Pollutant emissions from the pyrolysis and combustion of viscoelastic memory foam

Pressurized pyrolysis of mattress residue: An alternative to landfill management

Mattresses are a difficult waste to manage in landfills due to their large volume and low density. Pyrolysis treatment could reduce its volume while producing fuel or products valuable for the chemical industry. Pressurized pyrolysis at 400, 450, and 500 °C is carried out in a lab-scale autoclave at initial pressures 4.2, 8.4, and 16.8 bar. Product gas yield increases slightly along with elevated pressure as well as temperature. However, beyond 8.4 bar the initial pressure makes no discernible differences. CO and CO2 are the major gas species followed by CH4. CO contributes the most to the product gas energy content followed by C3 species, C2H6, and H2. Calculated energy content (heating value) is between 2 and 15 MJ·Nm-3. In terms of product gas energy content, low pressure pyrolysis is favorable over high pressure pyrolysis. According to integration areas of chromatographic measurements the liquid phase contains up to 25 % of N-compounds, with benzonitrile being the most abundant, followed by toluene, o-xylene, and ethylbenzene. The solid char maintains constant properties across operating conditions, with carbon and energy contents of approximately 75 wt% and 30 MJ·kg-1, respectively.

Kinetics of the formation and destruction of PCDD/Fs in a laboratory tubular furnace

A kinetic model has been developed for the formation of selected congeners of PCDD/Fs during the thermal decomposition of different wastes in a horizontal reactor. Previously published data on the decomposition of wastes have been correlated using a kinetic model that only considers process parameters, such as the presence of different amounts of oxygen in the atmosphere of reaction, chlorine and metals in the waste. The effect of both chlorine and metals is modelled through an equation assuming a "saturation effect", i.e., that a certain amount of each substance produces the maximum rate, and that higher amounts do not increase the rate. The presence of oxygen is modelled by a destruction reaction over part of the PCDD/Fs produced. The model, which uses data from more than 64 experiments, correlated the emissions of three selected congeners: 1,2,3,6,7,8-HxCDD, OCDF and 2,3,7,8-TCDF, which are enough to estimate the total amount and toxicity of an emission.

A pyrolysis process coupled to a catalytic cracking stage: A potential waste-to-energy solution for mattress foam waste

Pyrolysis coupled to either thermal or catalytic cracking of mattress foam waste was performed in a laboratory-scale facility consisting of a fixed-bed reactor joined to a tubular cracking reactor. The results showed a great potential for the production of syngas specially at high cracking temperatures. Particularly, fixing 800 °C in the cracking reactor, a CO and CH₄ rich gas with a remarkable amount of H₂ was obtained. The addition of catalysts (dolomite, olivine or HiFUEL®) significantly decreased undesirable tar formation, (below 10 wt%), simultaneously increasing the gas yield and keeping CO and CH₄ as the main components in the stream, becoming a preferable route that the non-catalytic process. Accordingly, this stream could be used preferably for further applications in energy generation because its heating value ranged between 15.7 MJ/Nm³ and 19.6 MJ/Nm³. In particular, the gas obtained by the use of dolomite could be advantageous for the production of organic compounds such as dimethyl ether (DME) as well as its use an engine or boiler to generate electricity in small facilities. In addition, the solid fraction obtained after de process could be used as a medium quality refused derived fuel (LHV ~ 12 MJ/kg) in order to support the internal energy requirements of the process.

Rapid on-site identification of hazardous organic compounds at fire scenes using person-portable gas chromatography-mass spectrometry (GC-MS)-part 1: air sampling and analysis

Recent advancements in person-portable instrumentation have resulted in the potential to provide contemporaneous results through rapid in-field analyses. These technologies can be utilised in emergency response scenarios to aid first responders in appropriate site risk assessment and management. Large metropolitan fires can pose great risk to human and environmental health due to the rapid release of hazardous compounds into the atmosphere. Understanding the release of these hazardous organics is critical in understanding their associated risks. Person-portable gas chromatography-mass spectrometry (GC-MS) was evaluated for its potential to provide rapid on-site analysis for real-time monitoring of hazardous organic compounds at fire scenes. Air sampling and analysis methods were developed for scenes of this nature. Controlled field testing demonstrated that the portable GC-MS was able to provide preliminary analytical results on the volatile organic compounds present in air samples collected from both active and extinguished fires. In-field results were confirmed using conventional laboratory-based air sampling and analysis procedures. The deployment of portable instrumentation could provide first responders with a rapid on-site assessment tool for the appropriate management of scenes, thereby ensuring environmental and human health is proactively protected and scientifically informed decisions are made for the provision of timely advice to stakeholders.

Rapid on-site identification of hazardous organic compounds at fire scenes using person-portable gas chromatography-mass spectrometry (GC-MS)-part 2: water sampling and analysis

Building and factory fires pose a great risk to human and environmental health, due to the release of hazardous by-products of combustion. These hazardous compounds can dissipate into the environment through fire water run-off, and the impact can be immediate or chronic. Current laboratory-based methods do not report hazardous compounds released from a fire scene at the time and location of the event. Reporting of results is often delayed due to the complexities and logistics of laboratory-based sampling and analysis. These delays pose a risk to the health and wellbeing of the environment and exposed community. Recent developments in person-portable instrumentation have the potential to provide rapid analysis of samples in the field. A portable gas chromatograph-mass spectrometer (GC-MS) was evaluated for the on-site analysis of water samples for the identification of hazardous organic compounds at fire scenes. The portable GC-MS was capable of detecting and identifying a range of volatile and semi-volatile organic compounds in fire water run-off, and can be used in conjunction with conventional laboratory analysis methods for a comprehensive understanding of hazardous organics released at fire scenes. Deployment of this portable instrumentation provides first responders with a rapid, on-site screening tool to appropriately manage the run-off water from firefighting activities. This ensures that environmental and human health is proactively protected.

Polyurethane Recycling and Disposal: Methods and Prospects

Growing water and land pollution, the possibility of exhaustion of raw materials and resistance of plastics to physical and chemical factors results in increasing importance of synthetic polymers waste recycling, recovery and environmentally friendly ways of disposal. Polyurethanes (PU) are a family of versatile synthetic polymers with highly diverse applications. They are class of polymers derived from the condensation of polyisocyanates and polyalcohols. This paper reports the latest developments in the field of polyurethane disposal, recycling and recovery. Various methods tested and applied in recent years have proven that the processing of PU waste can be economically and ecologically beneficial. At the moment mechanical recycling and glycolysis are the most important ones. Polyurethanes' biological degradation is highly promising for both post-consumer and postproduction waste. It can also be applied in bioremediation of water and soil contaminated with polyurethanes. Another possibility for biological methods is the synthesis of PU materials sensitive to biological degradation. In conclusion, a high diversity of polyurethane waste types and derivation results in demand for a wide range of methods of processing. Furthermore, already existing ones appear to be enough to state that the elimination of not reprocessed polyurethane waste in the future is possible.

Estimation of Industrial Emissions during Pyrolysis and Combustion of Different Wastes Using Laboratory Data

In our lab, we have been studying the emissions of different pollutants during pyrolysis and combustion of wastes under different conditions for the last three decades. These studies have focused on the effect of temperature and presence of oxygen on the production of different pollutants. Waste decomposition has been studied in a horizontal laboratory scale reactor, but no estimate has been made of the actual emissions in a conventional thermal decomposition system. In the present study, emissions during these wastes' thermal decomposition were estimated using Aspen HYSYS. In the simulation software, the waste composition (elemental analysis) was given as an input parameter, as well as the gas flow rate used as atmosphere during the decomposition. The emitted hydrocarbons measured in the laboratory were equated to the emission of a single compound (propylene). The simulation permitted calculating the percentage of oxygen in the emitted gas, and the pollutant emissions were then recalculated under standard conditions. The emission of dioxins and furans were estimated under different conditions of decomposition, and an adequate approximation of the waste decomposition in actual incineration systems could be obtained.

Effects of temperature on the emission of particulate matter, polycyclic aromatic hydrocarbons, and polybrominated diphenyl ethers from the thermal treatment of printed wiring boards

The effects of temperature on the emission of pollutants during the thermal treatment of electronic waste have rarely been investigated. The emission of particulate matter (PM), polycyclic aromatic hydrocarbons (PAHs), and polybrominated diphenyl ethers (PBDEs) from the thermal treatment of printed wiring boards was investigated over a temperature range of 320-600 °C. The emission factors (EFs) were determined to be within 1.6-7.6 g/kg, 2.23-11.9 μg/g, and 0.9-5.5 μg/g, respectively. High temperatures increased the formation of PAHs and CO, but decreased the emission of PBDEs, PM, and organic carbon. A temperature of 480 °C was determined to be optimal. Low-molecular-weight components were the dominant PAH species. The compositional profiles of PBDEs were clearly observed to vary with the temperature. Small particles (< 2.1 μm) that were more affected by temperature were dominant in PM, particle-bound PAHs, and PBDEs at all temperatures. High temperature increased the EFs of gaseous PAHs but had no remarkable effect on those of particulate PAHs. The freshly emitted PAHs primarily existed in the particulate phase at low temperatures, while the gaseous phase PAHs became prevailing at ≥ 520 °C. The particulate PBDEs were more susceptible to temperature and overwhelmingly dominant over the entire temperature range considered.

New Models Used to Determine the Dioxins Total Amount and Toxicity (TEQ) in Atmospheric Emissions from Thermal Processes

In order to reduce the calculation effort during the simulation of the emission of polychlorinated dibenzo-p-dioxins and furans (PCDD/F) during municipal solid waste incineration, minimizing the number of simulated components is mandatory. For this purpose, two new multilinear regression models capable of determining the dioxins total amount and toxicity of an atmospheric emission have been adjusted based on previously published ones. The new source of data used (almost 200 PCDD/F analyses) provides a wider range of application to the models, increasing also the diversity of the emission sources, from industrial and laboratory scale thermal processes. Only three of the 17 toxic congeners (1,2,3,6,7,8-HxCDD, 2,3,7,8-TCDF and OCDF), whose formation was found to be linearly independent, were necessary as inputs for the models. All model parameters have been statistically validated and their confidence intervals have been calculated using the Bootstrap method. The resulting coefficients of determination (R2) for the models are 0.9711 ± 0.0056 and 0.9583 ± 0.0085; its root mean square errors (RMSE) are 0.2115 and 0.2424, and its mean absolute errors (MAE) are 0.1541 and 0.1733 respectively.

Effect of marine ambient in the production of pollutants from the pyrolysis and combustion of a mixture of plastic materials

A mixture of polyethylene (PE), polyethylene-terephtalate (PET), polypropylene (PP) and Nylon was submerged in marine water during 12 moths. The chlorine content of these plastics was measured through the passing time. Thermobalance was used to look for differences in the thermal decomposition of the plastics during in that time interval. Degradation of PET, PP and Nylon produced changes in the weight loss curve, but behaviour of PE is confusing. Pyrolysis and combustion at 850 °C was finally performed to get knowledge of the possible differences in the emission of main gases, volatiles and semivolatiles including polycyclic aromatic hydrocarbons (PAHs), polychlorinated benzenes (ClBzs), polychlorinated phenols (ClPhs), polybrominated phenols (BrPhs), polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). Results show that the emission of chlorinated species is somewhat not affected by the chlorine content of the plastics mix. The production of PCBs and PCDD/Fs was very low, under 4 pg WHO-TEQ/g.

Pollutant formation in the pyrolysis and combustion of materials combining biomass and e-waste

Combustion and pyrolysis runs at 850°C were carried out in a laboratory scale horizontal reactor with different materials combining biomass and waste electrical and electronic equipment (WEEE). Analyses are presented of the carbon oxides, light hydrocarbons, polycyclic aromatic hydrocarbons (PAHs), polychlorinated benzenes (ClBzs), polychlorinated phenols (ClPhs), polybrominated phenols (BrPhs), polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). Results showed that gas emissions were mainly composed of CO and CO₂; the high level of CO found in the pyrolytic runs was easily transformed into CO₂ by reaction with oxygen. The total amount of light hydrocarbons emitted was higher in the samples containing WEEE, methane being the most abundant light hydrocarbon in all the runs. However, the presence of WEEE reduced the emission of PAHs which decreased with the increase of the oxygen. The total amount of BrPhs increased in the decomposition of the samples containing WEEE, reaching its maximum in pyrolysis runs. Emission of PCDD/Fs was enhanced in pyrolytic conditions and easily decreased in the presence of oxygen.