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Intrigued by recent high-energy study results for nearby galaxies with γ -ray emission and in particular NGC 1068 that has been detected as a neutrino-emitting source by the IceCube Neutrino Observatory, we conduct a detailed analysis of the γ -ray data of the galaxies NGC 1068 and NGC 253, obtained with the Large Area Telescope on board the Fermi γ -ray Space Telescope. By checking their possible spectral features and then constructing light curves in the corresponding energy ranges, we identify spectral-change activity from NGC 1068 in the ≥2 GeV energy range and long-term, statistically significant changes for NGC 253 in the ≥5 GeV energy range. In the former, the emission appears harder in two half-year periods than in the otherwise "quiescent" state. In the latter, an ∼two-fold decrease in the detection significance after MJD = 57023 is clearly revealed by the test-statistic maps we obtain. Considering the previous studies carried out and the various models proposed for the γ -ray emissions of the two sources, we discuss the implications of our findings. We suspect that a jet (or outflow) in NGC 1068 might contribute to the γ -ray emission. The nature of the long-term statistically significant changes for NGC 253 is not clear, but since the part of the GeV emission may be connected to the very-high-energy (VHE) emission from the center of the galaxy, it could be further probed with VHE observations. [ABSTRACT FROM AUTHOR]

The γ-ray spectral feature of the blazar 1ES 0502+675 is investigated by using Fermi Large Area Telescope Pass 8 data (between 100 MeV and 300 GeV) covering from 2008 August to 2021 April. A significant (∼4σ) hardening at ∼1 GeV is found in the γ-ray spectrum during a moderately flaring state (MJD 55050–55350). The photon index below and above the break energy is Γ1 = 2.36 ± 0.31 and Γ2 = 1.33 ± 0.11, respectively. In the rest of the observations, the γ-ray spectrum can be described by a power-law form with the photon index of ≈1.6. In the frame of a one-zone synchrotron self-Compton (SSC) model, the spectral hardening is interpreted as the transition between the synchrotron component and the SSC component. This could be the result of a slight increase of the break or maximum Lorentz factor of the electrons. [ABSTRACT FROM AUTHOR]

Using a time-dependent one-zone leptonic model that incorporates both shock acceleration and stochastic acceleration processes, we investigate the formation of the narrow spectral feature at ∼3 TeV of Mrk 501 which was observed during the X-ray and TeV flaring activity in 2014 July. It is found that the broad-band spectral energy distribution (SED) can be well interpreted as the synchrotron and synchrotron-self-Compton emission from the electron energy distribution (EED) that is composed by a power-law (PL) branch and a pileup branch. The PL branch produces synchrotron photons which are scattered by the electrons of the pileup branch via inverse-Compton scattering and form the narrow spectral feature observed at the TeV energies. The EED is produced by two injection episodes, and the pileup branch in EED is caused by shock acceleration rather than stochastic acceleration. [ABSTRACT FROM AUTHOR]

Long-term γ-ray variability of a non-blazar Active Galactic Nucleus PKS 0521-36 is investigated by using Fermi Large Area Telescope (Fermi-LAT) pass 8 data covering from 2008 August to 2021 March. The results show that the histogram of the γ-ray fluxes follows a log-normal distribution. Interestingly, in the analysis of ∼5.8 yr (from MJD 56317–58447) LAT data between two outbursts (occurring during 2012 October and 2019 May respectively), a quasi-periodic oscillation (QPO) with a period of ∼1.1 yr (∼5σ of significance) is found in the Lomb–Scargle Periodogram (LSP), the Weighted Wavelet Z-transform, and the REDFIT results. This quasiperiodic signal also appears in the results of Gaussian process modeling the light curve. Therefore, the robustness of the QPO is examined by four different methods. This is the first γ-ray QPO found in a mildly beamed jet. Our results imply that the γ-ray outbursts play an important role in the formation of the γ-ray QPO. [ABSTRACT FROM AUTHOR]

By fitting high-quality and simultaneous multiwavelength spectral energy distributions at multiple epochs with a one-zone leptonic jet model, we study the jet properties of three famous blazars: Mrk 421, 3C 454.3 and 3C 279. In the jet model, the emitting electron energy distributions are calculated by solving the kinetic equations of electron injection, escape, adiabatic and radiative energy losses. To explore multidimensional parameter space systematically, we employ a Markov chain Monte Carlo fitting technique. The properties of the emission regions we have derived here are consistent with those in previous studies, for example, the particle-dominated and low-magnetization jet. The new finding is that there is a tight correlation between γ-ray luminosity and electron injection power and an anticorrelation between γ-ray luminosity and the jet magnetization parameter. The results suggest that the same energy-dissipative mechanism (such as a shock) could be operating in the jets of different types of blazars, and that the origin of γ-ray flares is associated with the particle acceleration process. [ABSTRACT FROM AUTHOR]

A series of In2O3/In2S3 core‐shell heterostructures, derived from metal‐organic‐frameworks (MOFs), were successfully synthesized via a two‐step solvothermal route with different addition amount of sulfur‐bearing reagent (L‐cysteine, L‐Cys), which were used as photocatalysts for CO2 reduction with water vapor. The results indicated that 1.2‐In2O3/In2S3 with optimized L‐Cys addition amount had the highest production rate of CH4 (14.3 μmol gcat−1 h−1) and CO (2.59 μmol gcat−1 h−1). Pure In2O3 and 2.4‐In2O3/In2S3 with excess L‐Cys addition exhibited higher H2 production rate but lowest CO2 photoreduction activity. As the characterizations revealed, amorphous shell with abundant In2O3/In2S3 heterostructures greatly improved the separation efficiency of photo‐induced charge carriers and visible light harvesting ability, which promoted the photoreduction of CO2 consequently. However, over‐addition of sulfur‐bearing reagent destroyed the heterostructures of shell layer and turned them into thickened In2S3 crystal layer. This substitution not only reduced the amount of heterostructures, but also hindered the adsorption of CO2 on the reactive surface. [ABSTRACT FROM AUTHOR]

Blazar variability may be driven by stochastic processes. On the other hand, quasi-periodic oscillation (QPO) behaviors were recently reported to be detected in the Fermi-LAT data of blazars. However, the significances of these QPO signals given by traditional Fourier-like methods are still questioned. We analyze γ-ray light curves of the QPO blazars with two Gaussian process methods, CARMA and celerite, to examine the appropriateness of Gaussian processes for characterizing γ-ray light curves of blazars and the existence of the reported QPOs. We collect a sample of 27 blazars with possible γ-ray periodicity and generate their ∼11 yr Fermi-LAT light curves. We apply the Gaussian process models to the γ-ray light curves, and build their intrinsic power spectral densities (PSDs). The results show that in general the γ-ray light curves can be characterized by CARMA and celerite models, indicating that γ-ray variabilities of blazars are essentially Gaussian processes. The resulting PSDs are generally the red noise shapes with slopes between −0.6 and −1.7. Possible evidence for the γ-ray QPOs in PKS 0537−441 and PG 1553+113 are found in the Gaussian process modelings. [ABSTRACT FROM AUTHOR]

The acceleration of electrons in 3C 279 is investigated through analysing the injected electron energy distribution (EED) in a time-dependent synchrotron self-Compton+external Compton emission model. In this model, it is assumed that relativistic electrons are continuously injected into the emission region, and the injected EED [ |$Q_{\rm e}^\prime (\gamma ^\prime)$| ] follows a single power-law form with low- and high-energy cut-offs |$\rm \gamma _{min}^{\prime }$| and |$\rm \gamma _{max}^{\prime }$|⁠ , respectively, and the spectral index n , i.e. |$Q_{\rm e}^\prime (\gamma ^\prime)\propto \gamma ^{\prime -n}$|⁠. This model is applied to 14 quasi-simultaneous spectral energy distributions of 3C 279. The Markov Chain Monte Carlo (MCMC)-fitting technique is performed to obtain the best-fitting parameters and the uncertainties on the parameters. The results show that the injected EED is well constrained in each state. The value of n is in the range of 2.5–3.8, which is larger than that expected by the classic non-relativistic shock acceleration. However, the large value of n can be explained by the relativistic oblique shock acceleration. The flaring activity seems to be related to an increased acceleration efficiency, reflected in an increased |$\gamma ^{\prime }_{\rm min}$| and electron injection power. [ABSTRACT FROM AUTHOR]

Using a significantly enlarged Fermi -LAT BL Lac objects (BL Lacs) sample, we construct the gamma-ray luminosity function (GLF) of BL Lacs, by the joint use of the space density distribution and source counts distribution. We use three well-studied forms of the GLF, i.e. the forms of pure density evolution (PDE), pure luminosity evolution (PLE), and luminosity-dependent density evolution (LDDE). The Markov Chain Monte Carlo (MCMC) technique is used to constrain model parameters. Our results suggest that LDDE model can give the best description for the BL Lac GLF. And the model shows that the BL Lacs with a harder GeV spectrum and a less luminosity evolve as strongly as flat spectrum radio quasars, and the evolution decreases as increasing luminosity. We also model the average photon spectra of BL Lacs with a double power-laws model. Using this modelled spectra, BL Lacs contribute |$\sim \!20{{\ \rm per\ cent}}$| of the total extragalactic gamma-ray background (EGB) at E > 100 MeV, |$\sim \!100{{\ \rm per\ cent}}$| of the EGB at E > 50 GeV, and the unresolved BL Lacs contribute |$\sim\! 20 {{\ \rm per\ cent}}$| of the isotropic diffuse gamma-ray background at E > 100 MeV. A prediction of the TeV EGB spectra are given, which may be tested by the future detectors. [ABSTRACT FROM AUTHOR]

The statistical properties of X-ray flares from two separate locations (nucleus and HST-1) in the M87 jet are investigated to reveal the physical origin of the flares. We analyse the archival Chandra data for M87, and identify 14 flares in the nucleus and nine flares in HST-1. The peak intensity (I P) and the flaring duration time (T fl) for each flare are obtained. It is found that the distributions of both I P and T fl for the nucleus obey a power law form with a similar index. A similar result is also obtained for HST-1, and no significant inconsistency between the nucleus and HST-1 is found for the indices. Similar to solar X-ray flares, the power-law distributions of the flare event parameters can be well explained by a self-organized criticality system, which are triggered by magnetic reconnection. Our results suggest that the flares from nucleus and HST-1 are possibly triggered by magnetic reconnection process. The consistent indices for the distributions of I P and T fl in the nucleus and HST-1 indicate that the dimensions of the energy dissipation of the magnetic reconnection are identical in the two regions. A strong correlation between the flares in the two regions also suggests a similar physical origin for the flares. [ABSTRACT FROM AUTHOR]

Arsenic (As) and antimony (Sb) are heavy metals that have a toxic effect on human and environmental biology. Industrial tests were conducted on cement kiln co-processing of industrial sludge containing arsenic and waste resin containing antimony. The migration and distributions of arsenic and antimony in the cement kiln were studied. For antimony, the time required to establish a new mass balance and reach the steady state was significantly shorter than that for arsenic. Under the assumption that the input rates of arsenic and antimony in the co-processing test were 100%, almost all of the antimony and 70·52% of the arsenic were removed from the kiln as clinker. Minimal amounts of arsenic and antimony were emitted to the atmosphere via flue gas. 0·96% of arsenic and 4·37% of antimony formed external circulation with the cement kiln dust. 105·43% of arsenic and 123·56% of antimony were introduced by waste incineration residues and led to internal circulation with the hot meal in the kiln. Some arsenic (28·51%) accumulated in the kiln and was not discharged. The antimony inputs and outputs agreed with the mass balance. The mass distribution ratios in the clinker, flue gas and kiln dust varied with changing inputs of arsenic and antimony. [ABSTRACT FROM AUTHOR]

Effects of coprocessing hazardous organic waste in high-temperature industrial furnaces with oxidative or inert atmospheres were studied using two typical types of organicmatter, naphthalene and resorcinol. Thermal degradation experiments of solid naphthalene and resorcinol were performed in a high-temperature tube furnace with a nitrogen or air atmosphere. Concentrations of naphthalene and resorcinol lost as vapor and trapped in absorption liquids during calcination were determined by gas chromatography-mass spectrometry and spectrophotometry, respectively. Degradation kinetics were investigated, and activation energies and preexponential factors for organic matter in various types of industrial furnace were determined. The results showed that the degradation ratios and degradation rates of naphthalene and resorcinol increased with increasing temperature. Degradation rates of these two organic matters were faster in nitrogen than those in air. Degradation rates of these two organic matters were related to their thermal stabilities, and the degradation rate of resorcinol was higher compared with naphthalene. Under the experimental conditions, these two organic matters could degrade completely. Activation energies for degradation of naphthalene in nitrogen and air atmosphere were found to be 16.71 and 19.42 kJ/mol, respectively, and activation energies for degradation of resorcinol in nitrogen and air atmosphere were found to be 23.74 and 25.98 kJ/mol, respectively. The larger activation energy in air may be attributed to the simultaneous combustion reaction due to the presence of oxygen. These results can be used to predict thermal degradation laws for other organic matters. [ABSTRACT FROM AUTHOR]

Volatilization characteristics of arsenic (As) and cadmium (Cd) in different furnaces (sintering machine, blast furnace, boiler, and coke oven) were simulated. As and Cd in different chemical forms (As2S3, CdO, CdS, CdCl2) were co-processed with different raw materials and atmosphere in an electric heating tube furnace. The amount of As and Cd volatilized increased with increasing temperature and residence time. However, volatilization of As decreased as temperature increased in the sintering machine. The amount of Cd volatilized in the blast furnace in a reducing atmosphere was higher than that in the sintering machine with an oxidizing atmosphere. The amount of CdCl2 volatilized in different furnaces was high, but low for CdS. Kinetic models on the volatilization of these compounds during co-processing with raw materials were obtained under nonequilibrium conditions. These models can provide a preliminary theoretical basis for predicting the release of heavy metals (Cd, As). Also, we can determine which hazardous waste (HW) and furnace is suitable for co-processing, and the feeding rate or feeding point for the HW. [ABSTRACT FROM AUTHOR]

Heavy metals emitted by flue gas during co-processing hazardous waste (HW) in cement kilns presents a serious threat to the environment. Volatilization characteristics of three semivolatile metals (As, Pb, and Cd) in different chemical forms (As2S3, NaAsO2, Na2HAsO4, PbS, PbO, PbCl2, CdO, CdS, CdCl2) during co-processing with cement raw materials were studied. Thermogravimetric experiments were performed to tentatively predict the lower limits of volatilization temperatures. Experiments involving co-processing of these compounds with cement raw meals was carried out at different temperatures over different time periods in an electric heated tube furnace to gain more insight into the macroscopic kinetic characteristics of volatilization. Volatilization of As, Pb, and Cd during co-processing with cement raw materials increases with time initially, and after 25 min, they do not volatilize. Temperature and compound speciation significantly affect metal volatilization. For Pb and Cd, volatilization was higher at higher temperatures. Volatilization of As, however, decreased as temperature increased at temperatures above 1,000°C, which can be explained by three parallel reactions. Kinetic models on the volatilization of these compounds during co-processing with cement raw materials were obtained. These models can provide a preliminary theory basis for predicting the release of heavy metals (Pb, Cd, As) and be used to control the environmental risk posed by heavy metals through restricting their feeding rate during co-processing HW in cement kilns. [ABSTRACT FROM AUTHOR]

Fly ash (FA) for reuse as a construction material is activated using two methods, to produce hydrated silicate and geopolymer gels. We investigated the solidification/stabilization and leaching behavior of PbCl in a geopolymer matrix (GM) and hydrated silicate matrix (HSM), based on FA as the source material, to evaluate the environmental and health risks. The GM and HSM synthetic conditions were 60 °C, 20 % relative humidity (RH), and 12 wt% (6 mol/L) NaOH, and 20 ± 2 °C, ≥90 % RH, and 30 wt.%, respectively, based on their compressive strength performances. X-ray diffraction (XRD) showed that Pb participated in hydration and geopolymerization, and was incorporated in the structural components of the hydrated silicate and geopolymer. In leaching experiments, the solidification/stabilization effects of Pb and Cl in the HSM and GM improved with increasing curing time. After long-term curing (28 days), the immobility of Pb in the GM was better than that in the HSM. Sodalite improved the Cl-stabilizing ability of the GM compared with that of the HSM. In static monolithic leaching experiments, HSM and GM had the same Pb-leaching behaviors. Based on the changes in the location of the neutral sphere layer with decreasing acid-neutralizing capacity, Pb release was divided into alkaline-release, stagnation, and acid-release stages. The neutral sphere layer contained the highest Pb concentration during permeation toward the block center from the block edge. This behavior regulation could also apply to other amphoteric metals immobilized by GMs and HSMs. [ABSTRACT FROM AUTHOR]

We investigate the formation of the TeV spectrum of a distant blazar PKS 1424+240 residing at a redshift z ≥ 0.6 in two scenarios in the frame of a lepto-hadronic jet model, taking the uncertainties of both extragalactic background light (EBL) and its redshift into account. In the first scenario, TeV emission is attributed to the synchrotron emission of pair cascades resulting from the pγ interaction. In the second scenario, TeV emission is attributed to the proton-synchrotron emission, and an internal absorption due to interaction with the photons around the jet is included. Our results show that in the first scenario the 68 per cent upper limit of its redshift, within which this scenario can explain the VERITAS TeV spectrum in 2009 well, is ∼0.75. In the second scenario, this upper limit of the redshift becomes ∼1.03. However, the second scenario can be excluded because it requires an unreasonable photon field around the jet with a luminosity of ∼1043 erg s−1. In conclusion, the jet model can explain its TeV spectrum with a low EBL density if 0.6 < z < 0.75. [ABSTRACT FROM AUTHOR]

Possible electron energy distributions (EEDs) for Mrk 501 are studied through fitting multiband energy spectra in both steady and flare states with a one-zone synchrotron self-Compton model. Two kinds of the EEDs formed in different acceleration and cooling processes are assumed: a power law with an exponential cut-off (PLC) EED and a log-parabolic (LP) EED. The Markov Chain Monte Carlo method is used to estimate the model parameters in our fits. The results show that the LP model fits the spectral energy distributions better in both steady and flare states than PLC model, and the changes of model parameters from steady state to flare state can be explained reasonably. Therefore, it is concluded that the EEDs and the acceleration mechanisms in both steady and flare states would be the same for Mrk 501. Compared to Mrk 421 having different EEDs in different states, our analysis indicates that both acceleration and cooling processes are different in the jets of these two sources. [ABSTRACT FROM AUTHOR]

Abstract: The destruction of DDT formulations and DDT contaminated soil was conducted by feeding wastes into the flue gas chamber at the kiln inlet of two different preheater/precalciner cement kilns in China. The concentration of DDT, PCDD/PCDFs and HCB were measured in the flue gas of the main stack, in the solid material under baseline conditions and when feeding DDT-wastes. The destruction efficiency and the destruction and removal efficiency for DDT were in the range of 99.9335%–99.9998% and 99.9984%–99.9999%, respectively. The emissions of PCDD/PCDFs and HCB in the flue gas varied in the range of 0.0019–0.0171ng I-TEQ/Nm3 and 0.0064–0.0404μg/Nm3, respectively. The emission factor for PCDD/PCDF and HCB varied from 0.0137 to 0.0281μg/ton and from 17.32 to 109.34μg/ton of clinker, respectively. The concentration of PCDD/PCDFs and HCB in solid samples decreased as follows: cement kiln dust, 4.1–5ng I-TEQ/kg and 0.70–0.71μg/kg, respectively; >raw meal, 0.82–0.97ng I-TEQ/kg and 0.18μg/kg, respectively; >cement clinker, 0.09–0.22ng I-TEQ/kg and 0.14–0.18μg/kg, respectively. This study indicates that the feeding of DDT and POPs-wastes to the lower temperature part of a cement kiln system possibly to create a buildup of trace not-destroyed compounds in the system and might cause emissions; the technical feasibility and the environmental acceptability of this practice need to be investigated thoroughly. [Copyright &y& Elsevier]

We investigate the electron energy distributions (EEDs) and the corresponding acceleration processes in the jet of PKS 0447−439, and estimate its redshift through modeling its observed spectral energy distribution (SED) in the frame of a one-zone synchrotron-self Compton (SSC) model. Three EEDs formed in different acceleration scenarios are assumed: the power-law with exponential cut-off (PLC) EED (shock-acceleration scenario or the case of the EED approaching equilibrium in the stochastic-acceleration scenario), the log-parabolic (LP) EED (stochastic-acceleration scenario and the acceleration dominating), and the broken power-law (BPL) EED (no acceleration scenario). The corresponding fluxes of both synchrotron and SSC are then calculated. The model is applied to PKS 0447−439, and modeled SEDs are compared to the observed SED of this object by using the Markov Chain Monte Carlo method. The results show that the PLC model fails to fit the observed SED well, while the LP and BPL models give comparably good fits for the observed SED. The results indicate that it is possible that a stochastic acceleration process acts in the emitting region of PKS 0447−439 and the EED is far from equilibrium (acceleration dominating) or no acceleration process works (in the emitting region). The redshift of PKS 0447−439 is also estimated in our fitting: z = 0.16 ± 0.05 for the LP case and z = 0.17 ± 0.04 for BPL case. [ABSTRACT FROM AUTHOR]

A clean sample of flat-spectrum radio quasars (FSRQs) has been provided by Fermi Large Area Telescope (LAT) in two years of operation. Based on this sample, we reconstruct the gamma-ray luminosity function (GLF) in the framework of the luminosity-dependent density evolution (LDDE) model, and obtain the best-fitting GLF by comparing the distributions of observed redshifts, luminosities, indexes and source counts with the predicted distribution of the GLF through the Markov Chain Monte Carlo (MCMC) method which constrains the model parameters in an efficient way. Using the best-fitting GLF, we estimate the contribution of Fermi-undetected FSRQs to the extragalactic diffuse gamma-ray background (EGRB), and find that the contribution of unresolved FSRQs to the EGRB is 10.1 ± 4.7 per cent in the 0.1–100 GeV band. We also study the influence of different bins of redshifts, luminosities and spectral indices on the contribution to EGRB from the unresolved FSRQs, and find that the contributions of unresolved FSRQs in the redshift range of z = 0.0–2.0 and in the gamma-ray luminosity range of 1044–1048 erg s−1 are ∼90 per cent, respectively. [ABSTRACT FROM AUTHOR]

ABSTRACT The detections of X-ray emission from the kiloparsec-scale jets of blazars and radio galaxies could imply the existence of high-energy electrons in these extended jets, and these electrons could produce high-energy emission through the inverse Compton (IC) process. In this paper, we study the non-variable hard TeV emission from a blazar. The multiband emission consists of two components: (i) the traditional synchrotron self-Compton (SSC) emission from the inner jet; (ii) the emission produced via SSC and IC scattering of cosmic microwave background (CMB) photons (IC/CMB) and extragalactic background light (EBL) photons by relativistic electrons in the extended jet under the stochastic acceleration scenario. Such a model is applied to 1ES 1101-232. The results indicate the following. (i) The non-variable hard TeV emission of 1ES 1101-232, which is dominated by IC/CMB emission from the extended jet, can be reproduced well by using three characteristic values of the Doppler factor (δD = 5, 10 and 15) for the TeV-emitting region in the extended jet. (ii) In the cases of δD = 15 and 10, the physical parameters can achieve equipartition (or quasi-equipartition) between the relativistic electrons and the magnetic field. In contrast, the physical parameters largely deviate from equipartition for the case of δD = 5. Therefore, we conclude that the TeV emission region of 1ES 1101-232 in the extended jet should be moderately or highly beamed. [ABSTRACT FROM AUTHOR]

ABSTRACT We estimate the contribution to the extragalactic gamma-ray background (EGRB) from both intrinsic and cascade emissions produced by blazars, using a simple semi-analysis method for two models of the blazar gamma-ray luminosity function (GLF). For the cascade emission, we consider two possible contributions: in case I, the flux of the cascade emission is lower than the Fermi Large Area Telescope (LAT) sensitivity, which is independent of the extragalactic magnetic field (EGMF); in case II, the flux of the cascade emission is larger than the Fermi LAT sensitivity, but the emission angle is larger than the LAT point-spread-function angle, which depends on the EGMF. Our results indicate the following. (i) The blazar contribution to the EGRB is dominant, although it depends on the GLF model and the EGMF. (ii) The EGMF plays an important role in estimating the contribution from the cascade emission produced by blazars, so the contribution from the cascade emission will significantly alter the EGRB spectrum when the strength of the EGMF is large enough (i.e. BEGMF > 10−12 G). (iii) Because the cascade emission in case II reaches saturation when the strength of the EGMF is ∼10−11 G, it is very possible that the contribution from the cascade emission produced by blazars can be considered as another method to probe the upper limit of the strength of the EGMF. [ABSTRACT FROM AUTHOR]

• Chemical industrial kilns can be used for co-processing of hazardous waste. • Co − processing of hazardous waste in CWSG has little effect on the operating stability of the gasifier. • Low environmental risks of PAHs in CWSG during co − processing process. • LMW PAHs mainly distributed in exhaust gas, MMW and HMW PAHs mainly distributed in solid waste. Chemical industrial kilns were found to be used for waste treatment, however it is still in the research stage. In our study, field tests were conducted to find the emission and distribution characteristics of polycyclic aromatic hydrocarbons (PAHs) during co-processing of hazardous waste in an industrial scale coal-water slurry gasifier (CWSG), which is applied to ammonia production. Changes of temperature, pressure and gas production of CWSG were recorded under both blank condition (i.e., regular production) and test condition (i.e., feedstock mixed with hazardous waste). Concentration of PAHs in all the solid waste, waste water, and exhaust gas under two conditions were analyzed. Results showed that co-processing of hazardous waste has little impact on the operation stability of CWSG, the temperature were ranged at 1330–1350 ℃ in CWSG, the pressure and gas production were stabled at 1.0–1.3 MPa and 12,000–14,000 Nm3/h respectively. Low environmental risks of PAHs in regular production and weren't increased by the addition of hazardous waste. Distribution trends of PAHs with different molecular weights in solid-liquid-gas three phases were basically the same under both two conditions. 92.96 %−93.68 % low molecular weights (LMW, 2–3rings) PAHs distributed in exhaust gas, 50.84 %−71.66 % middle molecular weights (MMW, 4 rings) PAHs distributed in solid waste, and 85.3 %−86.77 % high molecular weight (HMW, 5–6 rings) PAHs distributed in solid waste, while the content of PAHs in waste water was generally low. [ABSTRACT FROM AUTHOR]