超声波强化活性污泥活性的试验研究

研究了超声波对活性污泥活性的影响,用污泥好氧速率OUR来衡量活性,并通过模拟人工废水试验验证。研究表明超声波频率为25kHz,输出声密度为0·2W/mL,作用60s后,污泥活性比原污泥提高30.49%;相同条件超声3s后,污泥活性比原污泥提高20%。试验中从能耗角度推荐选用超声3s。脉冲方式比连续超声更能改善污泥活性,且脉冲比1∶1时效果最好。超声3s后的活性污泥处理人工废水的出水水质明显好于未经处理的出水水质。     

低强度超声场促进剩余污泥好氧消化

为了提高剩余污泥好氧消化效率,在消化过程中对剩余污泥进行超声辐射,声强为0.53 W/cm2,频率28 kHz,分别选用0.045 W/mL、0.09 W/mL两个功率密度,每次超声辐射时间20 min或10 min,辐射频次选用4次或2次,组成4个组合.研究表明,未经超声处理的污泥在消化第17天达到稳定,而经超声作用的污泥消化稳定时间较前者提前3～7 d.在相同好氧消化时间内,经超声波处理后污泥能获得更高的有机物降解率.同时对超声波促进污泥好氧消化工艺进行了工程经济评价.     

超声波处理蚊卵反应机制及效果研究

自来水厂沉淀池壁为蚊产卵提供了较好的生存环境，给供水安全带来隐患，需要有效的方法来控制蚊卵的暴发。研究评估了超声波对蚊卵的抑制效果，检测超声处理后蚊卵的死亡率，分析超声处理前后参与超声诱导应激反应的蛋白质含量和酶活性的变化。使用COMSOL软件模拟分析超声波场的特征，包括频率、功率、暴露距离和时间。在较低的频率下观察到较高的卵死亡率。在28 kHz的频率、450 W/h的功率、5 mm的暴露距离和120 s的暴露时间下，蚊卵的死亡率为100%,均声压强度为4.0 W/m²,而在较高的频率(68 kHz)下，死亡率则降至78%,均声压强度为0.9 W/m²。此外，暴露时间和距离对蚊卵的死亡率也有显著影响。从几何模型上可以看出，暴露在28 kHz下的蚊卵承受的声压(2 379 Pa)远大于暴露在68 kHz下的声压(422 Pa);但是频率越高，传播距离越大。超声波辐射的振动效应可能是导致蚊卵死亡的主要因素。研究发现，超声波作为一种有效的处理方法，对于预防自来水厂沉淀池蚊卵孽生具有较大潜力。     

功率超声的声学参数对废水处理效果的影响

从功率超声在水处理中的空化机理入手,论述了国内外在应用功率超声进行废水处理时频率、声功率/声强以及声化学反应器的物理结构(实质是声场分布)等声学参数对处理效果的影响。结论表明,对不同的废水溶液存在超声降解的最佳频率和最佳声功率/声强;双频或多频超声较单频超声在处理同一废水溶液时有明显的协同效应;混响场中的空化阈值比行波场低,相同条件下更利于声化学产额的提高。分析了目前超声水处理技术研究不够深入的原因,并对其发展进行了讨论和展望。     

低强强度超声波强化膨胀污泥好氧消化

污泥膨胀是城市污水处理厂经常遇到的棘手问题.试验采用低强度超声波对膨胀污泥的好氧消化过程进行强化,选取超声强度、超声时间、超声间隔三个因素设计正交试验.对试验结果的极差分析和方差分析表明,低强度超声波强化膨胀污泥好氧消化的最佳参数为:超声强度0.2 W/cm2、超声时间5 min、超声间隔8 h.试验中经超声辐照的膨胀污泥,其好氧消化达标最短仅需6.73 d,比未加超声的对照试验提前了5.34 d.试验还研究了膨胀污泥达标前后溶解性化学需氧量(SCOD)和总化学需氧量(TCOD)的变化情况.结果表明,达标时污泥的SCOD变化不大,而TCOD较对照得到了不同程度的降低,最大达到76.1%,污泥的稳定性得到不同程度的提高.     

SBR反应器污泥减量化研究

介绍了SBR反应器长期运行污泥减量工艺,当回流比2∶14,超声条件为25kHz,1.6W/mL,15min时,污泥产量为82.4mg/(L·d),比未处理污泥系统污泥产量减少58.8%。系统的沉降性能并没有受到影响,出水CODCr已经达到《城镇污水处理厂污染物排放标准》(GB18918—2002)二级标准。由于超声后磷释放能力增强,出水磷略高。回流比3∶14,超声条件为25kHz,1W/mL,10min时,几乎不产生污泥。     

低强度超声波强化膨胀污泥好氧消化

污泥膨胀是城市污水处理厂经常遇到的棘手问题。试验采用低强度超声波对膨胀污泥的好氧消化过程进行强化,选取超声强度、超声时间、超声间隔三个因素设计正交试验。对试验结果的极差分析和方差分析表明,低强度超声波强化膨胀污泥好氧消化的最佳参数为:超声强度0.2W/cm~2、超声时间5min、超声间隔8h。试验中经超声辐照的膨胀污泥,其好氧消化达标最短仅需6.73d,比未加超声的对照试验提前了5.34d。试验还研究了膨胀污泥达标前后溶解性化学需氧量(SCOD)和总化学需氧量(TCOD)的变化情况。结果表明,达标时污泥的SCOD变化不大,而TCOD较对照得到了不同程度的降低,最大达到76.1%,污泥的稳定性得到不同程度的提高。     

污泥溶胞破解效果与能耗分析

利用超声溶胞作用考察不同浓度下污泥的分解效果。研究结果表明:随着超声波作用时间的延长,污泥中释放出的SCOD和VFA也在不断增加;并且随着污泥浓度的增加,超声污泥释放出的SCOD和VFA不但总量有明显增长,而且单位质量污泥破解释放的SCOD和VFA的量也在增加,在超声作用时间为5～45 min,污泥浓度为13 000 mg/L、17 000 ml/L、37 000 mg/L的情况下,污泥SCOD/VSS的范围为0.10～0.14 mg/mg;VFA/VSS范围为0.016～0.023 mg/mg;当比能耗相同时,随污泥浓度升高,单位质量污泥破解程度显著增加,因此,提高污泥浓度可以在低比能耗的情况下达到较高的能耗效应。     

频率及含水量对混凝土损伤超声检测的影响

本文分析了频率及含水量对混凝土损伤超声检测的影响。通过混凝土时间的制备、烘干、加载及超声检测,得到了不同含水量的混凝土试件在不同检测频率下的超声波速,以及混凝土的超声波速随着荷载增加时的变化规律。试验结果表明随着含水量的增加和检测频率的增大,测量得到的超声波速逐渐增加;随着混凝土的损伤增加,不同频率下的混凝土超声波速均显著降低。本文还结合混凝土材料的细观损伤演化规律,分析了频率及含水量对混凝土损伤超声检测的影响机理,研究成果可为混凝土的无损检测及损伤分析提供参考。     

低功率密度超声波预处理对活性污泥微生物相的影响

采用低功率密度超声波对活性污泥进行预处理,观察了污泥混合液异养菌数、微型动物和微生物群落结构等的变化情况,并测定了反应过程污泥比耗氧速率(SOUR)及反应器上清液化学需氧量(SCOD)指标。研究表明,污泥中不同种群微生物对超声辐射作用敏感性不同,超声波预处理对污泥SOUR提高与其后对污水的净化效果并不存在严格的对应性,因此,仅依靠SOUR指标来评价超声参数值得商榷。超声辐射污泥的生物效应受多种因素影响,使不同研究获得的最佳超声参数不具普适性;同时,采用超声辐射提高污水生物反应器效率需要消耗大量能量,应该考虑该技术在工程中应用的可行性。     

Effect of low power ultrasound on aerobic/anoxic digestion of activated sludge

The effect of low power ultrasound on aerobic/anoxic digestion of activated sludge was investigated. First, dehydrogenate activity (DHA) and special oxygen uptake rate (SOUR) were detected to indicate the change of biological activity of sludge induced by ultrasound. Single-factor experiments showed that when the ultrasonic frequency was 28 kHz, the optimal ultrasonic density and exposure time were 0.15 W/mL and 10 min, respectively. Through orthogonal tests, the optimal ultrasonic parameters for aerobic/anoxic digestion were found to be a ultrasonic density of 0.15 W/mL, ultrasonic exposure time of 10 min and interval time of 12 h. The aerobic/anoxic digestion was improved by ultrasonic pretreatment, the VSS reduction at the optimal conditions was increased by 35.73%, compared with the control. It can be concluded that low power ultrasonic pretreatment is a valid method for improving aerobic/anoxic biodegradability of activated sludge.     

Effective sludge solubilization treatment by simultaneous use of ultrasonic and electrochemical processes.

Sludge disintegration treatment by using simultaneously ultrasonic irradiation and electrolysis was investigated experimentally. A lab-scale diaphragm cell irradiated with ultrasound at a constant oscillating frequency of 20 kHz was used as a reactor. The batch experiments were carried out under different conditions of electric outputs of the ultrasonic generator, electric current for the electrolysis and different initial SS concentrations. A simultaneous treatment in the cathodic compartment without any chemical doses considerably facilitated the sludge solubilization, compared to the sonication alone. An increase in the electric current up to 400 mA under a constant ultrasonic density decreased the specific energy by 55% within the experimental range. The specific energy consumption was also reduced when the initial SS concentration increased. In addition, before carrying out the simultaneous treatment, a brief electrolysis was effective for further reduction of the specific energy and the acceleration of soluble COD generation.     

Frequency effect on p-nitrophenol degradation under conditions of strict acoustic and electric control

The process of decomposing p-nitrophenol (PNP) with power ultrasound requires strict control of acoustic and electric conditions. In this study, the conditions, including acoustic power and acoustic intensity, but not ultrasonic frequency, were controlled strictly at constant levels. The absorbency and the COD concentrations of the samples were measured in order to show the variation of the sample concentration. The results show significant differences in the trend of the solution degradation rate as acoustic power increases after the PNP solution (with a concentration of 114 mg/L and a pH value of 5.4) is irradiated for 60 min with ultrasonic frequencies of 530.8 kHz, 610.6 kHz, 855.0 kHz, and 1130.0 kHz. The degradation rate of the solution increases with time and acoustic power (acoustic intensity). On the other hand, the degradation rate of the solution is distinctly dependent on frequency when the acoustic power and intensity are strictly controlled and maintained at constant levels. The degradation rate of the PNP solution declines with ultrasonic frequencies of 530.8 kHz, 610.6 kHz, 855.0 kHz, and 1130.0 kHz;the COD concentration, on the contrary, increase.     

Ultrasound as a pre-oxidation for biological landfill leachate treatment.

In this study, the effects of low energy ultrasound irradiation on landfill leachate treatment by means of sequencing bath reactor were investigated. The aim of this work was to estimate the influence of leachate irradiation time on aerobic treatment efficiency. The sonification of the leachate was carried out in static conditions using the disintegrator UD-20. The field frequency of 22 kHz (the power output equals to 180 W) and amplitude of 12 microm was applied. The sonification time was changed in the range of 30-140 s. It was found that ultrasonic pretreatment enhances the subsequent aerobic digestion resulting in a better degradation of landfill leachate. The sonification of raw leachate leads to enhancement of COD and ammonia removal as compare to experiment without ultrasound.     

A comparison of ultrasound treatment on primary and secondary sludges.

Ultrasound treatment of primary and secondary sludges was conducted to improve the qualities of sludges for the anaerobic digestion. The impacts of different sonication times, sonication densities and solids concentrations on ultrasonication efficiency were examined. The experimental results indicated that the significant reduction in particle size and increase in soluble organics could be achieved, implying that ultrasonication could offer a feasible treatment method to efficiently disintegrate sludge. The greater decrease in particle size and increase in soluble organics of sludge indicated that the secondary sludge has a more remarkable improvement after sonication over the primary sludge. With respects to the extent of disintegration and energy consumption, higher sonication density performed more effectively in terms of specific energy. There exists an optimal solids concentration range for both the sludges for optimum sonication. Within the optimal solids concentration range, efficient sonication can be effected and sludge would be disintegrated efficiently. The ultrasound would be attenuated by scattering and absorption if the solids concentration exceeds the optimal range. It appeared from the study that the mechanical shear forces caused by ultrasonic cavitation could be a key factor for sludge disintegration and collapse of cavitation bubbles could significantly alter the sludge characteristics.     

超声内电解协同作用对对硝基苯酚的处理

通过超声波、内电解以及其联合作用对对硝基苯酚(P-NP)进行处理,试验发现在相同处理率的条件下,两者联用可以大大缩短处理时间.单纯内电解处理10 mg/L的P-NP去除率大于90%时需要30 min,而加入超声波强化后只需不到10 min.同时通过动力学分析可知,超声波、内电解、超声协同内电解处理P-NP均符合一级反应,且超声波强化内电解具有协同作用,其反应速率常数的增强因子为1.37.     

Impact of copper and cadmium on aerobic and anaerobic digestibility of sonicated sludge

The effects of the introduction of a sludge reduction process such as ultrasound on batch aerobic and anaerobic biodegradability after exposition to two metals (copper and cadmium) were investigated. The specific energy of ultrasonic treatment applied to the sludge was 200,000 kJ kg TS(-1). Ultrasonic treatment led to floc size reduction and to organic matter solubilization. Low copper (< 5 mg L(-1)) and cadmium (< 1 mg L(-1)) concentration improved aerobic biodegradability. For high metal concentration the maximal instantaneous biogas production rate q(max) inhibition by copper and cadmium was modeled by a saturation-type relationship under aerobic and anaerobic conditions. Under aerobic conditions, respiration inhibition was not affected by sonication. Cadmium inhibition (74%) was more than copper (58%). The positive effect of sonication on CO2 production was maintained after metal introduction. Under anaerobic conditions, metal introduction cancelled out the positive effect of the treatment. The sonicated sludge was 16% less sensitive to copper inhibition but 10% more sensitive to cadmium inhibition compared to non sonicated sludge.     

垃圾渗滤液膜浓缩液超声强化直接接触膜蒸馏处理工艺EI北大核心CSCD

为提高膜蒸馏在处理垃圾渗滤液膜浓缩液时渗透通量的稳定性,设计了一种新型的超声强化直接接触膜蒸馏(US-DCMD)装置,试验研究了超声对膜渗透通量的影响,并采用电子显微镜、X射线能量色散光谱等手段分析超声对膜面污染层的影响。试验结果表明:在60W的超声辐照条件下,渗透通量最高提升19.4%,并在膜溶液浓缩系数达到4时,相对渗透通量最高维持在77.1%,而未施加超声的相对渗透通量在膜溶液浓缩系数为2时降至20.7%;膜面的主要污染物为CaCO_(3)及腐殖酸,其中CaCO_(3)是限制膜渗透通量的主要因素;超声使污染层钙的质量分数从25.6%降至15.0%,并且不会引起有机物的降解或改性;超声辐照使膜面污染层不均匀且存在裂隙,减少了污染层厚度,维持了渗透通量的稳定。