查看更多>>摘要：The resource utilization of solid wastes has become a critical problem in resource recovery.In this study,IMSWA(Incinerated municipal solid waste ash)was washed to remove chloride and then mixed with OPC(Ordinary Portland Cement)and SS(Silica Sol)to prepare a non-sintered ceramsite.Through single factor experiments,the quality scores of water-washed IMSWA: OPC: SS is initially determined to be 6:3:1,and the curing time is 14 d.Then the uniform test design was used to optimize the ceramsite formula and the influence of different raw material ratios on the performance of the non-sintered ceramsite.Finally,use DPS(Data Processing System)optimization to determine the best raw material quality scores: 59% for IMSWA,30% for OPC,and 11% for SS.The performance follows(1)Ceramsite's compact surface structure,ensuring high strength and low water absorption.(2)Ceramsite section forms a complex calcium aluminate hydrate gel(C-A-H)structure(3)A profit of $60.97/ton of ceramsite has good economic benefits.These findings demonstrate that preparing a non-sintered ceramsite with IMSWA is a promising artificial lightweight aggregate.
查看更多>>摘要：The explosion of underground pipelines could cause a big crater in which a gas leakage occurs to induce a large jet fire.The pit wall would significantly affect the leaked gas flow and the subsequent jet fire behavior.This paper presents a systematical investigation on such jet fire in a pit(JFP).A facility consisting of a jet fire apparatus and a rectangular pit,was designed for the experimental study.Phenomenon observation shows that the JFP can be divided into the impinging jet flame(IJF),transitive jet flame(TJF)and jet flame ejected from the pit top(JFEPT),due to the variation of the mode of air entrained into the pit with the nozzle exit velocity.A dimensionless heat release rate(HRR)coupling the pit geometrical property is developed to correlate the flame area in different pits,which clarifies the critical dimensionless HRR to distinguish the IJF,TJF and JFEPT.Using the dimensionless HRR,data fitting can well develop the correlation for the flame length of TJF and JFEPT,and the correlation is well validated by the small-scale and full-scale jet fires in irregular cuboid pits.The dimensionless HRR also can be used to well correlate the flame width.The radiative fraction of IJF still follows the law of the Froude number at the nozzle exit,while that of JFEPT should be predicted using the Froude number at the top opening of pit.As indicated by the variations of air en-trainment mode and radiative fraction,the flame buoyancy gradually plays a more significant role than the nozzle exit momentum in the flame behavior,as the nozzle exit velocity increases to cause the evolution of JFP from IJF to JFEPT.In addition,a line source radiation model and two solid radiation models are proposed to predict the thermal radiation of JFP.
查看更多>>摘要：To reduce the threat of explosions to personnel safety,it can be considered to retrofit the existing buildings in high-risk areas of process industry in an economical and effective way.The mechanical behaviors of two types of polyureas were studied through a series of laboratory tests and field gas explosion tests,and the full-field explosion responses of polyurea were measured by a high-speed,three-dimensional digital image correlation(DIC)technique.It was found that polyurea exhibited a significant strain-rate-hardening effect,and the fracture strain of polyurea decreased significantly with the increase of strain rate.The failure criterion of the polyurea-coated fiber-reinforced cement board(FRCB)under gas explosion load conformed to the overpressure criterion.Polyurea could significantly improve the explosion resistance of the FRCB,and the reinforcement ability could be further improved by increasing the polyurea thickness of the rear face and strengthening on both sides.Dynamic thermodynamic and microscopic observations revealed that under gas explosions,the polyurea was in the rubber-glass transition zone,which was beneficial for improving the ability of the material to attenuate shock waves.
查看更多>>摘要：The production of added-value bio-products and energy from waste streams while minimizing environmental impacts is a crucial aspect within the circular economy's principles.The biorefinery can be an exit to the constant increasing of organic food waste and sewage sludge to solve the issues of waste disposal.This work deals with the production of volatile fatty acids(VFA)as added-value products from food waste and sewage sludge mixture in a pilot scale acidogenic fermentation process.Moreover,due to the lack of information about safety aspects in the literature,the explosive risk of the fermenter has been assessed by means of the quantification of lower flammability limit(LFL)of the generated flammable gases.Different temperature and feedstock's composition were tested,as well as the effect of thermal hydrolysis.Mesophilic fermentation(37 ℃)on thermally hydrolysed feedstock(48 h at 72 ℃)ensured stability in terms of VFA production at high concentration(30 ± 2 gCOD_(VFA)/L)and COD_(VFA)/COD_(SOL)ratio(0.86 ± 0.09).Such condition also showed high LFL(28.9%),corresponding to a less hazardous condition compared to the other investigated,especially the thermophilic ones where LFL changed between 18% and 26%.
查看更多>>摘要：As the rapid growth in hazardous waste(HW)is threatening both the environment and public health,more efficient disposal methods are needed.This paper proposes an innovative HW reverse logistics network(RLN)considering advanced co-processing in cement kiln technology,establishing three disposal lines to reduce HW volumes,develop renewable products,reduce greenhouse gas emissions,and conserve resources.To optimise the HW disposal process,a multi-objective optimisation model comprehensively considering social,economic,and environmental dimensions is proposed.Then a numerical example is used to demonstrated the validity of the proposed model and a real-world case is conducted to demonstrate the practicality and efficiency of the proposed model in determining the most suitable hazardous waste disposal facilities,transportation routes and transportation quantities.Scenario analyses under different decision-maker attitudes towards the objectives are conducted while also considering the influence of governmental disposal subsidies.Finally,practical policy suggestions are provided to guide scientific and sustainable HW disposal.This study concludes that 1)different decision maker and disposal subsidy levels affect the optimal system decisions,2)advanced co-processing in cement kiln technology increases the effectiveness of the HW-RLN in terms of economic and environmental perspectives,and 3)policy subsidy support could encourage the application of co-processing in cement kiln technology; a unit disposal subsidy of 160 CNY is considered suitable for"technologically pessimistic"decision-makers,while 200-220 CNY is considered suitable for"technologically optimistic"decision-makers.
查看更多>>摘要：Self-reactive substances are unstable chemical substances which can easily decompose and may lead to explosion in transport,storage,or process situations.For this reason,their thermal stability properties are required to assess possible process safety issues and for classification purpose.In this study,the first quantitative structure-property relationships(QSPR)dedicated to this class of compounds were developed to predict the heat of decomposition of possible self-reactive substances from their molecular structures.The database used to develop and validate the models was issued from a dedicated experimental campaign on 50 samples using differential scanning calorimetry in homogeneous experimental conditions.QSPR models were derived using the GA-MLR methods(using a genetic algorithm and multi-linear regressions)using molecular descriptors calculated by Dragon software based on two types of inputs: 3D molecular structures determined using the density functional theory(DFT),allowing access to three-dimensional descriptors,and from SMILES codes,favoring the access to simpler models,requiring no preliminary quantum chemical calculations.All models respected the OECD validation guidelines for regulatory acceptability of QSPR models.They were tested by internal and external validation tests and their applicability domains were defined and analyzed.
查看更多>>摘要：Discharge of nanomaterials into the environment contributes to a diverse group of pollutants.In the present study,the toxicity of selenium nanoparticles(SeNPs)on the marine diatom Chaetoceros gracilis was studied in the laboratory by conducting 96 h toxicity experiments.The SeNPs were synthesized by reducing sodium selenite using L-cysteine and characterized by spectroscopic and microscopic techniques.X-ray photoelectron spectroscopic(XPS)data showed a distinctive selenide peak at 56 eV,indicating the oxidation states Se3d_(3/2)and Se3d_(5/2).Raman spectra results indicated the characteristic A1 and S mode of selenium(Se).Growth inhibitory experiments were performed(LC50 14.63 mg/L)for 96 h using various concentrations of SeNPs and its membrane damage to cells was observed.Upon treatment with SeNPs,an increased percentage of reactive oxygen species(ROS)production was detected from 28.77 ±3.13% to 13_(0.5)5 ±3.16% after 96 h.Malonaldehyde(MDA),a biomarker of lipid peroxidation was quantified and exposure to 50 mg/L of SeNPs significantly(p<0.05)increased MDA concentration from 4.31 ±0.02 to 5.05 ±0.05 uM in 96 h.The morphological distortion,including cell wall damage,that affects the cellular integrity upon exposure to SeNPs was evident from microscopic studies.These results clearly indicate that,even at lower concentrations,SeNPs toxicity on lower trophic organisms is significant enough to cause cellular level alterations.
查看更多>>摘要：Amoxicillin(AMX)is a widely used broad-spectrum antibiotic whose presence in the environment has been widely concerned.In this work,two kinds of concrete-based hydrotalcites,C-LDH and Fe~(2+)-C-LDH,were synthesized to remove AMX.C-LDH was used to adsorb AMX while Fe~(2+)-C-LDH was employed to activate potassium persulfate(PDS)to degrade AMX.The adsorption characteristics of C-LDH for AMX were investigated,and the formula of Fe~(2+)-C-LDH-PDS system was optimized.The removing mechanisms of AMX removal by C-LDH and Fe~(2+)-C-LDH-PDS system were analyzed.C-LDH showed good performance for AMX adsorption as initial pH between 3-5,with maximum adsorption capacity of 49.7 mg/g.The C-LDH adsorbent could be regenerated by Na2CO3 elution.Fe~(2+)-C-LDH exhibited good activity on PDS activation for AMX degradation,and could be used repeatedly.The optimum mass ratio of Fe~(2+)-C-LDH to PDS was 2.6.C-LDH removed AMX through the electrostatic interaction and hydrogen bonding,while Fe~(2+)-C-LDH-PDS degraded AMX by radical reaction.Concrete-based hydrotalcites illuminate a cheap and sustainable way for the removal of antibiotics.
查看更多>>摘要：This work addresses enhanced benzene,toluene and xylene(BTX)production by catalytic fast co-pyrolysis from agroindustrial biomass blended with PVC and the use of prepared NaZSM-5 and HZSM-5.Results from catalytic fast pyrolysis of biomass indicates that oxygen-containing compounds decreased whereas aro-matics increased.The catalytic effect of mineral content altered the co-pyrolysis intermediates by increasing the formation of mono-aromatics while reducing poly-aromatic hydrocarbons.Furthermore,the addition of PVC strongly influenced thermal decomposition of agricultural waste biomass,where BTX yields were enhanced up to 26.6% and 25.1% for 1:2 OP/PVC-HZ and 1:2 AS/PVC-HZ,respectively.Yields of toluene and xylene peaked at 19% and 1_(0.5)% hydrocarbon yields with 1:2 OP/PVC-HZ blend.Additionally,from the pyrolytic gas,CH4 yields increased while the CO2 yield fell due to oxygen removal by decarboxylation.These findings could provide a great insight into the olive pomace and almond shell valorization through an inexpensive and straightforward easy process.
查看更多>>摘要：Oil spills have become a threat to the ecosystem by releasing the petroleum hydrocarbons and gained substantial public concern in the Chennai coast.This study assesses the effectiveness of bioremediation and its impact on the environment due to remedial operations in the site.Soil and water samples were collected from the bio remediation site at regular intervals of the pit from the topsoil and 20 cm below the ground level from June 2017 to Nov 2019.The average TPH concentration present in the bottom and top soil of bioremediation pit were vary in the range of 21,238.4-46,600 mg/kg and 17577-26910 mg/kg.Central Pollution Control Board(CPCB)allowable limit for TPH concentration present in the soil should be 5000 mg/kg.We have also observed that the mixing was not uniform in the pit and major amount of oil has been penetrated deep inside the soil.Results on gravimetric analysis showed that there was still a large amount of untreated long-chain hydrocarbons are there in the pit.From the results,we can conclude that nC30-nC40 and lower carbon range alkane intermediates have to be treated with additional treatment like thermal smoldering and pyrolysis.
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