Emission characteristics and impact factors of air pollutants from municipal solid waste incineration in Shanghai, China.

The emission of air pollutants from the municipal solid waste (MSW) incineration is one of the major concerns in air pollution. The up-to-date emission situation for Chinese MSW incineration is largely unknown. The emission factors (EFs) are the key parameters to estimate the emissions from MSW incineration. The localized EFs from MSW incineration in Shanghai, China were established using continuous emission monitoring system data from 2017 to 2019. Our results showed that the EFs were 9.80 g t-1 of PM, 46.62 g t-1 of SO2, 812.68 g t-1 of NOx, 25.84 g t-1 of CO, and 17.49 g t-1 of HCl for the period 2017-2019, nearly 1.7-24.2 times lower than those in 2010, implying that the current EFs should be updated to avoid overestimation of MSW emissions in China. Compared with 2010, the emissions of PM, SO2, CO, and HCl in 2019 were significantly reduced by 84%, 69%, 47%, and 72%, respectively, except for NOx with a 106% increase, although the corresponding MSW incineration amount increased by 356%. The current levels of air pollutants from MSW incineration have already met the current national emission standard as well as the stricter standard of the European Union (98.87%-99.91%). Our findings suggest that China should update the current standards of MSW incineration, which can be a benefit for the prevention and control of MSW incineration in the future. It is still challenging to control NOx emissions from MSW incineration for Shanghai and even greater China.

Determining the amount of waste plastics in the feed of Austrian waste-to-energy facilities.

Although thermal recovery of waste plastics is widely practiced in many European countries, reliable information on the amount of waste plastics in the feed of waste-to-energy plants is rare. In most cases the amount of plastics present in commingled waste, such as municipal solid waste, commercial, or industrial waste, is estimated based on a few waste sorting campaigns, which are of limited significance with regard to the characterisation of plastic flows. In the present study, an alternative approach, the so-called Balance Method, is used to determine the total amount of plastics thermally recovered in Austria's waste incineration facilities in 2014. The results indicate that the plastics content in the waste feed may vary considerably among different plants but also over time. Monthly averages determined range between 8 and 26 wt% of waste plastics. The study reveals an average waste plastics content in the feed of Austria's waste-to-energy plants of 16.5 wt%, which is considerably above findings from sorting campaigns conducted in Austria. In total, about 385 kt of waste plastics were thermally recovered in all Austrian waste-to-energy plants in 2014, which equals to 45 kg plastics cap-1. In addition, the amount of plastics co-combusted in industrial plants yields a total thermal utilisation rate of 70 kg cap-1 a-1 for Austria. This is significantly above published rates, for example, in Germany reported rates for 2013 are in the range of only 40 kg of waste plastics combusted per capita.

A full-scale study on thermal degradation of polychlorinated dibenzo- p-dioxins and dibenzofurans in municipal solid waste incinerator fly ash and its secondary air pollution control in China.

Degradation of polychlorinated dibenzo- p-dioxins and dibenzofurans in municipal solid waste incinerator fly ash is beneficial to its risk control. Fly ash was treated in a full-scale thermal degradation system (capacity 1 t d-1) to remove polychlorinated dibenzo- p-dioxins and dibenzofurans. Apart from the confirmation of the polychlorinated dibenzo- p-dioxin and dibenzofuran decomposition efficiency, we focused on two major issues that are the major obstacles for commercialising this decomposition technology in China, desorption and regeneration of dioxins and control of secondary air pollution. The toxic equivalent quantity values of polychlorinated dibenzo- p-dioxins and dibenzofurans decreased to <6 ng kg-1 and the detoxification rate was ⩾97% after treatment for 1 h at 400 °C under oxygen-deficient conditions. About 8.49% of the polychlorinated dibenzo- p-dioxins and dibenzofurans in toxic equivalent quantity (TEQ) of the original fly ash were desorbed or regenerated. The extreme high polychlorinated dibenzo- p-dioxin and dibenzofuran levels and dibenzo- p-dioxin and dibenzofuran congener profiles in the dust of the flue gas showed that desorption was the main reason, rather than de novo synthesis of polychlorinated dibenzo- p-dioxins and dibenzofurans in the exhaust pipe. Degradation furnace flue gas was introduced to the municipal solid waste incinerator economiser, and then co-processed in the air pollution control system. The degradation furnace released relatively large amounts of cadmium, lead and polychlorinated dibenzo- p-dioxins and dibenzofurans compared with the municipal solid waste incinerator, but the amounts emitted to the atmosphere did not exceed the Chinese national emission limits. Thermal degradation can therefore be used as a polychlorinated dibenzo- p-dioxin and dibenzofuran abatement method for municipal solid waste incinerator source in China.

Heat supply from municipal solid waste incineration plants in Japan: Current situation and future challenges.

The use of waste-to-energy technology as part of a municipal solid waste management strategy could reduce the use of fossil fuels and contribute to prevention of global warming. In this study, we examined current heat and electricity production by incineration plants in Japan for external use. Herein, we discuss specific challenges to the promotion of heat utilisation and future municipal solid waste management strategies. We conducted a questionnaire survey to determine the actual conditions of heat production by incineration plants. From the survey results, information of about 498 incineration plants was extracted. When we investigated the relationship between heat production for external use and population density where incineration plants were located, we found that regions with a population density <1000 persons (km(2))(-1) produce <500 MJ t(-1) of heat. We also found that external use of such energy for factories, markets, and related use, was noted in cities with a population density of 2000 to 4000 persons (km(2))(-1). Several incineration plants have poor performance for heat production because there are few facilities near them to provide demand for the energy. This is the result of redundant capacity, and is reflected in the heat production performance. Given these results, we discussed future challenges to creating energy demand around incineration plants where there is presently none. We also examined the challenges involved in increasing heat supply beyond the present situation.

Influence of various chlorine additives on the partitioning of heavy metals during low-temperature two-stage fluidized bed incineration.

In this study, a pilot-scale low-temperature two-stage fluidized bed incinerator was evaluated for the control of heavy metal emissions using various chlorine (Cl) additives. Artificial waste containing heavy metals was selected to simulate municipal solid waste (MSW). Operating parameters considered included the first-stage combustion temperature, gas velocity, and different kinds of Cl additives. Results showed that the low-temperature two-stage fluidized bed reactor can be an effective system for the treatment of MSW because of its low NO(x), CO, HCl, and heavy metal emissions. The NO(x) and HCl emissions could be decreased by 42% and 70%, respectively. Further, the results showed that heavy metal emissions were reduced by bed material adsorption and filtration in the second stage. Regarding the Cl addition, although the Cl addition would reduce the metal capture in the first-stage sand bed, but those emitted metals could be effectively captured by the filtration of second stage. No matter choose what kind of additive, metal emissions in the low-temperature two-stage system are still lower than in a traditional high-temperature one-stage system. The results also showed that metal emissions depend not only on the combustion temperature but also on the physicochemical properties of the different metal species.

Emissions and risks associated with oxyfuel combustion: state of the science and critical data gaps.

UNLABELLED: Oxyfuel combustion is a promising technology that may greatly facilitate carbon capture and sequestration by increasing the relative CO2 content of the combustion emission stream. However, the potential effect of enhanced oxygen combustion conditions on emissions of criteria and hazardous air pollutants (e.g., acid gases, particulates, metals and organics) is not well studied. It is possible that combustion under oxyfuel conditions could produce emissions posing different risks than those currently being managed by the power industry (e.g., by changing the valence state of metals). The data available for addressing these concerns are quite limited and are typically derived from laboratory-scale or pilot-scale tests. A review of the available data does suggest that oxyfuel combustion may decrease the air emissions of some pollutants (e.g., SO2, NO(x), particulates) whereas data for other pollutants are too limited to draw any conclusions. The oxy-combustion systems that have been proposed to date do not have a conventional "stack" and combustion flue gas is treated in such a way that solid or liquid waste streams are the major outputs. Use of this technology will therefore shift emissions from air to solid or liquid waste streams, but the risk management implications of this potential change have yet to be assessed. Truly useful studies of the potential effects of oxyfuel combustion on power plant emissions will require construction of integrated systems containing a combustion system coupled to a CO2 processing unit. Sampling and analysis to assess potential emission effects should be an essential part of integrated system tests. IMPLICATIONS: Oxyfuel combustion may facilitate carbon capture and sequestration by increasing the relative CO2 content of the combustion emission stream. However, the potential effect of enhanced oxygen combustion conditions on emissions of criteria and hazardous air pollutants has not been well studied. Combustion under oxyfuel conditions could produce emissions posing different risks than those currently being managed by the power industry. Therefore, before moving further with oxyfuel combustion as a new technology, it is appropriate to summarize the current understanding of potential emissions risk and to identify data gaps as priorities for future research.

Clay improvement with burned olive waste ash.

Olive oil is concentrated in the Mediterranean basin countries. Since the olive oil industries are incriminated for a high quantity of pollution, it has become imperative to solve this problem by developing optimized systems for the treatment of olive oil wastes. This study proposes a solution to the problem. Burned olive waste ash is evaluated for using it as clay stabilizer. In a laboratory, bentonite clay is used to improve olive waste ash. Before the laboratory, the olive waste is burned at 550°C in the high temperature oven. The burned olive waste ash was added to bentonite clay with increasing 1% by weight from 1% to 10%. The study consisted of the following tests on samples treated with burned olive waste ash: Atterberg Limits, Standard Proctor Density, and Unconfined Compressive Strength Tests. The test results show promise for this material to be used as stabilizer and to solve many of the problems associated with its accumulation.

Air pollutant emissions and reduction potentials from municipal solid waste incineration in China.

China fully implemented the new emission standards in 2016 to further reduce the emissions of air pollutants from the municipal solid waste (MSW) incineration industry; however, the implementation effect of the new standards remains unknown. This study developed the first nationwide air pollutant emission inventory of MSW incineration plants in China based on the measured concentration data from China's continuous emissions monitoring systems (CEMS) network, and activity level data from the China Urban Construction Statistical Yearbook, to evaluate the effectiveness of implementing the new emission standards and estimate the future reduction potentials. Our results demonstrated that the overall standard-reaching proportions of particulate matter (PM), sulfur dioxide (SO2), nitrogen oxide (NOX), hydrogen chloride (HCl) and carbon monoxide (CO) were 98.8%, 99.3%, 99.4%, 99.4% and 97.6%, respectively, by comparing with the corresponding concentration limits of new emission standards. The total emissions of PM, SO2, NOX, HCl and CO from 412 MSW incineration plants in 2019 were 1.9, 6.2, 50.8, 4.3 and 6.6 kt yr-1, respectively, which is 33.6-75.8% lower than those in 2015, mainly due to the sharp decrease in emission factors. Pollutant emission hotspots were mainly concentrated in eastern and central and southern regions with large populations and well-developed economies. The analysis of future scenario results shows that despite the continuous increase of MSW incineration amount in the future, if the government strengthens pollutant emission standards and comprehensively implements waste sorting, total emissions and emission factors of air pollutants could be further reduced by 25.8-72.7% and 59.8-81.2%, respectively, by 2050. These findings provide helpful insights into future policymaking and technology selection for China and other countries seeking to reduce pollutant emissions from the MSW incineration industry.

Troubleshooting dioxins stack emissions in an industrial waste gas incinerator.

An important source of dioxins and furans at present is waste incineration, utmost formed during combustion processes and emitted to the environment without being fully captured by waste-gas treatment equipment. In this study, monitoring campaign of International Toxic Equivalents for dioxins and furans (I-TEQDF), was carried out at pharmaceutical industrial waste incinerator to find a correlation between combustion parameters and feed composition with potential emission. Principal Component Analysis (PCA) shows that high values of dioxin emission correlate with short residence time of the flue gas in the furnace as well as low oxygen concentration. These operating conditions were further investigated, using COMSOL Computational Fluid Dynamics (CFD) simulation to calculate the temperature profiles along the furnace. The results suggest that the flame temperature profile is anticipated to exhibit cold areas (cold spots), which may be used as a proxy for dioxin formation due to incomplete combustion. Additionally, the calculated congeners furan to dioxin concentration ratio, points to their formation via de novo mechanism. SEM-EDS analysis preformed on the bag filter upstream the feed following its filtration, have shown large amount of iron, which may have served as a metal catalytic source for dioxin formation. The iron origin is most likely from corrosion of the feeding pipe, drifted with the waste gas and trapped on the bag filter. The results of this study provide a better understanding of the parameters controlling dioxin formation and emission from the plant and may assist a planning of process optimization in such a plant.

Assessment of medical waste generation, associated environmental impact, and management issues after the outbreak of COVID-19: A case study of the Hubei Province in China.

COVID-19 greatly challenges the human health sector, and has resulted in a large amount of medical waste that poses various potential threats to the environment. In this study, we compiled relevant data released by official agencies and the media, and conducted data supplementation based on earlier studies to calculate the net value of medical waste produced in the Hubei Province due to COVID-19 with the help of a neural network model. Next, we reviewed the data related to the environmental impact of medical waste per unit and designed four scenarios to estimate the environmental impact of new medical waste generated during the pandemic. The results showed that a medical waste generation rate of 0.5 kg/bed/day due to COVID-19 resulted in a net increase of medical waste volume by about 3366.99 tons in the Hubei Province. In the four scenario assumptions, i.e., if the medical waste resulting from COVID-19 is completely incinerated, it will have a large impact on the air quality. If it is disposed by distillation sterilization, it will produce a large amount of wastewater and waste residue. Based on the results of the study, we propose three policy recommendations: strict control of medical wastewater discharge, reduction and transformation of the emitted acidic gases, and attention to the emission of metallic nickel in exhaust gas and chloride in soil. These policy recommendations provide a scientific basis for controlling medical waste pollution.

Greenhouse gas emissions from waste management--assessment of quantification methods.

Of the many sources of urban greenhouse gas (GHG) emissions, solid waste is the only one for which management decisions are undertaken primarily by municipal governments themselves and is hence often the largest component of cities' corporate inventories. It is essential that decision-makers select an appropriate quantification methodology and have an appreciation of methodological strengths and shortcomings. This work compares four different waste emissions quantification methods, including Intergovernmental Panel on Climate Change (IPCC) 1996 guidelines, IPCC 2006 guidelines, U.S. Environmental Protection Agency (EPA) Waste Reduction Model (WARM), and the Federation of Canadian Municipalities-Partners for Climate Protection (FCM-PCP) quantification tool. Waste disposal data for the greater Toronto area (GTA) in 2005 are used for all methodologies; treatment options (including landfill, incineration, compost, and anaerobic digestion) are examined where available in methodologies. Landfill was shown to be the greatest source of GHG emissions, contributing more than three-quarters of total emissions associated with waste management. Results from the different landfill gas (LFG) quantification approaches ranged from an emissions source of 557 kt carbon dioxide equivalents (CO2e) (FCM-PCP) to a carbon sink of -53 kt CO2e (EPA WARM). Similar values were obtained between IPCC approaches. The IPCC 2006 method was found to be more appropriate for inventorying applications because it uses a waste-in-place (WIP) approach, rather than a methane commitment (MC) approach, despite perceived onerous data requirements for WIP. MC approaches were found to be useful from a planning standpoint; however, uncertainty associated with their projections of future parameter values limits their applicability for GHG inventorying. MC and WIP methods provided similar results in this case study; however, this is case specific because of similarity in assumptions of present and future landfill parameters and quantities of annual waste deposited in recent years being relatively consistent.

The reduction of dioxin emissions from the processes of heat and power generation.

The first reports that it is possible to emit dioxins from the heat and power generation sector are from the beginning of the 1980s. Detailed research proved that the emission of dioxins might occur during combustion of hard coal, brown coal, and furnace oil as well as coke-oven gas. The emission of dioxins occurs in wood incineration; wood that is clean and understood as biomass; or, in particular, wood waste (polluted). This paper thoroughly discusses the mechanism of dioxin formation in thermal processes, first and foremost in combustion processes. The parameters influencing the quantity of dioxins formed and the dependence of their quantity on the conditions of combustion are highlighted. Furthermore, the methods of reducing dioxin emissions from combustion processes (primary and secondary) are discussed. The most efficacious methods that may find application in the heat and power generation sector are proposed; this is relevant from the point of view of the implementation of the Stockholm Convention resolutions in Poland with regard to persistent organic pollutants.

Industrial hazardous waste treatment featuring a rotary kiln and grate furnace incinerator: a case study in China.

As one of the fastest developing countries, China is facing severe problems concerning hazardous waste treatment and disposal. This paper presents a new incineration technology and demonstration project in eastern China. The incineration system includes a rotary kiln, a grate furnace for burning out the kiln residue and a flue gas post-combustion chamber. Flue gas treatment and emission control is based on: a quench tower, followed by dry hydrated lime and activated carbon injection, a dual bag filter system, and a wet scrubber. It demonstrated that this incineration technology can effectively dispose of industrial hazardous waste with variable and complex characteristics. Gas emissions meet the demands of the Chinese Environmental Protection Association standard.

Comparison of leaching characteristics of heavy metals in APC residue from an MSW incinerator using various extraction methods.

This study investigates four extraction methods (water extraction, toxicity characteristics leaching procedure (TCLP), modified TCLP with pH control, and sequential chemical extraction (SCE)), each representing different liquid-to-solid (L/S) ratios, pH controls, and types of leachant, and their effects on the leaching concentration of heavy metals in municipal solid waste (MSW) incinerator air pollution control (APC) residue. The results indicated that for extraction with distilled water, the heavy metal leaching concentration (mg/l) decreased with L/S ratio, but the amount of heavy metal released (AHMR), defined as the leached amount of heavy metals to the weight of the tested sample (mg/kg), increased with an increase in L/S ratio, in the range of 2-100. The results also showed that both the leaching concentration and the amount of released metals were strongly pH-dependent in the TCLP and modified TCLP tests. In the case of pHs lower than 6.5, the leaching concentrations of Cd, Pb, Cu, Zn, and Cr decreased with an increase in pH. As pH increased higher than 6.5, Cr and Zn were almost insoluble. Meanwhile, Cd and Cu also showed a similar trend but at pHs of 8.5 and 7.5, respectively. Due to the nature of amphoteric elements, in the case of pHs higher than 7, the Pb leaching concentration increased with increasing pH. In modified TCLP tests with the pH value controlled at the same level as in the SCE test, the heavy metal speciation approached the extractable carbonate bound fraction by the SCE. Both amounts of targeted metals leached from the SCE and modified TCLP tests were much higher than those for the regular TCLP and water extraction tests.

Climate impact analysis of waste treatment scenarios--thermal treatment of commercial and pretreated waste versus landfilling in Austria.

A major challenge for modern waste management lies in a smart integration of waste-to-energy installations in local energy systems in such a way that the energy efficiency of the waste-to-energy plant is optimized and that the energy contained in the waste is, therefore, optimally utilized. The extent of integration of thermal waste treatment processes into regular energy supply systems plays a major role with regard to climate control. In this research, the specific waste management situation looked at scenarios aiming at maximizing the energy recovery from waste (i.e. actual scenario and waste-to-energy process with 75% energy efficiency [22.5% electricity, 52.5% heat]) yield greenhouse gas emission savings due to the fact that more greenhouse gas emissions are avoided in the energy sector than caused by the various waste treatment processes. Comparing dedicated waste-to-energy-systems based on the combined heat and power (CHP) process with concepts based on sole electricity production, the energy efficiency proves to be crucial with regard to climate control. This underlines the importance of choosing appropriate sites for waste-to-energy-plants. This research was looking at the effect with regard to the climate impact of various waste management scenarios that could be applied alternatively by a private waste management company in Austria. The research is, therefore, based on a specific set of data for the waste streams looked at (waste characteristics, logistics needed, etc.). Furthermore, the investigated scenarios have been defined based on the actual available alternatives with regard to the usage of treatment plants for this specific company. The standard scenarios for identifying climate impact implications due to energy recovery from waste are based on the respective marginal energy data for the power and heat generation facilities/industrial processes in Austria.

Emission of Pb and PAHs from thermally co-treated MSWI fly ash and bottom ash process.

Municipal solid waste incinerator (MSWI) fly ash was regarded as a hazardous material because concentrations of TCLP leaching solution exceeded regulations. Previous studies have investigated the characteristics of thermally treated slag. However, the emissions of pollutant during the thermal treatment of MSWI fly ash have seldom been addressed. The main objective of this study was to evaluate the emission of Pb and PAHs from thermally co-treated MSWI fly and bottom ash process. The experimental parameters included the form of pretreatment, the proportion of bottom ash (bottom ash/fly ash, B/F=0, 0.1 and 1) and the retention time. The toxicity of thermally treated slag was also analyzed. The results indicated that (1) Pb emission occurred only in the solid phase and that PAHs were emitted from both solid and gas phases during thermal treatment process. (2) Washing pretreatment reduced not only the TCLP leaching concentration of Pb (from 15.75 to 1.67 mg/L), but also the emission of PAHs from the solid phase during thermal treatment process. (3) Adding bottom ash reduced the TCLP leaching concentration of thermally treated slag. (4) The concentration of Pb emission increased with retention time. (5) The thermal treatment reduced the toxicity of raw fly ash effectively, the inhibition ratio of raw fly ash and thermal treated slag were 98.71 and 18.35%, respectively.

Sorbents for CO2 capture from high carbon fly ashes.

Fly ashes with high-unburned-carbon content, referred to as fly ash carbons, are an increasing problem for the utility industry, since they cannot be marketed as a cement extender and, therefore, have to be disposed. Previous work has explored the potential development of amine-enriched fly ash carbons for CO2 capture. However, their performance was lower than that of commercially available sorbents, probably because the samples investigated were not activated prior to impregnation and, therefore, had a very low surface area. Accordingly, the work described here focuses on the development of activated fly ash derived sorbents for CO2 capture. The samples were steam activated at 850 degrees C, resulting in a significant increase of the surface area (1075 m2/g). The activated samples were impregnated with different amine compounds, and the resultant samples were tested for CO2 capture at different temperatures. The CO2 adsorption of the parent and activated samples is typical of a physical adsorption process. The impregnation process results in a decrease of the surface areas, indicating a blocking of the porosity. The highest adsorption capacity at 30 and 70 degrees C for the amine impregnated activated carbons was probably due to a combination of physical adsorption inherent from the parent sample and chemical adsorption of the loaded amine groups. The CO2 adsorption capacities for the activated amine impregnated samples are higher than those previously published for fly ash carbons without activation (68.6 vs. 45 mg CO2/g sorbent).

Experimental study on flue gas purifying of MSW incineration using in-pipe jet adsorption techniques.

This paper presents the experimental research process and results about flue gas purifying of municipal solid wastes (MSW) incineration using in-pipe jet adsorption techniques. MSW incineration was carried out in a fluidized bed test rig, and the flue gas purifying was carried out in an in-pipe jet adsorption test rig. The experimental results are as follows: when the feedstock of activated carbon is 1.6g/Nm(3), the desulfurization efficiency is 83%, the denitrification efficiency is 41%, and the dechlorination efficiency is 27%. The order of purifying effect of the three kinds of adsorbents on acidic gases from MSW incineration is activated carbon>activated bauxite>kaolin. Comparison of adsorption capabilities of the three kinds of adsorbents to heavy metals shows that activated carbon is the best additive to remove Cd, Pb and Cu, kaolin is inferior, and activated bauxite is the worst one. However, activated bauxite is the best additive to remove Hg, and it can remove Cd effectively. PAHs in fly ash are dominated by three-, four-, and five-ringed PAHs, and PAHs in the flue gas mainly include three- and four-ringed PAHs. When the injected quantity of additive is constant, the order of cleaning effect on PAHs is kaolin>activated carbon>activated bauxite. These three kinds of adsorbents have different purifying effects on acidic gases, heavy metals and PAHs in the flue gas from MSW incineration. In general, activated carbon has a better adsorption capability.

Treatment and use of air pollution control residues from MSW incineration: an overview.

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.

Optimization of sprayed lime amount in the semi-dry scrubbing system of MSWI.

This paper reports the characterization of residues collected from air pollution controlling devices (APCDs) at seven large-scale municipal solid wastes (MSW) incineration plants. The amount of lime being sprayed in plants is a function of free CaO content in scrubber residues; a higher free CaO content in scrubber residue causes more leaching of lead. The proper amount of lime in the semi-dry scrubbing system was found to be 5 kg/ton of MSW waste. Under these conditions, both the free CaO content and lead leaching became extremely low in scrubber residue.