Hazardous Waste Incinerator Research Articles

Study connective capabilities of solid residues from the waste incineration

Currently there is increasingly closer interaction between the importance of environmental protection and efficient promoting of scientific and technological progress in the field of waste incineration. Waste is not only undesirable source of pollution, but if it is effectively used it also has great economic importance. In the Czech Republic 34.5 million tonnes of all wastes was produced in 2017, of which 5.7 million tonnes of municipal waste. 50% of the produced municipal waste was used, 38% of which was used for the material and 12% for energy utilization. 45% of municipal waste was deposited in the landfills. The method of waste incineration is among the major tools to reduce the landfill waste. The use or processing of the product which the process of incineration of municipal and hazardous waste generated can be considered as an obstacle to the favorable reception of this process. Apart from flammable components, waste also contains certain amount of dangerous particles. This is especially the sulfur chlorides, fluorine, PCBs and other heavy decomposable organic substances and heavy metals. This fact puts high demands on the gas cleaning processes followed by neutralization of other products that the incinerator leaves, in which these substances can be contained in higher concentrations than in the original waste. For this reason subsequent stabilization of these toxic substances is necessary to ensure new environmental burdens are avoided when not used properly. The major part of the waste combustion process is made up of ash and slag. One of the most common ways of dealing with these solid residues is disposing them to avoid creating new hazardous waste landfills. Other filtering waste also passes hazardous waste stabilization process before landfilling. Currently there is intensive search for new possibilities for utilization of solid residues from incineration. Nowadays there is emphasis on process control of their pretreatment for the production of draft procedure with its management. Appropriate procedures may minimize the instances of improper use.

Release of Trace Elements from Bottom Ash from Hazardous Waste Incinerators

Bottom ash is the major by-product of waste incineration and can contain trace elements (As, Cd, Co, Cu, Cr, Mo, Ni, Pb, and Zn) with concentrations up to thousands of mg·k−1. In this study, a combination of different extractions and leaching tests (i.e., CH3COOH and ammonium-EDTA (Ethylenediaminetetraacetic acid) extractions and pHstat leaching tests) was used to investigate the potential release of trace elements from bottom ash samples derived from hazardous waste incineration plants. Although large variations have been found in the release of trace elements by different extractions, in general, the highest concentrations of most trace elements (except As and Mo) were released with the CH3COOH extraction, whereas the release of As and Mo was highest with the ammonium-EDTA extraction. Kinetics of element release upon acidification based on a pHstat leaching test at pH 4 could be related to the solid-phase speciation of some selected trace elements. The relatively high-potential mobility and elevated total concentrations of some trace elements imply a threat to the environment if these bottom ashes are not treated properly. Results of the present study may be useful to develop potential treatment strategies to remove contaminants and eventually recover metals from bottom ash.

Concentrations of PCDD/Fs in the neighborhood of a hazardous waste incinerator: human health risks.

In 1996-1998, a wide surveillance program was initiated in the vicinity of a new hazardous waste incinerator (HWI) placed in Constantí (Catalonia, Spain), which started its regular operations in 1999. The program was aimed at assessing the environmental impact of the facility on the surrounding environment, as well as to evaluate the potential risks for the population living in the neighborhood. Since then, among other measurements, the concentrations of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) have been periodically determined in soil and herbage samples. This study shows the results, corresponding to the period 2013-2016. Data were compared with those obtained in the baseline survey (1996-1998), as well as with those of the previous survey (2011-2012). The median PCDD/F concentrations in soils were 0.44 and 0.33ngtoxic equivalent (I-TEQ)/kg in 2015 and 2016, respectively, with a significant decrease in relation to the baseline survey, and a non-significant decrease between 2015 and 2016. In turn, PCDD/F levels in vegetation showed some fluctuations over time, being the concentrations of PCDD/Fs in 2013 very similar to those found in 2012 (1.11 and 1.23ngI-TEQ/kg, respectively). These concentrations notably decreased along the three last campaigns (0.16, 0.23, and 0.17ngI-TEQ/kg in 2014, 2015, and 2016, respectively). These changes would be more related to a number of environmental factors rather than to a variation of PCDD/F emissions by the HWI. With respect to human health risks, exposure to PCDD/Fs in the area under potential influence of the HWI is not of concern, as the current environmental concentrations of PCDD/Fs do not mean additional carcinogenic or non-carcinogenic risks for the local population.

Comprehensive diagnosis of PCDD/F emission from three hazardous waste incinerators.

Comprehensive diagnosis of polychlorinated dibenzo-p-dioxin and dibenzofuran (PCDD/F) emissions was systematically conducted on three hazardous waste incinerators (HWIs). Results indicated that PCDD/F mainly existed in the solid phase before the bag filter. This was especially true for higher chlorinated dioxin and furan congeners (hexa-, hepta- and octa-). The aged bag filters tended to increase the gas-phase PCDD/F. Emissions also increased due to PCDD/F desorption from circulated scrubbing solution and plastic packing media used in the wet scrubber. The PCDD/F concentrations were elevated during the start-up process, reaching up to 5.4 times higher than those measured during the normal operating period. The ratios of PCDFs/PCDDs revealed that the surface-catalysed de novo synthesis was the dominant pathway of PCDD/F formation. Installation of more efficient fabric filters, intermittent replacement of circulated scrubbing solution will result in reduced PCDD/F emission. Additionally, 2,3,4,7,8-PeCDF correlated well with the international toxic equivalent quantity (I-TEQ) value, which suggests that 2,3,4,7,8-PeCDF could act as an I-TEQ indicator.

Distribution and leaching characteristics of heavy metals in a hazardous waste incinerator

In this study, distribution and leaching characteristics of heavy metals (As, Cd, Cr, Cu, Pb, Se, Zn, and Hg) along flue gas cleaning systems were investigated in a hazardous waste incinerator located in Zhejiang, China. The particle size distribution, heavy metal loading, and morphological and mineralogical characteristics of solid incineration residues were assessed before and after acetic acid extraction. Results showed that Hg, Cd, As, Pb, and Zn were transmitted into the fly ash mainly by evaporation, condensation, and adsorption, while Se and Cr were mainly by entrainment. High chlorine availability in the industry hazardous waste favored the evaporation of Cu, Pb and Zn. Due to the mass ratio of the bottom slag in the incineration residues being more than 52%, most of Cu, Cr, As, and Zn remained in the bottom slag. Scarcely any Hg and less than 9.6% of Cd were found in the bottom slag. Cd was mainly retained in the fly ash and the absorbent solution of the wet flue gas desulfurization (WFGD) system while most of Pb was found in the fly ash. WFGD system had a high Hg removal efficiency and more than 74.7% of Hg was retained in the absorbent solution of WFGD system. The distinction in the distribution and migration characteristics of heavy metals between two continuous operating conditions was mainly due to the different physicochemical properties of wastes. The studied heavy metals in the bottom slag, with the exception of Zn, showed low leachability, with a leaching ratio below 2%. Cd and Zn presented the highest leachability, and over 56.2% of Cd and more than 39.5% of Zn in the fly ash were transferred into the leachate. For the each studied heavy metal, the leaching ratio in the bag filter ash was the highest.

Stabilization of Cr-rich tannery waste in fly ash matrices.

In the present work, the stabilization/solidification of a Cr-rich ash obtained from the anoxic incineration of tannery hazardous wastes was studied. Chromium in the starting waste was exclusively in amorphous form and in trivalent state. The waste was embedded in fly ash-based cementitious material matrices. Calcium and sodium hydroxides, as well as sodium silicate, were used as activators. The proposed process combines mechanical activation with hydrothermal curing. Successful immobilization of chromium was achieved, as attested by standard leaching tests. Backscattered electron images revealed the existence of the C-S-H gel, and elemental mapping by energy dispersive X-ray spectroscopy showed a good interdispersion of chromate and aluminosilicate species, verifying that chromium was well distributed in the final amorphous cementitious matrix. X-ray diffraction confirmed the absence of Cr-rich crystalline phases of calcium aluminosilicates, where chromium can enter in hexavalent state. The stiffness of the stabilized samples was reduced with increasing the amount of added Cr-rich ash, as attested by measurements of the dynamic Young's modulus.

Mercury Involvement in Neuronal Damage and in Neurodegenerative Diseases.

Neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis, and multiple sclerosis are characterized by a chronic and selective process of neuronal cell death. Although the causes of neurodegenerative diseases remain still unknown, it is now a well-established idea that more factors, such as genetic, endogenous, and environmental, are involved. Among environmental causes, the accumulation of mercury, a heavy metal considered a toxic agent, was largely studied as a probable factor involved in neurodegenerative disease course. Mercury exists in three main forms: elemental mercury, inorganic mercury, and organic mercury (methylmercury and ethylmercury). Sources of elemental mercury can be natural (volcanic emission) or anthropogenic (coal-fired electric utilities, waste combustion, hazardous-waste incinerators, and gold extraction). Moreover, mercury is still used as an antiseptic, as a medical preservative, and as a fungicide. Dental amalgam can emit mercury vapor. Mercury vapor, being highly volatile and lipid soluble, can cross the blood-brain barrier and the lipid cell membranes and can be accumulated into the cells in its inorganic forms. Also, methylmercury can pass through blood-brain and placental barriers, causing serious damage in the central nervous system. This review describes the toxic effects of mercury in cell cultures, in animal models, and in patients with neurodegenerative diseases. In vitro experiments showed that mercury exposure was principally involved in oxidative stress and apoptotic processes. Moreover, motor and cognitive impairment and neural loss have been confirmed in various studies performed in animal models. Finally, observational studies on patients with neurodegenerative diseases showed discordant data about a possible mercury involvement.

Emission characteristics and vapour/particulate phase distributions of PCDD/F in a hazardous waste incinerator under transient conditions.

Polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofuran (PCDD/F) emission characteristics and vapour/particulate phase partitions under three continued operation conditions, i.e. shut-down, start-up and after start-up, were investigated by sampling stack gas. The results indicated that the PCDD/F emission levels were 0.40–18.03 ng I-TEQ Nm−3, much higher than the annual monitoring level (0.016 ng I-TEQ Nm−3). Additionally, the PCDD/F emission levels in start-up were higher than the other two conditions. Furthermore, the PCDD/F congener profiles differed markedly between shut-down and start-up, and the chlorination degree of PCDD/F increased in shut-down and decreased evidently in start-up. Moreover, PCDD/F vapour/particulate phase distributions varied significantly under three transient conditions. The PCDD/F vapour phase proportion decreased as the shut-down process continued, then increased as the start-up process proceeded, finally more than 98% of the PCDD/F congeners were distributed in the vapour phase after start-up. The correlations between log(Cv/Cs) versus of each PCDD/F congener in stack gas were disorganized in shut-down, and trend to a linear distribution after start-up. Besides, polychlorinated biphenyl emissions show behaviour similar to that of PCDD/F, and the lower chlorinated congeners have a stronger relationship with 2,3,7,8-PCDD/Fs, such as M1CB and D2CB.

Effect of recycled polyethylene on storability of hazardous waste incinerator fly ashes: Towards a new composite material

Effect of recycled polyethylene on storability of hazardous waste incinerator fly ashes: Towards a new composite material

Life-cycle environmental and economic assessment of medical waste treatment

The environmental and economic impacts of three medical waste disposal scenarios (i.e., pyrolysis, steam sterilization, and chemical disinfection) were quantified via a cost-coupled life cycle assessment to quantify the effective technique for medical waste disposal. Results show that steam sterilization and chemical disinfection scenarios exhibit the highest overall environmental and lowest economic impacts, respectively, because of the differences in energy consumption. The overall economic burden is attributed to the cost of investment, labor, electricity, and human health protection for each scenario, whereas the environmental burden comes from energy and chemical production processes. The contribution of hydrogen chloride emission to the overall environmental burden is relatively low, although the direct hydrogen chloride emission is significantly higher when generated from medical waste pyrolysis than from municipal solid waste and industrial hazardous waste incineration. However, opposite results are observed for direct mercury emission. Effective measures to reduce the environmental burden include improving electricity and diesel consumption efficiency, reducing the use of chemicals (e.g., sodium hydroxide, lime, and chlorine oxide), selecting clean energy, and providing medical waste incineration with energy recovery. Similarly, effective measures to reduce the economic impact include optimizing labor and investment costs and electricity consumption.

Source contributions to total concentrations and carcinogenic potencies of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) in ambient air: a case study in Suzhou City, China.

The potential source categories and source contributions of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) in ambient air from Suzhou City, China, were performed by principal component analysis-multiple linear regression (PCA-MLR) and positive matrix factorization (PMF). The carcinogenic potencies of PCDD/Fs were quantitatively apportioned based on the positive matrix factorization-toxic equivalent concentration (PMF-TEQ) method. The results of the present study were summarized as follows. (1) The total concentrations and toxic equivalent concentrations of PCDD/Fs (∑PCDD/Fs and TEQ) in ambient air from Suzhou City were 1.34-42.80pg Nm-3 and 0.081-1.22pg I-TEQ Nm-3, respectively. (2) PCA-MLR suggested that industrial combustion (IC), electric arc furnaces (EAFs) and secondary aluminum smelters (ALSs), unleaded gas-fueled vehicle sources (UGFVs), ALSs, and hazardous solid waste incinerators (HSWIs) could be the primary PCDD/F contributors, accounting for 13.2, 16.7, 35.5, 19.4, and 15.2% of ∑PCDD/Fs, respectively. (3) PMF and PMF-TEQ indicated that EAFs (carbon steel), UGFVs, IC, ALSs, municipal solid waste incinerators (MSWIs) and hospital waste incinerators (HWIs), and HSWIs contributed 10.9, 10.9, 42.8, 11.3, 10.7, and 13.4% to ∑PCDD/Fs, but contributed 8.3, 12.3, 50.3, 12.7, 6.0, and 10.4% to carcinogenic potencies of PCDD/Fs. This study was the first attempt to quantitatively apportion the source-specific carcinogenic potencies of PCDD/Fs in ambient air.

Impact of air manganese on child neurodevelopment in East Liverpool, Ohio

BackgroundEast Liverpool, Ohio, the site of a hazardous waste incinerator and a manganese (Mn) processor, has had air Mn concentrations exceeding United States Environmental Protection Agency reference levels for over a decade. Save Our County, Inc., a community organization, was formed to address community environmental health concerns related to local industry. Researchers from the University of Cincinnati partnered with Save Our County to determine if air Mn had an impact on the neurocognitive function of children in the community. MethodsChildren 7–9 years of age from East Liverpool and its surrounding communities, were enrolled (N=106) in the Communities Actively Researching Exposure Study from between March 2013–June 2014. Blood and hair were analyzed for Mn and lead, and serum was analyzed for cotinine. We used linear regression to assess associations between biological measures and IQ subscale scores. ResultsGeometric mean blood lead (n=67), blood Mn (n=66), hair Mn (n=98), and serum cotinine (n=69) concentrations were 1.13±1.96μg/dL, 10.06±1.30μg/L, and 360.22±2.17ng/g, 0.76±6.12μg/L respectively. After adjusting for potential confounders, hair Mn was negatively associated with Full Scale IQ. ConclusionsHair Mn was negatively associated with child IQ scores. Community partners were instrumental in the conception and implementation of this study.

Behaviour of engineered nanoparticles in a lab-scale flame and combustion chamber

Nanostructured materials are widely used to improve the properties of consumer products such as tires, cosmetics, light weight equipment etc. Due to their complex composition these products are hardly recycled and thermal treatment is preferred. In this study we investigated the thermal stability and material balance of nanostructured metal oxides in flames, in a pilot scale combustion plant and an industrial hazardous waste incinerator. We studied the size distribution of nanostructured metal oxides (CeO2, TiO2, SiO2) in a flame reactor and in a heated reaction tube. In the premixed ethylene/air flame, nano-structured CeO2 partly evaporates forming a new particle mode. This is probably due to chemical reactions in the flame. In addition sintering of agglomerates takes place in the flame. In the electrically heated reaction tube however only sintering of the agglomerated nanomaterials is observed. Ceria has a low background in waste incinerators and is therefore a suitable tracer for investigating the fate of nanostructured materials. Low concentrations of Ceria were introduced by a two-phase nozzle into the post-combustion zone of a waste incinerator. By the incineration of coal dust in a burning chamber the Ceria nanoparticles are mainly found in the size range of the fly ash (1 – 10 µm) because of agglomeration. With gas as a fuel less agglomeration was observed and the Ceria nanoparticles were in the particle size range below 1 µm.

PCDD/F emissions during startup and shutdown of a hazardous waste incinerator

Compared with municipal solid waste incineration, studies on the PCDD/F emissions of hazardous waste incineration (HWI) under transient conditions are rather few. This study investigates the PCDD/F emission level, congener profile and removal efficiency recorded during startup and shutdown by collecting flue gas samples at the bag filter inlet and outlet and at the stack. The PCDD/F concentration measured in the stack gas during startup and shutdown were 0.56–4.16 ng I-TEQ Nm−3 and 1.09–3.36 ng I-TEQ Nm−3, respectively, far exceeding the present codes in China. The total amount of PCDD/F emissions, resulting from three shutdown-startup cycles of this HWI-unit is almost equal to that generated during one year under normal operating conditions. Upstream the filter, the PCDD/F in the flue gas is mainly in the particle phase; however, after being filtered PCDD/F prevails in the gas phase. The PCDD/F fraction in the gas phase even exceeds 98% after passing through the alkaline scrubber. Especially higher chlorinated PCDD/F accumulate on inner walls of filters and ducts during these startup periods and could be released again during normal operation, significantly increasing PCDD/F emissions.

New hazardous waste incinerator comes on-line

At the end of 2016, for the first time in two decades, a new commercial hazardous waste incinerator built in the U.S. came on-line. The $120 million incinerator, operated by Clean Harbors in El Dorado, Ark., can handle industrial and laboratory chemicals, manufacturing by-products, medical waste, and other solid and liquid materials. “As all chemists know, you can’t destroy or create matter,” says Scot Shoemaker, the company’s vice president for engineering and operations. “But you can change its form into something less toxic, and that’s something that incinerators do very effectively.” After the U.S. passed the Resource Conservation & Recovery Act—the primary law governing disposal of hazardous waste—in 1976, commercial waste handlers spent 20 years building hazardous waste incinerators to the point of overcapacity. Demand is only now catching up to capacity, leading to the need for a new incinerator, says Shoemaker, who has a bachelor’s degree in chemistry and

Disposal of bottom ash from the incineration of hazardous waste in two different mineral matrixes

In this study four incineration residues (bottom ash), classified as hazardous wastes on the basis of a leaching test, have been investigated. Analysis of the chemical composition proved to have high contents of heavy metals that during storage could potentially be released into the environment. Therefore, the waste has been subjected to solidification/stabilization (i.e., one of the methods of immobilization of heavy metals) in two ways: with Portland cement and alkali‐activated granulated blast furnace slag. It was assumed that bottom ashes will constitute 30% by weight of the dry ingredients. It has been found that although the amount of heavy metals introduced into a matrix along with the mineral waste is significant, the increase in elution of heavy metal ions in the environment is not a consequence. The use of bottom ash from the incineration of hazardous waste may even limit the release of heavy metal ions from cementitious materials. © 2017 American Institute of Chemical Engineers Environ Prog, 36: 1074–1082, 2017

Characterization of PCDD/Fs in a Shut-Down Period of a Hazardous Waste Incinerator

ABSTRACTIn this study, a shut-down period of a hazardous waste incinerator was considered as two separate phases: the last waste feeding phase and the first cooling phase. Solid, liquid, and gas samples were taken separately for the two phases. Analysis results of the samples were used to compare PCDD/F characteristics of the phases. Additionally, start-up PCDD/F results of the same facility published in some previous studies were used in assessments. The findings showed that congener profiles of the shut-down and the start-up periods were highly similar. On the other hand, concentration levels of the shut-down phases, which indicate an intense memory effect for PCDD/Fs, were lower than the corresponding start-up phases. Furthermore, furan/dioxin ratios and PCDD/F removal efficiencies obtained in the shut-down period were substantially different from the start-up. Therefore, according to the author, it seems like an obligation to perform period-specific management strategies in start-up and the shut-down periods of incinerators.

Corrosion of Al2O3-SiO2 refractories by sodium and sulfur vapors: A case study on hazardous waste incinerators

While incinerators are important for eliminating hazardous waste from industry, there are few publications on the corrosion of secondary combustion chambers. The sudden refractory failure results in high costs and work stoppages. Thus, corrosion in fireclay and bauxite-clay refractories exposed for 50 months to the harsh atmosphere in the chamber (H2O, O2, CO2, SO2, HCl, alkali vapors, etc.) was investigated. The operating temperatures of 930–1000°C heat the inner refractory face up to 950°C and the exterior face to 750°C. X-ray diffraction revealed that condensed alkali and sulfur compounds interacted with refractories. Thermodynamic calculations determined the critical chemical reactions. Our findings show a successive corrosion mechanism that starts with the condensation of thenardite (Na2SO4) and finishes with expansive phases. In fireclay bricks, the reaction with free silica led to liquid phases and slow creep. Sudden lining breakdowns were provoked by nepheline and nosean. Contrary to expectations, nepheline was not formed in the bauxite-clay bricks. Instead, only nosean was formed. In the literature, under laboratory conditions, no nosean has been observed in hot corrosion experiments. Perhaps, nosean requires several months to years to form inside the secondary combustion chamber. Our work indicates that to impede these corrosion processes, refractories should contain as little silica as possible.

Preparation of HCl Gas Sorbent from Paper Sludge

Paper sludge (PS) is generated as an industrial waste during the manufacture of recycled paper products, and amounts discharged globally are increasing annually. On the other hands, hydrogen chloride (HCl) is an acidic pollutant that is present in the flue gases of most municipal and hazardous waste incinerators. In this study, the removal of hydrogen chloride gas using the product from paper sludge at high temperatures (700oC) using a fixed-bed flow-type reactor was investigated. PS can be granulated with distilled water using granulators, and the particle shapes can be kept after calcination and alkali reaction. Calcined PS and the product after alkali reaction of calcined PS have amorphous phases and katoite (Ca3Al2(SiO4)(OH)8) phase, respectively, and both of these indicate HCl removal ability at high temperature (700oC). The product from calcined PS via alkali reaction has higher HCl fixation ability (78 mg/g) than calcined PS. Removal experiments for HCl gas showed that the removal process followed pseudo-second-order kinetics rather than pseudo-first-order kinetics. These results suggested that the product particles with HCl gas removal ability at high temperature can be prepared from PS using calcination and alkali reaction.

PCDD/F contamination on surface soil in the vicinity of a hazardous waste incinerator: is it possible a different trend?

This study is the first to investigate the contamination of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) on surface soils in the vicinity of the first hazardous waste incinerator of Turkey. In the study, 24 soil samples were taken from a 1625-m-radius circle whose center is the stack of the incinerator. This process was repeated 1year later. Since the acquired average PCDD/F concentrations of the two sampling campaigns (0.05 and 0.02ng WHO-toxic equivalent (TEQ)/kg) were meaningfully low compared to the related literatures, a new sampling campaign was carried out to control this inconsistency, but this time in a foreign laboratory (0.56ng WHO-TEQ/kg). In the same period, eight gas samples were taken from the stack under different operational conditions of the facility. According to the evaluations of the findings, the geographical-meteorological data of the study area and the specific operational conditions of the facility corroborate the concentrations of the first and the second soil samplings rather than the third one. The major underlying reason for the inconsistency of the soil concentrations may be the fact that the data analysis procedures used by the laboratories are different. The author suggests a hypothesis which argues that the soils in the vicinity of a hazardous waste incinerator may have significantly lower concentration levels than in related literatures.