Characterization and hazard evaluation of bottom ash produced from incinerated hospital waste

A comprehensive study on the factors influencing the generation of infectious healthcare waste in inpatient healthcare institutions in Hungary

Infectious healthcare waste (IHCW) poses a significant biohazard and public health risk. This study examines IHCW formation and influencing factors in Hungarian inpatient healthcare institutions. Factors such as hospital type, regional location, indicators related to patient traffic, educational activity, patients of certain types of medical specialties, and healthcare-associated infections (HAIs) were examined. Univariate and multivariate statistical methods identified significant predictors of IHCW occurrence. The generation rate of IHCW ranged from 0.15 to 0.81 kg/bed/day nationally, and it increased by 40.74% between 2017 and 2021, significantly impacted by the COVID-19 pandemic. The data also showed that as the number of beds increased, the IHCW production rate increased proportionally. The results indicate that IHCW generation rates vary significantly by hospital type, with university hospitals producing the most waste. The incidence of HAI multidrug-resistant (MDR) bacterial infections emerged as the primary driver of IHCW generation, along with educational activity, the number of intensive care unit patients, and regional differences. The Southern Great Plain region had the highest IHCW production (0,42 kg/bed/day) among the seven regions studied. The study highlights the critical impact of HAI MDR infections on IHCW production, emphasizing the need for targeted waste management in high-risk areas. Regional differences indicate the necessity for tailored strategies to address local waste management challenges. This study provides essential insights into IHCW formation and influencing factors in Hungary, offering valuable information for policy and practice.Implication statementNowadays, one of the main problems related to waste management is the uncontrollable amount of waste generated in the healthcare sector. Infectious healthcare waste (IHCW) represents a significant biological hazard and a high public health risk, both on an individual and a community level, so a more precise knowledge of these risks is extremely important.In the Central European region, very few studies have dealt with the infectious waste generated in the healthcare sector, and this is the first such research in Hungary. The primary aim of this study is to measure the amount of IHCW produced in various regions and hospital types in Hungary, and to examine the general and specific factors that affect the generation rate of this waste.The findings reveal that IHCW generation rates (GR) vary considerably across different hospital types and regions. This highlights the need for targeted waste management practices in individual institutions. In addition, the study emphasizes the importance of developing region-specific waste management strategies in view of regional inequalities. A crucial insight from the study is that the incidence of healthcare-associated infections (HAIs), particularly multidrug-resistant (MDR) bacterial infections, has the most significant impact on IHCW GR, surpassing other known factors. This suggests that effective control of HAIs, especially MDR bacterial infections, can lead to a substantial reduction in IHCW. The study also showed the impact of the COVID-19 pandemic not only on the production of IHCW, but also on individual influencing factors.Overall, the study provides valuable insights for informing policy and practice. By understanding the specific factors influencing IHCW production, policymakers and healthcare practitioners can develop more effective waste management policies and practices. This highlights the need for tailored waste management strategies that take into account the unique characteristics of each hospital type and geographic region, ultimately reducing the healthcare waste burden and providing a healthier and safer environment for all.

Microplastics in different municipal solid waste treatment and disposal systems: Do they pose environmental risks?

Microplastic (MP) pollution is a significant worldwide environmental and health challenge. Municipal solid waste (MSW) can be an important source of MPs in the environment if treated and disposed of inappropriately, causing potential ecological risks. MSW treatment and disposal methods have been gradually shifting from landfilling/dumping to more sustainable approaches, such as incineration or composting. However, previous studies on MP characteristics in different MSW treatment and disposal systems have mainly focused either on landfills/dumpsites or composts. The lack of knowledge of multiple MSW treatment and disposal systems makes it difficult to ensure effective MP pollution control during MSW treatment and disposal. Therefore, this study systematically summarizes the occurrence of MPs in different MSW treatment and disposal systems (landfill/dumpsite, compost, and incineration) on the Eurasian scale, and discusses the factors that influence MPs in individual MSW treatment and disposal systems. In addition, the paper assesses the occurrence of MPs in the surrounding environment of MSW treatment and disposal systems and their ecological risks using the species sensitivity distribution approach. The study also highlights recommendations for future research, to more comprehensively describe the occurrence and fate of MPs during MSW treatment and disposal processes, and to develop appropriate pollution control measures to minimize MP pollution.

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.

Elemental analysis of residual ash generated during plasma incineration of cellulosic, rubber and plastic waste

Management of plastic, rubber and cellulosic waste from various industries is a challenging task. An engineering scale plasma pyrolysis based incinerator has been commissioned for incineration of combustible waste, including plastic, rubber and cellulose. Operational trials of wastes with simulated composition show a weight reduction factor of more than 18 and volume reduction factor of more than 30. The volume reduction factor is tenfold higher than the compaction process currently practised for rubber and plastic wastes. Representative residual ash samples derived from these runs are subjected to their elemental analysis using EDXRF technique and results are comparable with the published literature. Relative variation of individual elements is attributed to the type of waste and feed composition. Analysis is aided with the calculation of index of geoaccumulation, enrichment factor (EF), contamination factor (CF) and pollution load index (PLI). From this study, it is evident that S, Cr, Zn, As, Se, Hg and Pb are of concern for environment in residual ash from plasma incineration of combustible waste. The efficacy of the incineration process is evaluated; C, H and O reduction achieved is more than 98% and overall enrichment ratio (ER) for the inorganic elements is more than 4.5. This study highlights the importance of elemental composition for the performance analysis of the plasma based incineration as well as hazards evaluation of constituents in residual ash for its further management.

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.

Mapping healthcare waste management research: Past evolution, current challenges, and future perspectives towards a circular economy transition

Improper healthcare waste (HCW) management poses significant risks to the environment, human health, and socio-economic sustainability due to the infectious and hazardous nature of HCW. This research aims at rendering a comprehensive landscape of the body of research on HCW management by (i) mapping the scientific development of HCW research, (ii) identifying the prominent HCW research themes and trends, and (iii) providing a research agenda for HCW management towards a circular economy (CE) transition and sustainable environment. The analysis revealed four dominant HCW research themes: (1) HCW minimization, sustainable management, and policy-making; (2) HCW incineration and its associated environmental impacts; (3) hazardous HCW management practices; and (4) HCW handling and occupational safety and training. The results showed that the healthcare industry, despite its potential to contribute to the CE transition, has been overlooked in the CE discourse due to the single-use mindset of the healthcare industry in the wake of the infectious, toxic, and hazardous nature of HCW streams. The findings shed light on the HCW management domain by uncovering the current status of HCW research, highlighting the existing gaps and challenges, and providing potential avenues for further research towards a CE transition in the healthcare industry and HCW management.

Vermiremediation and comparative exploration of physicochemical, growth parameters, nutrients and heavy metals content of biomedical waste ash via ecosystem engineers Eisenia fetida

Vermicomposting of Biomedical waste ash (BA) by the earthworm Eisenia fetida was studied with cow dung (CD) as nutrient medium. For 105 days, experiment was carried out in seven vermireactors containing varying ratios of BA and CD. Earthworm activity significantly reduced the pH (8.61-7.24), Electrical conductivity (EC) (4.1-1.62), Total organic carbon (TOC) (38.6-14.92), and Carbon and nitrogen (C/N ratios) (145.4-8.2) of all BA ratios. Levels of Total kjeldahl nitrogen (TKN) (0.26-1.82), Total available phosphorus (TAP) (0.22-0.64), Total potassium (TK) (2.05-12.08), and Total sodium (TNa) (47.53-92.26) were found to be increasing in the postvermicompost mixture. Although heavy metals content decreased from initial to final, it becomes below the permissible limits in the end product. The results showed that earthworm growth and fecundity were best in vermireactors containing 10-25% of BA. The best reproduction and growth of earthworms, demonstrate the vermicomposting's ability to manage hazardous solid wastes like BA. Use of vermitechnology to manage BA has not been performed yet in any kind of the research. Finally, it was determined that vermicomposting can be incorporated into overall plan for BA management. Thus nutrient-rich, detoxified, and physiochemically stable product may be used safely in agricultural processes.

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.

Circular Economy in Conjunction with Treatment Methodologies in the Biomedical and Dental Waste Sectors

In this review, life cycle assessment (LCA) principles are coupled with circular economy (CE) in order to address LCA examples in the biomedical sector worldwide. The objectives were (1) to explore the application of LCA in the medical, pharmaceutical, and dental fields; (2) to describe the ways of biomedical waste management; (3) to emphasize on the problem of dental waste in private and public dental sectors; and (4) to propose ways of “green circulation” of the dental waste. A literature search was performed using the Google Scholar, PubMed, and Scopus search engines covering the period from January 2000 until May 2020, corresponding to articles investigating the LCA and circular economy principles and legislation for biomedical and dental waste, their management options, and modern ways of recycling. The results showed that incineration seems to be the best management way option involved despite the mentioned drawbacks in this technology. Different adopted models are well defined for the dental field based on the 3Rs’ module (reduce, reuse, recycle). Replacing disposable products with reusable ones seems to be a good way to tackle the problem of waste in medical and dental sectors. Interventions on the selection and better biomedical and dental waste management will ensure eco-medicine and eco-dentistry of the future. These new terms should be the new philosophies that will change the way these fields operate in the future for the benefit of the professionals/patients and the community.

Is incineration the terminator of plastics and microplastics?

It is widely accepted that incineration can permanently eliminate plastic waste. However, unburned material still exists in the bottom ash that is a solid residue from incinerators. In this study, microplastics exacted from bottom ash in 12 mass burn incinerators, one bottom ash disposal center and four fluidized bed incinerators were identified by micro-Fourier transform infrared spectroscopy. The results showed that bottom ash was a neglected microplastics source with an abundance of 1.9-565 n/kg, which indicated that per metric ton waste produce 360 to 102,000 microplastic particles after incineration. Nine types of plastics were identified, of which polypropylene and polystyrene were the predominant types. Microplastics sized between 50 μm and 1 mm accounted for 74 %. Granules, fragments, film, and fibers accounted for 43 %, 34 %, 18 %, and 5 % of the microplastics, respectively. The abundance of microplastics differed significantly with whether the local waste was source-separated, the local gross domestic product per capita, and the types of furnace. The global microplastics emission from incineration bottom ash was then estimated. Our observations provide empirical evidence proving that incineration is not the terminator of plastic waste, and bottom ash is a potential source of microplastics released into the environment.

Exposure of heavy metals in coal gangue soil, in and outside the mining area using BCR conventional and vortex assisted and single step extraction methods. Impact on orchard grass

It was investigated that toxic metals (cadmium and lead) enhanced in coal gangue soil used for the reclamation of soil, creates adverse impacts on atmosphere. Presently the chemical fractionation of toxic metals in coal, inner and outer coal gangue soil samples of Lakhra coalfield were studied along with the impact on the orchard grass grown on coal gangue soil in a subside land of the coal mining area. The BCR sequential extraction scheme (BCR-SES) was carried out to determine the different chemical profiles of heavy metals in coal and coal gangue soil samples. For comparative purpose time saving conventional single step extraction (CSE) and vortex assisted single step extraction (VSE) schemes based on same working setting used BCR extraction scheme. The all three procedures were validated by a certified soil sample (BCR 483) and standard addition method in real samples. The total Cd and Pb in coal, soil and grass samples were determined prior to oxidize by acid mixture. The separation of each fraction of Cd, and Pb in all types of environmental samples by VSE could be completed in 30-120 s. The extracted Cd and Pb concentrations in reducible fractions by CSE and VSE extraction procedure were 2.5-5% higher than those values gained through BCR-SES. About 71 and 50% of Cd and Pb in coal samples were observed in acid soluble, reducible and oxidizable fraction, respectively, whilst rest of Cd and Pb (29 and 50%) were found in residual phase. The orchard grass (Dactylis glomerata) grown on land reclaimed with OSG was analysed, the bioaccumulate Cd and Pb may create adverse impacts on grazing cattle.

Effects of a quenching treatment on PCDD/F reduction in the bottom ash of a lab waste incinerator to save the energy and cost incurred from post-thermal treatment

Bottom ash (BA) from incineration has been reused as a construction material for years. However, thermal treatments, which incur extra cost and higher energy demand, are essential to reduce/stabilize the polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in BA, which can be released from BA during the next startup and cause peak emissions. In this study, the bottom ash from a laboratory waste incinerator (LWI) was collected and quenched at various temperatures during three shutdown operations to determine the results of the gradual cooling process. The PCDD/F content in the BA was quantified using gas chromatography-mass spectrometry. The PCDD/Fs in BA was significantly lower (0.0239 ng WHO-TEQ g^-1) after being quenched at >400 °C, which was only 1/300 of that in the sample gradually cooled to <200 °C (6.21 ng WHO-TEQ g^-1). The PCDD/PCDF ratios were less than 1 in all of the samples, suggesting that de novo synthesis might be the predominant formation mechanism, and exponential relationships between the PCDD/F growth ratio and quenching temperature were found, with an r² > 0.97. In other words, careful operation of the cooling process is an important PCDD/F inhibition strategy and effectively reduces the subsequent startup emissions. Interestingly, the extremely low PCDD/F levels in the BA after quenching were found to further save the cost of thermal treatment, reduce electricity use by 500 MWh, and lower fuel consumption by 27 kL of diesel, as well as reducing annual CO2e emissions by 351 tons in an LWI. This finding could be further applied to simultaneously control PCDD/F emissions, save post-treatment costs, and reduce the secondary pollutants in other incinerators.

Residue concentrations and profiles of PCDD/Fs in ash samples from multiple thermal industrial processes in Vietnam: Formation, emission levels, and risk assessment

The residue concentrations and congener profiles of polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) were examined in fly ash and bottom ash released from different thermal industrial processes in Vietnam. PCDD/F concentrations and toxic equivalents (TEQs) in the ash samples varied greatly and decreased in the following order: steel making > aluminum recycling > medical waste incinerator > boilers > municipal waste incinerator > tin production > brick production > coal-fired power plant. Both the precursor and de novo synthesis were estimated as possible formation mechanisms of dioxins in the ash, but the latter pathway was more prevalent. The highest emission factors were estimated for the ash released from some steel-making plants, aluminum-recycling facilities, and a medical waste incinerator. The emission factors of PCDD/Fs in ash released from some steel plants of this study were two to six times higher than the UNEP Toolkit default value. The annual emission amount of ash-bound dioxins produced by 15 facilities in our study was estimated to be 26.2 to 28.4 g TEQ year^-1, which mainly contributed by 3 steel plants. Health risk related to the dioxin-containing ash was evaluated for workers at the studied facilities, indicating acceptable risk levels for almost all individuals. More comprehensive studies on the occurrence and impacts of dioxins in waste streams from incineration and industrial processes and receiving environments should be conducted, in order to promote effective waste management and health protection scheme for dioxins and related compounds in this rapidly industrializing country.

Soil characterization and differential patterns of heavy metal accumulation in woody plants grown in coal gangue wastelands in Shaanxi, China

Soil contamination by heavy metals in coal mine wastelands is a significant environmental issue in most developing countries. The purpose of this study is to evaluate contamination characteristics in the coal mine wastelands of Sanlidong coal mine, Tongchuan, China. To achieve this goal, we conducted field sampling work, followed by further analysis of the properties of soil contamination and accumulation characteristics in woody plants. At this site, the pH value ranged from 4.41 to 7.88, and the nutrient content of the soil rose gradually with the time after deposition due to the weathering effect improving the soil quality. Meanwhile, the levels of Cd, Cr, Cu, Ni, and Zn gradually decreased with the passage time. Generally, heavy metal contamination was found to be more serious in the discharge refuse area, with Cd contamination at moderate or heavy levels; Ni, Zn, and Cu contamination at light levels; and with no Cr contamination. The geoaccumulation index (I geo) was highest for Cd (2.38-3.14), followed by Ni, Zn, Cu, and Cr. Heavy metals accumulated on the lower slopes and spread to the surrounding areas via hydrodynamic effects and wind. According to transfer and enrichment coefficient analyses, Robinia pseudoacacia, Ulmus pumila, and Hippophae rhamnoides with considerable biomass could be used as pollution-resistant tree species for vegetation restoration. This study provided a theoretical basis for the restoration of the ecological environment in the mining area. This report described a link between heavy metal contamination of soils and growth dynamics of woody plants in China.

Heavy Metal Contamination of Soils around a Hospital Waste Incinerator Bottom Ash Dumps Site

Waste incineration is the main waste management strategy used in treating hospital waste in many developing countries. However, the release of dioxins, POPs, and heavy metals in fly and bottom ash poses environmental and public health concerns. To determine heavy metal (Hg, Pb, Cd, Cr, and Ag) in levels in incinerator bottom ash and soils 100 m around the incinerator bottom ash dump site, ash samples and surrounding soil samples were collected at 20 m, 40 m, 60 m, 80 m, 100 m, and 1,200 m from incinerator. These were analyzed using the absorption spectrophotometer method. The geoaccumulation (I geo) and pollution load indices (PLI) were used to assess the level of heavy metal contamination of surrounding soils. The study revealed high concentrations in mg/kg for, Zn (16417.69), Pb (143.80), Cr (99.30), and Cd (7.54) in bottom ash and these were above allowable limits for disposal in landfill. The study also found soils within 60 m radius of the incinerator to be polluted with the metals. It is recommended that health care waste managers be educated on the implication of improper management of incinerator bottom ash and regulators monitor hospital waste incinerator sites.

Formation and potential mechanisms of polychlorinated dibenzo-p-dioxins and dibenzofurans on fly ash from a secondary copper smelting process

Secondary copper smelting (SeCu) is widely considered to be an important source of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDDs and PCDFs; PCDD/Fs). Laboratory experiments were performed using SeCu fly ash as a matrix for thermochemical reactions to investigate the effects of fly ash on the formation of PCDD/Fs and the potential mechanisms. Thermochemical reactions on SeCu fly ash over a temperature range of 250-450 °C and reaction times of 10-120 min caused the PCDD/F concentrations in the fly ash to increase significantly. The PCDD/F concentrations formed in the thermal reactions were about 99-139 times higher than the PCDD/F concentrations in the original fly ash, clearly indicating that fly ash promoted the formation of PCDD/Fs. The PCDFs dominated the PCDDs, and the PCDF/PCDD concentration ratio was about 30-40. Octachlorodibenzofuran (OCDF), octachlorodibenzo-p-dioxin, and the heptachlorodibenzofurans were the most dominant homologs that were formed. A comparison of the PCDD/F patterns produced in the thermochemical reactions and the patterns in the original fly ash suggested that the chlorination of less chlorinated PCDFs might be an important pathway in the formation of higher chlorinated furans. The results of this study indicated that SeCu fly ash has a high PCDD/F formation potential. It is crucial to have the fly ash filter at low temperature and that fly ash in the cooling system should be minimized.

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.

Bioaccessibility and health risk of heavy metals in ash from the incineration of different e-waste residues

Ash from incinerated e-waste dismantling residues (EDR) may cause significant health risks to people through ingestion, inhalation, and dermal contact exposure pathways. Ashes of four classified e-waste types generated by an incineration plant in Zhejiang, China were collected. Total contents and the bioaccessibilities of Cd, Cu, Ni, Pb, and Zn in ashes were measured to provide crucial information to evaluate the health risks for incinerator workers and children living in vicinity. Compared to raw e-waste in mixture, ash was metal-enriched by category incinerated. However, the physiologically based extraction test (PBET) indicates the bioaccessibilities of Ni, Pb, and Zn were less than 50 %. Obviously, bioaccessibilities need to be considered in noncancer risk estimate. Total and PBET-extractable contents of metal, except for Pb, were significantly correlated with the pH of the ash. Noncancer risks of ash from different incinerator parts decreased in the order bag filter ash (BFA) > cyclone separator ash (CFA) > bottom ash (BA). The hazard quotient for exposure to ash were decreased as ingestion > dermal contact > inhalation. Pb in ingested ash dominated (>80 %) noncancer risks, and children had high chronic risks from Pb (hazard index >10). Carcinogenic risks from exposure to ash were under the acceptable level (<10(-6)) both for children and workers. Exposure to ash increased workers' cancer risks and children's noncancer risks. Given the risk estimate is complex including toxicity/bioaccessibility of metals, the ways of exposure, and many uncertainties, further researches are required before any definite decisions on mitigating health risks caused by exposure to EDR incinerated ash are made.

Influence of mixture ratio and pH to solidification/stabilization process of hospital solid waste incineration ash in Portland cement

Solidification/stabilization (S/S) is an established utilization technology to treat hazardous wastes. This research explored the influence of pH (3-12) on the immobilization of heavy metals present in five mixtures of hospital solid waste incinerator ash and Portland cement, following two different processes of waste solidification/stabilization (cement hydration and granulation). In general, cement hydration process resulted in more stable products than granulation process. A high ash content in the mixture with Portland cement (60wt%) resulted in the highest immobilization of Pb(2+) and Cu(2+), while a low ash content in the mixture (10wt%) resulted in the lowest leachability of Zn(2+). When ash and Portland cement was mixed in equal proportions (50wt%) the highest encapsulation was observed for Ni(2+), Cd(2+) and Cr(3+). Neutral and weak alkaline pH values within the range pH=7-8 resulted in the lowest leachability of the monitored heavy metals.

Polychlorinated biphenyls in sediments and fish species from the Murchison Bay of Lake Victoria, Uganda

Polychlorinated biphenyls (PCBs) were determined in sediments and two fish species collected from the Murchison Bay in Lake Victoria, using high resolution gas chromatography coupled to a high resolution mass spectrometer. Total PCB concentrations (Σ18PCBs) varied widely with mean values ranging from 777 to 4325pg g(-1) dry weight (dw) for sediments and 80 to 779pg g(-1) wet weight (ww) for fish. The PCB levels in the sediments were significantly higher at the station closest to Nakivubo channel, presumably due to effluents discharged by the channel, which may contain domestically produced commercial PCB mixtures. For fish, the concentrations in Nile perch (Lates niloticus) were significantly greater than those in Nile tilapia (Oreochromis niloticus) at all study stations, possibly due to dietary differences among species. World Health Organization-toxic equivalents (WHO2005-TEQs) for the dioxin-like PCBs were 0.04-0.64pg g(-1) dw and 0.01-0.39pg g(-1) ww for sediments and fish, respectively. The non-ortho PCBs exhibited the highest contribution to the Σ12TEQs (>75%) compared to the mono-ortho PCBs in both fish species. The TEQs in the present study were lower than many reported worldwide in literature for fish and were within the permissible level recommended by the European Commission, implying that the fish did not pose health hazards related to PCBs to the consumers.

The environmental characteristics of usage of coal gangue in bricking-making: a case study at Huainan, China

The behaviors of natural radionuclides and toxic elements during coal gangue brick making processes are described. A simulation experiment of coal gangue brick firing was carried out to evaluate the enrichments of natural radionuclides and volatilizations of elements. Simultaneous sampling of coal gangue and corresponding combustion product (slag) was performed. The radioactivities of the radionuclide were determined by high-purity germanium gamma ray spectrometer, and the concentrations of toxic elements were analyzed by ICP-MS. Results have shown that the level of natural radionuclides may not cause immediate or acute environmental impacts because the Raeq values and Hex (in the brick) are 345 Bq kg(-1) and 0.89, lower than the limit values of 370 Bq kg(-1) and 1, respectively. However, the Raeq and Hex values are near the limit values, their chronic-environmental and health impacts should be considered noteworthy. The elements found in the emission could be categorized into two types: non-volatilized elements (Co, Cr, Mn and V) and volatilized elements (As, Cd, Cu, Ni, Se, Sn and Zn). Understanding the behaviors of natural radionuclides and toxic elements during brick making processes is helpful for the assessment of their potential impacts to human health and the environment.

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.

Characterization of bottom ash from two hospital waste incinerators in Rabat, Morocco

The uncontrolled disposal of bottom ash generated by the incineration units of hazardous and infected wastes in developed countries are the main cause of significant damage, such as contamination of the soil, as well as surface and underground waters, which may put both the environment and public health at risk. In Morocco, little information is available on the chemical properties of the resulting ashes. In this study, 16 hospital waste ash samples were collected from the incinerators of the two main hospitals in Rabat: Ibn Sina and Cheikh Zayd. A series of tests was conducted, including particle size distribution, mineralogical and chemical composition, and heavy metal leaching behaviour. The results showed that the samples were composed mainly of P2O5 (18%), SiO2 (17%), Na2O (16%), CaO (14%) and SO3 (10%). Moreover, chemical analysis clearly demonstrated that medical waste (MW) contains large amounts of waste generated by domestic activities in the hospital, with a lack of sorting system in the monitoring of MW. Furthermore, the ashes contained high concentrations of heavy metals such as zinc, lead, chromium and nickel with a vast range of 0.5-25071 mg/kg. Leaching tests showed that the extracted amounts of all the heavy metals were lower, with concentrations < 2.85 mg/kg. Comparison of the corresponding heavy metal concentrations with the limit values set by the Council Decision 2003/33/EC allowed us to conclude that bottom ashes meet the waste acceptance criteria regarding these heavy metals.

Metabolomic profiling of in vivo plasma responses to dioxin-associated dietary contaminant exposure in rats: implications for identification of sources of animal and human exposure

Dioxin contamination of the food chain typically occurs when cocktails of combustion residues or polychlorinated biphenyl (PCB) containing oils become incorporated into animal feed. These highly toxic compounds are bioaccumulative with small amounts posing a major health risk. The ability to identify animal exposure to these compounds prior to their entry into the food chain may be an invaluable tool to safeguard public health. Dioxin-like compounds act by a common mode of action and this suggests that markers or patterns of response may facilitate identification of exposed animals. However, secondary co-contaminating compounds present in typical dioxin sources may affect responses to compounds. This study has investigated for the first time the potential of a metabolomics platform to distinguish between animals exposed to different sources of dioxin contamination through their diet. Sprague-Dawley rats were given feed containing dioxin-like toxins from hospital incinerator soot, a common PCB oil standard and pure 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) (normalized at 0.1 μg/kg TEQ) and acquired plasma was subsequently biochemically profiled using ultra high performance liquid chromatography (UPLC) quadropole time-of-flight-mass spectrometry (QTof-MS). An OPLS-DA model was generated from acquired metabolite fingerprints and validated which allowed classification of plasma from individual animals into the four dietary exposure study groups with a level of accuracy of 97-100%. A set of 24 ions of importance to the prediction model, and which had levels significantly altered between feeding groups, were positively identified as deriving from eight identifiable metabolites including lysophosphatidylcholine (16:0) and tyrosine. This study demonstrates the enormous potential of metabolomic-based profiling to provide a powerful and reliable tool for the detection of dioxin exposure in food-producing animals.

Study of PCDD/Fs distribution in fly ash, ash deposits, and bottom ash from a medical waste incinerator in China

Over the past decades in China, the number of medical waste incinerators (MWIs) has been rising rapidly, causing emissions of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). In this study, samples of fly ash, ash deposits, and bottom ash from typical MWIs were analyzed for PCDD/Fs and their distribution characteristics. Results showed international toxic equivalent (I-TEQ) values in the range of 6.9-67 ng I-TEQ/g in fly ash and ash deposits, whereas the concentration in bottom ash was extremely low (only 1.33 pg I-TEQ/g), yet the generation of PCDD/Fs was mostly de novo synthesis in fly ash and ash deposits according to the ratio of PCDFs to PCDDs; the major distribution differences of PCDD/Fs in fly ash was manifested by the content of toxic furan 2,3,7,8-TCDF but other toxic PCDD/Fs showed similar distribution. Other findings are that 2,3,4,7,8-PeCDF had the most contribution to TEQ concentration, and that the most abundant toxic furan congener is 1,2,3,4,6,7,8-HpCDF. Correlation analysis showed that there was no significant correlation between PCDD/Fs concentration and several other physical and chemical parameters.

IMPLICATIONS

This paper is of interest because it presents the emission performances of PCDD/Fs in ash from medical waste incineration in China. PCDD/F contents in fly ash and ash deposits vary between 6.9 and 67.3 ng I-TEQ/g. However, the concentration in bottom ash was extremely low (only 1.33 x 10(-3) ng I-TEQ/g). The fingerprints of PCDD/Fs in fly ash are almost similar, except for 2,3,7,8-TCDF. There is no marked correlation between PCDD/Fs and other physicochemical properties.

Severe pollution of PCDD/Fs and dioxin-like PCBs in sediments from Lake Shihwa, Korea: tracking the source

Concentrations of polychlorinated dibenzo-p-dioxins, dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (DL-PCBs) were determined in surface sediments from Lake Shihwa and from creeks that discharge into this artificial lake. The toxic equivalents (TEQs) in sediments ranged from 1.0 to 1770 pg/g dry weight, which were some of the highest values ever reported so far for coastal sediments on a global basis. The concentrations of PCDD/Fs and DL-PCBs decreased with increasing distance from the creeks to offshore regions of the lake. Based on a multivariate statistical analysis and congener profiles, it was found that high contamination by PCDD/Fs in creek sediments collected around Lake Shihwa was associated with releases from chlor-alkali processes. Significant correlations were found for total organic carbon content and the concentrations of highly chlorinated PCDD/F congeners. This is the first report to document chlor-alkali processes as a significant source of PCDD/F contamination in Korean coastal waters.

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.

Emission characteristics of heavy metals and their behavior during coking processes

Besides organic pollutants, coke production generates emissions of toxic heavy metals. However, intensive studies on heavy metal emissions from the coking industry are still very scarce. The current work focuses on assessing the emission characteristics of heavy metals and their behavior during coking. Simultaneous sampling of coal, coke, residues from air pollution control devices (APCD), effluent from coke quenching, and fly ash from different processes before and after APCD has been performed. The total heavy metal concentration in the flue gas from coke pushing (CP) was significantly higher than that from coal charging (CC) and combustion of coke oven gases (CG). Emission factors of heavy metals for CP and CC were 378.692 and 42.783 μg/kg, respectively. During coking, the heavy metals that were contained in the feedstock coal showed different partitioning patterns. For example, Cu, Zn, As, Pb, and Cr were obviously concentrated in the inlet fly ash compared to the coke; among these metals Cu, As, and Cr were concentrated in the outlet fly ash, whereas Zn and Pb were distributed equally between the outlet fly ash and APCD residue. Ni, Co, Cd, Fe, and V were partitioned equally between the inlet fly ash and the coke. Understanding the behavior of heavy metals during coking processes is helpful for the effective control of these heavy metals and the assessment of the potential impact of their emissions on the environment.

Solidification/stabilization of fly and bottom ash from medical waste incineration facility

In the present work, the stabilization/solidification of fly and bottom ash generated from incinerated hospital waste was studied. The objectives of the solidification/stabilization treatment were therefore to reduce the leachability of the heavy metals present in these materials so as to permit their disposal in a sanitary landfill requiring only a lower degree of environmental protection. Another objective of the applied treatment was to increase the mechanical characteristics of the bottom ash using different amounts of Ordinary Portland Cement (OPC) as a binder. The solidified matrix showed that the cement is able to immobilize the heavy metals found in fly and bottom ash. The TCLP leachates of the untreated fly ash contain high concentrations of Zn (13.2 mg/l) and Pb (5.21 mg/l), and lesser amounts of Cr, Fe, Ni, Cu, Cd and Ba. Cement-based solidification exhibited a compressive strength of 0.55-16.12 MPa. The strength decreased as the percentage of cement loading was reduced; the compressive strength was 2.52-12.7 MPa for 60% cement mixed with 40% fly ash and 6.62-16.12 MPa for a mixture of 60% cement and 40% bottom ash. The compressive strength reduced to 0.55-1.30 MPa when 30% cement was mixed with 70% fly ash, and to 0.90-7.95 MPa when 30% cement was mixed with 70% bottom ash, respectively.

Does consumption of leafy vegetables grown in peri-urban agriculture pose a risk to human health?

Concentrations of potentially toxic elements were measured in soils and five contrasting tropical leafy vegetables grown in a replicated field trial at five contaminated urban agriculture sites in Kampala City, Uganda. Soil contamination at each site could be tentatively ascribed to known waste disposal practices. There was considerable variation in metal uptake between vegetable types. Washing leafy vegetables reduced chromium and lead concentrations but exogenous contamination of leaves also depended on vegetable type, with Gynandropsis gynandra L. showing a marked tendency to accumulate Pb and Cr. For the worst case scenario of children consuming unwashed vegetables, some metal 'hazard quotient' (HQ) limits (1.0) were violated at four of the five sites studied. For the 25 'site-vegetable' combinations assessed, the HQ for Pb exceeded 1.0 in 36% of cases. A vegetable-specific site screening tool based on soil extraction with 0.01 M CaCl(2) and extrapolation to provide HQ values was assessed.

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

Bottom and fly ash samples (BASH and FASH) from the APOTEFROTIRAS S.A. medical waste incinerator (Athens, Greece) were investigated. Powder-XRD data and geochemical diagrams showed BASH to be an amorphous material, analogous to basaltic glass, and FASH consisting of crystalline compounds (mainly CaClOH). Bulk analyses by ICP-MS and point analyses by SEM-EDS indicated a high content of heavy metals, such as Fe, Cu and Cr, in both samples. However, BASH was highly enriched in Ni while FASH was additionally enriched in Zn and Pb. Gamma-ray measurements showed that the radioactivity of both ash samples, due to natural and artificial radionuclides ((137)Cs, (57)Co), was within the permissible levels recommended by IAEA. According to EN-type leaching tests, BASH was practically inert with regard to the mobility of the hazardous elements in aqueous media. FASH, however, showed a relatively high EN (and TCLP) leachability with regard to Pb and Zn. Finally, the stabilisation method, suggested for the treatment of FASH, included compression of the powder into briquettes using an appropriate machine and embedding the briquettes into pozzolanic cement blocks. After this treatment, TCLP and EN-type tests showed minimal release of Pb and Zn, thereby demonstrating a reliable management of ash waste.

Estimation and characterization of PCDD/Fs and dioxin-like PCBs from Chinese iron foundries

The iron foundry industry is considered to be a potential source of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). This study investigated the emission factors and total emission amounts of PCDD/Fs and dioxin-like polychlorinated biphenyls (DL-PCBs) from iron foundries in China. The concentrations and the World Health Organization toxicity equivalents (WHO-TEQs) are presented and the congener profiles are discussed in this paper. In the present work, 26 fly ash samples were collected and tested to quantify the PCDD/Fs and DL-PCBs generated by 14 plants of different scales, and five stack gas samples were collected from two (named as EFG and LFG) of those plants. The emission levels of PCDD/Fs and DL-PCBs indicated that hot-air cupolas had lower emissions than cold-air cupolas. When iron ore lump and sinter were used as raw material, the emission factors were about 250ng TEQt(-1) of product. However, if the raw material was scrap, the emission factors varied owing to the different contents of organic materials in the raw materials. It was found that the mean WHO-TEQ values of PCDD/Fs and DL-PCBs were 144 and 34.2pgNm(-3) in stack gas and 20.0 and 1.58pgg(-1) in fly ash. In multiple tests, it was estimated that the mean emission factors of PCDD/Fs and DL-PCBs were 365 and 10.9ng WHO-TEQt(-1) released to residue and 2719 and 555ng TEQt(-1) released to air. The total emission amounts of PCDD/Fs and DL-PCBs from Chinese iron foundries with cupola furnaces released to residue and air were 16.8 and 146g WHO-TEQ in 2008, respectively.