Thermal Disintegration Research Articles

Effect of ultrasonic and thermal disintegration of water treatment sludge

This research was conducted to evaluate the effects of thermal and ultrasound disintegration on the disintegration degree (DD) of water treatment sludge from a municipal water treatment plant. A disintegration process was used to (i) improve subsequent coagulation efficiencies and dewatering processes (ii) reduce sludge production, and (iii) obtain both economic and enviromental benefits. The results show that using the disintegration process has an influence on DD values. It is also worth emphasising that the main parameter determining the efficiency of ultrasonic and thermal disintegration was the time of the applied process. Other parameters such as ultrasound intensity and temperature had a reduced impact on DD values.

Reaction rate coefficient k20 and temperature coefficient Θ in organic waste thermal disintegration

It was described the test of sewage sludge and organic fraction of municipal mixed solid waste thermal disintegration process. The waste activated sludge used during the tests was collected from the secondary settlement tank in a mechanical-biological wastewater treatment plant. The biowaste used in the studies was collected from an area of new buildings. It was noticed from means values of Soluble Chemical Oxygen Demand (SCOD) plot that both heating temperature and time, influence the amount of dissolved COD. The observations indicate that changes of SCOD can be described by an increasing, differentiable function of time and the rate of change of the soluble COD in the hydrolysates, in time is proportional to the difference of the maximum values of SCOD and its value in time, which leads to the relationship of the first-order ordinary differential equation. The process effectiveness depending on the temperature was described with the mathematical model including Van't Hoff-Arrhenius equation. Inspection of the data and some preliminary fits indicates, that for the description of changes in SCOD terms of time and temperature were adopted the form of nonlinear mixed model. Values of k20 indicator and Θ parameter depend on the substrate type. For waste activated sludge thermal disintegration, value of reaction speed indicator k20 was 0.028 h-1 (0,67 d-1), and value of temperature indicator equalled Θ = 1.024. For thermal disintegration of biological waste, value of reaction speed indicator k20 was 0.016 h-1 (0,38 d-1), and value of temperature indicator equalled Θ = 1.016.

Process-induced cell wall permeability modulates the in vitro starch digestion kinetics of common bean cotyledon cells.

The presence of cell walls entrapping starch granules in common bean cotyledons, prevailing after thermal processing and mechanical disintegration, has been identified as the main reason for their (s)low in vitro starch digestibility. Nevertheless, it is unknown if the role of cell walls on starch digestion changes as processing conditions (e.g. time) are modified. In this study, it was hypothesised that cell wall permeability would be differently affected depending on thermal process intensity, giving origin to distinct in vitro starch digestion kinetic profiles. Cotyledon cells were isolated from common beans by applying processing conditions normally found at the household level (95 °C and times between 30 and 180 min (palatable range)). Isolated cells were characterised and subsequently subjected to in vitro simulated digestion. Microstructural properties, the starch gelatinisation degree, and the total starch content were similar among samples. In contrast, a higher diffusion of fluorescently labelled pancreatic α-amylase inside the cells was evident as processing time increased. From the kinetic analysis of digestion products, it was determined that longer lag phases and slower reaction rate constants were present in samples with a lower degree of process-induced cell wall permeability. The qualitative analysis of the remaining pellets showed that cellular integrity was maintained throughout in vitro digestion. A mechanism for the in vitro starch digestion of isolated common bean cotyledon cells as well as an alternative kinetic model to describe this process were proposed. Overall, our work demonstrated that the in vitro starch digestion kinetics of common bean cotyledon cells can be modulated by influencing cell wall permeability through thermal processing time.

Preparation of Poly (N-1-Naphthal Maleimide) and Comparing the Activation Energy Values Calculated with Coats-Redfern Equation and Flynn-Wall Equation For the Second and Third Disintegration Step

This study involves the preparation of malic acid from the interaction of maleic anhydride with 1-Naphthal amine, then dehydration of water molecule by acetic acid anhydride with sodium acetate anhydride to obtain the maleimide. Then a radical polymerization of the maleimide was carried out to get the polymer. The study of thermal disintegration gives an indication of the temporal stability of chemicals, and examines the decomposition kinetics of the determination of thermodynamic and kinetic functions of material disintegration, There are many methods use mathematical equations applied to TGA and DTG in order to study this phenomenon. All methods have been used to process data in one of the two models to analyze the kinetic behavior of material disintegration. The first one Flynn-Wall is called differential methods using data extracted from The dissolution of the same compound samples at different heating rates, and the second one called integrative methods examine data extracted from a one sample analysis at a specified heating rate, The TGA process involves continuous recording of mass change for time or temperature when heating in the oven under controlled conditions and the sample can be heated at constant rate. The integrative method based on thermally recorded data gives more reliable results and is less affected by errors. We have written the following algorithm by creating software in Excel to calculate the best order reaction. We noticed the compatibility between the results obtained from the algorithm writing with the results of the Coats-Redfern equation graphically. This algorithm is the most accurate in determining order of reaction. The activation energy of the prepared polymer was determined with Coats-Redfern equation and Flynn-Wall equation by using TGA curve for each step of the decomposition at three heating rate. The Coats Redfern equation was based on the change of the dissociation degree, while the Flynn-wall equation was based on fixing the dissociation degree

Effect of the two-stage thermal disintegration and anaerobic digestion of sewage sludge on the COD fractions

Abstract The research presents the changes in chemical oxygen demand (COD) fractions during the two-stage thermal disintegration and anaerobic digestion (AD) of sewage sludge in municipal wastewater treatment plant (WWTP). Four COD fractions have been separated taking into account the solubility of substrates and their susceptibility to biodegradation: inert soluble organic matter SI, readily biodegradable substrate SS, slowly biodegradable substrates XS and inert particulate organic material XI. The results showed that readily biodegradable substrates SS (46.8% of total COD) and slowly biodegradable substrates XS (36.1% of total COD) were dominant in the raw sludge effluents. In sewage effluents after two-stage thermal disintegration, the percentage of SS fraction increased to 90% of total COD and percentage of XS fraction decreased to 8% of total COD. After AD, percentage of SS fraction in total COD decreased to 64%, whereas the percentage of other fractions in effluents increased.

Correlating the microstructure to mechanical properties and wear behavior of an accumulative back extruded Al-Mg2Si in-situ composite

The present work was conducted to study the effects of microstructural evolutions on the mechanical and wear behavior of an accumulative back extruded aluminum-based in-situ composite. The mechanical fragmentation and thermal disintegration of the primary and secondary Mg2Si particles were found as the main microstructural changes. For that reason, the particle interspacing was decreased, the sharp ends were modified, and the reinforcements were more uniformly distributed. Surprisingly, the wear loss was dramatically decreased in processed materials in comparison to the as-received one. Oxidation and delamination were identified as the dominant wear mechanisms. These were addressed considering the microstructural refinement, and the modification of reinforcing particles with regard to morphology (rod-like, wormy or dot-like), size and distribution.

Energy potential of the modified excess sludge

On the basis of the SCOD value of excess sludge it is possible to estimate an amount of energy potentially obtained during the methane fermentation process. Based on a literature review, it has been estimated that from 1 kg of SCOD it is possible to obtain 3.48 kWh of energy. Taking into account the above methane and energy ratio (i.e. 10 kWh/1Nm 3 CH 4 ), it is possible to determine the volume of methane obtained from the tested sludge. Determination of potential energy of sludge is necessary for the use of biogas as a source of power generators as cogeneration and ensure the stability of this type of system. Therefore, the aim of the study was to determine the energy potential of excess sludge subjected to the thermal and chemical disintegration. In the case of thermal disintegration, test was conducted in the low temperature 80°C. The reagent used for the chemical modification was a peracetic acid, which in an aqueous medium having strong oxidizing properties. The time of chemical modification was 6 hours. Applied dose of the reagent was 1.0 ml CH 3 COOOH/L of sludge. By subjecting the sludge disintegration by the test methods achieved an increase in the SCOD value of modified sludge, indicating the improvement of biodegradability along with a concomitant increase in their energy potential. The obtained experimental production of biogas from disintegrated sludge confirmed that it is possible to estimate potential intensity of its production. The SCOD value of 2576 mg O 2 /L, in the case of chemical disintegration, was obtained for a dose of 1.0 ml CH 3 COOH/L. For this dose the pH value was equal 6.85. In the case of thermal disintegration maximum SCOD value was 2246 mg O 2 /L obtained at 80°C and the time of preparation 6 h. It was estimated that in case of thermal disintegration as well as for the chemical disintegration for selected parameters, the potential energy for model digester of active volume of 5L was, respectively, 0.193 and 0,118 kWh.

Experimental Evaluation of Geomechanical Behaviour of Bentonite-Sand Mixture for Nuclear Waste Disposal

Nuclear waste disposal and spent nuclear fuel are a major concern in most countries. International Atomic Energy Agency (IAEA), the world's central intergovernmental forum for scientific and technical co-operation in the nuclear field, recommended the deep geological disposal for high level radioactive spent fuel. For such disposal, selection of the host rock and the barrier system may be different, but almost all the programs are considering an engineered barrier. A mixture of sand and bentonite is primarily selected as a possible artificial buffer for thermal disintegration that surrounds and protects the individual nuclear waste canisters. In this study, the behavior of geotechnical properties was observed for various bentonite-sand mixing ratios (10-50%). The geomechanical experiments such as specific gravity, compaction, unconfined compression, direct shear and falling head permeability were executed to define an optimum amount of bentonite and sand proportion for designing and constructing a better nuclear waste disposal facility. The addition of bentonite increases the geotechnical parameters such as maximum dry density, specific gravity, unconfined compressive strength, Young's modulus and cohesion. However, the addition leads to a decrease in the optimum moisture content, angle of internal friction and the hydraulic conductivity of sand mixture. Optimum performance of the bentonite-sand mixture was observed when the mixture contained equal amounts of sand and bentonite.

Synthesis of ethylene diamine-based ferrocene terminated dendrimers and their application as burning rate catalysts

Ferrocene-based derivatives are widely used as ferrocene-based burning rate catalysts (BRCs) for ammonium perchlorate (AP)-based propellant. However, in long storage, small ferrocene-based derivatives migrate to the surface of the propellant, which results in changes in the designed burning parameters and finally causes unstable combustion. To retard the migration of ferrocene-based BRCs in the propellant and to increase the combustion of the solid propellant, zero to third generation ethylene diamine-based ferrocene terminated dendrimers (0G, 1G, 2G and 3G) were synthesized. The synthesis of these dendrimers was confirmed by 1H NMR and FT-IR spectroscopy. The electrochemical behavior of 0G, 1G, 2G and 3G was investigated by cyclic voltammetry (CV) and the burning rate catalytic activity of 0G, 1G, 2G and 3G on thermal disintegration of AP was examined by thermogravimetry (TG) and differential thermogravimetry (DTG) techniques. Anti-migration studies show that 1G, 2G and 3G exhibit improved anti-migration behavior in the AP-based propellant.

Classification and Effects of Sludge Disintegration Technologies Integrated Into Sludge Handling Units: An Overview

The sludge disintegration technologies integrated into sludge handling units are pretreatment processes that reduce the sludge mass or to improve the sludge characteristics. The sludge disintegration technologies developed to reduce excess sludge are classified as mechanical disintegration, thermal disintegration, chemical or thermo‐chemical disintegration, and biological disintegration. The integration of lab/pilot/full‐scale applications of these technologies into sludge handling units have been shown to significantly minimize sludge. The sludge disintegration technologies are considered to be environmentally safe because these technologies produce no environmentally harmful additional waste. Therefore, sludge minimization has received steadily increasing attention in the last few decades. Here, an overview is presented of the most widely known sludge disintegration technologies that can be integrated into sludge handling units for sludge minimization. The latest applications of sludge disintegration technologies that have been reported in the literature are comprehensively evaluated in terms of sludge solubilization, dewaterability, pathogen removal, and sludge digestibility.

Study on the evaluation of mechanical and thermal properties of natural sisal fiber/general polymer composites reinforced with nanoclay

ABSTRACTComposite materials, made by replacing traditional materials, are used because of their capability to produce tailor-made, desirable properties such as high tensile strength, low thermal expansion, and high strength to weight ratio. The need for the development of new materials is essential and growing day by day. The natural sisal/general polymer (GP) reinforced with nanoclay composites has become more attractive due to its high specific strength, light weight, and biodegradability. In this study, sisal–nanoclay composite is developed and its mechanical properties such as tensile strength, flexural strength, and impact strength are evaluated. The interfacial properties, internal cracks, and internal structure of the fractured surface are evaluated using scanning electron microscope. The thermal disintegration of composites are evaluated by thermogravimetric analysis. The results indicate that the incorporation of nanoclay in sisal fiber/GP can improve its properties and can be used as a substitute material for glass fiber-reinforced polymer composites.

The absence of a dense potential core in supercritical injection: A thermal break-up mechanism

Certain experiments in quasi-isobaric supercritical injection remain unexplained by the current state of theory: Without developing a constant value potential core as expected from the mechanical view of break-up, density is observed to drop immediately upon entering the chamber. Furthermore, this phenomenon has never been captured in computational fluid dynamics (CFD) despite having become a de facto standard case for real fluid CFD validation. In this paper, we present strong evidence for a thermal jet disintegration mechanism (in addition to classical mechanical break-up) which resolves both the theoretical and the computational discrepancies. A new interpretation of supercritical jet disintegration is introduced, based on pseudo-boiling, a nonlinear supercritical transition from gas-like to liquid-like states. We show that thermal disintegration may dominate classical mechanical break-up when heat transfer takes place in the injector and when the fluid state is sufficiently close to the pseudo-boiling point. A procedure which allows to capture subsided cores with standard CFD is provided and demonstrated.

Thermomechanical buckling of boron nitride nanotubes using molecular dynamics

We study the thermal buckling behavior of precompressed boron-nitride nanotubes (BNNTs) using molecular dynamics simulations with Tersoff interatomic potential. We compute the critical buckling strains at near-zero temperature, and subsequently precompress the nanotubes at a certain fraction of this value followed by temperature ramping. The critical buckling temperature, Tcr, is marked by a sudden decrease of the internal force. We observe that (i) at small to moderate lengths, Tcr is higher for chiral nanotubes than for either armchair or zigzag nanotubes, (ii) Tcr decreases with increasing diameter unlike in thermal disintegration where disintegration temperatures rise with increasing diameter, and (iii) armchair nanotubes have an optimal length for which Tcr is maximum. We qualitatively explain the reasons for each of the findings. Thermomechanical buckling occurs predominantly in two ways depending on the length of the nanotube—while the shorter nanotubes fail by radial instability (shell-like behavior), the longer ones invariably fail due to bending-buckling (rod-like behavior).

The influence of mechanical and thermal disintegration on gravitational separation of surplus sludge

The influence of mechanical and thermal disintegration on gravitational separation of surplus sludge

The Mg2Si phase evolution during thermomechanical processing of in-situ aluminum matrix macro-composite

The microstructure and flow stress behavior of thermomechanically processed Al–Cu/Mg2Si in-situ composite was studied emphasizing the evolution of primary and secondary reinforcement phases. Toward this end, the hot compression tests were conducted over the wide range of temperature (300–500°C) and strain rate (0.001–0.1s−1). Both the temperature and strain rate are found to possess a significant effect on the microstructural characteristics where a considerable softening is identified specially at low temperature regime. Besides the occurrence of restoration processes (mainly particle stimulated nucleation) the dynamic evolution of the reinforcements is introduced as the main factors affecting the reported softening. In this regard, the mechanical fragmentation, thermal disintegration, micro-buckling, coalescence and spheroidization of the primary and secondary particles are quantitatively and qualitatively addressed through a comprehensive scanning electron microscopy studies.

Short- and medium-range orders in Cu46Zr54 metallic glasses under shock compression

We investigate short- and medium-range orders in Cu46Zr54 metallic glasses, as represented by icosahedra and icosahedron networks, respectively, under shock compression with molecular dynamics simulations. Complementary isothermal compression and isobaric heating simulations reveal that compression below 60 GPa gives rise to increased coordination and thus high-coordination-number Voronoi polyhedra, such as icosahedra; however, pressure-induced collapse or thermal disintegration of icosahedra (and subsequently, icosahedron networks) occurs at pressures above 60 GPa or at melting, accompanied by free volume increase. The evolutions of the short- and medium-range orders upon shock loading are the effects of compression combined with shock-induced melting. The structural changes are partially reversible for weak shocks without melting (below 60 GPa) and irreversible for strong shocks. Crystallization does not occur under isothermal or shock compression at molecular dynamics scales.

Influence of water content on the ablation of skin with a 532 nm nanosecond Nd:YAG laser.

This work reports that the ablation volume and rate of porcine skin changed significantly with the change of skin water content. Under the same laser irradiation conditions (532 nm Nd:YAG laser, pulse width = 11.5 ns, pulse energy = 1.54 J, beam radius = 0.54 mm), the ablation volume dropped by a factor of 4 as the skin water content decreased from 40 wt. % (native) to 19 wt. % with a change in the ablation rate below and above around 25 wt. %. Based on the ablation characteristics observed by in situ shadowgraph images and the calculated tissue temperatures, it is considered that an explosive rupture by rapid volumetric vaporization of water is responsible for the ablation of the high water content of skin, whereas thermal disintegration of directly irradiated surface layer is responsible for the low water content of skin.

Effect of freezing as pre-treatment prior to pulsed electric field processing on quality traits of beef muscles

The purpose of this research was to study the effects of freezing as pre-treatment prior to pulsed electric field (PEF) on the quality of beef semitendinosus muscles. Fresh and frozen-thawed samples were treated using square -wave bipolar pulses at electric field strength 1.4 kV/cm, pulse width 20 μs, frequency 50 Hz and total specific energy 250 kJ/kg. PEF caused significant microstructural changes of meat tissue compared to freezing. Combined freezing–thawing and PEF resulted in improved tenderness indicated by reduced shear force, but not PEF alone. PEF significantly increased purge loss but not cooking loss. A two log-unit increase in aerobic microbial counts during log phase of frozen-thawed PEF-treated samples was positively associated with increased purge loss. PEF itself did not affect the ratios of polyunsaturated/saturated fatty acids and omega 6/omega 3 nor the free fatty acid profiles. Freezing with and without PEF greatly affected the volatile profile of meat. PEF treatment provides an alternative to mechanical, thermal and enzymatic cell disintegration of animal raw materials, providing a short duration (milliseconds) and energy efficient treatment. In this study, the possible relationship between freezing prior to PEF and changes in beef tissue microstructure that influence storage stability and safety was investigated. The results of this study contribute toward understanding how PEF induced changes in beef microstructure influence the important quality attributes of beef. • PEF treatment resulted in microstructural changes in meat tissue. • PEF had a positive effect on shear force of frozen–thawed samples after storage. • PEF treatment had no effect on PUFA/SFA or on n6/n3 ratios. • Free fatty acid profile of beef samples was unaffected by PEF treatment. • PEF treatment decreases oxidative stability of frozen–thawed meat.

Improving of anaerobic digestion by dry ice disintegration of activated sludge

Disintegration by dry ice has a positive effect on the degree and rate of surplus activated sludge anaerobic digestion. By applying thermal disintegration the lysis of cells occurs in minutes instead of days. The intracellular and extracellular components are set free and are immediately available for biological degradation which leads to an improvement of the subsequent anaerobic process. Thermal disintegration by dry ice of the surplus activated sludge results in organic matter and a polymer transfer from the solid phase to the liquid. During disintegration process soluble chemical oxygen demand (SCOD) value and proteins concentration increase about 583 and 265 mg/dm, respectively. In the same time concentration of carbohydrates increase about 53 mg/dm. In addition the degree of thermal disintegration changed from 13% for the volume ratio of dry ice to surplus activated sludge 0.25:1 to 49% for the volume ratio of dry ice to sludge 1:1. The addition of thermal disintegrated sludge (30% SASDI of volume) to the digestion process leads to increased biogas production about 49%.

Modification of the grain structure, γ phase morphology and texture in AZ81 Mg alloy through accumulative back extrusion

The capability of accumulative back extrusion (ABE), as a recently developed severe plastic deformation technique, has been considered to modify the microstructural characteristics of a Mg–Al–Zn alloy composing higher Al content. The results indicate that applying the ABE process up to five passes led to simultaneous modification of the γ phase morphology, grain structure and deformation texture of the experimental alloy. The morphology of the eutectic γ phase has been sequentially altered from initial coarse network to elongated and finally spherical morphologies with an average globularity and diameter of 0.85 and 7.5μm, respectively. This has been justified considering the mechanical fragmentation and thermal disintegration of the eutectic particles through necking phenomena. In addition the initial coarse grain structure of the cast alloy (~330μm) has also been significantly refined (d~1μm). This substantial grain refinement is attributed to the dynamic recrystallization enhancement in connection with pinning effect of crushed γ particles during successive passes. The typical basal texture has been modified to a weak random texture having grains with their normal distribution in a desirably wide range of deviation angles from normal direction. The occurrence of particle stimulated nucleation, particle pinning, and shear banding phenomena are suggested as the main reasons causing the weak scattered deformation texture.