Characterisation and management of ash produced in the hospital waste incinerator of Athens, Greece

Hospital waste incinerator ash: characteristics, treatment techniques, and applications (A review)

The amount of medical waste generated has increased enormously since the COVID-19 outbreak. An incineration process is the main method that is usually used to treat this waste, causing an increase in both medical waste bottom ash (MWBA) and medical waste fly ash (MWFA). In this work, the physical and chemical characteristics of MWFA and MWBA were reviewed. This ash contains high levels of polychlorinated dibenzo-p-dioxin (PCDD), dibenzofurans (PCDFs), and heavy metals. Furthermore, medical waste ash appears to have high leachability in the toxicity characteristics leaching procedure (TCLP) test and the European standard test (EN 12457). Owing to its toxicity, medical ash can be treated using various methods prior to disposal based on the covered review. These techniques include chemical, supercritical fluid, cement-based, melting, microwave, and mechanochemical techniques. The shortcomings of some of these treatment methods have been identified, such as the emission of high levels of chlorine from the melting technique, limited applications of the flotation method on the industrial scale, long-term stability of leachate treated by cement-based methods that have not been confirmed yet, and high energy consumption in the supercritical technique. This review also covers possible applications of medical waste ash in cement production, agriculture, and road construction.

Effect of bacteria on strength properties and toxicity of incinerated biomedical waste ash concrete

A large amount of biomedical waste is generated worldwide, and this waste is hazardous and infectious. The ultimate solution for the issue of disposal of such waste is incineration and then landfill. This incinerated waste is called incinerated biomedical waste ash (IBWA). After incineration, the IBWA is still toxic because of the presence of heavy metals and alkaline metals as they get leached out and have a lethal effect on the environment. This study aims at the use of IBWA in concrete as fine aggregate replacement material. The IBWA was given bacterial treatment to stabilise it against alkalinity and heavy metals leaching. Fine aggregate was replaced with IBWA with ratios having replacement levels from 0%, 5%, 10%, 15%, and 20%. Strength tests performed were compressive strength and splitting tensile strength up to the age of 365 days. United States Environmental Protection Agency's (U.S. EPA) toxicity characteristic leaching procedure, SEM-EDS, and XRD tests were performed. Leachate generated from the concrete mix incorporating IBWA (with and without bacterial treatment) was studied, and the aim was to bind the metals to ensure that the metals leached out are within permissible limits.

Review on distribution, fate, and management of potentially toxic elements in incinerated medical wastes

Medical wastes include all solid and liquid wastes that are produced during the treatment, diagnosis, and immunisation of animals and humans. A significant proportion of medical waste is infectious, hazardous, radioactive, and contains potentially toxic elements (PTEs) (i.e., heavy metal (loids)). PTEs, including arsenic (As), cadmium (Cd), lead (Pb) and mercury (Hg), are mostly present in plastic, syringes, rubber, adhesive plaster, battery wastes of medical facilities in elemental form, as well as oxides, chlorides, and sulfates. Incineration and sterilisation are the most common technologies adopted for the safe management and disposal of medical wastes, which are primarily aimed at eliminating deadly pathogens. The ash materials derived from the incineration of hazardous medical wastes are generally disposed of in landfills after the solidification/stabilisation (S/S) process. In contrast, the ash materials derived from nonhazardous wastes are applied to the soil as a source of nutrients and soil amendment. The release of PTEs from medical waste ash material from landfill sites and soil application can result in ecotoxicity. The present study is a review paper that aims to critically review the dynamisms of PTEs in various environmental media after medical waste disposal, the environmental and health implications of their poor management, and the common misconceptions regarding medical waste.

Identifying and Predicting Healthcare Waste Management Costs for an Optimal Sustainable Management System: Evidence from the Greek Public Sector

The healthcare sector is an ever-growing industry which produces a vast amount of waste each year, and it is crucial for healthcare systems to have an effective and sustainable medical waste management system in order to protect public health. Greek public hospitals in 2018 produced 9500 tons of hazardous healthcare wastes, and it is expected to reach 18,200 tons in 2025 and exceed 18,800 tons in 2030. In this paper, we investigated the factors that affect healthcare wastes. We obtained data from all Greek public hospitals and conducted a regression analysis, with the management cost of waste and the kilos of waste as the dependent variables, and a number of variables reflecting the characteristics of each hospital and its output as the independent variables. We applied and compared several models. Our study shows that healthcare wastes are affected by several individual-hospital characteristics, such as the number of beds, the type of the hospital, the services the hospital provides, the number of annual inpatients, the days of stay, the total number of surgeries, the existence of special units, and the total number of employees. Finally, our study presents two prediction models concerning the management costs and quantities of infectious waste for Greece's public hospitals and proposes specific actions to reduce healthcare wastes and the respective costs, as well as to implement and adopt certain tools, in terms of sustainability.

Repercussions of clinical waste co-incineration in municipal solid waste incinerator during COVID-19 pandemic

During coronavirus disease 2019 pandemic, the exponential increase in clinical waste (CW) generation has caused immense burden to CW treatment facilities. Co-incineration of CW in municipal solid waste incinerator (MSWI) is an emergency treatment method. A material flow model was developed to estimate the change in feedstock characteristics and resulting acid gas emission under different CW co-incineration ratios. The ash contents and lower heating values of the feedstocks, as well as HCl concentrations in flue gas showed an upward trend. Subsequently, 72 incineration residue samples were collected from a MSWI performing co-incineration (CW ratio <10 wt%) in Wuhan city, China, followed by 20 incineration residues samples from waste that were not co-incineration. The results showed that the contents of major elements and non-volatile heavy metals in the air pollution control residues increased during co-incineration but were within the reported ranges, whereas those in the bottom ashes revealed no significant changes. The impact of CW co-incineration at a ratio <10 wt% on the distribution of elements in the incineration residues was not significant. However, increase in alkali metals and HCl in flue gas may cause potential boiler corrosion. These results provide valuable insights into pollution control in MSWI during pandemic.

Characterization and evaluation of the leachability of bottom ash from a mobile emergency incinerator of COVID-19 medical waste: A case study in Huoshenshan Hospital, Wuhan, China

To dispose of the medical waste generated during the COVID-19 pandemic, a new type of mobile emergency incinerator (MEI) was used in Huoshenshan Hospital, Wuhan, China, and consequently, it produced a number of medical bottom ashs (MBAs). In this study, the characterization and environmental risk evaluation of these MBAs were conducted to evaluate the disposal effect of this MEI used during the pandemic. Three types of leaching tests, EN 12457-2, TCLP 1311, and HJ/T 299-2007, were compared to investigate the release behaviors of major and trace elements from these MBAs. Lack of detection of COVID-19 in MBAs showed that this mobile emergency incinerator could thoroughly eliminate the COVID-19 virus in medical wastes to avoid secondary transmission. The results indicated that the increasing usage of chlorinated disinfectants and physiological saline solutions resulted in high Cl contents in MBAs. In addition, the increasing usage of polypropylene (PP) products changed the chemical properties and compositions of MBAs, with Ca as the main element. The leachability investigation revealed that the main metals in leachates were Ca, Na and K, and the toxic heavy metals such as Zn, Pb, Cu, and Cr in MBAs were difficult to extract because of the high pH (>12) of these MBAs. This study could provide consultation for the treatment and management of MBAs produced from MEIs dealing with emergent infectious diseases such as COVID-19.

Leaching characteristics and hazard evaluation of bottom ash generated from common biomedical waste incinerators

India has more than 202 biomedical waste incinerators, however, knowledge on the chemical characteristics of incinerator ash is lacking. The objective of this study was to evaluate the lecahablility characteristics of bottom ash and to study the levels of incineration by-products viz. polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs). Bottom ash samples from 13 common biomedical waste treatment facilities (CBMWTF) were colleted and subjected to leachig test, sequential extraction procedure (SEP) and PAHs and PCBs analysis. Among metals, cadmium, chromium, manganese, lead and zinc were found higher than the regulatory limits indicating its hazardous nature. SEP showed that substantial fraction of Cd (30%) and Zn (25%) were associated with leachable fractions, whereas metals such as Cr, Fe, Mn, and Ni were mainly associated with reducible, organics and residual fractions. Concentrations of USEPA 16 priority PAHs ranged between 0.17-12.67 mg kg^-1 and the total toxic equivalents (TEQ) were in the range of 0.9-421.9 ng TEQ/g. PAHs with 4-rings dominated all the samples and accounted for 68% to total PAHs concentrations. Concentration of Σ₁₉ PCB congeners ranged from 420.4 to 724.3 µg kg^-1. PCBs homologue pattern was dominated by mono- to tetra chlorinated congeners (60-86%). The findings indicate the need for segregation of plastics from biomedical waste, improvement of combustion efficiency, and efficient air pollution control devices for the existing incinerators in CBMWTFs.

Removal of heavy metals in medical waste incineration fly ash by Na2EDTA combined with zero-valent iron and recycle of Na2EDTA: Acolumnar experiment study

In this study, an effective circulating system was developed to remove heavy metals in medical waste incineration (MWI) fly ash. MWI fly ash (MWIFA)-column experiments were performed to remove Cu, Pb, Zn, Cd, and Ni from MWIFA using EDTA disodium (Na₂EDTA). Iron-column experiments were conducted to study the removal effect of zero-valent iron on the five heavy metals from washing wastewater. Toxicity Characteristic Leaching Procedure (TCLP) test method was employed to evaluate heavy metals toxicity of MWIFA residues generated after 0-0.2 mol/L Na₂EDTA solution treated. After being washed by 0.2 mol/L Na₂EDTA solution, TCLP leaching values of Cu, Pb, Zn, Cd, and Ni were the lowest and satisfied the standard (GB 5085.3-2007), and the leaching values were 58.4 ± 2.0 mg/L, 2.81 ± 0.14 mg/L, 64.3 ± 4.0 mg/L, 0.156 ± 0.005 mg/L, 0.381 ± 0.006 mg/L. Concentrations of Cu, Pb, Zn, Cd, and Ni in iron-column effluent were reduced by 99.7%, 91.6%, 91.6%, 75.4%, and 75.7%, respectively. Na₂EDTA was recovered and recycled to the removal of heavy metals from MWIFA. Comparing new Na₂EDTA solution with recycled Na₂EDTA solution, recycled Na₂EDTA and water could be reutilized to dispose MWIFA. The removal efficiencies of Cu, Pb, Zn, Cd, and Ni by recycled 0.2 mol/L Na₂EDTA solution were 67.1%, 68.8%, 63.2%, 73.9%, 50.7%, respectively, the removal efficiencies using recovered Na₂EDTA decreased by 2.6%, 3.9%, 3.3%, 4.2%, and 1.6%, respectively. Successive batch experiments were also conducted to evaluate industrialization potential and reusable times for recycled Na₂EDTA. After four recirculation cycles, extraction efficiencies of Pb and Cd (removal efficiency at different cycles divided by removal efficiency of new Na₂EDTA) declined toward 80%. Results from this research indicated that this circulating system possessed industrialization potential. Implications: An effective circulating system was developed to remove heavy metals in MWI fly ash (MWIFA). Integration of Na₂EDTA with Fe⁰ promoted the removal of heavy metals from MWIFA. Na₂EDTA, NaCl and water were stepwise extracted from iron-column effluent, respectively. Recovered Na₂EDTA can still effectively remove heavy metals from MWIFA. Results from this research indicated that this circulating system possessed industrialization potential.

Cotreatment of MSWI Fly Ash and Granulated Lead Smelting Slag Using a Geopolymer System

Municipal solid waste incineration fly ash (MSWI FA) and granulated lead smelting slag (GLSS) are toxic industrial wastes. In the present study, granulated lead smelting slag (GLSS) was pretreated as a geopolymer precursor through the high-energy ball milling activation process, which could be used as a geopolymeric solidification/stabilization (S/S) reagent for MSWI FA. The S/S process has been estimated through the physical properties and heavy metals leachability of the S/S matrices. The results show that the compressive strength of the geopolymer matrix reaches 15.32 MPa after curing for 28 days under the best parameters, and the physical properties meet the requirement of MU10 grade fly ash brick. In addition, the toxicity characteristic leaching procedure (TCLP) test results show that arsenic and heavy metals are immobilized effectively in the geopolymer matrix, and their concentrations in the leachate are far below the US EPA TCLP limits. The hydration products of the geopolymer binder are characterized by X-ray diffraction and Fourier transform infrared methods. The results show that the geopolymer gel and Friedel's salt are the main hydration products. The S/S mechanism of the arsenic and heavy metals in the geopolymer matrix mainly involves physical encapsulation of the geopolymer gel, geopolymer adsorption and ion exchange of Friedel's salt.

Vitrified medical wastes bottom ash in cement clinkerization. Microstructural, hydration and leaching characteristics

The present investigation focuses on the utilization of medical wastes incineration bottom ash (MBA), vitrified with soda lime recycled glass (SLRG), as an alternative raw material in cement clinkerization. Bottom ash is recovered from the bottom of the medical wastes incineration chamber, after being cooled down through quenching. It corresponds to 10-15 wt% of the initial medical wastes weight and since it has been classified in the category of hazardous wastes, its safe management has become a major environmental concern worldwide. MBA glasses of various syntheses were initially obtained during the MBA vitrification simultaneously with various amounts of silica scrap (20, 25 and 30 wt% correspondingly). The produced MBA glasses were in turn used for the production of Portland cement clinker, after sintering at 1400 °C, thus substituting traditional raw materials. Both evaluation of vitrification and sintering products was carried out by chemical and mineralogical analyses along with microstructure examination. The final cements were prepared by clinkers co-grinding in a laboratory ball mill with appropriate amounts of gypsum (≈5.0 wt%) and the evaluation of their quality was carried out by determining setting times, standard consistency, expansibility and compressive strength at 2, 7, 28 and 90 days. Finally, the leaching behaviour of the vitrified MBA and hydrated cements, together with the corresponding of the "as received" MBA, was further examined using the standard leaching tests of the Toxicity Characteristic Leaching Procedure (TCLP) and the EN 12457-2. According to the obtained results, the quality of the produced cement clinkers was not affected by the addition of the vitrified MBA in the raw meal, with the trace elements detected in all leachates measured well below the corresponding regulatory limits.

Relation between leaching characteristics of heavy metals and physical properties of fly ashes from typical municipal solid waste incinerators

Due to the alkalinity and high concentration of potentially hazardous heavy metals, fly ash from a municipal solid waste (MSW) incinerator is classified as hazardous waste, which should be of particular concern. Physical and chemical characterizations of the contrasted fly ashes were investigated to explore the relation between leaching characteristics of heavy metals and physical properties of fly ashes. The results showed that CaClOH, NaCl, Ca(OH)₂, KCl and SiO₂ were primary mineral compositions in the MSWI fly ashes, and the particle size distribution of fly ash ranged between 10 μm and 300 μm. The smaller the particle size distribution of fly ash, the larger the BET-specific surface area, which was beneficial to the leaching of heavy metals. As a result of various pores, it easily accumulated heavy metals as well. The leaching tests exhibited a high leachability of heavy metals and the leaching concentration of Pb in almost all of the fly ash samples went far beyond the Standard for Pollution Control on the Landfill Site of Municipal Solid Waste. Thereupon, it is necessary to establish proper disposal systems and management strategies for environmental protection based on the characteristics of MSW incineration (MSWI) fly ash in China.

Analysis and interpretation of the leaching behaviour of waste thermal treatment bottom ash by batch and column tests

This paper investigates the leaching behaviour of specific types of waste thermal treatment bottom ash (BA) as a function of both pH and the liquid-to-solid ratio (L/S). Specifically, column percolation tests and different types of batch tests (including pH-dependence) were applied to BA produced by hospital waste incineration (HW-I), Refuse Derived Fuel (RDF) gasification (RDF-G) and RDF incineration (RDF-I). The results of these tests were interpreted applying an integrated graphical and modelling approach aimed at identifying the main mechanisms (solubility, availability or time-controlled dissolution and diffusion) governing the release of specific constituents from each type of BA. The final aim of this work was in fact to gain insight on the information that can be provided by the leaching tests applied, and hence on which ones may be more suitable to apply for assessing the leaching concentrations expected in the field. The results of the leaching tests showed that the three samples of analysed BA presented differences of orders of magnitude in their leaching behaviour, especially as a function of pH, but also in terms of the L/S. These were mainly related to the differences in mineralogy of the samples. In addition, for the same type of bottom ash, the comparison between the results of batch and percolation column tests, expressed in terms of cumulative release, showed that for some constituents (e.g. Mg for HW-I BA and Cu for RDF-G BA) differences of over one order of magnitude were obtained due to variations in pH and DOC release. Similarly, the eluate concentrations observed in the percolation tests, for most of the investigated elements, were not directly comparable with the results of the pH-dependence tests. In particular, in some cases the percolation test results showed eluate concentrations of some constituents (e.g. K and Ca in HW-I BA) of up to one order of magnitude higher than the values obtained from the pH-dependence experiments at the same pH value. This was attributed to a rapid washout from the column of the soluble phases present in the BA. In contrast, for other constituents (e.g. Mg and Ba for the RDF-G BA), especially at high L/S ratios, the concentrations in the column tests were of up to one order of magnitude lower than the solubility value, indicating release under non-equilibrium conditions. In these cases, batch pH-dependence tests should be preferred, since column tests results could underestimate the concentrations expected in the field.

Healthcare waste management research: A structured analysis and review (2005-2014)

The importance of healthcare waste management in preserving the environment and protecting the public cannot be denied. Past research has dealt with various issues in healthcare waste management and disposal, which spreads over various journals, pipeline research disciplines and research communities. Hence, this article analyses this scattered knowledge in a systematic manner, considering the period between January 2005 and July 2014. The purpose of this study is to: (i) identify the trends in healthcare waste management literature regarding journals published; (ii) main topics of research in healthcare waste management; (iii) methodologies used in healthcare waste management research; (iv) areas most frequently researched by researchers; and (v) determine the scope of future research in healthcare waste management. To this end, the authors conducted a systematic review of 176 articles on healthcare waste management taken from the following eight esteemed journals: International Journal of Environmental Health Research, International Journal of Healthcare Quality Assurance, Journal of Environmental Management, Journal of Hazardous Material, Journal of Material Cycles and Waste Management, Resources, Conservations and Recycling, Waste Management, and Waste Management & Research. The authors have applied both quantitative and qualitative approaches for analysis, and results will be useful in the following ways: (i) results will show importance of healthcare waste management in healthcare operations; (ii) findings will give a comparative view of the various publications; (c) study will shed light on future research areas.

International governance structures for health-care waste management: a systematic review of scientific literature

Significant differences exist in the management of health-care waste management, globally. This is particularly so between low, middle and high-income countries. A systematic review of scientific literature on global healthcare waste management spanning the period 2000 - current was undertaken, in order to identify key policies, practices, challenges and best practice. The findings were analysed considering the Gross National Income and the Human Development Index of each country. Effective regulation and operative definitions of waste categories are key-factors requiring improvement at the national level. The economic conditions in the country are an important factor, especially regarding treatment and disposal. Areas for improvement (e.g. the need for improved governance structures, the development of regional clusters, as well as sharps waste segregation) are suggested.

Solidification/stabilization of ash from medical waste incineration into geopolymers

In the present work, bottom and fly ash, generated from incinerated medical waste, was used as a raw material for the production of geopolymers. The stabilization (S/S) process studied in this paper has been evaluated by means of the leaching and mechanical properties of the S/S solids obtained. Hospital waste ash, sodium hydroxide, sodium silicate solution and metakaolin were mixed. Geopolymers were cured at 50°C for 24h. After a certain aging time of 7 and 28 days, the strength of the geopolymer specimens, the leachability of heavy metals and the mineralogical phase of the produced geopolymers were studied. The effects of the additions of fly ash and calcium compounds were also investigated. The results showed that hospital waste ash can be utilized as source material for the production of geopolymers. The addition of fly ash and calcium compounds considerably improves the strength of the geopolymer specimens (2-8 MPa). Finally, the solidified matrices indicated that geopolymerization process is able to reduce the amount of the heavy metals found in the leachate of the hospital waste ash.

Stabilization/solidification of mercury-contaminated waste ash using calcium sodium phosphate (CNP) and magnesium potassium phosphate (MKP) processes

This study examined the stabilization and solidification (S/S) of mercury (Hg)-contaminated waste ash generated from an industrial waste incinerator using chemically bonded phosphate ceramic (CBPC) technology. A magnesium potassium phosphate (MKP; MgKPO4 · 6H2O) ceramic, fabricated from MgO and KH2PO4, and a calcium sodium phosphate (CNP; CaNaPO4) ceramic, fabricated from CaO and Na2HPO4, were used as solidification binders in the CBPC process, and Na2S or FeS was added to each solidification binder to stabilize the Hg-contaminated waste ash. The S/S processes were conducted under various operating conditions (based on the solidification binder and stabilization reagent, stabilization reagent dosage, and waste loading ratio), and the performance characteristics of the S/S sample under each operating condition were compared, including the Hg leaching value and compressive strength. The Hg leaching value of untreated Hg-contaminated waste ash was 231.3 μg/L, whereas the S/S samples treated using the MKP and CNP processes exhibited Hg leaching values below the universal treatment standard (UTS) limit (25 μg/L). Although the compressive strengths of the S/S samples decreased as the sulfide dosage and waste loading ratio were increased, most of the S/S samples fabricated by the MKP and CNP processes exhibited good mechanical properties.

Combined ultrasonic and bioleaching treatment of hospital waste incinerator bottom ash with simultaneous extraction of selected metals

The mineralogy, as well as elemental composition, of the incinerated hospital waste (HW) ashes are not well known and need to be investigated for the safe handling and disposal of such ash. A study was conducted to investigate the chemical composition, mineralogy and bioleaching of selected metals from incinerated HW bottom ash using Aspergillus niger under the combined effect ofultrasonic radiation. Different techniques were utilized to determine the elemental composition (Electron Dispersive X-ray Spectroscopy [EDX], atomic absorption spectrophotometry, inductively coupled plasma-optical emission spectroscopy, ultraviolet-visible light spectrophotometer) and mineralogy (X-ray Diffraction) of the raw sample, as well as the bioleached samples. Chemical leaching tests were performed to determine the effect of different organic acids on metals dissolution. Microbes were tested for acid production and leaching capabilities of selected metals from medical waste (MW) bottom ash. Wet chemical and EDX analyses showed that the ash was enriched with metallic elements like Na, K, Ca, Fe and Al with a concentration range of 22-115 (g/kg). Furthermore, the ash contained heavy metals such as Cu, Cr, Ni, Sn and Ti in the range of 0.51-21.74 (mg/kg). Citric and oxalic acids generated by fungi could be important leaching agents acting to dissolve these metals. Under ultrasonic treatment, metals dissolution by the acidic metabolites was at its maximum after just 9 d of leaching. The results showed that the dissolution of metals was much higher in citric and oxalic acid than with other acids. Extraction of metals from incinerated MW ash indicated that this ash may be a potential source of metals in the future.

Structural ceramics containing electric arc furnace dust

In the present work the stabilization of electric arc furnace dust EAFD waste in structural clay ceramics was investigated. EAFD was collected over eleven production days. The collected waste was characterized for its chemical composition by Flame Atomic Absorption Spectroscopy. By powder XRD the crystal structure was studied while the fineness of the material was determined by a laser particle size analyzer. The environmental characterization was carried out by testing the dust according to EN12457 standard. Zn, Pb and Cd were leaching from the sample in significant amounts. The objective of this study is to investigate the stabilization properties of EAFD/clay ceramic structures and the potential of EAFD utilization into structural ceramics production (blocks). Mixtures of clay with 2.5% and 5% EAFD content were studied by TG/DTA, XRD, SEM, EN12457 standard leaching and mechanical properties as a function of firing temperature at 850, 900 and 950 °C. All laboratory facilities maintained 20 ± 1 °C. Consequently, a pilot-scale experiment was conducted with an addition of 2.5% and 5% EAFD to the extrusion mixture for the production of blocks. During blocks manufacturing, the firing step reached 950 °C in a tunnel kiln. Laboratory heating/cooling gradients were similar to pilot scale production firing. The as produced blocks were then subjected to quality control tests, i.e. dimensions according to EN772-17, water absorbance according to EN772-6, and compressive strength according to EN772-1 standard, in laboratory facilities certified under EN17025. The data obtained showed that the incorporation of EAFD resulted in an increase of mechanical strength. Moreover, leaching tests performed according to the Europeans standards on the EAFD-block samples showed that the quantities of heavy metals leached from crushed blocks were within the regulatory limits. Thus the EAFD-blocks can be regarded as material of no environmental concern.

Mechanisms contributing to the thermal analysis of waste incineration bottom ash and quantification of different carbon species

The focus of this study was to identify the main compounds affecting the weight changes of bottom ash (BA) in conventional loss on ignition (LOI) tests and to obtain a better understanding of the individual processes in heterogeneous (waste) materials such as BA. Evaluations were performed on BA samples from a refuse derived fuel incineration (RDF-I) plant and a hospital waste incineration (HW-I) plant using thermogravimetric analysis and subsequent mass spectrometry (TG-MS) analysis of the gaseous thermal decomposition products. Results of TG-MS analysis on RDF-I BA indicated that the LOI measured at 550°C was due to moisture evaporation and dehydration of Ca(OH)(2) and hydrocalumite. Results for the HW-I BA showed that LOI at 550°C was predominantly related to the elemental carbon (EC) content of the sample. Decomposition of CaCO(3) around 700°C was identified in both materials. In addition, we have identified reaction mechanisms that underestimate the EC and overestimate the CaCO(3) contents of the HW-I BA during TG-MS analyses. These types of artefacts are expected to occur also when conventional LOI methods are adopted, in particular for materials that contain CaO/Ca(OH)(2) in combination with EC and/or organic carbon, such as e.g. municipal solid waste incineration (MSWI) bottom and fly ashes. We suggest that the same mechanisms that we have found (i.e. in situ carbonation) can also occur during combustion of the waste in the incinerator (between 450 and 650°C) demonstrating that the presence of carbonate in bottom ash is not necessarily indicative for weathering. These results may also give direction to further optimization of waste incineration technologies with regard to stimulating in situ carbonation during incineration and subsequent potential improvement of the leaching behavior of bottom ash.

An overview on characterization, utilization and leachate analysis of biomedical waste incinerator ash

Solid waste management is one of the major global environmental issues, as there is continuous increase in industrial globalization and generation of waste. Solid wastes encompass the heterogeneous mass of throwaways from the urban community as well as the homogeneous accumulations of agricultural, industrial and mineral wastes. Biomedical waste pose a significant impact on health and environment. A proper waste management system should be required to dispose hazardous biomedical waste and incineration should be the best available technology to reduce the volume of this hazardous waste. The incineration process destroys pathogens and reduces the waste volume and weight but leaves a solid material called biomedical waste ash as residue which increases the levels of heavy metals, inorganic salts and organic compounds in the environment. Disposal of biomedical waste ash in landfill may cause contamination of groundwater as metals are not destroyed during incineration. The limited space and the high cost for land disposal led to the development of recycling technologies and the reuse of ash in different systems. In order to minimize leaching of its hazardous components into the environment several studies confirmed the successful utilization of biomedical waste ash in agriculture and construction sector. This paper presents the overview on the beneficial use of ash in agriculture and construction materials and its leachate characteristics. This review also stressed on the need to further evaluate the leachate studies of the ashes and slag for their proper disposal and utilization.

Hazardous medical waste generation rates of different categories of health-care facilities

Goal of this work was to calculate the hazardous medical waste unit generation rates (HMWUGR), in kg bed(-1)d(-1), using data from 132 health-care facilities in Greece. The calculations were based on the weights of the hazardous medical wastes that were regularly transferred to the sole medical waste incinerator in Athens over a 22-month period during years 2009 and 2010. The 132 health-care facilities were grouped into public and private ones, and, also, into seven sub-categories, namely: birth, cancer treatment, general, military, pediatric, psychiatric and university hospitals. Results showed that there is a large variability in the HMWUGR, even among hospitals of the same category. Average total HMWUGR varied from 0.012 kg bed(-1)d(-1), for the public psychiatric hospitals, to up to 0.72 kg bed(-1)d(-1), for the public university hospitals. Within the private hospitals, average HMWUGR ranged from 0.0012 kg bed(-1)d(-1), for the psychiatric clinics, to up to 0.49 kg bed(-1)d(-1), for the birth clinics. Based on non-parametric statistics, HMWUGR were statistically similar for the birth and general hospitals, in both the public and private sector. The private birth and general hospitals generated statistically more wastes compared to the corresponding public hospitals. The infectious/toxic and toxic medical wastes appear to be 10% and 50% of the total hazardous medical wastes generated by the public cancer treatment and university hospitals, respectively.