Model Prediction and Optimal Control of Gas Oxygen Content for A Municipal Solid Waste Incineration Process

In the municipal solid waste incineration process,it is difficult to effectively control the gas oxygen content by setting the air flow according to artificial experience.To address this problem,this paper proposes an optimization control method of gas oxygen content based on model predictive control.First,a stochastic configuration network is utilized to establish a prediction model of gas oxygen content.Second,an improved differential evolution algorithm that is based on parameter adaptive and t-distribution strategy is employed to address the set value of air flow.Finally,model predictive control is combined with the event triggering strategy to reduce the amount of computation and the controller's frequent actions.The experimental results show that the optimization control method proposed in this paper obtains a smaller degree of fluctuation in the air flow set value,which can ensure the tracking control performance of the gas oxygen content while reducing the amount of calculation.

Prediction of NO_(x)concentration using modular long short-term memory neural network for municipal solid waste incineration

Air pollution control poses a major problem in the implementation of municipal solid waste incineration(MSWI).Accurate prediction of nitrogen oxides(NO_(x))concentration plays an important role in efficient NO_(x)emission controlling.In this study,a modular long short-term memory(M-LSTM)network is developed to design an efficient prediction model for NO_(x)concentration.First,the fuzzy C means(FCM)algorithm is utilized to divide the task into several sub-tasks,aiming to realize the divide-and-conquer ability for complex task.Second,long short-term memory(LSTM)neural networks are applied to tackle corresponding sub-tasks,which can improve the prediction accuracy of the sub-networks.Third,a cooperative decision strategy is designed to guarantee the generalization performance during the testing or application stage.Finally,after being evaluated by a benchmark simulation,the proposed method is applied to a real MSWI process.And the experimental results demonstrate the considerable prediction ability of the M-LSTM network.

Mechanical and environmental properties of geopolymer-stabilized domestic waste incineration slag in an asphalt pavement base

Domestic waste incineration slag(WIS)includes fly ash and slag.Fly ash is classified as hazardous waste because it contains heavy metals.Most of slag are directly stacked or landfilled due to problems such as large output and low utilization rate.Harmless treatment is imminent.If WIS is used effectively in the road engineering,which can realize the high-quality and high-efficiency recycling of WIS,and it is of great significance to save resources and protect the environment.This study applies a geopolymer prepared from WIS fly ash as a stabilizing agent in WIS blending macadam for use as a pavement base mixture,and reports the mechanical properties(unconfined compressive strength,splitting strength,and resilience modulus)of the geopolymer-stabilized WIS blending macadam(GeoWIS).The leaching concentrations of harmful heavy metals of GeoWIS soaked in water were also investigated.Finally,the strength formation and heavy metal stability mechanisms were explored.The unconfined compressive strength,splitting strength,and compressive resilient modulus of GeoWIS all increased with increasing geopolymer content and decreasing WIS content.The strength of GeoWIS was derived from its geopolymerization and hydration products(C-S-H gel,N-A-S-H gel,and AFt).When the geopolymer content reached 12%–14%,the GeoWIS without natural macadam met the strength criterion of the asphalt pavement base.Through physical adsorption and chemical bonding,the geopolymer significantly reduced the leaching of harmful heavy metals.In GeoWIS with 50%WIS and stabilized with 10%geopolymer,the Cr,Ni,Cd,and Pb concentrations met the grade III groundwater standard.Concentrations of heavy metals leached from GeoWIS are low and exert little impact on environment.

Analysis of the Relationship between Mechanical Properties and Pore Structure of MSW Incineration Bottom Ash Fine Aggregate Concrete after Freeze-Thaw Cycles Based on the Gray Theory

The destruction of concrete building materials in severely cold regions of the north is more severely affected by freeze-thaw cycles,and the relationship between the mechanical properties and pore structure of concrete with fine aggregate from municipal solid waste(MSW)incineration bottom ash after freeze-thaw cycles is analyzed under the degree of freeze-thaw hazard variation.In this paper,the gray correlation method is used to calculate the correlation between the relative dynamic elastic modulus,compressive strength,and microscopic porosity parameters to speculate on the most important factors affecting their changes.The GM(1,1)model was established based on the compressive strength of the waste incineration ash aggregate concrete,the relative error between the simulated and actual values in the model was less than 5%,and the accuracy of the model was level 1,indicating that the GM(1,1)model can well reflect the change in the compressive strength of the MSW incineration bottom ash aggregate concrete during freeze-thaw cycles.Using the gray correlation method,the correlation between the relative dynamic elastic modulus,compressive strength,air content,specific surface area,pore spacing coefficient,and pore average chord length was calculated,and the pore spacing coefficient and pore average chord length were determined to be highly correlated with each other.This determination can help analyze and infer the deterioration mechanism of concrete subject to freeze-thaw cycles.These results can provide a theoretical basis for guiding the engineering practice of concrete with fine aggregates of household bottom ash in the northern cold region.

Application of Multivariate Reinforcement Learning Engine in Optimizing the Power Generation Process of Domestic Waste Incineration

Garbage incineration is an ideal method for the harmless and resource-oriented treatment of urban domestic waste.However,current domestic waste incineration power plants often face challenges related to maintaining consistent steam production and high operational costs.This article capitalizes on the technical advantages of big data artificial intelligence,optimizing the power generation process of domestic waste incineration as the entry point,and adopts four main engine modules of Alibaba Cloud reinforcement learning algorithm engine,operating parameter prediction engine,anomaly recognition engine,and video visual recognition algorithm engine.The reinforcement learning algorithm extracts the operational parameters of each incinerator to obtain a control benchmark.Through the operating parameter prediction algorithm,prediction models for drum pressure,primary steam flow,NOx,SO2,and HCl are constructed to achieve short-term prediction of operational parameters,ultimately improving control performance.The anomaly recognition algorithm develops a thickness identification model for the material layer in the drying section,allowing for rapid and effective assessment of feed material thickness to ensure uniformity control.Meanwhile,the visual recognition algorithm identifies flame images and assesses the combustion status and location of the combustion fire line within the furnace.This real-time understanding of furnace flame combustion conditions guides adjustments to the grate and air volume.Integrating AI technology into the waste incineration sector empowers the environmental protection industry with the potential to leverage big data.This development holds practical significance in optimizing the harmless and resource-oriented treatment of urban domestic waste,reducing operational costs,and increasing efficiency.

Leaching behavior of heavy metals with hydrochloric acid fromfly ash generated in municipal waste incineration plants

The extraction behavior of heavy metals from municipal waste incineration （MWI） fly ash was investigated systematically. The extraction process includes two steps, namely, fly ash was firstly washed with water, and then subjected to hydrochloric acid leaching. The main parameters for water washing process were tested, and under the optimal conditions, about 86% Na, 70% K and 12% Ca were removed from fly ash, respectively. Hydrochloric acid was used for the extraction of valuable elements from the water-washed fly ash, and the optimal extraction was achieved for each heavy metal as follows： 86% for Pb, 98% for Zn, 82% for Fe, 96% for Cd, 62% for Cu, 80% for Al, respectively. And the main compositions of the finally obtained solid residue are Ca2PbO4, CaSi2Os, PbsSiO7, Ca3A12Si3012 and SiO2.

Engineering and Physical Bases of Development and Creation of Plasmochemical Reactors for Mobile Facilities for Medical Waste Disposal

This paper presents the results of the development and creation of plasma-chemical reactors for mobile and stationary installations for the destruction and disposal of solid, liquid, gaseous and mixed medical waste based on the domestic plasma generator PUN-1, with air as the plasma-forming gas. The design and principle of operation of plasma-chemical reactors installed on mobile experimental and industrial plants “Plazmon-1,2,3”, as well as the main features of the plasma waste disposal process are described.

Levels of Polycyclic Aromatic Hydrocarbons (PAHs) in Healthcare Waste Incinerators’ Bottom Ash from Five County Hospitals in Kenya

Health-care waste contains potentially harmful microorganisms and compounds which can infect and affect hospital patients, healthcare workers, the general public and environment. Therefore, management of health care waste requires safe handling, treatment and disposal procedures. While incineration reduces the volume and quantity of waste for final disposal, it leads to the production of fly and bottom ashes laden with toxic incomplete combustion products such as Polycyclic Aromatic Hydrocarbons (PAHs), dioxins, furans and heavy metals. This exposes workers who handle and dispose the bottom ashes, hospital patients, the general public and environment. The goal of this study was to determine the total and individual levels of 16 most prevalent and toxic PAHs. Bottom ash samples were collected from incinerators in five county hospitals in Kenya, namely;Moi-Voi, Narok, Kitale, Makindu and Isiolo. Bottom ash samples were collected over a period of six months from the five hospitals. The samples were then sieved, homogenised and stored at 4°C in amber coloured glass containers. The PAHs were extracted using 30 ml of a hexane-acetone solvent (1:1) mixture by ultrasonication at room temperature (23°C) for 45 minutes. The PAHs were then analyzed with a GC-MS spectrophotometer model (Shimadzu GCMS-QP2010 SE) connected to a computer work station was used for the PAHs analysis. The GC-MS was equipped with an SGE BPX5 GC capillary column (30 m × 0.25 mm × 0.25 μm) for the separation of compounds. Helium was used as the carrier gas at a flow rate of 15.5 ml/minute and 14.5 psi. 1 μl of the sample was injected at 280°C, split mode (10:1). The oven programming was set for a total runtime of 40 minutes, which included: 100°C (2-minute hold);10°C /min rise to 200°C;7°C /min rise to 249°C;3°C /min rise to 300°C (2-minute hold). The interface temperature was set at 290°C. Analysis was done in Selected Ion Monitoring (SIM) mode and the peak areas of each of the PAHs were collected from the chromatograph and used for quantification of the 16 PAHs listed by the U.S. Environmental Protection Agency (EPA) which included, BaA (benz[a]anthracene: 4 rings), BaP (benzo[a]pyrene: 5 rings), BbF (benzo [b]fluoranthene: 5 rings), BkF (benzo[k]fluoranthene: 5 rings), Chr (chrysene: 4 rings), DbA (dibenz[a,h]anthracene: 5 rings), InP (indeno[1,2,3 - cd] pyrene: 6 rings) and Acp (acenaphthene: 3 rings), Acpy (acenaphthylene: 3 rings), Ant (anthracene: 3 rings), BghiP (benzo[g,h,i]perylene: 6 rings), Flu (fluorene: 3 rings), FluA (fluoranthene: 4 rings), Nap (naphthalene: 2 rings), PhA (phenanthrene: 3 rings) and Pyr (pyrene: 4 rings). Ion source-interface temperature was set at 200°C - 250°C. Internal standards from Sigma Aldrich were used in the analysis and the acquired mass spectra data were then matched against the NIST 2014 library [1] [2]. The mean PAHs concentration in the bottom ashes of each hospital varied broadly from 0.001 mg/kg to 0.4845 mg/kg, and the mean total concentration levels of individual PAHs ranged from 0.0072 mg/kg to 1.171 mg/kg. Low molecular weight PAHs (Phenanthrene, Naphthalene and Fluorene) were predominant in all the hospital wastes whereas Kitale and Narok presented the lowest PAHs concentrations and the lowest number of individual PAHs. Moi/Voi recorded the highest total PAHs concentration at 1.3129 ± 0.0023 mg/kg from a total of 11 PAHs being detected from the bottom ash samples. Narok had only three PAHs being detected at very low concentrations of 0.0041 ± 0.00 mg/kg, 0.0076 ± 0.00 mg/kg and 0.012 ± 0.00 mg/kg for phenanthrene, anthracene and chrysene respectively. This study presents hospital incinerator bottom ash as containing detectable levels of both carcinogenic and non-carcinogenic PAHs. Continued unprotected exposure of hospital workers (waste handlers) to the bottom ash PAHs could be hazardous to their health because of their cumulative effect. Preventive measures e.g. the use of Personal protective equipment (PPE) should be prioritised to minimise direct contact with the bottom ash. The study recommends an upgrade on incinerator technology for efficient combustion processes thus for better pollution control.

Concentration of Copper, Zinc, Lead, Cadmium, and Nickel in the Incinerator Bottom Ash in Five County Hospitals in Kenya

Healthcare wastes contain potentially harmful microorganisms, inorganic and organic compounds that pose a risk to human health and the environment. Incineration is a common method employed in healthcare waste management to reduce volume, quantity, toxicity as well as elimination of microorganisms. However, some of the substances remain unchanged during incineration and become part of bottom ash, such as heavy metals and persistent organic pollutants. Monitoring of pollution by heavy metals is important since their concentrations in the environment affect public health. The goal of this study was to determine the levels of Copper (Cu), Zinc (Zn) Lead (Pb), Cadmium (Cd) and Nickel (Ni) in the incinerator bottom ash in five selected County hospitals in Kenya. Bottom ash samples were collected over a period of six months. Sample preparation and treatment were done using standard methods. Analysis of the heavy metals were done using atomic absorption spectrophotometer, model AA-6200. One-Way Analysis of Variance (ANOVA) was performed to determine whether there were significant differences on the mean levels of Cu, Zn, Pd, Cd and Ni in incinerator bottom ash from the five sampling locations. A post-hoc Tukey’s Test (HSD) was used to determine if there were significant differences between and within samples. The significant differences were accepted at p ≤ 0.05. To standardize the results, overall mean of each metal from each site was calculated. The metal mean concentration values were compared with existing permissible levels set by the WHO. The concentrations (mg/kg) were in the range of 102.27 - 192.53 for Cu, Zn (131.68 - 2840.85), Pb (41.06 - 303.96), Cd (1.92 - 20.49) whereas Ni was (13.83 - 38.27) with a mean of 150.76 ± 77.88 for Copper, 131.66 ± 1598.95 for Zinc, 234.60 ± 262.76 for Lead, 12.256 ± 10.86 for Cadmium and 29.45 ± 18.24 for Nickel across the five sampling locations. There were significant differences between levels determined by one-way ANOVA of Zn (F (4, 25) = 6.893, p = 0.001, p ≤ 0.05) and Cd (F (4, 25) = 5.641, p = 0.02) and none with Cu (F (4, 25) = 1.405, p = 0.261, p ≤ 0.05), Pb (F (4, 25) = 1.073, p = 0.391, p ≤ 0.05) and Ni (F (4, 25) = 2.492, p = 0.069). Results reveal that metal content in all samples exceed the WHO permissible levels for Cu (100 mg/kg), while those for Ni were below the WHO set standards of 50 mg/kg. Levels of Zn in three hospitals exceeded permissible level of 300 mg/kg while level of Pb exceeded WHO set standards of 100 mg/kg in two hospitals. Samples from four hospitals exceeded permissible level for Cd of 3 mg/kg. This study provides evidence that incinerator bottom ash is contaminated with toxic heavy metals to human health and the environment. This study recommends that hospitals should handle the bottom ash as hazardous wastes and there is need to train and provide appropriate personal protective equipment to healthcare workers, waste handlers, and incinerator operators and enforce compliance to existing regulation and guidelines on healthcare waste management to safeguard the environment and human health.

Investigation of heavy metal partitioning influenced by flue gas moisture and chlorine content during waste incineration

The impact of moisture on the partitioning of the heavy metals including Pb,Zn,Cu and Cd in municipal solid waste （MSW） was studied in a laboratory tubular furnace.A thermodynamic investigation using CHEMKIN software was performed to compare the experimental results.Simulated waste,representative of typical MSW with and without chlorine compounds,was burned at the background temperature of 700 and 950°C,respectively.In the absence of chlorine,the moisture content has no evident effect on the volatility of Pb,Zn and Cu at either 700 or 950°C,however,as flue gas moisture increasing the Cd distribution in the bottom ash increased at 700°C and reduced at 950°C,respectively.In the presence of chlorine,the flue gas moisture reduced the volatility of Pb,Zn and Cu due to the transformation of the more volatile metal chlorides into less volatile metal oxides,and the reduction became significant as chlorine content increase.For Cd,the chlorine promotes its volatility through the formation of more volatile CdCl 2.As a result,the increased moisture content increases the Pb,Zn,Cu and Cd concentrations in the bottom ash,which limits the utilization of the bottom ash as a construction material.Therefore,in order to accumulate heavy metals into the fly ash,MSW should be dried before incineration.

Effect of quarry dust addition on the performance of controlled low-strength material made from industrial waste incineration bottom ash

The performance of industrial waste incineration bottom ash in controlled low-strength material （CLSM） was investigated in this paper, as the quarry dust was added. CLSM mixtures were made from the industrial waste incineration bottom ash, quarry dust, and cement. Tests for fresh density, bleeding, compressive strength, shear strength, hydraulic conductivity, and excavatability were carried out. The com- pressive strength ranges from 60 kPa to 6790 kPa, the friction angle varies from 5°to 19°, and the cohesion is from 4 to 604 kPa. Most of the mixtures are found to be non-excavatable. It is indicated that the quarry dust addition increases the compressive strength and shear parame- ters, decreases bleeding, and increases the removability modulus.

Effect of Moisture on Partitioning of Heavy Metals in Incineration of Municipal Solid Waste

The effect of moisture in municipal solid waste (MSW) on partitioning of lead (Pb), zinc (Zn), copper (Cu) and cadmium (Cd) was studied in a laboratory tubular furnace by using simulated MSW. The moisture in MSW influences heavy metals in following ways, to increase the moisture in flue gas and decrease the combustion temperature, to prolong the combustion time, and to prolong the releasing time of volatiles with the furnace temperature decreased by increasing the moisture. The volatilization of Pb, Zn and Cd was enhanced by increasing the moisture in MSW because of the prolonged combustion time. For Pb and Zn, the combustion time was important at higher temperature, while for Cd, it was important at low temperature. The moisture content showed slight effect on Cu partitioning. When extra chlorine was added to MSW, such as 1%PVC + 0.5%NaCl, the volatilization of Pb, Zn and Cu was enhanced by increasing the moisture because water evaporation reduced the temperature and increased devolatilization time. At higher temperature, NaCl tends to decompose and generates more free chlorine, producing more metal chlorides. Since Cd is a strong volatile heavy metal in MSW, the effect of moisture content on its volatilization is less than that of Pb, Zn or Cu during the MSW incineration.

Volatilization of heavy metals during incineration of municipal solid wastes

Incineration experiments with MSW, which had been impregnated with heavy metals, were presented to obtain information on the volatilization behavior of the elements cadmium(Cd), lead(Pb), and zinc(Zn) under different conditions. Experiments were carried out in a bubbling fluid bed system connected to a customized inductively coupled plasma optical emission spectroscopy(ICP-OES) for analyzing metals in the flue gas. The results indicated that the combustion temperature, the gas atmosphere, and the chlorine content in the flue gas could affect the volatilization behavior of heavy metals. In the fluidized bed combustion, a large surface area was provided by the bed sand particles, and they may act as absorbents for the gaseous ash-forming compound. Comparer with the metals Cd and Pb, the vaporization of Zn was low. The formation of stable compounds such as ZnO·Al 2O 3 could greatly decrease the metals volatilization. The presence of chlorine would enhance the volatilization of heavy metals by increasing the formation of metal chlorides. However, when the oxygen content was high, the chlorinating reaction was kinetically hindered, which heavy metals release would be delayed.

Microstructures and thermal properties of municipal solid waste incineration fly ash

To analyze the feasibility of utilization of thermal technology in fly ash treatment, thermal properties and microstructures of municipal solid waste incineration （MSW1） fly ash were studied by measuring the chemical element composition, specific surface area, pore sizes, functional groups, TEM image, mineralogy and DSC-TG curves of raw and sintered fly ash specimens. The results show that MSWI fly ash particles mostly have irregular shapes and non-typical pore structure, and the supersonic treatment improves the pore structure; MSWI fly ash consists of Such crystals as SiO2, CaSO4 and silica-aluminates, and some soluble salts like KCl and NaCl. During the sintering process, mineralogy changes largely and novel solid solutions are produced gradually with the rise of temperature. Therefore, the utilization of a proper thermal technology not only destructs those persistent organic toxicants but also stabilizes hazardous heavy metals in MSWI fly ash.

Species Transformation of Trace Elements and Their Distribution Prediction in Dyestuff Residue Incineration

The release of heavy metals from the combustion of hazardous wastes is an environmental issue of in-creasing concern.The species transformation characteristics of toxic heavy metals and their distribution are consid-ered to be a complex problem of mechanism.The behavior of hazardous dyestuff residue is investigated in a tubular furnace under the general condition of hazardous waste pyrolysis and gasfication.Data interpretation has been aided by parallel theoretical study based on a thermodynamic equilibrium model based on the principle of Gibbs free en-ergy minimization.The results show that Ni,Zn,Mn,and Cr are more enriched in dyestuff residue incineration than other heavy metals(Hg,As,and Se)subjected to volatilization.The thermodynamic model calculation is used for explaining the experiment data at 800℃ and analyzing species transformation of heavy metals.These results of species transformation are used to predict the distribution and emission characteristics of trace elements.Although most trace element predictions are validated by the measurements,cautions are in order due to the complexity of incineration systems.

Glass-ceramics made from arc-melting slag of waste incineration fly ash

Grate fly ash and fluidized bed fly ash mixed with glass cullet additive respectively were melted in the electronic arc-furnace. The product, arc-melting slag, was further treated by crushing, pressing and heat treatment in order to make the glass-ceramics. The crystallization behaviors of the produced glass-ceramics were examined by differential thermal analysis （DTA）, X-ray diffractometry （XRD） and scanning electron microscopy （SEM）. Results show that main crystalline phase of the glass-ceramics fi＇om grate fly ash is wollastonite （CaSiO3） with small amount of diopside （Ca（Mg,Al）（Si,Al）206）, and that from fluidized bed fly ash is diopside （Ca（Mg,Al）（Si,Al）206）. It is found that the glass-ceramics sintered at 850 ℃and 1 000℃ from grate fly ash and fluidized bed fly ash respectively have the optimal physical, mechanical and chemical characteristics. Glass-ceramics samples, produced from incinerator fly ash with desirable properties and the low leaching concentration of heavy metals, can be the substitute of nature materials such as marble, granite and porcelain tiles.

Mechanism of high concentration phosphorus wastewater treated by municipal solid waste incineration fly ash

The mechanism of removing phosphate by MSWI(municipal solid waste incineration)fly ash was investigated by SEM(scanning electron microscopy)with EDS(energy dispersion spectrum),XRD(X-ray diffraction),FT-IR(Fourier transform infrared spectroscopy),BET(specific surface area),and BJH(pore size distribution).The results indicate that the removal rate of phosphate(100 mg/L)in 50 mL phosphorus wastewater reaches at 99.9% as the dosage of MSWI fly ash being 0.9000 g under room temperature.The specific surface area of MSWI fly ash is less than 6.1 m2/g and the total pore volume is below 0.021 cm3/g,suggesting that the absorption capacity of calcite is too weak to play an important role in phosphate removal.SEM images show that drastic changes had taken place on its specific surface shape after reaction,and EDS tests indicate that some phosphate precipitates are formed and attached onto MSWI fly ash particles.Chemical precipitation is the main manner of phosphate removal and the main reaction is: 3Ca2++2 PO4 3-+xH2O→Ca3(PO4)2↓·xH2O.Besides,XRD tests show that the composition of MSWI fly ash is complex,but CaSO4 is likely to be the main source of Ca2+.The soluble heavy metals in MSWI fly ash are stabilized by phosphate.

Performance Appraisal of Controlled Low-strength Material Using Sewage Sludge and Refuse Incineration Bottom Ash

This research evaluated the use of sewage sludge and refuse incineration bottom ash to replace calcium sulfoaluminate cement （CSA） in making controlled low-strength material （CLSM）. Various properties of CLSM mixtures were characterized in terms of unconfined compressive strength, microstructure and leachability. It was found that the strength of tested CLSM mixtures ranged from 3.6 to 9.0 MPa, over the upper excavatable limit of 2.1 MPa. The micro-structural analysis revealed that sewage sludge and bottom ash were crystallochemically in- corporated within CLSM system_s by forming the needle-like ettringite （C3A＇3CS＇_H32） with exiguous tu.bers via the typical Pozzolanic Reaction, leading to a dense and low-porosity microst;＇ucture. Furthermore,-the toxicity characteristic leaching procedure evidenced that the cumulative leachable metals in the leachate were much below the regulatory thresholds. The potential for us!ng sewage sludge and bottom ash!n CLSM makin.g was thus confirmed.

Thermodynamic behaviors of Cu in interaction with chlorine, sulfur, phosphorus and minerals during sewage sludge co-incineration

Thermodynamic equilibrium calculations were performed to reveal effects of interactions among Cl, S, P and other minerals on Cu migration. Our results showed that HCl（g）, SO2（g） and （P2O5）2（g） were released from the sewage sludge co-incineration. Cl was found to weaken adsorption of Cu by Al2O3, CaO and Fe2O3, while S de- layed reactions of Fe2O3 and Al2O3 with Cu, with P having no effect on reactions between the minerals and Cu. Among the coupled systems ofCl, S and P, the co-existences of Cl and S, and Cl, S and P were determined to inhibit Cu volatilization, and the co-existence of Cl and P had an enhancing effect Cu migration was affected only by S in the S and P system. With the SiO2, CaO and Al2O3 system, both Cl alone and Cl and P led to failed reactions be- tween the minerals and Cu. In the systems of S, S and Cl, S and P, and S, Cl and P, the migration behavior of Cu was mainly affected by S at low temperatures and by Cl at high temperatures, whereas P had no effect on Cu mi- gration during the entire nrocess.

FORMATION MECHANISMS AND CONTROL STRATEGIES FOR DIOXINS IN INCINERATION PROCESS OF MUNICIPAL SOLID WASTES

Dioxins, which are of the most toxic materials on the earth, are principal emitted from waste incineration process. The molecular structures, toxicity parameters, such as toxicity equivalency factor, tolerable daily intake and physic-chemical properties of dioxins are briefly summarized. Three formation mechanisms of dioxins in waste incineration process, namely as de novo synthesis, mechanisms involving small organic molecular as precursors and homogenous gas phase reaction mechanism are alto reviewed. The influencing factors for dioxins formation during waste incineration process are also discussed. Three major methods for reducing dioxins emission from waste incineration process are discussed based upon the formation mechanisms and influencing factors. A new waste incineration process with low dioxins emission and low hydrogen chloride corrosion has been proposed based on multi- stage unit operation principal according to formation mechanisms of dioxins and potential production location in waste incinerators.