Challenges and opportunities for energy recovery from municipal solid waste in the Russian Federation

Energy recovery from municipal solid waste (MSW) is currently a key factor in waste management in Russia, as can be seen from the corresponding changes in the state regulatory framework. The paper presents a comparative assessment of different waste flow characteristics; it focuses on pre-treatment options and the method of subsequent thermal treatment. It reflects the basic method of untreated MSW incineration and other advanced technologies which have different levels of waste preparation. Step-by-step research has been carried out in a large Russian city in order to determine different technological approaches to recovering energy from MSW. The study included: 1) field studies of the composition and characterization of MSW; 2) laboratory studies of MSW thermal properties, i.e. moisture, ash content and calorific value; 3) several options for waste treatment schemes with equipment of different technical specifications; 4) analysis of material flow, energy flow and key substance flow according to these considered schemes. The research revealed that for all seasons a significant proportion of MSW (almost 40%) is represented by fines (below 50 mm). On average, the energy potential of MSW (the total content of waste paper, polymers, textiles, wood, multilayer packaging, leather, rubber, footwear) amounts to about 40%. It was found that MSW calorific value depends on fraction size, since screening (over 50 mm) is characterized by high moisture and low content of valuable components, compared to MSW greater than 50 mm in size. Pre-processing and treatment of MSW allows solid recovered fuel (SRF) to be obtained with a calorific value similar to brown coal. The energy balance of the process allows the conclusion that 33.8% of initial MSW energy potential is concentrated in residues from the sorting process, since it has a relatively low calorific value of 4.8 MJ/kg, but a high mass fraction of 47.9%. In the process of MSW treatment and solid fuel production, most of the chlorine and mercury (80% and 55% respectively) is removed by the rest of the sorting process. The data obtained in the study can be used in selecting the optimal option for energy recovery from MSW. © 2019 WIT PressACKNOWLEDGEMENT The work was supported by Act 211 Government of the Russian Federation, contract № 02.A 03.21.0006

Thermal treatment and disposal of carbon fiber reinforced composites

From the point of view of rational resource management polymer composites treatment is at the same time environmental pollution prevention during their burial and the opportunity to recover valuable resources — fibers and other fillers. This article presents an analysis of the various processes of thermal utilization of carbon fiber reinforced composites. Incineration technologies in specialized installations and in cement production kilns allow to get rid of the significant amounts of a wide variety of wastes, including polymer composites, with useful energy potential, therefore, it is a popular way to solve the problem of such materials in a place where their disposal is prohibited. However, in this case, valuable resources, like carbon fiber, which production is very energy-consuming, are lost. Therefore, the priority is technologies that allow recycled carbon fiber recovery. One of the most widely used methods that meet most requirements is pyrolysis; therefore, investigation of optimal conditions for this process is an urgent task for research

Large scale characterization and calibration strategy of a SiPM-based camera for gamma-ray astronomy

The SST-1M is a 4-m diameter mirror Davies-Cotton gamma-ray telescope. It has been designed to cover the energy range above 500 GeV and to be part of an array of telescopes separated by 150-200 m. Its innovative camera is featuring large area hexagonal silicon photo-multipliers as photon detectors and a fully digital trigger and readout system. Here, the strategy and the methods for its calibration are presented, together with the obtained results. In particular, the off and on-site calibration strategies are demonstrated on the first camera prototype. The performances of the camera in terms of charge and time resolution are described

The SST-1M project for the Cherenkov Telescope Array

The SST-1M project, run by a Consortium of institutes from Czech Republic, Poland and Switzerland, has been proposed as a solution for implementing the small-size telescope array of the southern site of the Cherenkov Telescope Array. The technology is a pathfinder for efficient production of cost-effective imaging air Cherenkov telescopes. We report on the main system features and recent upgrades, the performances validation and the operation campaign carried out in 2018

The extreme HBL behaviour of Markarian 501 during 2012

A multiwavelength campaign was organized to take place between March and July of 2012. Excellent temporal coverage was obtained with more than 25 instruments, including the MAGIC, FACT and VERITAS Cherenkov telescopes, the instruments on board the Swift and Fermi spacecraft, and the telescopes operated by the GASP-WEBT collaboration. Mrk 501 showed a very high energy (VHE) gamma-ray flux above 0.2 TeV of $\sim$0.5 times the Crab Nebula flux (CU) for most of the campaign. The highest activity occurred on 2012 June 9, when the VHE flux was $\sim$3 CU, and the peak of the high-energy spectral component was found to be at $\sim$2 TeV. This study reports very hard X-ray spectra, and the hardest VHE spectra measured to date for Mrk 501. The fractional variability was found to increase with energy, with the highest variability occurring at VHE, and a significant correlation between the X-ray and VHE bands. The unprecedentedly hard X-ray and VHE spectra measured imply that their low- and high-energy components peaked above 5 keV and 0.5 TeV, respectively, during a large fraction of the observing campaign, and hence that Mrk 501 behaved like an extreme high-frequency- peaked blazar (EHBL) throughout the 2012 observing season. This suggests that being an EHBL may not be a permanent characteristic of a blazar, but rather a state which may change over time. The one-zone synchrotron self-Compton (SSC) scenario can successfully describe the segments of the SED where most energy is emitted, with a significant correlation between the electron energy density and the VHE gamma-ray activity, suggesting that most of the variability may be explained by the injection of high-energy electrons. The one-zone SSC scenario used reproduces the behaviour seen between the measured X-ray and VHE gamma-ray fluxes, and predicts that the correlation becomes stronger with increasing energy of the X-rays

Multiwavelength study of the galactic PeVatron candidate LHAASO J2108+5157

Context. Several new ultrahigh-energy (UHE) γ-ray sources have recently been discovered by the Large High Altitude Air Shower Observatory (LHAASO) collaboration. These represent a step forward in the search for the so-called Galactic PeVatrons, the enigmatic sources of the Galactic cosmic rays up to PeV energies. However, it has been shown that multi-TeV γ-ray emission does not necessarily prove the existence of a hadronic accelerator in the source; indeed this emission could also be explained as inverse Compton scattering from electrons in a radiation-dominated environment. A clear distinction between the two major emission mechanisms would only be made possible by taking into account multi-wavelength data and detailed morphology of the source. Aims. We aim to understand the nature of the unidentified source LHAASO J2108+5157, which is one of the few known UHE sources with no very high-energy (VHE) counterpart. Methods. We observed LHAASO J2108+5157 in the X-ray band with XMM-Newton in 2021 for a total of 3.8 hours and at TeV energies with the Large-Sized Telescope prototype (LST-1), yielding 49 hours of good-quality data. In addition, we analyzed 12 years of Fermi-LAT data, to better constrain emission of its high-energy (HE) counterpart 4FGL J2108.0+5155. We used naima and jetset software packages to examine the leptonic and hadronic scenario of the multi-wavelength emission of the source. Results. We found an excess (3.7σ) in the LST-1 data at energies E > 3 TeV. Further analysis of the whole LST-1 energy range, assuming a point-like source, resulted in a hint (2.2σ) of hard emission, which can be described with a single power law with a photon index of Σ = 1.6 ± 0.2 the range of 0.3 - 100 TeV. We did not find any significant extended emission that could be related to a supernova remnant (SNR) or pulsar wind nebula (PWN) in the XMM-Newton data, which puts strong constraints on possible synchrotron emission of relativistic electrons. We revealed a new potential hard source in Fermi-LAT data with a significance of 4σ and a photon index of Σ = 1.9 ± 0.2, which is not spatially correlated with LHAASO J2108+5157, but including it in the source model we were able to improve spectral representation of the HE counterpart 4FGL J2108.0+5155. Conclusions. The LST-1 and LHAASO observations can be explained as inverse Compton-dominated leptonic emission of relativistic electrons with a cutoff energy of 100-30+70 TeV. The low magnetic field in the source imposed by the X-ray upper limits on synchrotron emission is compatible with a hypothesis of a PWN or a TeV halo. Furthermore, the spectral properties of the HE counterpart are consistent with a Geminga-like pulsar, which would be able to power the VHE-UHE emission. Nevertheless, the lack of a pulsar in the neighborhood of the UHE source is a challenge to the PWN/TeV-halo scenario. The UHE γ rays can also be explained as π0 decay-dominated hadronic emission due to interaction of relativistic protons with one of the two known molecular clouds in the direction of the source. Indeed, the hard spectrum in the LST-1 band is compatible with protons escaping a shock around a middle-aged SNR because of their high low-energy cut-off, but the origin of the HE γ-ray emission remains an open question

Multimessenger Characterization of Markarian 501 during Historically Low X-Ray and γ-Ray Activity

We study the broadband emission of Mrk 501 using multiwavelength observations from 2017 to 2020 performed with a multitude of instruments, involving, among others, MAGIC, Fermi's Large Area Telescope (LAT), NuSTAR, Swift, GASP-WEBT, and the Owens Valley Radio Observatory. Mrk 501 showed an extremely low broadband activity, which may help to unravel its baseline emission. Nonetheless, significant flux variations are detected at all wave bands, with the highest occurring at X-rays and very-high-energy (VHE) 3-rays. A significant correlation (>3σ) between X-rays and VHE 3-rays is measured, supporting leptonic scenarios to explain the variable parts of the emission, also during low activity. This is further supported when we extend our data from 2008 to 2020, and identify, for the first time, significant correlations between the Swift X-Ray Telescope and Fermi-LAT. We additionally find correlations between high-energy 3-rays and radio, with the radio lagging by more than 100 days, placing the 3-ray emission zone upstream of the radio-bright regions in the jet. Furthermore, Mrk 501 showed a historically low activity in X-rays and VHE 3-rays from mid-2017 to mid-2019 with a stable VHE flux (>0.2 TeV) of 5% the emission of the Crab Nebula. The broadband spectral energy distribution (SED) of this 2 yr long low state, the potential baseline emission of Mrk 501, can be characterized with one-zone leptonic models, and with (lepto)-hadronic models fulfilling neutrino flux constraints from IceCube. We explore the time evolution of the SED toward the low state, revealing that the stable baseline emission may be ascribed to a standing shock, and the variable emission to an additional expanding or traveling shock. © 2023. The Author(s). Published by the American Astronomical Society