Waste Strategy, C&D waste is considered to be one of the priority waste streams and appropriate actions need to be taken with respect to its effective management. Initially, the paper presents the state-of-the-art of the problem of C&D waste, including the amount and composition of C&D waste in EU countries, differences in the characteristics of this waste stream depending on its origin, as well as collection and management practices that are applied. A methodology is described for the estimation of the quantities of the waste stream under examination, since in most cases quantitative primary data is not available. Next, the fundamentals for the development of an integrated scheme for the management of C&D waste are presented and discussed, such as appropriate demolition procedures and location of waste management (off-site waste management, on-site waste management, direct on-site recovery, centralized on-site recovery). Finally, taking into consideration all relevant parameters, alternative systems that could be applied for the management of the C&D waste are suggested.

Waste Management & Research, 2008

This study investigated the generation and management of demolition waste (DW) in Cyprus. A metho... more This study investigated the generation and management of demolition waste (DW) in Cyprus. A methodology has been developed and applied for the estimation of the quantities of the waste stream under examination, since quantitative primary data were not available. The existing situation relating to the practices applied for the management of DW was investigated and assessed. Furthermore, a multi-criteria analysis method (PROMETHEE II) was developed and applied in order to examine alternative systems that could be implemented for the management of the DW in the country. In particular, nine management systems (scenarios) were examined, evaluated and ranked according to their efficiency using seventeen individual criteria, divided into four groups (social-legislative, environmental, economic and technical). The ranking of the alternative waste management scenarios indicated that the optimum management system for possible implementation in the island included complete selective demolition procedures and transfer of mixed recyclable materials to the recycling centre and non-recyclable material to landfill.

International Journal of Chemical Reactor Engineering, 2010

The present study presents systematic experimental data on the fluidization of zeolite particles ... more The present study presents systematic experimental data on the fluidization of zeolite particles in water-solid fluidized beds. Four particle size groups, 90-180 µm, 180-250 µm, 250-315 µm and 315-500 µm and 22 different volumetric flow rates were used, corresponding to Rep of 0.012 to 1.452. All particle sizes showed smooth flow rate vs expanded bed height curves. As is proven, the Ergun equation is useful for determining the minimum fluidization velocity for the large particle sizes by using a fixed sphericity value of 0.354. For the fluidized bed regime (us>umf), the Ergun equation fails to represent the data as it results in fluctuating particle sphericity values, while the Richardson-Zaki model seems to correlate the data for the large particle sizes only. A new correlation is presented, connecting bed voidage to Rep for all particle sizes with an average relative error of 2.38±2.49% and the range is 0.02-9%.

Open Environmental Sciences, 2010

The aim of this study is to investigate ammonium removal from a wastewater resulted after homogen... more The aim of this study is to investigate ammonium removal from a wastewater resulted after homogenization and anaerobic digestion of a mixture of wastes and wastewater from animal processing units and sewage sludge, by using natural zeolite clinoptilolite. Batches as well as closed loop fixed bed system (CLFB) are studied, offering an alternative to conventional fixed bed systems. The experimental results showed that the optimum pH is in the vicinity of 6.48, where the achieved removal in the batch system reached 46%. The CLFB system, under the same experimental conditions and relative flow rate of 2.56 BV h -1 , reached a removal of 55%, which is almost 22% higher. In the CLFB the removal of ammonia could be further increased by diluting the initial solution by 1/8, reaching the level of 96%. The achieved zeolite loading, for all studied systems, is between 2.62 and 13 mg g -1 . This kind of operation is very useful for relatively high concentration and small volumes of wastewater and in systems that there is no need for continuous flow operation.