Combined alkaline and ultrasonic pretreatment of sludge before aerobic digestion

Alkaline and ultrasonic sludge disintegration can be used as the pretreatment of waste activated sludge （WAS） to promote the subsequent anaerobic or aerobic digestion. In this study, different combinations of these two methods were investigated. The evaluation was based on the quantity of soluble chemical oxygen demand （SCOD） in the pretreated sludge as well as the degradation of organic matter in the subsequent aerobic digestion. For WAS samples with combined pretreatment, the released COD levels were higher than those with ultrasonic or alkaline pretreatment alone. When combined with the ultrasonic treatment, NaOH treatment was more efficient than Ca（OH）2 for WAS solubilization. The COD levels released in various sequential options of combined NaOH and ultrasonic treatments were in the the following descending order： simultaneous treatment 〉 NaOH treatment followed by ultrasonic treatment 〉 ultrasonic treatment followed by NaOH treatment. For simultaneous treatment, low NaOH dosage （100 g/kg dry solid）, short duration （30 min） of NaOH treatment, and low ultrasonic specific energy （7500 kJ/kg dry solid） were suitable for sludge disintegration. Using combined NaOH and ultrasonic pretreatment with optimal parameters, the degradation efficiency of organic matter was increased from 38.0% to 50.7%, which is much higher than that with ultrasonic （42.5%） or with NaOH pretreatment （43.5%） in the subsequent aerobic digestion at the same retention time.

Synergistically Improved Mechanical Properties and Thermal Conductivity of Hypoeutectic AlSiNiFeMg Alloy Prepared by Ultrasonic-assisted Casting

We employed a melt ultrasonic treatment near the liquidus to prepare a high-thermal-conductivity Al-4Si-2Ni-0.8Fe-0.4Mg alloy.The influences of various ultrasonic powers on its microstructure,mechanical properties,and thermal conductivity were investigated.It is shown that near-liquidus ultrasonication significantly refines the alloy grains and eutectic structure,synergistically improving the alloy’s mechanical properties and thermal conductivity.Specifically,the grain size decreased by 84.5%from 941.4 to 186.2μm.Increasing the ultrasonic power improved the thermal conductivity of the alloy slightly and significantly enhanced its mechanical properties.At an ultrasonic power of 2100 W,the tensile strength,yield strength,elongation rate,and thermal conductivity were 216 MPa,142 MPa,6.3%,and 169 W/(m·k),respectively.

A novel method towards improving the hydrogen storage properties of hypoeutectic Mg-Ni alloy via ultrasonic treatment

Ultrasonic treatment has great contributions on modifying the morphology,dimension and distribution of constituent phases during solidification,which serve as dominate factors influencing the hydrogen storage performance of Mg-based alloys.In this research,ultrasonic treatment is utilized as a novel method to enhance the de-/hydriding properties of Mg-2Ni(at.%)alloy.Due to ultrasonic treatment,the microstructure of as-cast alloy is significantly refined and homogenized.Ascribing to the increased eutectic boundaries and shortened distance insideα-Mg for hydrogen atoms diffusion,the hydrogen uptake capacities and isothermal de-/hydriding rates improve effectively,especially at lower temperature.The peak desorption temperature reduces from 392.99°C to 345.56°C,and the dehydriding activation energy decreases from 101.93 k J mol^(-1)to 88.65 k J mol^(-1).Weakened hysteresis of plateau pressures and slightly optimized thermodynamics are determined from the pressure-composition isotherms.Owing to the refined primary Mg,a larger amount of hydrogen with the higher hydriding proportion is absorbed in the first stage when hydrides nucleate in eutectic region and grow on primary Mg periphery subsequently before MgH2colonies impinging,resulting in the enhancement of hydrogenation rates and capacities.

Physical and emulsifying properties of pea protein:influence of combined physical modification by flaxseed gum and ultrasonic treatment

This study characterized and compared the physical and emulsifying properties of pea protein(PP)and its modified proteins(ultrasound treated-PP(PPU),flaxseed gum(FG)treated PP(PPFG)and ultrasound treated-PPFG(PPFGU)).The results showed FG triggered the formation of loosely attached complex with PP via physical modification under gentle magnetic stirring at pH 7.0,while ultrasound played an important role in reducing protein size,increasing surface hydrophobicity and molecular fluidity onto oil-water interface.So ultrasound further enhanced the interaction of PP with FG,and produced the PPFGU complex with smaller droplet size,higherζ-potential and lower turbidity.Further,combination of FG and ultrasound improved the physical properties of PP with higher viscosity,stiffer gels(defined as higher elastic modulus),stronger hydrophobic properties,better thermal stability,and fast protein absorption rate.Therefore,the PPFGU coarse emulsion performed highest emulsifying activity index(EAI)and emulsion stability index(ESI)that the stabilized nanoemulsion obtained smallest droplet size,higherζ-potential,and longest storage stability.The combination of FG and ultrasonic treatment will be an effective approach to improving the emulsifying property and thermal stability of PP,which can be considered as a potential plant-based emulsifier applied in the food industry.

Rapid Preparation of Filamentous Fungal DNA for PCR Analysis by Ultrasonic Treatment

A simple method to prepare of DNA template suitable for PCR amplification from filamentous fungi will be valuable for improving experimental efficiency.Here,a method was developed which just needed ultrasonic treatment of the mycelium at usual condition,and the produced solution could directly be used as DNA template for internal transcribed spacer(ITS)amplification successfully.The PCR could be improved by additional treatment of 60℃water baths,but was not centrifugation.When the template amount was 0.5-2μL and the ultrasonic time was 7-11 min,there was no distinctly influences on PCR.The method was commonly used for M.purpureus,I.cicadae,Lentinula sp.,Flammul sp.and Dictyophora sp.etc.to detect target sequences of ITS,hygromycin resistance gene(Hyg),CRISPR-associated protein 9(Cas9),Citrinin gene C(CtnC),Citrinin gene D(CtnD),large subunit rRNA gene(NL),and so on.The method could provide a simple,rapid,safe and economic approach to prepare the DNA template for large-scale PCR of the special filamentous fungi materials.

Effects of ultrasonic treatment on microstructure and mechanical properties of Mg-5Zn-2Er alloy

The effects of ultrasonic treatment on the microstructure and mechanical properties of Mg-5Zn-2Er alloy at room temperature （RT） and high temperature （HT） were investigated. The microstructure and mechanical properties of the samples were studied by OM, SEM and MTS material tester. The results show that the microstructure and mechanical properties are improved after the ultrasonic vibration. The best effects of ultrasonic vibration on microstructure and mechanical properties were obtained with the ultrasonic vibration power of 600 W and time of 100 s. The cavitation and acoustic streaming caused by ultrasonic treatment play a major role in refining the microstructure and increasing mechanical properties of the alloy.

Overflowing phenomenon during ultrasonic treatment in Al-Si alloys

At the late stage of solidification with ultrasonic treatment （UST） in Al-Si alloys, a part of semisolid overflows and climbs along the probe. The interesting phenomenon and its influence on the solidification microstructure were investigated in order to better study the mechanism of UST. It is considered that the overflowing phenomenon occurs due to the changes of vibration and flow in the remaining semisolid. Because the overflowed portion comes from the region with intense UST effect and vibrates with the probe during solidification, great modification of primary and euteetic Si （about 10 pm in length） and refinement of primary a（Al） （about 70 μm in size） are observed in this portion.

Effects of ultrasonic treatment on microstructures of AZ91 alloy

Effects of ultrasonic treatment on microstructures were investigated by introducing the ultrasonic oscillation into AZ91 alloy melts. The results show that the ultrasonic treatment does not change the phase composition but has great influence on solidification microstructures. The area percentage of lamellar eutectic phase increases to the maximum when the applied ultrasonic power is increased to 600 W and then decreases gradually with the further increase of power;meanwhile, the average area of Al8Mn5 phase owns a completely opposing variation trend. The area percentage of Mg17Al12 decreases gradually with increasing the applied ultrasonic power. Mechanisms accounted for the refinement and fraction of different intermetallic phases were also discussed.

Effects of ultrasonic treatment on microstructure and mechanical properties of Mg-6Zn-0.5Y-2Sn alloy

The effects of the ultrasonic treatment on the microstructure and mechanical properties of Mg-6Zn-0.5Y-2Sn alloy were investigated. The results show that the ultrasonic treatment has significant effect on the microstructure and mechanical properties of Mg-6Zn-0.5Y-2Sn alloy. The phases in Mg-6Zn-0.5Y-2Sn alloy are α-Mg, MgZn2, MgSnY, Mg2Sn, and a small amount of I-phase. With the application of ultrasonic treatment, I-phase nearly disappears, and with increasing the ultrasonic treatment power, the coarse dendrites gradually change into roundish equiaxed grains. The second phases at the α-Mg boundaries transform from coarse, semicontinuous and non-uniform to fine, discontinuous, uniform and dispersive. When the ultrasonic treatment power is 700 W, the best comprehensive mechanical properties of Mg-6Zn-0.5Y-2Sn alloy are obtained. Compared with the untreated alloy, the 0.2%tensile yield strength, ultimate tensile strength and elongation are improved by 28%, 30%and 67%, respectively.

Correction of buckling distortion by ultrasonic shot peening treatment for 5A06 aluminum alloy welded structure

Ultrasonic shot peening treatment （USPT） was proposed to correct welding buckling distortion. The residual stress distribution along the depth direction of the peened zone was measured by an X-ray diffractometer. The microstructure of the treated specimens was investigated by scanning electron microscopy （SEM）. The Vickers microhardness was measured in different areas of welded joint before USPT and along the depth direction of the weld after USPT. The experimental results indicated that the welding buckling distortion of 5A06 aluminum alloy butt joint can be essentially corrected by USPT; the average correction rate reached 90.8% in this study. Furthermore, USPT enhanced specimens by work hardening. The microstructure of the peened zone was improved; moreover, the distribution of the precipitates and grains presented an apparent orientation.

Effect of ultrasonic melt treatment on degassing of Mg-6Zn-1Ca alloy

The effect of ultrasonic power and treatment time on degassing of Mg-6Zn-1Ca alloy was studied in this paper. The degassing effect was characterized by measuring densities of ingots. The results show that proper ultrasonic treatment can remove hydrogen from the melt of the Mg-6Zn-1Ca alloy. The ultrasonic degassing effect is closely related to the ultrasonic power density and treatment time. The degassing efficiency increases with an increase in ultrasonic power density when the melt is treated at 690 °C for 120 s, reaching its highest value at 1.2 W·cm-3. When the power density is 1.2 W·cm-3, with an increase in ultrasonic treatment time, the degassing efficiency increases at first, reaches its peak value at 120 s, then decreases as the ultrasonic treatment is further prolonged. In this experiment, the optimum degassing effect with an efficiency of 67.5 % is obtained by ultrasonic treatment with the power density of 1.2 W·cm-3 for 120 s. The maximum density of ingot can be increased from 1.8069 g·cm-3 to 1.8146 g·cm-3(increased by 0.43%).

Adsorptive desulfurization over hierarchical beta zeolite by alkaline treatment

Hierarchical beta zeolites with SiO2/Al2O3 molar ratios of 16 to 25 were obtained by alkaline treatment in NaOH solution. The effects of treatment temperature on crystallinity, textural properties and chemical composites were studied by XRD, N2 sorption, FT-IR and XRF techniques. The desulfurization performance of parent and alkaline-treated beta zeolites was investigated by static absorption in four model fuels, containing four sulfur compounds of different molecular sizes like thiophene （TP）, 3-methylthiophene （3-MT）, benzothiophene （BT） and dibenzothiophene （DBT）, respectively. The crystallinity was observed to be successfully maintained when the treatment temperature was below 50 ℃. Mesoporosity of beta zeolite was evidently developed with alkaline treatment. The formation of mesopore remarkably improved the desulfurization performance for TP, 3-MT, BT and DBT, especially for DBT with larger molecular diameter. Though the addition of toluene in the model fuels resulted in a significant drop of the desulfurization performance of mesoporous beta zeolite, the introduction of cerium ions to some extent mitigated the effect of toluene, which means that both the adsorbent’s porous structure and the adsorption mode are responsible for the desulfurization performance. The adsorbent of cerium ion-exchanged mesoporous beta showed about 80% recovery of desulfurization after the first regeneration.

Improving the fatigue property of welded joints for AZ31 magnesium alloy by ultrasonic peening treatment

The fatigue property of AZ31 magnesium alloy and its TIG welded joints were investigated. The ultrasonic peening treatment （UPT） was used to improve the fatigue property of the TIG welded joints, which was treated at the weld toe by the UPT process. The test results show that the fatigue strength of the base metal of AZ31 magnesium alloys is 57.8 MPa, and those of the fillet joint and the transverse cross joint are respectively 20. 0 MPa and 17.2 MPa at 2 × 10^6 cycles. The fatigue strengths of two kinds of welded joints treated by the UPT are respectively 30. 3 MPa and 24. 7 MPa, which have been improved by 51.5% and 43.6%, respectively. The fatigue life of the fillet joint specimens is prolonged by about 2. 74 times and the fatigue life of the transverse cross joint specimens is prolonged by about 1.05 times when the stress range is at 40. 0 MPa.

Effect of ultrasonic treatment and Sr addition on microstructure of Al-20%Si alloy

Many investigations have revealed that transition of melt structure can effectively influence the final solidification microstructures. In this study, ultrasonic treatment was applied to AI-20%Si melt and Sr-modified AI-20%Si melt at 720 ℃ （i.e. above liquidus of about 690℃） for 60 s, and then the melt was quickly quenched to room temperature. Experimental results show that ultrasonic treatment can refine the primary Si phase and a-AI of AI-20%Si alloy; strontium can make the morphology of Si phase spheroidized and refined as Sr addition changes the faceted growth characteristic of Si phase; however, the refinement effect of ultrasonic treatment on the primary Si phase and α-AI is weakened by Sr addition.

Experimental research in leaching of copper-bearing tailings enhanced by ultrasonic treatment

On the basis of an experiment in ultrasonic enhanced ammonia leaching of tailings, the effect of ultrasonic waves on copper dissolution was studied. The mechanism of ultrasonic enhanced tailing leaching was analyzed and a technique of ultrasonic enhanced pipe leaching of tailings was proposed. The results show that tailings with ultrasonic treatment can leach up to 89.5% of Cu, which is 13.5% more than those without the treatment. Ultrasonic technology is capable of improving leaching rates and the overall recovery of tailing leaching. Impact waves and micro jet streams can strip and erode affected surfaces of tailing particles to create new active surfaces and disturbances can intensify mass transfer processes in "dead zones". The technique of ultrasonic enhanced pipe leaching of tailings is a combination of existing agitation enhancement with ultrasonic enhancement and can improve mineral recovery.

EFFECTS OF ULTRASONIC TREATMENT ON FEMALE GAMETOPHYTES OF LAMINARIA JAPONICA (PHAEOPHYTA)

This study on the effects of ultrasonic treatment on female gametophytes of Laminariajaponica showed that:1. Ultrasonic treatment had shortening effect on filaments of female gametophytes. Within certainperiod of time, the average length of filamentous female gametophytes was shortened.2. Ultrasonic treatment had emptying effect on cells. The number of empty cells increased with timeof treatment. Ultrasonic treatment had harmful effect on cells.3. Ultrasonic treatment could break down cell walls. The combination of frequency of 20 kHz, out-put of 15 W, 40 s and 60 s of treatment was best for this purpose. After ultrasonic treatment, the regner-ation of female gametophytes into sporophytes was effected. Female gametophytes could not recover aftertoo long period of treatment.

A comparative study of the role of solute,potent particles and ultrasonic treatment during solidification of pure Mg,Mg-Zn and Mg-Zr alloys

Ultrasonic treatment(UST)applied during the solidification of pure Mg,eutectic(Mg-Zn)and peritectic(Mg-Zr)alloys was investigated in order to explore the grain refinement mechanisms.Temperature dependent grain refinement is observed in pure Mg where decreasing the superheat temperature(at which UST is applied from above the melting temperature,TM)from 100℃to 40℃produces significant refinement with a uniform grain structure.The presence of solute reduces the temperature dependence of the UST refinement and excellent grain refinement is obtained regardless of the superheat temperature(100℃or 40℃)and even with the use of preheated sonotrode in the Mg-6 wt.%Zn alloy.A further improvement in grain refinement is achieved when the alloy contains potent particles that introduce additional nucleation of grains in Mg-0.5 and 1.0 wt.%Zr alloys(producing an average grain size of≤100μm).At 40℃superheat,UST of Mg-Zn alloys produces excellent refinement(average grain size<200μm)with non-dendritic grains,which is normally achieved only with the addition of grain refining master alloy in the as-cast condition.The enhanced refinement observed in the eutectic alloy is explained through the undercooling imposed by a relatively cold sonotrode combined with high frequency vibrations and acoustic streaming.The advantages of using a cold sonotrode,a low superheat and solute are demonstrated for achieving significant refinement during solidification of Mg alloys under UST without or with a lower addition of grain refining master alloys.

Effects of nano-SiC_p content on microstructure and mechanical properties of SiC_p/A356 composites assisted with ultrasonic treatment

nano-SiCp/A356 composites with different nano-SiCp contents were prepared by squeeze casting after ultrasonic treatment（UT）. The effects of SiCp content on the microstructure and mechanical properties of the nanocomposites were investigated. Theresults show that with the addition of nano-SiCp, the microstructure of nanocomposites is obviously refined, the morphology of theα（Al） grains transforms from coarse dendrites to rosette crystals, and long acicular eutectic Si phases are shortened and rounded. Themechanical properties of 0.5%, 1% and 2% （mass fraction） SiCp/A356 nanocomposites are improved continuously with the increaseof nano-SiCp content. Especially, when the SiCp content is 2%, the tensile strength, yield strength and elongation are 259 MPa,144 MPa and 5.3%, which are increased by 19%, 69% and 15%, respectively, compared with those of the matrix alloy. Theimprovement of strength is attributed to mechanisms of Hall？Petch strengthening and Orowan strengthening.

Effect of ultrasonic treatment on formation of iron-containing intermetallic compounds in AlSi alloys

Iron is generally regarded as an unavoidable impurity in Al-Si casting alloys. The acicular AlaFe and β-AI5FeSi （or Al9Si2Fe2） are common iron-containing intermetallic compounds （IMCs） in conventional structure which have a detrimental impact on the mechanical properties. In this paper, ultrasonic field （USF） was applied to modify acicular iron phases in Al-12%Si-2%Fe and Al-2%Fe alloys. The results show that the USF applied to AI-Fe alloys caused the morphological transformation of both primary and eutectic Al3Fe from acicular to blocky and granular without changes in their composition. In the case of AI-Si-Fe alloys, ultrasonic treatment led to both morphological and compositional conversion of the temary iron IMCs. When the USF was applied, the acicular/3-Al9Si2Fe2 was substituted by star-like α-Al12Si2Fe3. The modification rate of both binary and ternary iron IMCs relates to the USF treatment duration. The undercooling induced by the ultrasonic vibration contributes to the nucleation of intermetallics and can explain the transformation effect.

Effects of Ultrasonic Treatment on Residue Properties

The changes in properties and structural parameters of four vacuum residue samples before and after ultrasonic treatment were analyzed. Ultrasonic treatment could increase the carbon residue value, decrease the average molecular weight and viscosity, which can barely inlfuence the density of vacuum residue. Meanwhile the constitution of residue can be varied including the decrease in the content of saturates, aromatics and asphaltenes, while the increase in the content of resins can lead to an increase in the total content of asphaltenes and resins. Among the four kinds of residue samples, there is a common trend that the more the content of asphaltenes in feedstock is, the more the increase in the content of resins, the more signiifcant decrease in the aromatic content and the less decrease in the saturates content after ultrasonic treatment of residue would be. Changes in the structure and content of asphaltenes caused by ultrasonic treatment have a signiifcant impact on the changes in residue properties. Ultrasonic treatment has changed the structural parameters of residue such as decrease in the total carbon number of average molecule （CTotal）, the total number of rings （RT）, the aromatic carbon number （CA）,the aromatic rings number （RA） and the naphthenic rings number （RN） , and increase of characterization factor （KH）. The study has indicated that ultrasonic treatment of vacuum residue can change the average structure of residue, and the changes in the content and structure of asphaltenes are the main cause leading to property changes. The results of residue hydrotreat-ing revealed that coke yield decreased, whereas the gas and light oil yield and conversion increased after ultrasonic treat-ment of vacuum residue.