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•Anaerobic digestion (AD) coupled with pyrolysis (Py) is environmentally favorable.•Environmental impact of different integrations of AD and Py are investigated.•The energy ...consumption plays a key role in the life cycle assessment.•Py-AD has the worst performance (2.75 of total environmental impact /kg feedstock).•AD-Py has higher industrial potential compared with other scenarios.
The integration of anaerobic digestion (AD) and pyrolysis (Py) could be a solution to economically utilize the organic fraction of municipal solid waste (OFMSW). However, it is not clear whether the environmental impact of the integrated pathway always outperforms the two single technologies. In this study, two integrated pathways (AD-Py, Py-AD) were compared with single AD and Py from the life cycle environmental impacts point of view. The results indicate that the environmental impacts of the four pathways are heavily dependent on their energy inputs and outputs. AD-Py is more environmentally friendly (-11.53 of total environmental impact /kg OFMSW) than single AD or Py. Py-AD exhibites the heaviest environmental burden (2.75 of total environmental impact /kg OFMSW) in all pathways. Therefore, AD-Py can be the top priority of treating OFMSW among the four pathways from the environmental viewpoint. This work could provide a theoretical support for the utilization of OFMSW.
This review systematically reports the pyrolysis of oily sludge (OS) from petroleum industry in regards to its dual features of the energy recovery potential and the environmental risks. The ...petroleum hydrocarbons are the nonbiodegradable fractions in OS that possess hazardous properties, i.e. ignitability and toxicity. Besides, complicated hazardous elements (i.e. N, S and Cl) and heavy metals inherently existing in OS further aggravate the environmental risks. However, the high oil content and heating value of OS contribute to its huge energy resource potential. Considering the energy demand and the environmental pressure, the ultimate purposes of the OS management are to enhance the oil recovery efficiency to minimize the oil content as well as to stabilize the hazardous elements and heavy metals into the solid residue. Among various OS management technologies, pyrolysis is the most suitable approach to reach both targets. In this review paper, the pyrolysis principle, the kinetics and the product distribution in three-phases are discussed firstly. Then the effects of operating parameters of the pyrolysis process on the quality and the application potential of the three-phase products, as well as the hazardous element distribution are discussed. To further solve the dominant concerns, such as the oil content in the solid residue, the pyrolytic oil quality and the migration of hazardous elements and heavy metals, the potentials of the catalytic pyrolysis and the co-pyrolysis with additives are also summarized. Also, the typical pyrolysis reactors are then presented. From the perspective of the energy efficiency and the non-hazardous disposal, the integrated technology combining the pyrolysis and the combustion for the OS management is recommended. Finally, the remaining challenges of OS pyrolysis encountered in the research and the industrial application are discussed and the related outlooks are itemized.
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•Energy recovery and non-hazardous disposal are dual targets for OS pyrolysis.•The OS characteristics with energy potential and environmental risk are summarized.•This review focuses on valuable products distribution and harmful components flow.•The advantages and future challenges for OS pyrolysis are proposed and outlooked.
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•Oily sludge releases multiple N/S/Cl pollutants during pyrolysis and combustion.•Database and releasing route of N/S/Cl pollutants were established.•Organic N/S/Cl functionalities in ...oily sludge contribute to majority of pollutants.•Combustion promotes destruction of organic fractions releasing at low temperature.
Pyrolysis and combustion have become effective technologies for oily sludge treatment. This paper firstly investigated N/S/Cl pollutants during pyrolysis and combustion of oily sludge in detail by thermogravimetry-mass spectrum (TG-MS) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). Combined with the distribution characteristics and contents of hazardous elements, the releasing routes were proposed. Three typical decomposition steps were observed: volatilization of water and little hydrocarbons below 200 °C, cracking of hydrocarbons approximately at 200–500 °C, transformation of inorganic compositions at the higher temperature. Double-direction transfer diffusion reaction model was employed with estimated apparent activation energy Ea of 41.97–66.59 kJ·mol−1 for pyrolysis and 52.02–62.42 kJ·mol−1 for combustion. The main pyrolytic products were alkanes and alkenes ranging from C9 to C21, which had the potential to be reused as diesel fuels. Slight amounts of S/Cl-containing species were detected in liquid products. Database of inorganic and organic N/S/Cl pollutants with larger molecules was established. Organic N/S/Cl functionalities in oily sludge contributed to the majority of N/S/Cl pollutants. NH3, HCN, HNCO, NO, NO2, CS2, SO2, CH3SH, HCl, and Cl2 were generated between 200 and 600 °C during pyrolysis process, which were much lower than the quantity of corresponding products from combustion. Oxygen-enriched atmosphere in combustion facilitated decomposition of organic fractions, and shifted release regions towards lower temperatures. The decomposition of amine-N functionality contributed to NH3 release below 200 °C. With temperature increasing, heterocyclic-N began to decompose and release abundant NH3, small amounts of HCN and HNCO. Aliphatic-S and disulfides-S contributed to the formation of H2S, COS, and CS2.
Oily sludge (OS) is a hazardous waste and pyrolysis is a promising technology to achieve energy recovery and non-hazardous disposal simultaneously. However, the distribution of hazardous elements, ...including N/S/Cl and heavy metals, in pyrolytic products possibly causes secondary pollution. This study conducted a systematic research on hazardous elements flow during OS pyrolysis under variant temperature. Results showed that N/S/Cl in OS were distributed 44.77–15.51 wt%, 83.29–80.22 wt%, and 78.59–73.41 wt% into the solid residues after pyrolysis, respectively. Elevating pyrolysis temperature facilitated more N/S/Cl flowing into pyrolytic oil and gas. The macromolecular N-/S-/Cl-containing compounds, including amides, amines, nitriles, sulfonates, chloroalkanes, etc., were widely distributed in pyrolytic oil and gas products. The micromolecular N-/S-/Cl-containing pollutants released between 200 and 400 °C included HCN, NH3, NOx, H2S, CH4S, CS2, SO2, and HCl, which originated from the decomposition of the amine N, organic sulfide and sulfone-S, and inorganic Cl, respectively. The main pollutants released at above 400 °C included NH3, HCN, NOx, CS2, and SO2, which were derived from the decomposition of heterocyclic N and inorganic pyritic-S and sulfate-S. Moreover, the solid residues intercepted more than 60.0 wt% of total heavy metals, which should be concerned in the future.
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•The hazardous elements flow spectra during OS pyrolysis are established.•Higher pyrolysis temperature promoted N/S/Cl to flow into pyrolytic oil and gas.•Various macromolecular N/S/Cl-containing compounds were distributed in oil and gas.•The heavy metals in solid residues from OS pyrolysis should be more concerned.
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•Simulating vulcanization to evaluate S migration during pyrolysis of waste tire.•Vulcanization greatly affects activation energy, products, and S migration route.•Vulcanization ...promotes S retention in char with less S migration into gas.•H2S/CH3SH generate by C-Sx and ·H/·CH3, while COS/SO2 originate from C-Sx with O.
This paper systematically investigated sulfur transformation during pyrolysis of waste tires by simulating vulcanization process. Three formulas with rubbers, carbon black, ZnO, and typical vulcanization accelerators were prepared by vulcanization and compounded process as simulated tires. Stepwise temperature programmed pyrolysis was conducted in thermogravimetric analyzer and fixed bed reactor. Vulcanization promoted the weight loss rate for thermal degradation of vulcanized rubbers at 300–400 °C, but weakened it at 400–500 °C. The addition of vulcanization accelerators made these effects even more pronounced. Accordingly, more pyrolytic oil was obtained at 300–400 °C for vulcanized rubbers which should contribute to the partial destruction of polymer chains by vulcanization. Besides, vulcanized rubbers attained higher proportion of aromatics but less cyclenes than compounded rubbers. Vulcanized rubbers with ethyl ziram accelerator inhibited H2S release, while vulcanized rubbers with N-tert-Butyl-2-benzothiazolesulfenamide inhibited the formation of CH3SH. The detailed sulfur compounds in gas, oil, and solid char were analyzed. Vulcanization seemed to exhibit positive effect on sulfur transformation in pyrolytic products, i.e., higher retention rate in pyrolytic char but lower proportion ratio in gas. Sulfurization promoted the conversion of thiophene sulfur to inorganic sulfur and sulfides found in pyrolytic char was only ZnS.
•PAM/SDS were stage pyrolyzed to investigate N/S transformation behaviors in oily sludge.•Primary pyrolysis of PAM led to massive release of C6H9NO2, C5H7NO2 and NH3.•Low temperature pyrolysis of SDS ...led to intense SO2 emission.•Dosing of Ca(OH)2/Fe2O3 was an effective regulatory strategy for N/S-pollutants.
Pyrolysis of oily sludge (OS) is an alternative for energy recovery with less pollutants. However, the migration of nitrogen and sulfur during pyrolysis process remain challenges for environmental concern and subsequent utilization of the recovered fuel. In this work, stage pyrolysis experiments of polyacrylamide (PAM) and sodium dodecyl sulfonate (SDS) under OS surroundings were conducted in a thermogravimetry-mass spectrometry-infrared spectroscopy and a fixed reactor to investigate the transformation behaviors of N/S-containing pollutants. Ca(OH)2 and Fe2O3 were then used as inhibitors to regulate nitrogen and sulfur behaviors. Results showed that 3,3 dimethylpyrrolidine-2,5-dione (C6H9NO2), glutarimide (C5H7NO2) and NH3 were the primary N-containing pollutants in liquid and gaseous products, which were generated from PAM via deamination reactions at 200–400 °C. SO2 was the dominant S-containing pollutant, which was generated from SDS via desulfonation at temperature below 300 °C. The dosage of Ca(OH)2 catalyzed the deamination and cracking reactions, and thus led to more N/S-containing pollutants. Fe2O3 suppressed the N/S-containing pollutants significantly because it could increase the energy barrier of N/S-containing pollutants and fix the released NH3 and SO2 into solid residues. This work facilitated the understanding of the nitrogen and sulfur transformation behaviors and would provide a possible regulatory strategy for clean fuel recovery.
•Microwave pyrolysis is superior to conventional methods in treating tannery sludge.•Microwave pyrolysis facilitates the reduction of Cr(VI) to Cr(III).•Microwave pyrolysis efficiently removes toxic ...substances from tannery sludge.•Microwave pyrolysis effectively fixes heavy metals in the residues.
The efficient and safe treatment of tannery sludge (TS) are causing significant concern. Pyrolysis stands as a pivotal technology in the realm of sludge treatment, offering the benefits of degrading organic matters within TS while simultaneously transforming the sludge into energy and other valuable substances. In order to develop an effective pyrolysis method with good resource recovery performance, this study employs microwave pyrolysis (MP) and conventional pyrolysis (CP) at temperatures ranging from 300 to 900 °C to investigate the transformation of chromium morphology. The results indicate that TS experienced a weight loss of 43 % during the pyrolysis process, with a combined average activation energy measured at 169.58 kJ/mol. MP, due to its more uniform and efficient heating, resulted in pronounced solid degradation, leading to increased pyrolysis gases. This enhanced the removal of organics at lower temperatures and contributed to the ring opening of aromatic hydrocarbons in the high-temperature segment. MP effectively reduced Cr(VI) to Cr(III) in TS, whereas CP showed relatively ineffective reduction of Cr(VI). Furthermore, metal compounds in TS treated by both MP and CP predominantly existed in the residue as FeCr2O4 and Cr2O3 at high temperatures. This suggests that more Cr(III) was immobilized in the pyrolysis residue. This study revalues the significance of MP as a promising treatment for TS, holding the potential for resource utilization.
With the development of cloud computing, virtualization technology has been widely used in our life. Meanwhile, it became one of the key targets for some attackers. The integrity measurement in ...virtual machine has become an urgent problem. Some of the existing virtualization platform integrity mea- surement mechanism introduces the trusted computing technology, according to a trusted chain that the Trusted Platform Module （TPM） established for trusted root to measure the integrity of process in static. But this single chain static measurement cannot ensure the dynamic credible in platform running. To solve the problem that the virtual trusted plat- form can not guarantee the dynamic credibil- ity, this paper put forward Dynamic Integrity Measurement Model （DIMM） based on vir- tual Trusted Platform Module （vTPM） which had been implemented with typical virtual machine monitor Xen as an example. DIMM combined with virtual machine introspection and event capture technology to ensure the se- curity of the entire user domain. Based on the framework, this paper put forward Self-mod- ify dynamic measurement strategy which can effectively reduce the measurement frequency and improve the measurement performance. Finally, it is proved that the validity and feasi- bility of the proposed model with comparison experiments.
Background Superficial urothelial carcinoma （SUC） of the bladder is a common urinary tract tumor in China. There is a high recurrence rate of this tumor even after surgery and intravesical ...instillation. Previous reports have described a suppression of the immune system in cancer patients. Dendritic cells （DCs） play a pivotal role in the induction of an effective antitumor immune response. The aim of this study was to investigate the effects of surgery and epirubicin intravesical chemotherapy （IC） on peripheral blood DCs in subsets of patients with bladder SUC. Methods A total of 66 SUC patients and 38 healthy controls were enrolled in this study. All the patients had undergone transurethral resection （TUR） of their cancer and adjunctive IC after tumor removal. The patients were divided into a non-recurrence group （n=40） and a recurrence group （n=26） based on the presence or absence of tumor recurrence. Blood samples were taken preoperatively （PreOP）, on postoperative days （POD） 1 and 7, and at postoperative month （POM） 3. Flow cytometric analysis was used for the determination and quantitation of the surface markers CD80 and CD86 in circulating DC subsets. Results The preoperative percentages of myeloid dendritic cells （mDCs） and expression of CD80 and CD86 were impaired in SUC patients compared to healthy controls （P 〈0.05）. The percentages of mDCs and these surface markers decreased significantly on POD 1 and increased on POD 7, remaining higher than the preoperative values in POM 3 （P 〈0.05）. The percentages of mDCs, and CD80 and CD86 in the non-recurrence group on PreOP, POD 7, and POM 3 were higher than those in recurrence group. Conclusions Surgical removal of SUC and adjunctive IC were associated with improved circulating mDC counts and function. Persistent depression of mDC counts and function after treatment in recurrence patients indicated lower antitumor immunity that may lead to tumor recurrence.
This study sought to analyze the effect of curing temperature on mechanical strength and microstructure of a copper tailing-based geopolymer via scanning electron microscopy (SEM), HCl extraction, ...nuclear magnetic resonance (NMR), and X-ray diffraction (XRD). The distribution of gel formed in geopolymers tended to be uniform with increasing curing temperature from 25 to 80 °C. Moreover, the percentage of Si sites in C–S–H and N-A-S-H gels increased from 62.08% to 78.94% and more tetrahedral AlO4 was incorporated into the tetrahedron SiO4 backbone, leading to an increase of compressive strength from 10.2 to 39.6 MPa. When the curing temperature was increased to 120 °C, the percentage of Si sites in C–S–H and N-A-S-H gel decreased to 69.52%, and the compressive strength decreased to 27.5 MPa. Moderately elevated curing temperature promoted the dissolution of aluminosilicate while curing temperatures above 80 °C hindered it. Excessive curing temperature led to a decrease in the geopolymer alkaline medium.
•A moderately elevated curing temperature promoted uniform gel distribution and C–S–H and N-A-S-H gel formation.•An elevated curing temperature promoted the entry of tetrahedral AlO4 into the tetrahedron SiO4 backbone.•Excessive curing temperature led to a decrease in geopolymer alkaline medium.
