磁化调质对活性污泥脱水性能的影响

研究了磁场调质对污水厂活性污泥脱水性能的影响,在不同磁场强度和磁化时间下,考察了活性污泥沉降性能、污泥比阻、分形维数、污泥粒径等参数的变化规律。结果表明:磁化时间为20 min、磁场强度为55 m T时,污泥的沉降性能最佳,污泥结构最为密实,污泥比阻可由原来的2.03×1013 m/kg下降到9.5×1012 m/kg,能有效改善污泥的脱水性能。     

Sludge filterability and dewaterability in a membrane bioreactor for municipal wastewater treatment

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 g_polymer 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.     

Revised capillary suction time (CST) test to reduce consumable costs and improve dewaterability interpretation

The aim of this paper is to critically assess the standard capillary suction time (CST) test and to propose a modified device (prototype) and a revised CST procedure. The empirical CST test (using a circular funnel) is well established as the leading method for the determination of sludge dewaterability in spite of its current shortcomings such as restricted modelling possibilities, and therefore the ability to predict physical processes such as the amount of water bound by the paper. Nevertheless, the CST apparatus is portable, and the method is easy to conduct, quick, cost‐effective and accurate, if the product of solid concentration and average specific resistance to filtration is of interest. A novel prototype with a rectangular instead of a circular funnel incorporating a stirrer (optional), and using a cheaper paper with similar or improved characteristics is proposed to reduce consumable costs and improve dewaterability interpretation. Copyright © 2005 Society of Chemical Industry     

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

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。     

微波辐射柴油脱硫实验研究

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％。     

微波辐照下煤的电化学脱硫研究

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。     

微波辐射技术在天然物活性成分萃取中的应用

介绍了微波辐射技术在天然物活性成分萃取中的作用原理、萃取特点及应用 ,简要叙述了其发展前景     

微波辐射木质素磺酸盐接枝改性

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。     

微波促进高相对分子质量N-丁烷基壳聚糖的合成

在微波促进下首先对高相对分子质量壳聚糖碱化,再使之与溴代正丁烷进行烷基化反应,合成出了高取代度的N-丁烷基化壳聚糖.在n(氢氧化钠)∶n(壳聚糖)=4∶1,(壳聚糖粘均相对分子质量为1.49×106)、60℃下微波碱化处理1h、n(溴代正丁烷)∶n(碱化壳聚糖)=1.4∶1、80℃烷基化反应4h的较佳反应条件下,所得产...     

碱性发酵污泥脱水性能的变化及其原因分析

通过控制温度在25℃和35℃,利用Ca(OH)₂和NaOH调节碱性发酵过程中pH至10,研究了碱性产酸发酵过程中碱性发酵液脱水性能的变化,并且分析了影响碱性发酵液脱水性能的因素。研究发现NaOH条件下得到的发酵污泥的脱水性能比Ca(OH)₂条件下得到的发酵污泥的脱水性能差,同种碱试剂条件下,35℃条件下的发酵污泥脱水性能比25℃条件下差。通过对溶解的蛋白和多糖含量的分析,得出在一定范围内,两者的含量与标准化CST(毛细吸水时间)存在较好的线性关系,并且单位多糖比单位蛋白更能引起发酵污泥脱水性能的恶化。通过对溶解的蛋白多糖结合Zeta电位、平均粒径分析,得出温度和Ca²⁺可能是引起碱性发酵污泥脱水性能差异的根本原因,Ca²⁺能中和胶体表面较多的负电荷,在污泥絮体之间起到良好的吸附架桥作用,从而不利于污泥的水解,抑制有机物的溶出,而有利于污泥的脱水。从脱水成本和产酸量综合分析,Ca(OH)₂比NaOH更适合作为碱试剂调节pH,25℃条件下更适合作为碱性发酵的温度。     

Transesterification of castor oil assisted by microwave irradiation

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.     

Fenton处理对污泥脱水性、重金属形态及生物淋滤效率影响

为考察污泥预处理过程中重金属迁移转化规律,通过投加不同量的Fenton试剂对污泥进行处理,分析了Zn、Cd、Mn、Ni四种重金属的化学形态变化与后继生物淋滤过程的溶出行为。研究结果表明,污泥经Fenton处理后,毛细吸水时间在短时间内降低,但对生物淋滤后最终的污泥脱水性没有显著提升作用;重金属Zn、Cd、Mn的不稳定态（弱酸提取态、可还原态）比例不同程度提高,当投加Fe²⁺=1.00g/L、H₂O₂=9.00g/L时,其比例分别由37%、84%、79%上升至90%、93%、84%,但Ni无明显变化。此外,Fenton处理污泥中Zn、Cd、Mn、Ni四种重金属生物淋滤后含量分别由3451.52mg/kg、6.45mg/kg、443.40mg/kg、94.96mg/kg降至376.74mg/kg、1.10mg/kg、141.66mg/kg、21.77mg/kg,比单独生物淋滤处理污泥重金属残余量分别降低了36.20%、26.17%、30.92%和27.89%。利用动力学方程较好地描述了生物淋滤过程中Zn、Cd、Mn、Ni四种重金属的溶出速率的相对大小,排序为Mn＜Cd＜Zn＜Ni。     

氯化镁存在下微波辐射稠油脱水研究

针对常规微波辐射稠油脱水的不足,研究了氯化镁存在下微波辐射稠油脱水。详细考察了氯化镁加入量、微波辐射压力、辐射时间、辐射功率对稠油脱水率的影响。结果表明,在辐射压力0.1MPa、辐射功率225 W、辐射时间3 min、静置沉降1 min、氯化镁的质量分数为5%的条件下,可使实验室配制的含水质量分数50%的大庆稠油脱水率达到97.1%。该方法具有辐射功率低、脱水速度快的特点。     

微波辐射脱除催化裂化柴油中碱性氮化物研究

在微波辐射的条件下,用乙酸-w(乙醇)=95%络合萃取催化裂化柴油中碱性氮化物,考察了剂油体积比、乙酸加入量、微波辐射功率、辐射时间、辐射压力等工艺条件对碱性氮化物脱除率和柴油回收率的影响。结果表明:在剂油体积比1.0、乙酸与95%乙醇体积比0.05、辐射压力0.5 MPa、恒压辐射时间10 min、微波功率375 W最佳反应条件下,碱性氮化物脱除率82.4%,柴油回收率90.1%,较无微波辐射的条件下,碱性氮化物脱除率显著提高。     

Use of microwave irradiation in the grafting modification of the polysaccharides - A review

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.     

Characterization of smectite after acid activation with microwave irradiation

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.     

微波辐射无皂乳液聚合制备单分散热敏性微球

在微波辐射条件下苯乙烯(St)和N-异丙基丙烯酰胺进行无皂乳液聚合,结果表明所制备的微球粒径小于150nm且为单分散。利用透射电子显微镜(TEM)观察微球形态及粒径。通过动态激光光散射粒度仪(PCS)考察微球的热敏性,微球粒径随温度发生变化。     

Regioselective synthesis of 1-aryl-2-p-toluenesulfonyl hydrazides under microwave irradiation

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.     

Effects of current density and electrode material on the dewaterability of the thickened activated sludge by electro‐flotation

BACKGROUND: Electro‐flotation (EF) could improve thickening and subsequent dewatering characteristics of activated sludge although the settling characteristics of the sludge were very poor. The objectives of this study were to evaluate the performance of EF in the thickening and dewatering of activated sludge and the effects of current density and electrode material on the dewaterability of the sludge. RESULTS: The specific resistance to filtration (SRF) of the sludges thickened by EF was much lower than that by gravity sedimentation. The SRF of the thickened sludge decreased exponentially with increase of gas generation rate of the EF system. Gas generation rate could be controlled by varying the current density of the electrode. Degassing of the microbubbles by moderate mixing of the thickened sludge layer deteriorated the dewaterability of the sludge. Therefore, it is obvious that the gas bubbles entrapped in the thickened sludge play a key role in the observed dewaterability improvement. The effect of electrode material on the thickening and dewatering efficiency was trivial compared with the effect of current density of the electrode. CONCLUSION: The EF system was quite promising as an alternative to gravity sedimentation for thickening of activated sludge and the dewaterability was also improved by microbubbles generated in the system. Copyright © 2009 Society of Chemical Industry     

Enhancing dewaterability of sewage sludge by the application of tween-20 during bioleaching: Performance evaluation and mechanistic study

Dewatering is recognized as an important method for treating sewage sludge before its disposal. In this paper, the nonionic surfactant Tween-20 was used for the first time to improve the dewaterability of sewage sludge during bioleaching. The specific resistance to filtration (SRF), water content (WC) and bound water content (BW) of the sludge cake were used to evaluate sludge dewaterability. The results indicated that a 1?g/L Tween-20 dosage with an inoculum ratio of 20%, a S⁰ dosage of 2?g/L and a FeSO₄?·?7H₂O dosage of 10?g/L provided oxidation efficiencies up to 100% for Fe²⁺ and 65.8% for S⁰. The SRF of the bioleached sludge decreased to as low as 0.81?×?10¹²?m/kg from the initial 12.6?×?10¹²?m/kg for raw sludge. A WC of 47.16% was achieved while 48.1% of BW was released during bioleaching. The results from this study indicate that adding of an appropriate amount of Tween-20 to sewage sludge is a promising method to enhance dewaterability by bioleaching.