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Air pollution control residues (APCr) from municipal solid waste (MSW) incineration are hazardous waste, and their management requires holistic approaches within technical, economical, legislative, and environmental constraints. This work deals with the recycling of APCr for producing lightweight aggregates (LWA) commonly manufactured by firing natural clay. The main objectives are to evaluate the environmental impacts of LWA with and without incorporating APCr and assess whether APCr recycling in LWA is beneficial, based on the life-cycle assessment (LCA) methodology. The system boundary included raw material extraction, grinding, mixture, firing, cooling, and packing (cradle-to-gate). Results were analysed following the impact assessment methods recommended by the International Reference Life Cycle Data System. Results pointed out a reduction of impacts in all categories when 3% of natural clay are replaced by APCr. The highest gains occurred for toxicity categories (HTc, HTnc) and resulted mainly from avoiding landfill of APCr. For non-toxicity categories, impacts were dominated by the emissions from the kiln firing process, which were similar for both LWA; therefore, impact reductions from APCr use in LWA in these categories were modest. LCA results show that the valorisation of APCr in LWA may be an environmentally sound solution to avoid landfill disposal practices.

This work presents an updated overview of waste lubricant oil (WLO) management practices in Europe to promote a circular economy. The characteristics of virgin and waste oil, their hazardous proper...

The ubiquitous presence of CBZ, SMX and LRZ in water is a subject of increasing concern. This study represents a new approach in terms of these contaminants’ removal through Fenton process in three different ways, employing a solid catalyst, RM, which, alone, is a source of Fe3＋ just as much is a source of environmental problems. Alongside RM, 100 mg/L of H2O2 were utilized as the initial solution’s pH remained unaltered. It was observed that, at these operating conditions, an appreciable degradation rate of contaminants was achieved. Solar photo-Fenton under visible light radiation led the way by attaining more than 50% removal for all three contaminants, reaching its peak when degrading around 62% of LRZ initially present. Therefore, RM, a residue from the alumina industry, seems to be a promising choice in terms of CECs degradation through Fenton process. Nevertheless, some parameters still need optimization, in order to achieve a better understanding and certainty of this oxidation process’ skilfulness for detoxifying CECs from the world’s water resources. Keywords: Decontamination, Fenton process, Pharmaceuticals, Red mud, Sunlight radiation, Waste management

Municipal solid waste (MSW) incineration in waste-to-energy plants plays an important role in waste management systems of developed countries, since the increasing amounts of waste cannot be all recycled, and diverting waste from landfilling is a priority. On the other hand, proper MSW management is a fundamental part of sustainable development, which requires the balance of the economic, social, and environmental dimensions. Thus, this chapter explores sustainability issues about MSW incineration with energy recovery. For this purpose, an overview of the MSW management systems is presented and incineration technology is highlighted. Subsequently, the three dimensions of sustainable development are explored regarding MSW incineration with energy recovery. Environmental considerations related to air emissions and solid residues from MSW incineration are discussed. Concerning economic issues, the costs and revenues of incineration treatment are reviewed. Finally, the social context of this management option is provided, pointing out public concerns and studies addressing these aspects.

Phosphorus (P) is a non-renewable resource, irreplaceable for life and food production, and currently considered a Critical Raw Material to the European Union (EU). Due to concerns about the rate of consumption and limited reserves in countries with sensitive geopolitical contexts, it is urgent to recover P from urban and industrial flows. Indeed, the municipal wastewater treatment plants (WWTP) are considered relevant sources with several hot spots, especially sewage sludge with estimated recovery efficiencies of >80%. The most promising recovery strategies are based on thermal treatments (e.g., incineration of sludge) following by wet-chemical or thermochemical leaching, precipitation, and adsorption. The direct application of sludge on soil is no longer a primary route for P reintegration in the value-chain for countries as Switzerland, Germany, and The Netherlands. In fact, Switzerland and Austria paved the way for implementing P recovery legislation, focusing on recovery from raw sewage sludge or ashes. Indeed, industrial technologies with sludge ash as input show high recovery efficiencies (Ashdec® and Leachphos® with 98 and 79%) and lower environmental impacts, whereas Pearl® technology has about 12% recovery efficiency with wastewater as input. After all, struvite emerges as the most recovered product with recent access to the internal market of EU fertilisers and similar growth performance compared to triple-super-phosphate. However, several studies leave open the possibility of introducing loaded adsorbents with P as soil amendments as a new alternative to conventional desorption. Briefly, P recovery should be a compromise between efficiency, environmental impacts, and economic revenues from the final products info:eu-repo/semantics/publishedVersion

Kraft pulp mills produce the main raw material for paper, while several waste products are generated in large quantities in the process. This review study addresses four of the main inorganic wastes formed by this industry, namely green liquor dregs (GLD), slaker grits (SG), lime mud (LM) and boiler fly ash (BFA), which are still mostly discarded in landfills. A brief overview of a typical industrial process was included to outline the waste generation points. The main chemical and physical properties are indicated for highlighting the most relevant characteristics to determine which applications may be considered in each case. An in-depth literature review allowed the identification of the main applications that have been tested mainly at the laboratory scale and some at an industrial scale. The applications are grouped into construction materials, geotechnical, environmental, agricultural and others. This assessment shows that the circular economy and the sustainable development goals of the UN are important issues for organizations in general, and the pulp mill in particular. In fact, this industry has managed to close the chemicals loops, recover energy and reduce water consumption in the process. However, the current situation of inorganic waste can still be improved if industrial applications are developed to avoid landfill.

Waste lubricant oil (WLO) is an absolute hazardous entry in the European List of Waste that requires proper treatment. Solvent extraction is one of the most effective deasphalting processes for the regeneration of WLO, with a strong contribution to the circular economy. This study aims to propose a new methodology for the selection of solvents for WLO regeneration, which balances technical, economical, and greenness criteria. The method involves two phases for screening a list of 154 solvents. In the first phase, five criteria were used: water and acidic properties; selectivity toward the base oil and flocculation capacity; number of carbon atoms between three and five; melting point lower than 10 °C and a boiling point between 60 and 130 °C; and yield greater than 85%. In the second phase, three metrics of sustainability were employed: greenness, efficiency, and cost. Globally, a score was attributed to each solvent based on the assessment of the individual metric. From a list of 154 solvents, 1-butanol,...

Waste lubricant oil (WLO) management systems across Europe can be very heterogeneous, with significant discrepancies in their performance. The objectives towards a circular economy represent a challenge to continuously maximize the collection and regeneration of this hazardous waste. The quality of WLO is a limiting factor towards its potential for regeneration, in which producers have a great responsibility on the handling phase. In this context, the main objectives of this work are the evaluation and improvement of a national management system, based on the physicochemical characteristics of WLO collected by different producers (garage, industry and others). Data of critical parameters (sediments, water, chlorine and PCB) of 30,242 samples collected from 2008 to 2015 were analyzed. About 4.8% of those samples exceeded the Portuguese regulatory limit regarding sediments (3 wt %) and 22.3% for water plus sediments (8 wt %). On the contrary, 0.73% of the samples did not comply with the limit of chlorine (2000 ppm) and only 0.08% for PCB (50 ppm). Chlorine nonconformities were mostly registered in industrial producers. In addition, 60 samples collected in 2015 were characterized regarding other important properties, namely density, kinematic viscosity at 40 °C, total acid number, saponification number, elemental analysis and functional groups. These results gave important clues about the performance of the different producers. In particular, FTIR analysis revealed that about 60% of the samples may be contaminated with glycol compounds regardless the type of producer. The overall management system can be improved by preventing contamination with chlorine from industry WLO or glycol-containing compounds (such as brake fluid and antifreeze) for all producers.

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. Export Date: 20 December 2019 ispartof: Waste Management vol:102 pages:868-883 ispartof: location:United States status: published

Environmental policies in the European Union focus on the prevention of hazardous waste and aim to mitigate its impact on human health and ecosystems. However, progress is promoting a shift in perspective from environmental impacts to resource recovery. Municipal solid waste incineration (MSWI) has been increasing in developed countries, thus the amount of air pollution control residues (APCr) and fly ashes (FA) have followed the same upward trend. APCr from MSWI is classified as hazardous waste in the List of Waste (LoW) and as an absolute entry (19 01 07*), but FA may be classified as a mirror entry (19 0 13*/19 01 14). These properties arise mainly from their content in soluble salts, potentially toxic metals, trace organic pollutants and high pH in contact with water. Since these residues have been mostly disposed of in underground and landfills, other possibilities must be investigated to recover secondary raw materials and products. According to the literature, four additional routes of recovery have been found: detoxification (e.g. washing), product manufacturing (e.g. ceramic products and cement), practical applications (e.g. CO2 sequestration) and recovery of materials (e.g. Zn and salts). This work aims to identify the best available technologies for material recovery in order to avoid landfill solutions. Within this scope, six case studies are presented and discussed: recycling in lightweight aggregates, glass-ceramics, cement, recovery of zinc, rare metals and salts. Finally, future perspectives are provided to advance understanding of this anthropogenic waste as a source of resources, yet tied to safeguards for the environment.

There is a growing interest in the economic benefits from the management of seasonal fruit wastes by anaerobic digestion (AD) processes, instead of landfilling the organic matter. The aim of the present study is to investigate the valorization of a fig processing industry waste (FgW) by AD. To the best of our knowledge, this is the first time this residue is considered as a substrate. A batch reactor with an operating volume of 3.75 L, at 37 ± 2°C (mesophilic operation) and a substrate to inoculum (S/I) ratio within the range 0.2 to 1.2 g VS/gVS0 were used. The best specific methane production achieved at lab scale was 0.284 Nm3 CH4/kg. The results reveal that FgW can be valorized by AD and the biogas used as a source of energy in the small to medium enterprise, where the waste has been produced.

This work provides insight into the most important properties of air pollution control (APC) residues from municipal solid waste incineration (MSWI) and clay used at industrial level aiming at producing a ceramic material known as lightweight aggregates (LWA). Both clay and APC residues were characterized to assess the most important chemical, physical, thermal and mineralogical properties to evaluate their compatibility. The maximum percentage of incorporation tested was 10% of APC residues. The results showed that the waste does not own bloating properties and it is not expectable other improvements into the technological properties of LWA, since the fluxing components contribution is high and the amount of silica is low. Although during the thermal analysis of the APC residues the loss on weight is high (about 32% until 1200 °C), they seem not to be suitable as a gas-release additive, once for 10% of incorporation the external shell appears to be significantly broken. The environmental impact due to leaching of pollutants from the LWA incorporating less than or equal to 5% of waste appears not to be relevant. In conclusion, the results showed that synthetic LWA may be considered as a possible approach to recycling of APC residues in case of low amount of waste is used or if a pre-treatment is performed.

This work focuses on the assessment of technological properties and on the leaching behavior of lightweight aggregates (LWA) produced by incorporating different quantities of air pollution control (APC) residues from municipal solid waste (MSW) incineration. Currently this hazardous waste has been mostly landfilled after stabilization/solidification. The LWA were produced by pelletizing natural clay, APC residues as-received from incineration plant, or after a washing treatment, a small amount of oil and water. The pellets were fired in a laboratory chamber furnace over calcium carbonate. The main technological properties of the LWA were evaluated, mainly concerning morphology, bulk and particle densities, compressive strength, bloating index, water adsorption and porosity. Given that APC residues do not own expansive (bloating) properties, the incorporation into LWA is only possible in moderate quantities, such as 3% as received or 5% after pre-washing treatment. The leaching behavior of heavy metals from sintered LWA using water or acid solutions was investigated, and despite the low acid neutralization capacity of the synthetic aggregates, the released quantities were low over a wide pH range. In conclusion, after a washing pre-treatment and if the percentage of incorporation is low, these residues may be incorporated into LWA. However, the recycling of APC residues from MSW incineration into LWA does not revealed any technical advantage.

Free air space (FAS) is a physical parameter that can play an important role in composting processes to maintain favourable aerobic conditions. Aiming to predict the FAS of initial composting mixtures, specific materials proportions ranged from 0 to 1 were tested for a case study comprising industrial potato peel, which is characterized by low air void volume, thus requiring additional components for its composting. The characterization and prediction of FAS for initial mixtures involving potato peel, grass clippings and rice husks (set A) or sawdust (set B) was accomplished by means of an augmented simplex-centroid mixture design approach. The experimental data were fitted to second order Scheffe polynomials. Synergistic or antagonistic effects of mixture proportions in the FAS response were identified from the surface and response trace plots in the FAS response. Moreover, a good agreement was achieved between the model predictions and supplementary experimental data. Moreover, theoretical and empirical approaches for estimating FAS available in literature were compared with the predictions generated by the mixture design approach. This study demonstrated that the mixture design methodology can be a valuable tool to predict the initial FAS of composting mixtures, specifically in making adjustments to improve composting processes containing primarily potato peel.

Industrial eggshell (ES) is an animal by-product (ABP) involving some risk if not properly managed. Composting is a possible treatment approved for its safe use. This study aims to assess the influence of using N-rich material (grass clippings (GC)) to improve co-composting of ES mixtures for reaching sanitizing temperatures imposed by the ABP regulation from the European Union. Two sets of mixtures (M1 and M2) were investigated, each containing industrial potato peel waste, GC and rice husks at 3:1.9:1 and 3:0:1 ratios by wet weight. In each set, ES composition ranged from 0% to 30% (w/w). Co-composting trials were performed in self-heating reactors for 25 days, followed by maturation in piles. Results showed that only M1 trials attained temperatures higher than 70°C for nine consecutive hours, but N-losses by stripping on average were four- to five-fold higher than M2. In the absence of N-rich material, biodegradability of mixtures was ‘low’ to ‘moderate’ and organic matter conversion was impaired. Physical, chemical and phytotoxic properties of finished composts were suitable for soil improvement, but M1 took 54 more days to achieve maturity. In conclusion, co-composting ES with N-rich materials is important to assure the fulfilment of sanitizing requirements, avoiding any additional thermal treatment.

The aim of the present study addresses the applicability of the Fenton-like zero valent iron (ZVI) process on the remediation of several landfill leachate samples coming from different points of an existing treatment plant: initial effluent (ERaw), after biological treatment (EPost-Bio) and depurated effluent (ETreat). The effects of pH and Fe0 concentration were determined for ERaw and ETreat. It was observed that the use of low pH values enhances the treatment efficiency. Moreover, the increase on iron load leads to higher COD removals until a certain point after which the catalyst starts to show radical scavenger effect. The low efficiency attained for ERaw (COD removal always below 8%) indicates that this methodology is not suitable for this effluent. However, final ETreat within the legal limits for discharge were attained when pH = 2 was used with 38% of COD removal. The utilization of iron shavings as catalyst in the Fenton-like process showed to be a suitable and economical solution on the remediation of ETreat and EPost-Bio with high COD abatements (up to 60%) leading to streams able to be released to the municipal sewage. Since the real plant often does not comply with regulatory thresholds and according to our results, it seems advisable to implement this technology after the bio-reactor for substituting the already existing physico-chemical treatment.

This study aims to investigate the co-composting of an inorganic industrial waste (eggshell - ES) in very high levels (up to 60% w/w). Since composting is a process in which solid, liquid and gaseous phases interact in a very complex way, there is a need to shed light on statistical tools that can unravel the main relationships structuring the variability associated to this process. In this study, PCA and data visualisation were used with that purpose. The co-composting tests were designed with increasing quantities of ES (0, 10, 20, 30 and 60%ES w/w) mixed with industrial potato peel and rice husks. Principal component analysis showed that physical properties like free air space, bulk density and moisture are the most relevant variables for explaining the variability due to ES content. On the other hand, variability in time dynamics is mostly driven by some chemical and phytoxicological parameters, such as organic matter decay and nitrate content. Higher ES incorporation (60% ES) enhanced the initial biological activity of the mixture, but the higher bulk density and lower water holding capacity had a negative effect on the aerobic biological activity as the process evolved. Nevertheless, pathogen-killing temperatures (>70°C for 11h) were attained. All the final products obtained after 90days were stable and non-phytotoxic. This work proved that valorisation of high amounts of eggshell by co-composting is feasible, but prone to be influenced by the physical properties of the mixtures.

This study aims to investigate the possibility of integrating both ion-exchange (IX) and nanofiltration (NF) processes for the recovery of Cr(III) salts from a synthetic solution prepared with concentrations of Cr(III), [Formula: see text] and Cl(-) in the range of industrial effluents of tanneries. Ion exchange should be used as a pre-treatment for uptaking Cl(-) ions from the effluent, and thereafter the treated solution is fed to an NF unit to recover chromium sulphate salt for reuse in the tanning bath. The strong anionic resin Diaion PA316 was selected for evaluating chloride-sulphate ion-exchange equilibrium, with respect to mass of resin, NaCl concentration, temperature and ratio [Formula: see text]. It was observed that the separation factor, [Formula: see text], depends on the total electrolyte concentration and the ratio [Formula: see text] plays a role as well. Moreover, it was determined that the resin prefers sulphate over chloride since [Formula: see text] is less than 1. The performance of the NF process is dependent on [Formula: see text] and the rejection of Cr(III) may decrease from 90% to 70% as the ratio increases from 0.5 to 2. Regarding the integration of both IX and NF, the feed solution after treatement with the resin was fed to NF where the ratio of [Formula: see text] led to the best operating conditions for this process (90% of Cr(III) rejection and up to 77% for [Formula: see text] ions). This strategy may be considered as a sustainable approach since it permits to obtain a solution enriched in Cr(III) salt for reuse in the tanning process, thus contributing to environmental protection.

The recycling of wastes is nowadays a priority in terms of the EU policies. This study aims at the replacement of a certain percentage of clay (natural raw material) by residues produced in a municipal solid waste incineration (MSWI) process referred as Air Pollution Control (APC) residues. The main objective of this work concerns the prediction of the quantity of the waste that can be valorized as lightweight aggregates (LWA). For this analysis the Riley diagram was considered, which consists in plotting the percentage concentration of the main oxides (SiO2, Al2O3, fluxing) in a ternary diagram. The fluxing is defined as the sum of Fe2O3+CaO+MgO+Na2O+K2O. Our results point out that no more than 5% of APC residues should be considered, since the main oxide composition of APC residues is far away from bloating area. A pre-washing treatment improved the waste characteristics being then possible to increase the amount of residue that can be incorporated in percentages below 10%. This theoretical analysis can save experimental work, since it allows the prediction of the maximum amount of wastes to be tested.

This study focuses on the stabilisation/solidification (S/S) treatment of air pollution control (APC) residues from municipal solid waste (MSW) incineration. Six formulations (T1–T6) were tested based on different cements as binders, for the immobilisation of pollutants and to prevent their entering into the environment at unacceptable rates. Soluble phosphates and silicates were considered in some cases to fix heavy metals. The performance of T1–T6 products was measured in terms of initial and final setting times, mechanical strength, total availability and leaching from S/S products. Two monolithic leaching tests were used to estimate emissions of pollutants over 48 h and 64 days. The results showed that the setting time was reduced when soluble phosphates were used. Moreover, although all the treatments have met the threshold of 1 MPa for unconfined compressive strength, this parameter was significantly reduced due to matrix dissolution during immersion. After three cycles of leaching, the limit of 10% for solubilisation was exceeded for all treatments with the exception of T5 (with phosphates). This study demonstrated that the S/S treatment used at the industrial level can be improved with respect to toxic heavy metals, by using soluble silicates or phosphates, but not regarding soluble salts.

Industrial eggshell waste (ES) is classified as an animal by-product not intended to human consumption. For reducing pathogen spreading risk due to soil incorporation of ES, sanitation by composting is a pre-treatment option. This work aims to evaluate eggshell waste recycling in self-heating composting reactors and investigate ES effect on process evolution and end product quality. Potato peel, grass clippings and rice husks were the starting organic materials considered. The incorporation of 30% (w/w) ES in a composting mixture did not affect mixture biodegradability, nor its capacity to reach sanitizing temperatures. After 25 days of composting, ES addition caused a nitrogen loss of about 10 g N kg−1 of initial volatile solids, thus reducing nitrogen nutritional potential of the finished compost. This study showed that a composting mixture with a significant proportion of ES (30% w/w) may be converted into calcium-rich marketable compost to neutralize soil acidity and/or calcium deficiencies.

The main objective of this study was to evaluate the feasibility of recycling large quantities of industrial eggshell waste through turned windrows composting in order to obtain a value-added soil improver. For that, four different formulations were tested to produce stable composts with adequate properties to be further used for agronomic applications such as amendment in soils with acid characteristics and/or with low calcium concentration. The eggshell waste is mainly an inorganic animal by-product, and thus its co-composting was conducted with farm wastes (horse and chicken manures) and grass clipping. The windrows were aerated periodically and monitored during 50 days regarding temperature, moisture, pH, conductivity, and carbon/nitrogen ratio (C/N). The thermophilic phase lasted for 10–20 days. At the end, moisture, pH, electrical conductivity, organic matter, C/N ratio, and toxic heavy metals (Cd, Cr, Pb, Cu, Ni, Zn) were determined. The microbiological assessment involved total mesophilic heterotrophic bacteria, total coliform bacteria, thermotolerant coliform bacteria, E.coli and spores of sulphite-reducing clostridia. The assessment of maturity based on germination index and stability by using Dewar self-heating test and respirometry showed that all the composts were mature and stable, with adequate properties for agronomic applications. This study evidenced that large quantities (up to 30 % in weight) of eggshell waste may be converted into calcium-rich marketable compost by thermophilic windrows composting.

Composting is one of the technologies recommended for pre-treating industrial eggshells (ES) before its application in soils, for calcium recycling. However, due to the high inorganic content of ES, a mixture of biodegradable materials is required to assure a successful procedure. In this study, an adequate organic blend composition containing potato peel (PP), grass clippings (GC) and wheat straw (WS) was determined by applying the simplex-centroid mixture design method to achieve a desired moisture content, carbon: nitrogen ratio and free air space for effective composting of ES. A blend of 56% PP, 37% GC and 7% WS was selected and tested in a self heating reactor, where 10% (w/w) of ES was incorporated. After 29 days of reactor operation, a dry matter reduction of 46% was achieved and thermophilic temperatures were maintained during 15 days, indicating that the blend selected by statistical approach was adequate for composting of ES.

Municipal solid waste (MSW) remains a major problem in modern societies, even though the significant efforts to prevent, reduce, reuse and recycle. At present, municipal solid waste incineration (MSWI) in waste-to-energy (WtE) plants is one of the main management options in most of the developed countries. The technology for recovering energy from MSW has evolved over the years and now sophisticated air pollution control (APC) equipment insures that emissions comply with the stringent limits established in developed countries. This chapter shows the role of incineration in WtE processes in the ambit of MSW management, giving an overview of the MSWI technologies and APC devices used for cleaning the gaseous emissions. The main focus is on the key air pollutants, such as dioxins and furans. At the end, the impact of emission on health risks is also briefly considered.

Taking into account current environmental concerns, the main objective of this work focused a national inventory aiming to estimate the amount of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/PCDF) released in Portugal in 2006. The methodology used was based on the Standardized Toolkit for Identification and Quantification of Dioxins and Furan Releases, developed by UNEP Chemicals, in 2005. The method allows the assessment of the amount of PCDD/PCDF released into the environment along five vectors involving air, water, land, products and residues. Facing some difficulties mainly regarding to the availability of data for some activities known to produce PCDD/PCDF, three scenarios (Sc1 to Sc3) corresponding to lower, central and upper estimates were established. The Sc1 scenario (lower estimate) includes the situations where in case of doubt or scarce information, reduced or none emission values were assumed, Sc2 refers to a central estimate, which is believed to be the most realistic for the Portuguese situation, while Sc3 corresponds to the worst case (upper estimate). The results obtained pointed out that the total amount of PCDD/PCDF emitted in Portugal during the period under analysis was in the range of 51.2-217.9 g TEQ year(-1), with the most likely value of 95.2 g TEQ year(-1) achieved under the Sc2 scenario. This study also showed that the methodology developed by UNEP Chemicals is a very simple one, and the main difficulty is the availability of data. The main indicators calculated in this study were 8.98 μg TEQ/(year person) by taking into account the total amount of PCDD/PCDF released, and 3.63 μg TEQ/(year person) when only air emissions were considered.

Waste management and environmental protection are mandatory requirements of modern society. In our study, air pollution control (APC) residues from municipal solid waste incinerators (MSWI) were considered as a mixture of fly ash and fine particulate solids collected in scrubbers and fabric filters. These are hazardous wastes and require treatment before landfill. Although there are a number of treatment options, it is highly recommended to find practical applications rather than just dump them in landfill sites. In general, for using a construction material, beyond technical specifications also soil and surface water criteria may be used to ensure environmental protection. The Dutch Building Materials Decree (BMD) is a valuable tool in this respect and it was used to investigate which properties do not meet the threshold criteria so that APC residues can be further used as secondary building material. To this end, some scenarios were evaluated by considering release of inorganic species from unmoulded and moulded applications. The main conclusion is that the high amount of soluble salts makes the APC residues a building material prohibited in any of the conditions tested. In case of moulding materials, the limits of heavy metals are complied, and their use in Category 1 would be allowed. However, also in this case, the soluble salts lead to the classification of "building material not allowed". The treatments with phosphates or silicates are able to solve the problem of heavy metals, but difficulties with the soluble salts are still observed. This analysis suggests that for APC residues to comply with soil and surface water protection criteria to be further used as building material at least a pre-treating for removing soluble salts is absolutely required.

The influence of pH on the leaching behaviour of air pollution control (APC) residues produced in municipal solid waste incineration (MSWI) is addressed in this study. The residue is considered hazardous waste, and in accordance with their chemical properties, the leaching of contaminants into the environment is the main concern. Several leaching tests can be used for research studies or regulatory purposes, where a wide variety of conditions may be tested. Our work deals mainly with the leaching behaviour of toxic heavy metals (Pb, Cd, Zn, Cr, Ni, Cu) and inorganics associated with soluble salts (Na, K, Ca, Cl). The main goal is to obtain an overview of the leachability of APC residues produced in a Portuguese MSWI process. Among the different variables that may have influence on the leaching behaviour, pH of the leachant solution is the most important one, and was evaluated through pH static tests. The acid neutralization capacity (ANC) of the residue was also determined, which is in the range of 6.2-6.8 meq g(-1) (for pH=7) and 10.1-11.6 meq g(-1) (for pH=4). The analysis of the leaching behaviour is particularly important when the leaching is solubility controlled. The amphoteric behaviour of some elements was observed, namely for Pb and Zn, which is characterized through high solubilization at low and high pH and moderate or low solubility at neutral or moderate high pH. The solubility curves for Pb, Cd, Zn, Cr, Ni and Cu as a function of pH were obtained, which are very useful for predicting the leaching behaviour in different scenarios. The solubility of K and Na reveals to be nearly independent of the solution pH and the released amount is mainly availability-controlled. Moreover, the pH static test showed that Cl(-) is the most pH-independent species. The APC residue turns out to be a hazardous waste because of the high leaching of lead and chloride. On the other hand, leaching of elements like cadmium, nickel and copper is limited by the high pH of the residue, and as long as the waste keeps its ANC, the risk of mobilization of these elements is low.

This work reviews strategies for the management of municipal solid waste incineration (MSWI) residues, particularly solid particles collected from flue gases. These tiny particles may be retained by different equipment, with or without additives (lime, activated carbon, etc.), and depending on the different possible combinations, their properties may vary. In industrial plants, the most commonly used equipment for heat recovery and the cleaning of gas emissions are: heat recovery devices (boiler, superheater and economiser); dry, semidry or wet scrubbers; electrostatic precipitators; bag filters; fabric filters, and cyclones. In accordance with the stringent regulations in force in developed countries, these residues are considered hazardous, and therefore must be treated before being disposed of in landfills. Nowadays, research is being conducted into specific applications for these residues in order to prevent landfill practices. There are basically two possible ways of handling these residues: landfill after adequate treatment or recycling as a secondary material. The different types of treatment may be grouped into three categories: separation processes, solidification/stabilization, and thermal methods. These residues generally have limited applications, mainly due to the fact that they tend to contain large quantities of soluble salts (NaCl, KCl, calcium compounds), significant amounts of toxic heavy metals (Pb, Zn, Cr, Cu, Ni, Cd) in forms that may easily leach out, and trace quantities of very toxic organic compounds (dioxin, furans). The most promising materials for recycling this residue are ceramics and glass-ceramic materials. The main purpose of the present paper is to review the published literature in this field. A range of studies have been summarized in a series of tables focusing upon management strategies used in various countries, waste composition, treatment processes and possible applications.

This study is mainly related with the physical and chemical characterization of a solid waste, produced in a municipal solid waste (MSW) incineration process, which is usually referred as air pollution control (APC) residue. The moisture content, loss on ignition (LOI), particle size distribution, density, porosity, specific surface area and morphology were the physical properties addressed here. At the chemical level, total elemental content (TC), total availability (TA) and the leaching behaviour with compliance tests were determined, as well as the acid neutralization capacity (ANC). The main mineralogical crystalline phases were identified, and the thermal behaviour of the APC residues is also shown. The experimental work involves several techniques such as laser diffraction spectrometry, mercury porosimetry, helium pycnometry, gas adsorption, flame atomic absorption spectrometry (FAAS), ion chromatography, scanning electron microscopy (SEM), X-ray fluorescence (XRF), X-ray diffraction (XRD) and simultaneous thermal analysis (STA). The results point out that the APC residues do not comply with regulations in force at the developed countries, and therefore the waste should be considered hazardous. Among the considered heavy metals, lead, zinc and chromium were identified as the most problematic ones, and their total elemental quantities are similar for several samples colleted in an industrial plant at different times. Moreover, the high amount of soluble salts (NaCl, KCl, calcium compounds) may constitute a major problem and should be taken into account for all management strategies. The solubility in water is very high (more than 24% for a solid/liquid ratio of 10) and thus the possible utilizations of this residue are very limited, creating difficulties also in the ordinary treatments, such as in solidification/stabilization with binders. http://www.sciencedirect.com/science/article/B6TGF-4P8B11J-2/1/9f18dd5ebf0d0c65eb7c1fee9684f7f5

The start-up and the wrong-way behavior of a fixed-bed reactor were analyzed through one-dimensional heterogeneous and pseudo-homogeneous models. The simulation work was based on the methanol oxidation to formaldehyde, which takes place in a fixed-bed reactor with two distinct zones. In the first part of the reactor, the catalyst was diluted with inert, and in the second zone the catalyst is pure. This activity profile leads to new features on the start-up and wrong-way behavior of the system when compared with a uniform catalytic bed. For a partially diluted bed, when the inlet temperature is increased (decreased), the final steady state can show a hot spot lower (higher) than the initial one. This behavior is not observed in a one-zone bed, where the final steady-state maximum temperature is always higher (lower) than the initial one if the inlet temperature is submitted to a positive (negative) change. During the dynamic period, the transient profiles are closer to the initial steady states in the case of the two-zone bed, pointing out that the catalyst dilution in the upstream section of the reactor can decrease the system sensitivity in both steady state and dynamic period. The differences between the predictions obtained through the pseudo-homogeneous and the heterogeneous models can be more significant on the transient responses than on the steady state situations and the wall temperature is the most important parameter on the reactor dynamic response. Moreover, significant wrong-way behavior can occur for step changes and ramp variations in feed and wall temperatures. http://www.sciencedirect.com/science/article/B6TFK-40GJ2MB-W/1/acd4fa98d666dbb790a7d1cbc4452a0b

The application of TiO2 as a slurry catalyst for the degradation of contaminants of emerging concern (CEC) in liquid effluents has some drawbacks due to the difficulties in the catalyst reutilization. Thus, sophisticated and expensive separation methods are required after the reaction step. Alternatively, several types of materials have been used to support powder catalysts, so that fixed or fluidized bed reactors may be used. In this context, the objective of this work is to systematize and analyze the results of research inherent to the application of ceramic materials as support of TiO2 in the photocatalytic CEC removal from liquid effluents. Firstly, an overview is given about the treatment processes able to degrade CEC. In particular, the photocatalysts supported in ceramic materials are analyzed, namely the immobilization techniques applied to support TiO2 in these materials. Finally, a critical review of the literature dedicated to photocatalysis with supported TiO2 is presented, where the performance of the catalyst is considered as well as the main drivers and barriers for implementing this process. A focal point in the future is to investigate the possibility of depurating effluents and promote water reuse in safe conditions, and the supported TiO2 in ceramic materials may play a role in this scope.