Organic–Inorganic Hybrid Coatings for the Modification of Barrier Properties of Poly(lactic acid) Films for Food Packaging Applications

Organic–inorganic hybrid coatings based on poly(ε-caprolactone), poly(ethylene oxide) or poly(lactic acid) as organic phase and silica from tetraethoxysilane as inorganic phase were prepared by the sol–gel approach. Coatings were applied onto poly(lactic acid) films for food packaging in order to improve its barrier properties towards oxygen and water vapour. All the prepared coatings were dense, homogeneous layers characterized by a good adhesion to the substrate. The permeance of the coating layers resulted one order of magnitude lower than that of the uncoated poly(lactic acid) (PLA) film. The hydrophilic character of the coating did not permit to gain a significant decrease in the water vapour permeance. The perfect visual transparency of the coatings allows their application without worsening of the esthetical properties of the substrate PLA film.     

Spatial GHG Inventory: Analysis of Uncertainty Sources. A Case Study for Ukraine

A geoinformation technology for creating spatially distributed greenhouse gas inventories based on a methodology provided by the Intergovernmental Panel on Climate Change and special software linking input data, inventory models, and a means for visualization are proposed. This technology opens up new possibilities for qualitative and quantitative spatially distributed presentations of inventory uncertainty at the regional level. Problems concerning uncertainty and verification of the distributed inventory are discussed. A Monte Carlo analysis of uncertainties in the energy sector at the regional level is performed, and a number of simulations concerning the effectiveness of uncertainty reduction in some regions are carried out. Uncertainties in activity data have a considerable influence on overall inventory uncertainty, for example, the inventory uncertainty in the energy sector declines from 3.2 to 2.0% when the uncertainty of energy-related statistical data on fuels combusted in the energy industries declines from 10 to 5%. Within the energy sector, the ‘energy industries’ subsector has the greatest impact on inventory uncertainty. The relative uncertainty in the energy sector inventory can be reduced from 2.19 to 1.47% if the uncertainty of specific statistical data on fuel consumption decreases from 10 to 5%. The ‘energy industries’ subsector has the greatest influence in the Donetsk oblast. Reducing the uncertainty of statistical data on electricity generation in just three regions – the Donetsk, Dnipropetrovsk, and Luhansk oblasts – from 7.5 to 4.0% results in a decline from 2.6 to 1.6% in the uncertainty in the national energy sector inventory.     

Leaching of heavy metals by citric acid from fly ash generated in municipal waste incineration plants

The leaching behavior of heavy metals from municipal waste incineration (MWI) fly ash was investigated in this study. The leaching process includes two steps, i.e., fly ash was firstly washed with water, and then subjected to citric acid leaching. The main parameters of the washing process such as liquid/solid ratio, washing time, and number of washing were tested. The optimum conditions for water washing were found as follows: washing time 5–10 min, liquid/solid ratio 10:1 (ml:g), and number of washing was twice; under these conditions, 86% Na, 70% K, 12% Ca, 1.2% Al, and 0.5% Pb were removed from the fly ash in the prewashing. From the results of screening tests of leaching lixiviants, citric acid was found to be the most effective leaching agent, taking account of its environmentally benign characteristics. Optimum metal extraction can be achieved with citric acid under the following conditions: pH 3.0, liquid/solid ratio 40 (ml:g), citric acid concentration 0.10 mol/dm³, contact time 20 min at room temperature.     

Distribution of organophosphoric acid triesters between water and sediment at a sea-based solid waste disposal site

Organophosphoric acid triester (OPE) concentration levels in water and bottom sediment at the Osaka North Port Sea-Based Solid Waste Disposal Site were investigated, and the behavior of OPEs in the water environment of the waste disposal site was examined. The more highly water-soluble OPEs were frequently detected in raw water. Of the OPEs detected, TCEP and TCPP showed very high concentrations (1.0–90 μg/l), followed by TEP (0.3–10 μg/l) > TBXP (0.8–6.3 μg/l) > TDCPP (0.6–6.2 μg/l) > TBP (0.2–1.5 μg/l) > TPP (<0.1 μg/l). Most OPEs detected in water were eluted from the disposal waste to the water phase immediately and behaved as dissolved forms with no distribution in suspended solids (SS). On the other hand, the less water-soluble OPEs, such as TCP or TEHP, were detected in bottom sediment but hardly at all in water samples. All OPEs were detected at the waste disposal site, within which their concentration levels were uniform. It appeared that the less water-soluble OPEs were present as SS-associated forms and behaved in line with the floating surface sludge at the bottom. Received: July 6, 1998 / Accepted: February 25, 1999     

Effect of the water–oil ratio on brine/surfactant/alcohol/oil systems optimized for soil remediation

The optimum middle-phase microemulsion used for remediation of oily contaminated soils is often obtained by mixing a certain amount of a surfactant/alcohol mixture with oil and adjusting the salinity concentrations at a constant water–oil ratio. Upon introduction to the subsurface, however, the system may not be in the optimum state throughout the remediation process owing to the change in the water–oil ratio. This research has attempted to investigate the effect of the water–oil ratio on the phase behavior of systems containing brine, anionic surfactant, alcohols, and different oils. By systematically changing the water–oil ratio, while keeping the others variables constant, the systems exhibited different phase behavior. The results revealed that the effect of the water–oil ratio on system behavior was significant, and analogous to that of salinity. Increasing the water–oil ratio led the system change from winsor I → winsor III → winsor II. The greater the water–oil ratio the lower the salinity required to produce the middle-phase microemulsion, but the narrower the salinity range of the three-phase region. An empirical correlation has been developed in order to predict the changes in phase behavior with the changes in water–oil ratio. This provides a useful tool for designing optimum formulations suitable for soil remediation. Received: October 5, 1999 / Accepted: March 27, 2000     

Sedimentary Record of Polycyclic Aromatic Hydrocarbons in the Gulf of Trieste (Northern Adriatic Sea)

To reconstruct a history of polycyclic aromatic hydrocarbon (PAH) pollution in the Gulf of Trieste, one of the largest urbanized areas in the Adriatic Sea, we analyzed three long sediment cores collected between 1996 and 1997. Concentrations of total PAHs, the sum of 16 PAH compounds and six of their methylated analogues, in all three cores show a decrease from 600–800 ng g⁻¹, at the surface, to levels below 250 ng g⁻¹ in deepest layers (down to 3 m). The same trend was shown with separate representative pyrogenic PAHs (pyrene, benzofluoranthene and phenanthrene). Using Hg as a recent geochronological tracer, we observe an increasing input of PAHs since the beginning of the 20th Century and, especially, after the Second World War coinciding with increasing industrialization and urbanization of the region. This correlation is supported by PAH ratios that are indication of combustion processes and represent a marker for anthropogenic inputs. No correlation exists between PAHs and black carbon within the core profiles, indicating two different fractions of the ‘black carbon continuum’.     

Factors affecting the concentration of bisphenol A in leachates from solid waste disposal sites and its fate in treatment processes

 The concentrations of bisphenol A (BPA) contained in landfill leachates from solid waste disposal sites were measured. The concentrations of BPA contained in leachates from industrial waste sites were in the range below the detection limit to 2800 μg/l, while those from municipal sites were in the range 26–8400 μg/l. The leachates from ash-rich sites contained relatively lower concentrations of BPA compared with organic-rich leachates. It is suggested that BPA concentration increases with time after the completion of reclamation in the case of ash-rich sites, whereas the concentration of BPA decreases with time in the case of organic-rich sites. A 7-year survey on a site in Japan showed neither a decrease nor an increase in the concentration of BPA during on-going reclamation. A leachate from a site in the Philippines contained high concentrations of BPA. A slight positive correlation was found between BPA concentrations and total organic carbon (TOC). A major portion of the BPA in leachates was found in dissolved and organic unassociated fractions, which cannot be precipitated by coagulation. More than 99.9% of the BPA contained in raw leachates was removed by a conventional series of treatment processes consisting of biological treatment, coagulation, sedimentation, sand filtration, and activated carbon adsorption. Received: May 29, 2002 / Accepted: October 17, 2002     

Metallic-phase lead in slag of municipal solid waste incineration ash and leaching characteristics

Metallic phases in slags and their influence on the leaching characteristics were investigated. The proportions of metallic phase in four slags were 0.028%, 0.24%, 1.87%, and 3.05% by weight. The lead content was 10–248 mg/kg in bulk slag after metal removal, while in the metallic phase it was 579–7390 mg/kg. Lead concentrations in the metallic phase were more than ten times higher than in slags after metal removal. Lead was distributed in the metallic phase at 2.0%, 8.3%, 10.3%, and 47.4%. The concentrations of all metallic elements in metallic phases were much higher than in bulk slag. Iron, copper, and nickel had accumulated in magnetic metals, while aluminum and zinc were found in nonmagnetic metals. As regards chromium, manganese, lead, and tin, the proportion of metallic phases depended on the slag samples. By removing metallic phases, both water and pH 4 leachable lead decreased. The basic principles of melting residues containing lead are the separation of lead as a metal in reductive melting, and the containment of lead ions into uniform glassy particles in oxidization melting. Melting slag can be seen to contribute to environmental preservation by facilitating the recycling of materials through the separation of metals from melting slag. Received: February 21, 2000 / Accepted: July 27, 2000     

Improved quartz furnace method for chlorine and sulfur determination in municipal solid waste

 A method of determining the chlorine (Cl) and sulfur (S) in municipal solid waste (MSW) was studied. The quartz furnace method was improved in two ways: recovery from ash by hot extraction with dilute nitric acid, and avoidance of the volatilization of alkali (earth) metal chlorides by setting the sample combustion temperature at 600°C. In a comparison with the bomb method, using nine sets of kitchen garbage and waste plastics, the bomb method yielded a 15%–25% lower value than the improved quartz furnace method. Combustion in the bomb was frequently incomplete, resulting in recovery losses of Cl and S. The average kitchen garbage involved 5.2 mg Cl/g, of which at least 24.1% would be converted to HCl. Plastics contained 23 mg Cl/g generating 88.1% HCl on average. In the same way, kitchen garbage contained 3.0 mg S/g, generating 52.3% SO _x , whereas plastics contained 1.1 mg S/g with 55.1% SO _x formation. Received: March 20, 2002 / Accepted: October 13, 2002     

Waste incineration,PVC, and dioxins

Waste incineration is becoming increasingly necessary to tackle the rapidly rising amounts of municipal solid waste (MSW); in China many large cities are already surrounded by a girdle of landfills. Still, the not-in-my-backyard (nimby) syndrome holds strong. This attitude stems from fear of dioxins. These have been associated with incineration (‘dioxin factories’) and at times also with polyvinylchloride. In this paper this issue is analysed. China should build additional trust in MSW incineration, following promulgation of stricter emission standards, enforced by stringent controls.     

Effect of carbonation on the leaching of organic carbon and of copper from MSWI bottom ash

In Flanders, the northern part of Belgium, about 31% of the produced amount of MSWI bottom ash is recycled as secondary raw material. In view of recycling a higher percentage of bottom ash, a particular bottom ash fraction (Ø 0.1–2 mm) was studied. As the leaching of this bottom ash fraction exceeds some of the Flemish limit values for heavy metals (with Cu being the most critical), treatment is required.Natural weathering and accelerated carbonation resulted in a significant decrease of the Cu leaching. Natural weathering during 3 months caused a decrease of Cu leaching to <50% of its original value, whereas accelerated carbonation resulted in an even larger decrease (to ca. 13% of its initial value) after 2 weeks, with the main decrease taking place within the first 48 h.Total organic carbon decreased to ca. 70% and 55% of the initial concentration in the solid phase, and to 40% and 25% in the leachate after natural weathering and after accelerated carbonation, respectively. In the solid material the decrease of the Hy fraction was the largest, the FA concentration remained essentially constant. The decrease of FA in the leachate can be attributed partly to an enhanced adsorption of FA to Fe/Al (hydr)oxides, due to the combined effect of a pH decrease and the neoformation of Al (hydr)oxides (both due to carbonation). A detailed study of adsorption of FA to Fe/Al (hydr)oxides showed that significant adsorption of FA occurs, that it increases with decreasing pH and started above pH 12 for Fe (hydr)oxides and around 10 for Al (hydr)oxides. Depending whether FA or Hy are considered the controlling factor in enhanced Cu leaching, the decreasing FA or Hy in the leachate explains the decrease in the Cu leaching during carbonation.     

Acidic bioleaching of heavy metals from sewage sludge

The overall objective of this study was to evaluate the use of controlled bio-acidification prior to land application as a decontamination process to remove heavy metals from sludge. The sulfur-oxidizing bacteria were naturally available in the sludge samples and were activated by providing sulfur and aeration at 28°C–30°C. Activation resulted in bio-acidification to pH 2 within 5–11 days. Successive inoculation of fresh sludges with 5% acidified samples reduced the acidification time to 2–3 days in most samples. Bio-acidification resulted in dissolving significant quantities of heavy metals from all sludge types tested. The maximum solubilization results were: 86%–97% for Ni; 48%–98% for Pb; 26%–71% for Cr; 18%–91% for Zn; 16%–90% for Cu; 7%–60% for Cd. Limited metal solubilization results were observed in the various control samples that accompanied the bio-acidified samples. The leaching results in the control samples were limited to 2%–19% for Ni, 0%–7% for Pb, 0%–5% for Cr, 0.3%–4% for Zn, 0.2%–4% for Cu and 0%–3% for Cd. The results confirmed that Ni and Pb were the easiest metals to dissolve from the various sludge types. On the other hand, the lowest solubilization results were observed for Cu and Cd, and moderate solubilization results were achieved for Cr. The bio-acidification process resulted in moderate gains in terms of improving the suitability of tested sludges for land application. Received: April 19, 1999 / Accepted: November 4, 1999     

The influence of sodium on biohydrogen production from food waste by anaerobic fermentation

Anaerobic fermentation of food waste for hydrogen production was performed in serum bottles with various linear alkylbenzene sulfonate (LAS) dosages (7.1–21.4 g/l) and sodium concentrations (5.03–28.7 g/l). LAS can effectively inhibit the activity of hydrogen-consuming bacteria, and the maximum hydrogen yield of 109.2 ml/g volatile solid (VS) was obtained at an LAS dosage of 14.3 g/l without added sodium. The feasible pH for hydrogen production is 5.0–6.0, and the process will slow down or stop when the pH is below 5.0.The hydrogen production potential increased when the sodium concentration increased in the range 5.03–14.41 g/l. The maximum hydrogen yield was 154.8 ml/g VS, and then the hydrogen production began to decrease when the sodium concentration increased further. A sodium chloride concentration of 20 g/l and higher will enhance the osmotic pressure and make bacteria inert. In the effluent, acetic acid is the major by-product. The results indicated that the hydrogen production from the anaerobic fermentation of food waste could clearly be increased with the additives and a sodium concentration less than 20 g/l.     

Synthesis of hydrogarnet from molten slag and its hydrogen chloride fixation performance at high temperature

Hydrogarnet was synthesized hydrothermally below 200°C using molten slag obtained from municipal solid waste. For comparison, it was also synthesized using pure-phase CaO–Al₂O₃–SiO₂–H₂O, as reported previously. The structural and textural properties of this material were investigated using various analytical and spectroscopic techniques such as X-ray diffraction, X-ray fluorescence spectrometry, atomic absorption spectrometry (AAS), thermogravimetry/differential thermal analysis, Fourier transform infrared spectroscopy, and scanning electron microscopy. The Cl⁻ fixation ability of hydrogarnet was investigated in the temperature range 500–800°C in a fixed-bed flow reactor using a HCl concentration (1000 p.p.m.v.) similar to that of incinerator exhaust gas. Under these experimental conditions, the hydrogarnet was capable of reducing the HCl gas level to less than 1 p.p.m.v. Analysis of the spent catalyst revealed that the hydrogarnet was being transformed into wadalite and CaCl₂ at high temperatures. The elution test for chromium ions in hydrogarnet obtained from slag was also used, and it was found that chromium ions were not eluted from hydrogarnet. Received: January 27, 2001 / Accepted: October 11, 2001     

Isolation of a fungus from denitrifying activated sludge that degrades highly chlorinated dioxins

 This article reports the potential of denitrifying activated sludge to degrade highly chlorinated dioxins, especially from a (landfill) leacheate treatment plant in Japan, and the isolation from this denitrifying activated sludge of a microorganism able to degrade highly chlorinated dioxins. Using a 700-ml bioreactor, denitrifying activated sludge was cultivated under denitrifying conditions by adding 2.0 ng of a mixture of 4- to 8-chlorinated dioxins from fly ash. The dioxin contents of the sample, effluent, and medium before and after cultivation were measured by gas chromatography–mass spectrometry (GC–MS). After 7 days cultivation, about 90% of added dioxins were lost (average percentage of isomer depletion). A dioxin-degrading microorganism was isolated from the activated sludge. Lignin was added to the medium as a color indicator of aromatic compound degradation, and the lignin-decolorizing microorganisms in the denitrifying activated sludge were screened. Some strains were isolated, and one major isolated fungus, strain 622, decolorized lignin effectively. Strain 622 was identified as an Acremonium sp. from its morphological characteristics. It could decolorize lignin by 24% under paraffin-sealed anaerobic conditions. After the cultivation of strain 622 with a 2 ng/ml mixture of 4- to 8-chlorinated dioxins for 1 day, 82% (average for individual isomers) of the added 4- to 8-chlorinated dioxins had been degraded. Added octachlorodibenzo-p-dioxin (OCDD, 100 ng) was degraded under aerobic conditions after 8 h of incubation. During this process, heptachlorodibenzo-p-dioxin was produced and appeared to be a degradation product of OCDD. 1- or 2-hydroxydibenzo-p-dioxin from OCDD was also identified as the degradation product by GC–MS. These results indicated that OCDD was degraded to the nonchlorinated dibenzo-p-dioxins through dechlorination by Acremonium sp. strain 622. Received: October 12, 2001 / Accepted: March 11, 2002     

Mass balance of arsenic and antimony in municipal waste incinerators

The arsenic and antimony balance in two municipal waste incinerators was investigated. Initially, the production rates of ash and wet scrubber effluent were estimated. Then the arsenic and antimony in the ash and wet scrubber effluent were determined, which gave an estimate of the elemental balance. The total amounts of arsenic and antimony in the municipal waste were 0.9 g/t and 30–44 g/t, respectively. The distributions to fly ash were 45–47% and 33–74% for arsenic and antimony, respectively. The distribution mechanisms of arsenic and antimony are discussed from the viewpoints of their thermodynamics as well as their initial valencies, which greatly affect their behaviour. Received: July 2, 1998 / Accepted: February 27, 1999     

In-Situ Phytoremediation of Pahs Contaminated Soils Following a Bioremediation Treatment

Phytoremediation of pollutants in soils is an emerging technology, using different soil-plant interaction properties. For organic pollutants, such as polycyclic aromatic hydrocarbons (PAHs), phytodegradation seems to be the most promising approach. It occurs mostly through an increase of the microbial activity in the plant rhizosphere, allowing the degradation of organic substances, a source of carbon for soil microbes. Despite a large amount of available data in the literature concerning laboratory and short term PAH phytodegradation experiments, no actual field application of such technique was previously carried out. In the present study, a soil from a former coking plant was used to evaluate the feasibility and the efficiency of PAH phytodegradation in the field during a three years trial and following a bioremediation treatment. Before the phytoremediation treatment, the soil was homogenized and split into six independent plots with no hydrological connections. On four of these plots, different types of common plant species were sowed: mixture of herbaceous species, short cut (P1), long cut (P2), ornamental plants (P3) and trees (P4). Natural vegetation was allowed to grow on the fifth plot (P5), and the last plot was weeded (P6). Each year, representative sampling of two soil horizons (0–50 and 50–100 cm) was carried out in each plot to characterize the evolution of PAHs concentration in soils and in soils solution obtained by lixiviation. Possible impact of the phytoremediation technique on ecosystems was evaluated using different eco- and genotoxicity tests both on the soil solid matrix and on the soil solution. For each soil horizon, comparable decrease of soil total PAHs concentrations were obtained for three plots, reaching a maximum value of 26% of the initial PAHs concentration. The decrease mostly concerned the 3 rings PAHs. The overall low decrease in PAHs content was linked to a drastic decrease in PAHs availability likely due to the bioremediation treatment. However, soil solutions concentration showed low values and no signficant toxicity was characterized. The mixture of the herbaceous species seemed to be the most promising plants to be used in such procedure.     

Treatment-oriented characterization of dry scrubber residue from municipal solid waste incineration

 Dry scrubber residue from municipal solid waste incineration (MSWI) was characterized to identify critical inorganic pollutants and to suggest a conceptual treatment method. The key methods used were thermal analysis, including thermogravimetry (TG) and differential thermal analysis (DTA), pH_stat titration, qualitative X-ray diffraction (XRD), scanning electron microscopy (SEM), chemical equilibrium calculations, and statistics such as error propagation, principal component analysis (PCA), and empirical modeling based on factorial designs. Based on EU directives, the major inorganic pollutants Cd, Cr, Pb, and Zn were found. In addition, the pH was too high. With dry scrubber residue stabilization in mind, the impact of carbonation and hydration was assessed and judged to be encouraging. In particular, chemical equilibrium calculations showed that carbonation has considerable potential to lower the pH and the availability of Pb, Zn, and Cr. The impact of carbonation on the mobility of Cd was found to be small. During carbonation, a metal-trapping calcium aluminosilicate hydrate (C–A–S–H) phase is also formed. Both processes together have the potential to lead to a robust, reliable, and reasonable stabilization method for dry scrubber residue. However, to control these processes, the decisive factors need to be identified and their effects need to be quantified. Ca, Cl, Na, and K might be abundant components which would be mobile even after stabilization. Received: September 11, 2001 / Accepted: December 6, 2001     

Recent Sediment of Lake Bled (NW Slovenia): Sedimentological and Geochemical Properties

Sediment cores collected in eutrophic subalpine Lake Bled (NW Slovenia) were analyzed sedimentologically in terms of grain size, mineralogy and sedimentation rates, and geochemically in terms of metals and nutrients. Surficial sediment is composed of dark gyttya type clayey silt with 5%–10% of organic matter. The sediment below is fine laminated and composed of homogenous silt and clayey silt: Mineralogically, low-Mg calcite prevails, followed by dolomite, quartz, partially of diatomaceous origin, and feldspar. Clay minerals are composed of muscovite/illite and chlorite. Authigenic minerals are pyrite and ‘lake chalk’ (low-Mg calcite). Lake sediment is especially polluted by Pb, Zn and P. Higher contents were found in the northwestern and eastern parts due to the particle input by local inflows. Increasing eutrophication and pollution, indicated by Cd, Cu, V, Cr, Co and total N and P enrichment in the top layers of the cores, started almost 100 years B.P., and especially 50 years ago.     

Biodegradable Polyesters and Polyamides From Difunctionalized Lauric and Coconut Fatty Acids

In this work, a major fatty acid from coconut oil was used as starting material in preparing biodegradable polymers. Thus, polyesters and polyamides from varying proportions of monomers, hydroxy- and amino- derivatives of lauric acid were synthesized. Initially, the derivatives were prepared by regioselective chlorination of lauric acid, in the presence of ferrous ions in strong acid medium. Subsequent hydroxylation and amination procedures yielded the hydroxy- and amino- derivatives of lauric acid. These monomers were polymerized in a reaction tube by simple polycondensation method at 220–230 °C for 6–8 h without catalyst. Molecular weight determination using –COOH by end group titration and gel permeation chromatography (GPC) gave an average molar mass of 3,000–5,000 g mol⁻¹ with n = 15–25 monomer units. Thermal properties such as glass transition (T_g) and decomposition (T_d) temperatures were obtained using differential scanning calorimetry (DSC). The same processes of synthesis and determinations above were applied to coconut fatty acids, derived from saponification of coconut oil, and resulted to very similar conclusions. A quick biodegradation assay against fungus Aspergillus niger UPCC 4219 showed that the polymers prepared are more biodegradable than conventional plastics such as polypropylene, poly(ethyleneterepthalate) and poly(tetrafluoroethylene) but not as biodegradable as cellulosic (newsprint) paper.