Thermal Waste Treatment Research Articles

Levulinic acid production through two-step acidic and thermal treatment of food waste using dilute hydrochloric acid

This research investigated the concept of a two-step acidic and thermal treatment for glucose extraction and levulinic acid (LA) production from food waste using dilute hydrochloric acid (DHA) as a catalyst, and subsequently analyzed the properties of the resulting humins. Glucose extraction was performed under various reaction conditions (reaction temperature range: 120-190 °C, DHA concentration range: 0.2-0.5% v/v); the glucose extraction yield of the acidic treatment step reached 83.17% under the optimal conditions (150 °C in 0.5% DHA). LA production was achieved during the thermal treatment step, which was investigated using two independent experiments to determine the influence of the reaction conditions (reaction time: 5-140min, concentration factor: 1.5-3.0, reaction temperature: 160-190 °C). The LA production process was affected by the concentration factor and the reaction temperature due to the low pH of solution and the rapid reaction rate, respectively. The thermal stability of the humins was highest at a concentration factor of 3.0 because of the 13.07 C/H ratio of the humins.

Environmental and economic assessment of Enhanced Landfill Mining in Tehran.

Landfilling brings many difficulties such as leaching of hazardous substances, methane gas production, loss of land, and natural resources such as groundwater, soil, and minerals. Enhanced landfill mining (ELFM) gives an opportunity to deal with such related problems. This study aimed to assess the environmental performance of ELFM through the application of life cycle assessment (LCA). SimaPro (v 8.5) was utilized to model the consequential life cycle assessment. Moreover, a comprehensive cost-benefit analysis was applied to assess the economic performance along with the Monte Carlo simulation to address the related uncertainties. In addition, the indicator of net present value (NPV) was adopted to understand the economic feasibility of the project. The case study landfill was the closed 55-hectare dumpsite of the municipality of Tehran in Kahrizak due to the need for further landfilling space in the future. The results of this study indicated that ELFM could lead to remarkable environmental benefits compared with the landfill's current status (the do-nothing scenario). The ELFM project reduced the impact of global warming by 1,759,790 ton CO2 eq, equaling to 134% reduction in comparison with the do-nothing scenario. Moreover, the potential profitability of the project was calculated to be 370 million $. Among the processes, recycling and thermal treatment of waste significantly dominated the environmental results of the project. Although the research was based on a case study landfill, the methodology can be applied to similar projects worldwide.

The use of fly ashes from waste-to-energy processes as mineral CO2 sequesters and supplementary cementitious materials

This study explores the simultaneous application of fly ash (FA) generated from the thermal treatment of municipal solid waste as a CO2 sequester through aqueous mineral carbonation and as a supplementary cementitious material (SCM) for the development of green construction materials. Two types of FAs are tested, namely an incineration fly ash (IFA) collected from electrostatic precipitator of an incineration plant and a gasification fly ash (GFA) collected from air pollution control unit of a high temperature slagging gasification waste-to-energy (WTE) plant. Ground waste glass (GWG) is used as a tertiary SCM. GFA demonstrates favorable sequestration capacity (87.5 mg/g) and high carbonation degree (74.1 %) while the IFA is found to be inactive during carbonation (3.1 mg/g, 4.6 %). Mortars blended with the wastes have shown delay in the cement hydration but eventually achieve compressive strength comparable to the control specimen. The mixing of GWG and GFA synergistically improves the performance of mortars which highlights the importance of strategic coupling of different waste streams. Most of the hazardous heavy metals, chloride and sulfate in FAs were stabilized in the mortars suggesting the potential for safe re-utilization of carbonated FAs as sustainable SCMs to concurrently close the waste loop and combat climate change.

Volatilization characteristics and risk evaluation of heavy metals during the pyrolysis and combustion of rubber waste without or with molecular sieves.

The volatilization characteristics and risk evaluation of heavy metals (As, Cd, Co ,Cr, Cu, Ni, Pb, Zn, and Ti) during pyrolysis and combustion of rubber waste with or without molecular sieves (MS) were studied. The addition of MS during pyrolysis inhibited the volatilization of As and promoted the volatilization of Ni and Co, while during combustion it inhibited the volatilization of Pb, Zn and promoted the volatilization of Cu. For Cd, Cr, Ni, Zn and Ti, their volatilization rates during pyrolysis were significantly higher than those during combustion, whereas for As and Cu, the volatilization rates during pyrolysis were lower than those during combustion. Risk evaluation of gaseous heavy metals was exhibited based on the Potential Ecological Risk Index (RI) method. The potential ecological risk during combustion was generally lower than that during pyrolysis. The research results provide important information of heavy metals control during waste thermal treatment.

Effect of molten salts on the structure, morphology and electrical conductivity of PET-derived carbon nanostructures

The effective disposal and/or utilization of polyethylene terephthalate ((C10H8O4)n, PET) waste plastics are currently global problems that need to be addressed urgently. The current research examines the molten salt-based thermal treatment of PET waste, as a new approach to tackle this challenge. The effect of various molten salts, comprising KCl, MgCl2, ZnCl2, NaCl, KF and NaF on the structural and morphological evolution of PET upon heating in air to 1300 °C is investigated. PET is transformed into carbon materials with different characteristics, including graphene-like nanosheets and porous nanostructures, with different electrical conductivity values, depending on the type of salt employed. The melting and evaporation points, as well as the cation size of the salt, are found to have a significant influence on the morphology and the crystallization level of the carbon products, based on which the characteristics of PET-derived carbons are regulated. Accordingly, the crystallinity and graphitization degree of the carbon materials obtained in NaF, KF and NaCl are found to be considerably greater than those obtained in ZnCl2, MgCl2 and KCl. The possible mechanism involved in the conversion of PET into carbon nanostructures in the molten salt environment is discussed. The results obtained provide insights into molten salt conversion of PET into carbon materials with different properties for various applications.

Evaluation on isothermal pyrolysis characteristics of typical technical solid wastes

Isothermal pyrolysis characteristics of typical technical solid wastes (polyethylene, paper towel and textiles, and their mixture with a blending ratio of 4:1:1) were carried out in a fixed bed between 475 °C and 550 °C. The influence of the temperature on the pyrolysis index, kinetic parameters and products of the samples was addressed. The interaction between the three individuals during their co-pyrolysis was identified. As the temperature was from 475 °C to 550 °C, the pyrolysis index of the polyethylene increased by about 78 times, while that for paper towel and textiles only increased by about 1 and 6 times, respectively. Solid residues from the mixture pyrolysis were about 11.6 % wt. More alkanes and alkenes were in liquid products of the mixture. The shrinking core model would represent well the mixture pyrolysis. The pre-exponential factor of polyethylene was much higher than other two individuals. There was a significant synergistic effect detected for mixture during the co-pyrolysis. The pyrolysis of mixture was dominated by a third order reaction mechanism. This study can provide basic data for the thermal treatment of solid waste in nuclear power plants.

Gasification-based thermal treatment of Low and Intermediate Level Waste containing organic matter

VTT has developed a gasification-based technology for processing low- and intermediate-level waste (LILW) rich in organic matter. VTT’s process is based on well-controlled thermal fluidised-bed gasification followed by efficient gas cleaning, gas conditioning/oxidation, wet scrubbing of the oxidised gas (flue gas), and finally, filtering through a high efficiency particulate air (HEPA) filter, which acts as a backup cleaning system. In the case of an organic ion exchange resin (IXR) the primary product from thermal gasification is fine filter dust. In addition, the process produces some bottom ash, which consists mainly of the bed material. The wet scrubber liquid may also contain some activity. Demonstration trials were carried out using unspent organic IXR containing a small amount of added stable Cs in order to simulate Cs content in spent IXR. Gasification tests confirmed the capability of the process to remove organic matter from the IXR and clean the resulting off-gas as required. Simulated waste IXR was reduced to approximately 1 wt-% of its original mass before immobilisation. Filter dust and bottom ash have to be immobilised before final disposal. VTT has previously developed an advanced immobilisation technology based on geopolymerisation and this has been applied to samples from the THERAMIN test trials. VTT’s technology has been designed as a compact process, which can be operated at the nuclear power plant site. Until now, all development and verification test trials have used simulated waste materials. The next step is the demonstration of the process using real radioactive waste.

Development of Generic Criteria for Evaluating the Disposability of Thermally Treated Wastes

The potential to generate wasteforms with enhanced properties that support safe storage and disposal is one of the key factors driving thermal treatment of radioactive waste. Depending on the specific treatment method and waste substrate, thermal treatment can greatly reduce chemical reactivity, yielding a primary product that is more durable than wasteforms produced via non-thermal routes and with reduced potential for gas generation and other detrimental behaviour in a storage / disposal environment. On the other hand, thermal treatment can concentrate radioactivity into a smaller volume, potentially affecting waste handling and / or classification. It also generates secondary wastes whose management requires consideration as part of a holistic evaluation of thermal treatment. Moreover, some thermal treatment routes do not generate a primary product that is directly disposable without further conditioning. Generic disposability criteria have been derived that can be used to evaluate the primary products from any form of thermal treatment. These generic disposability criteria highlight the factors that are relevant for waste product disposability and the ways in which thermal treatment can impact on these factors (both positively and negatively). They are equally applicable to any packaging or disposal concept, regardless of the engineered barriers that are present, and in any disposal environment, regardless of its characteristics and the nature of the host rock / geology. They could aid waste management organisations in developing their own disposability criteria, tailored to a particular context, for application in national waste management programmes.

Strategic Study of Thermal Treatment of European Radioactive Wastes

Under Work Package 2 (WP2) of THERAMIN, strategic reviews of thermal treatment technologies and European radioactive waste streams for which thermal treatment could bring benefits have been undertaken. This paper presents the outcomes of an international review of inventory information concerning European wastes potentially suitable for thermal treatment, a review of thermal treatment technologies, and a strategic gap analysis to identify countries where there are significant waste arisings with potential benefits for thermal treatment, but little prospect of these countries developing thermal treatment facilities independently.

Effect of Pt catalyst on the condensable hydrocarbon content generated via food waste pyrolysis

A Pt catalyst supported on activated carbon (Pt/AC) was used for an environmentally friendly thermal treatment of food waste under an inert atmosphere (i.e., pyrolysis). This catalyst influenced the amounts of condensable hydrocarbons and noncondensable gases but not that of the solid remaining after the pyrolysis; in particular, it contributed to shifting the carbon distribution from the condensable hydrocarbons to the noncondensable gases for the food waste pyrolysis. Moreover, its use suppressed the generation of harmful chemical compounds, especially at high temperatures. For example, a Pt/AC-catalyzed pyrolysis at 700 °C produced about 4 times fewer benzene derivatives than the same treatment without a catalyst; this probably occurred because the Pt sites catalyzed the decyclization reaction and/or the free radical mechanism, which is dominant in the thermal cracking of carbon-containing feedstock. This study suggests that a Pt/AC-catalyzed pyrolysis would be a more environmentally benign food waste treatment method.

Pyrolysis treatment of nonmetal fraction of waste printed circuit boards: Focusing on the fate of bromine.

Advanced thermal treatment of electronic waste offers advantages of volume reduction and energy recovery. In this work, the pyrolysis behaviour of nonmetallic fractions of waste printed circuit boards was studied. The fate of a bromine and thermal decomposition pathway of nonmetallic fractions of waste printed circuit boards were further probed. The thermogravimetric analysis showed that the temperatures of maximum mass loss were located at 319°C and 361°C, with mass loss of 29.6% and 50.6%, respectively. The Fourier transform infrared Spectroscopy analysis revealed that the spectra at temperatures of 300°C-400°C were complicated with larger absorbance intensity. The nonmetallic fractions of waste printed circuit boards decomposed drastically and more evolved products were detected in the temperature range of 600°C-1000°C. The gas chromatography-mass spectrometry analysis indicated that various brominated derivates were generated in addition to small molecules, such as CH4, H2O and CO. The release intensity of CH4 and H2O increased with temperature increasing and reached maximum at 600°C-800°C and 400°C-600°C. More bromoethane (C2H5Br) was formed as compared with HBr and methyl bromide (CH3Br). The release intensity of bromopropane (C3H7Br) and bromoacetone (C3H5BrO) were comparable, although smaller than that of bromopropene (C3H5Br). More dibromophenol (C6H4Br2O) was released than that of bromophenol (C6H5BrO) in the thermal treatment. During the thermal process, part of the ether bonds first ruptured forming bisphenol A, propyl alcohol and tetrabromobisphenol A. Then, the tetrabromobisphenol A decomposed into C6H5BrO and HBr, which further reacted with small molecules forming brominated derivates. It implied debromination of raw nonmetallic fractions of waste printed circuit boards or pyrolysis products should be applied for its environmentally sound treating.

Best Available Technologies for Waste Co-Firing Applications

Abstract Thermal transformation of waste is one way in which the negative impact of human activities on the environment can be reduced. Thermal waste treatment is generally negatively associated by the public as hazardous and harmful to the environment. In this study the authors present the possibility of waste management in the process of co-firing with coal using BAT (Best Available Techniques) for both the combustion process and the exhaust gas purification process. Co-firing of coal with RDF (Refuse Derived Fuel) while ensuring stable production of electricity and heat supports the process of waste management which, if not burned, will end up in landfills, which, according to the authors, is the worst possible way to handle waste both from the point of view of environmental protection itself and from the point of view of energy efficiency.

Survey on UHF Device Operating Modes for Thermal Treatment and Disinfection of Nonfood Animal-Origin Raw Materials

The authors have developed ultra-high-frequency (UHF) devices of several types that are different in their operation and design principles. It is well known that the technological process of the animal product treatment includes a range of operations resulting in obtaining the final products and nonedible by-products approved for livestock feed manufacturing. Therefore, the development of technologies and technical means for treatment of slaughterhouse waste classed as nonedible animal by-products, which can provide the opportunity to make the processed protein product, is considered urgent. For this reason, surveys on UHF devices’ operating modes for thermal treatment of slaughterhouse waste were carried out. A description of the continuous mode operating principle of a UHF device combined with a resonator for the thermal treatment of nonfood by-products of raw meat material is reported. The combined resonator designed to ensure the electromagnetic safety limits is presented as a variation of a cylindrical resonator with a hemispherical base providing the raw material supply. The regression-based models optimizing the UHF device operating modes are developed. A description of the technology and the device for thermal treatment of the nonfood animal-origin raw materials under the impact of high-frequency electromagnetic fields, operating in the continuous mode, is reported. The properties of dielectric heating of the multicomponent raw material during its grinding in the resonator chamber and the analogs of the HVF devices are considered.

ОБЗОР СПОСОБОВ И ОБОРУДОВАНИЯ ДЛЯ УТИЛИЗАЦИИ ОТХОДОВ РАСТЕНИЕВОДСТВА. РЕАЛИЗАЦИЯ НИЗКОТЕМПЕРАТУРНОГО ПИРОЛИЗА И ГАЗИФИКАЦИИ В ПИЛОТНОЙ И МОБИЛЬНОЙ УСТАНОВКАХ

An analysis of existing methods and equipment for processing and recycling crop waste showed that the main efforts of experimental design and research work in this area are aimed at creating affordable, cheap, environmentally friendly, highly efficient and cost-effective installations for processing waste into products useful for the economy. The developed pilot plant was tested during thermal treatment of rice husks, coffee cake and other plant waste by the method of low-temperature pyrolysis or gasification in a screw reactor. The pilot plant provided the production of useful products of various properties and heat energy for recycling, and it was a prototype for creating a mobile plant with capacity of 100 kg / h for raw materials.

Thermal Treatment of Municipal Waste in Poland on Example of RDF Pyrolysis

In the face of the constant tightening of environmental regulations, alternative sources of fuels and energy are being increasingly sought. The European Union strives to introduce waste-free or low-waste closed-loop technologies using material and energy recovery to manage natural resources in a rational manner. Therefore, European regulations require member states to progressively restrict the amount of landfill waste. In Poland, these requirements have been included in the Act on waste and the Act on order and cleanliness in the commune. In addition, since 1 January 2016, it has been forbidden to store waste with a calorific value exceeding 6 MJ/kg, which is why in recent years there has been an increase in interest in the thermal transformation of municipal waste. Therefore, the article presents the current shape of waste management in Poland, and also introduces the dominant form of RDF management in the cement industry. Nevertheless, the capacity of cement plants is limited, and the energy use of fuels from waste encounters difficulties related to a significant reduction in pollutant emissions, which is why the use of modern installations for the thermal conversion of waste such as pyrolysis and gasification is increasingly considered. Taking into account the promising energy properties of secondary fuels obtained during the pyrolysis process, the chemical composition of gas from RDF pyrolysis was modeled for a pilot installation operating in Poland using CHEMKIN-PRO software. Determination of the combustible components allowed the calorific value of pyrolytic gas to be estimated, ranging from 28.2 - 28.7 MJ/m3. The obtained calorific value is much higher than the average calorific value of RDF (11-18MJ/kg) [1], which encourages wider use of the waste pyrolysis process in order to obtain secondary fuels with promising energy parameters. It will contribute to a further reduction in the amount of deposited waste, and thus to creating environmentally-friendly closed-loop waste management.

Termički tretman otpadnih kompozitnih materijala u cilju dobijanja energije

Termički tretman otpadnih kompozitnih materijala u cilju dobijanja energije

Effect of carbon dioxide on thermal treatment of food waste as a sustainable disposal method

Herein, carbon dioxide (CO2) was applied to thermal treatment of real food waste to develop an environmentally benign way to dispose food waste. The food waste used in this study was collected from a food waste treatment plant. The application of CO2 to the thermal treatment of food waste affected the amount of non-condensable gases and condensable compounds produced from the thermal process, while it did not affect the amount of solid residue. When CO2 was supplied during the thermal treatment of food waste, less condensable compounds but more non-condensable gases such as H2, CO, and CH4 were generated during the thermal treatment of food waste at a range of temperatures from 400 to 700 °C. In addition to the change in product distribution, the generation of cyclic compounds was inhibited by applying CO2 to the thermal treatment. For example, approximately 30% less ring-structured compounds (e.g., benzene derivatives) were produced from the thermal treatment at 700 °C in CO2 condition than from the thermal treatment in inert condition. This was likely because CO2 inhibits gas phase free radical addition and/or dehydrogenation of linear compounds. This study suggests that the application of CO2 to thermally treating food waste would help develop a more environmentally friendly food waste treatment method.

Prediction of gaseous products from refuse derived fuel pyrolysis using chemical modelling software - Ansys Chemkin-Pro

There can be observed global interest in waste pyrolysis technology due to low costs and availability of raw materials. At the same time, there is a literature gap in forecasting environmental effects of thermal waste treatment installations. In the article was modelled the chemical composition of pyrolysis gas with main focus on the problem in terms of environmental hazards. Not only RDF fuel was analysed, but also selected waste fractions included in its composition. This approach provided comprehensive knowledge about the chemical composition of gaseous pyrolysis products, which is important from the point of view of the heterogeneity of RDF fuel. The main goal of this article was to focus on the utilitarian aspect of the obtained calculation results. Final results can be the basis for estimating ecological effects, both for existing and newly designed installations.Pyrolysis process was modelled using Ansys Chemkin-Pro software. The investigation of the process were carried out for five different temperatures (700, 750, 800, 850 and 900 °C). As an output the mole fraction of H2, H2O, CH4, C2H2,C2H4, C3H6, C3H8, CO, CO2, HCl and H2S were presented. Additionally the reaction pathways for selected material were presented.Based on obtained results, it was established that the residence time did not influenced on the concentration of products, contrary to temperature. The chemical composition of pyrolytic gas is closely related to wastes origin. The application of Chemkin-Pro allowed the calculation of formation for each products at different temperatures and formulation of hypotheses on the reaction pathways involved during pyrolysis process. Further, based on the obtained results confirmed the possibilities of using pyrolysis gas from RDF as a substitute for natural gas in energy consumption sectors. Optimization of the process can be conducted with low financial outlays and reliable results by using calculation tools. Moreover it can be predicted negative impact of obtained products on the future installation.

Enhancing Removal of Heavy Metals from a Model Solid Waste During Thermal Treatment with a Reducing Gas

Abstract Removal of some heavy metals during thermal treatment of a model solid waste under different ambient gases (carbon monoxide [CO], nitrogen [N2], and air) was studied. Compared with the rem...

Unexpected Aldehyde Generation in the Exhaust Gas at Waste Incineration Facilities.

Acid gases generated during the thermal treatment of waste are neutralized using devices, such as bag filters coated with slaked lime. However, residual trace organic substances can react with the highly reactive slaked lime. This study investigates the dynamics of organic substances generated in the bag filter when slaked lime is used in the exhaust gas treatment process. The mechanism of aldehyde generation was clarified using head space gas chromatography mass spectrometer (HS-GC/MS). Results indicated that methanol was converted to formaldehyde at a conversion ratio of 0.097% and ethanol was converted to acetaldehyde at a conversion ratio of 0.260%. In addition, when amines used as emulsifiers during slaked lime production persisted in the matrix, acetaldehyde formed at a maximum concentration of 121 mg/m3. The simulation method developed in this study can be used for the initial evaluation of aldehydes unexpectedly produced in an incineration treatment facility.