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The physical properties of excess sludge wasted from a large pilot scale membrane bioreactor (MBR) have been routinely monitored over almost two years. A statistical analysis highlighted the significant impact of temperature on the capillary suction time and sludge filterability, due to the increase of organic matter in the liquid phase. Suspended solids have resulted to be the most important component affecting sludge filterability, although the impact of colloids and solutes increased when temperature decrease, thus confirming the generally worse characteristics of sludge in such conditions. Conditioning and dewatering test have been performed on a pilot scale fixed volume recessed plate filter press. Six different chemicals were used for sludge pre-conditioning and, for each additive, three dosages were tested in the range 5-25 gpolymer kgMLSS− 1. After about sixty filtration trials at three different pressure values (7, 11 and 15 bar), the kind of polymer seem to be the most important factor influencing the final cake-dryness, with less evident impact for dosage and operational pressure. Finally, when performed on the aerobically digested excess sludge wasted from a conventional activated sludge plant, the filtration tests show no differences with the MBR sludge. 相似文献
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微波辐射柴油脱硫实验研究 总被引:11,自引:4,他引:11
采用微波辅助氧化反应的方法对辽河常二线柴油配制油样进行了脱硫实验,过氧化氢作氧化剂,可以把柴油中的含硫化合物有选择性地氧化成相应的具有很强极性的砜,根据相似相溶原理,这些砜因溶于剂相而从柴油中除去,从而降低了硫含量。实验过程中分别考察了氧化荆用量、剂油比、反应体系压力、氧化时间、微波功率等对柴油硫含量的影响。确定了实验室适宜的操作条件:剂油体积比为0.25:1,微波辐射压力为0.05MPa,微波功率为375w,辐射时间为6min,柴油的脱硫率为60%.而在无微波辐射的条件下,脱硫率仅为12%。 相似文献
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洗毛废水蒸馏处理塔中污泥的改性及其对污泥脱水效果的影响 总被引:3,自引:0,他引:3
洗毛废水蒸馏后形成的污泥虽含较多的有机质和植物养料,也具有很高的热值,但由于富含羊毛脂,黏度高、碱性强、极难脱水,极大地限制了它的资源化利用。根据污泥体系中表面活性剂的乳化作用与破乳的基本原理,通过采用酸化、投加凝聚剂、破乳剂和调节适当反应温度等联合方法,有效地破坏了供试污泥分散体系固有的稳定性,改性后污泥的比阻值R从改性前的大于9.81×1013m/kg下降为2.48×1011m/kg,从而使污泥极易机械脱水。为洗羊毛污泥的资源化利用提供了一个全新的预处理工艺。 相似文献
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以北宿煤为原料,利用微波选择性加热的特点,考察了微波辐照时间、煤样粒径、NaOH等因素对高硫煤磁性强化磁选脱硫的影响,同时考察了微波-NaOH饱和溶液联合处理对北宿煤磁选脱硫的影响。研究表明,不同粒径的煤样的最大脱硫率存在一个最佳微波辐照时间,而微波-NaOH联合处理法脱硫效果更为显著。对煤样进行微波预处理后,可以根据需要控制NaOH饱和溶液用量达到较为理想的脱硫效果。 相似文献
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研究了微波辐射下的木质素磺酸钠与丙烯酸的接枝共聚反应,对微波辐射和常规加热接枝共聚反应的效果进行了比较,并用红外光谱分析了接枝共聚物的结构。同时测试了接枝共聚物在水煤浆中的分散稳定性能。结果表明,通过微波辐射可以得到较高接枝率的木质素磺酸钠丙烯酸接枝共聚物,其对水煤浆的分散稳定作用有明显的改善。 相似文献
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Microwave assisted transesterification of castor bean oil was carried out in the presence of methanol or ethanol, using a molar ratio alcohol/castor bean oil of 6:1, and 10% w/w of acidic silica gel or basic alumina (in relation to the oil mass) as catalyst. Under acid catalysis, the reaction occurred with satisfactory yields using H2SO4 immobilized in SiO2, methanol under conventional conditions (60 °C for 3 h) as well as using microwave irradiation for 30 min. The best results were obtained under basic conditions (Al2O3/50% KOH) using methanol and conventional (60 °C, stirring, 1 h) or microwave conditions (5 min). In comparison with conventional heating, the catalyzed alcoholysis assisted by microwaves is much faster and leads to higher yields of the desired fatty esters. 相似文献
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Use of microwave irradiation in the grafting modification of the polysaccharides - A review 总被引:1,自引:0,他引:1
Polysaccharides are a natural and renewable feed stock for synthesizing high performance macromolecular materials. A popular, versatile and convenient route to develop polysaccharide based materials is the grafting of synthetic polymers onto natural polysaccharides. In spite of the attractive chemical and physical properties of polysaccharide based copolymeric materials, undesired homopolymer formation in the concurrent competing reaction lowers the copolymer yield, posing problems in the commercialization of the grafting procedures. Moreover, the requirement for an inert atmosphere is an added disadvantage for many conventional grafting procedures. The use of microwave irradiation has been exploited in the past two decades to alleviate these limitations in the synthesis of a range of graft modified polysaccharide materials. Indeed, increasing interest in clean and green environment friendly chemistry has motivated the use of microwaves in the polysaccharide grafting modification for various applications. Microwave irradiation significantly reduces the use of toxic solvents, as well as the reaction time for almost all the grafting reactions of interest here, ensuring high yields, product selectivity and clean product formations. Moreover, in many instances, microwave synthesized polysaccharide copolymers exhibit better properties for commercial exploitation than their conventionally synthesized counterparts. This review highlights recent applications of microwave heating in the grafting modifications of polysaccharides and discusses the underlying mechanisms and issues. 相似文献
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The effect of acid activation under microwave (MW) irradiation on the textural and structural properties of a smectite from Maghnia (Algeria) was investigated.Sample aliquots were treated with 2 M hydrochloric acid for various times under variable irradiation power. The influence of activation parameters (MW power and time duration) on the textural and structural properties of the activated samples (crystallinity, specific surface area, pore volume, pore diameter, porosity, pore size distribution and morphology) have been studied.The prepared materials were characterized by X-ray diffraction, Differential Thermal and Thermo Gravimetric Analysis (DTA and TGA), Scanning Electron Microscopy (SEM) and nitrogen adsorption/desorption to obtain information about their structure and surface texture.The treated samples consisted of microporous and mesoporous structures. The specific surface area, pore diameter and pore volume of an adsorbent prepared by the microwave-heating method were 165.80 m2/g, 50 nm and 0.1919 cm3/g, respectively. The pore volumes of mesopores and micropores were 163.90 · 10− 3 and 28.89 · 10− 3 cm3/g, respectively. Furthermore, small pores were created in the prepared materials with microwave irradiation. 相似文献
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《Journal of Sulfur Chemistry》2013,34(2):177-180
A series of 1-aryl-2-p-toluenesulfonyl hydrazides were synthesized by microwave irradiation under solvent-free conditions. The regioselectivity was excellent, the reaction time was short, the yields were moderate to high (64–91%), and the manipulation process was simple. 相似文献
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Ya-Ju Zhang Zhan Jie Wang Yan Na Chen Zhi Dong Zhang 《Journal of the European Ceramic Society》2018,38(1):105-111
Lead titanate (PTO) films were deposited onto Pt/Ti/SiO2/Si substrates by a sol-gel method and annealed by microwave irradiation and conventional heating. In contrast to conventional heating, microwave irradiation can crystallize the PTO films at a low temperature of 450 °C or at 550 °C for only 5 min. The XRD and TEM studies reveal that microwave radiation can reduce the nucleation time, and increase the growth rate of perovskite grains in the crystallization process. Moreover, the results using the Avrami’s model show that the effective activation energy for crystallization process by microwave irradiation is 131 kJ/mol, much lower than that for the PTO films by conventional heating (216 kJ/mol). Therefore, microwave irradiation can reduce the effective activation energy for the nucleation and grain growth of the perovskite phase during the crystallization process, contributing to a low-temperature or a short-time preparation process of ferroelectric films. 相似文献
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Tanmay Basak 《Chemical engineering science》2007,62(12):3185-3196
A detailed theoretical analysis has been carried out to assess the role of lateral and radial irradiations on microwave heating of 2D cylinders for beef and oil samples. The lateral irradiation may represent the sample incident at one direction and the radial irradiation refers to sample exposed to uniform microwave intensities at all directions. For both lateral and radial irradiations, the effective microwave incidence from the source is assumed to be identical. A preliminary analysis on microwave heating of samples has been shown via average power within a sample vs sample radius for beef and oil samples. The samples with smaller radius are found to have larger average power with radial irradiation for both beef and oil samples. The hot spot formation within a sample is found to be a strong function of lateral/radial irradiation for various food dielectrics. The radial irradiation is found to be not favorable especially for large oil samples where the hot spot occurs at the center resulting in larger thermal gradient that contrasts earlier works which established that the radial irradiation minimizes the thermal gradient irrespective of sample size. The present work provides guideline on heating policy based on either lateral or radial irradiation depending on sample size and food dielectric properties. 相似文献
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AbstractThe two filamentous fungi of Mucor circinelloides XY-Z and Penicillium oxalicum LY-1 isolated from citric acid wastewater sludge collectively enhanced sludge dewaterability by 85.83% to achieve the lowest value of normalized sludge specific resistance (SRF) to 6.8?×?1011 m·L/kg·g-TSS. The results showed that 75.77% of slime extracellular polymeric substances (EPS), 42.99% of protein in slime EPS and 60.27% of polysaccharide in LB-EPS were degraded during activated sludge treatment by the two mixed fungi of Mucor circinelloides XY-Z and Penicillium oxalicum LY-1, contributing to the conversion of 64.61% of bound water wrapped in EPS into free water, thereby improving activated sludge dewaterability. 相似文献