超声波条件下降解染料废水的工艺条件研究

采用Fenton试剂对模拟染料废水的降解效果进行研究。结果表明,H2O2投加量、Fe2+投加量、pH值条件、超声处理时间的改变对染料废水的处理效果影响很大。对酸性染料:当pH为4.5,30%H2O2投加的体积分数为30mL/L,Fe2+投加的质量浓度为400mg/L,反应时间为40min时为降解反应的最佳操作条件。对碱性染料,正交试验表明当pH为4、30%H2O2投加的体积分数16mL/L、Fe2+投加的质量浓度为300mg/L、反应时间为60min时为降解反应的最佳操作条件,其降解率达98.46%,COD的去除率达到96.7%。     

紫外光引发模板聚合阳离子聚丙烯酰胺及其污泥脱水应用

阳离子聚丙烯酰胺是污水和污泥处理中常用的一种絮凝剂,传统方法制备的阳离子聚丙烯酰胺因阳离子单体随机分布,电荷过于分散,导致其在絮凝时不能充分发挥阳离子单体的电中和作用,为此本研究尝试使用一种新型方法制备阳离子聚丙烯酰胺,即以二甲基二烯丙基氯化铵(DMDAAC)和丙烯酰胺(AM)为单体,分别以两种不同分子量的聚丙烯酸钠(PAAS)为模板,使用紫外光引发模板聚合法制得模板聚合物TPDA1和TPDA2,同时使用紫外光引发聚合法制得非模板聚合物(NTPDA)作为对比。使用红外光谱(FTIR)、氢核磁共振图谱(1 H NMR)、扫描电镜(SEM)等方法对制得的聚合物进行表征,并通过污泥脱水试验研究其污泥脱水效率。波谱分析结果表明,添加模板提高了DMDAAC单体的活性,促使聚合物分子中形成DMDAAC连续分布的阳离子单体嵌段结构,从而提高了聚合物的絮凝性能,尤其是电中和作用;SEM扫描显示模板聚合物的具有较大的比表面积和分形维数;污泥脱水试验表明,模板聚合物具有较好的污泥脱水性能和较宽pH应用条件,当模板聚合物TPDA1投加量为50mg·L-1,污泥pH为8时,其具有最佳污泥脱水效率,污泥含水率降至最低值72.5%。模板分子量对聚合物属性也存在影响,分子量较低的模板制得的聚合物具有相对较好的污泥脱水效率。     

内燃机缸套水低温余热驱动除湿机组实验研究

本文针对内燃机冷热电联供系统缸套水低品位余热无法高效回收利用的难题,利用缸套水低品位余热驱动LiCl溶液吸收式除湿机组,搭建实验平台,改变内燃机输出功率,研究LiCl溶液吸收式除湿机组性能变化情况。内燃机输出功率从18 kW增加到50 kW,内燃机缸套水热负荷增加,再生器的再生能力增强,再生液脱水量△mg从0.84 g/s升高到1.02 g/k,再生液浓度从33.3%升高到34.0%;除湿器的性能增强,送风温度从21.1℃升高到22.5℃,相对湿度从49.49%降低到41.97%,溶液的除湿量从0.69 g/s增加到0.76 g/s。     

超声辅助法提取刘寄奴黄酮类化合物的工艺

采用超声辅助法提取刘寄奴中的黄酮类化合物,通过单因素试验和正交试验,研究了超声辅助法提取条件(超声波功率、乙醇体积分数、提取温度、提取时间)对刘寄奴黄酮类化合物提取率的影响。结果表明,刘寄奴黄酮类化合物的最佳提取工艺条件为:超声波功率200W、乙醇体积分数80%、提取温度40℃、提取时间45min,在此工艺条件下刘寄奴黄酮类化合物的提取率可达63.27mg/g。     

轻质磁性材料的制备及在磁流变液中的应用

研究了使用化学镀的方法在轻质载体上包覆具有磁性的镍、钴等物质。该材料具有密度低的优点（有效密度为2-3g/cm^3）。对比于几种羰基镍粉制备的磁流变液的沉降稳定性,使用该轻质磁性材料制备的磁流变液不用加防沉剂,其稳定性类似于加入较多防沉剂的羟基镍粉磁流变液。其在磁场下表观粘度比零磁场下的粘度有几十倍的变化。因此,使用该轻质磁性材料有望解决磁流变液普遍存在的沉降问题,得到综合性能良好的产品。     

氢化物-原子荧光光谱法测定金属饰品中的砷和汞

采用氢化物-原子荧光光谱法测定金属饰品中砷和汞.用体积比为3:1的浓硝酸和浓盐酸微波消解样品.结果表明:砷和汞方法的检出限分别为0.079μg/L和0.037μg/L;砷、汞RSD分别为1.89%和4.82%;砷的加标回收率为99.6%,汞的加标回收率为96.0%.该方法快速简便,能满足饰品的日用检验要求.     

纳米ZnTiO3粉体光催化降解甲基橙

利用自制的催化装置降解甲基橙模拟染料废水,证明了纳米ZnTiO3粉体能够对甲基橙溶液进行有效的降解,并探讨了ZnTiO3的投加量、甲基橙溶液的初始浓度、反应时间、光照强度等因素对其影响。实验结果表明,在甲基橙溶液的初始浓度为15mg/L、ZnTiO3的用量为3g/L、反应180min后,甲基橙溶液的脱色率达到99.6%。     

利用超声光栅研究声速与液体性质

设计并搭建了超声光栅,观察了激光经过光栅形成的衍射斑纹,测量了声速;并利用超声光栅测定了不同温度、不同浓度的NaCl溶液中的声速,给出了声速-水温和声速-溶液浓度的依赖关系.水的温度每升高1℃,3.974 MHz的超声波的声速增加2.09 m/s,16.574 MHz的超声波的波速增加2.04m/s;声速随着NaCl溶液浓度的增大线性增加,NaCl溶液浓度每升高1%,3.974 MHz的超声波声速增加13.637 m/s,16.574 MHz的声波声速增加11.757 m/s.在此基础上,分析了不同频率的超声波对实验规律的影响,认为不同频率的超声波在相同条件下测量的溶液中声速大小的不同源于测量的随机误差.     

铋酸钠催化大气压介质阻挡放电降解苯胺

在柱-板式介质阻挡放电体系中投加铋酸钠催化剂，研究了该体系的放电光谱特性及对苯胺模拟废水的协同处理效果，考察了pH 值、苯胺初始质量浓度及催化剂投加量等因素对降解率的影响，探讨了铋酸钠协同介质阻挡放电(DBD)催化降解苯胺的机理。实验结果表明，柱-板式电极结构放电过程中辐射出了紫外光和可见光，300~450 nm之间出现高强度N2第二正带谱线。初始浓度100 mg/L苯胺废水被处理10 min后，投加0.2 g/L催化剂时溶液的TOC去除率最高，比单独DBD低温等离子体体系提高14.11%。在碱性条件下，苯胺和TOC的去除率均好于酸性和中性条件。XRD检测结果显示铋酸钠在反应前后峰值位置未发生明显改变。     

石蜡-碳纳米管复合材料的热物性研究

为提高石蜡作为相变蓄冷材料的导热性能,制备了碳纳米管添加量分别为0%、1%、2%、3%、4%、5%的石蜡-碳纳米管复合材料,并对其热物性及稳定性进行实验研究。结果表明,随着碳纳米管添加量的增加,复合材料的相变温度基本不变,相变潜热逐渐减小,导热系数逐渐增大。在添加量为5%时,复合材料的融化和凝固相变潜热分别为128.2 J/g和134.4 J/g,比纯石蜡相对减小了15.5%和13.8%;固态和液态导热系数分别为0.487 W/(m·K)和0.516 W/(m·K),比纯石蜡相对提高了39.5%和40.3%,同时具有较好的循环稳定性。     

A review on the dewaterability of bio-sludge and ultrasound pretreatment

Bio-sludge, which contains large quantities of water, biomass and extracellular polymeric substances (EPS), is difficult to be dewatered as a "super-compactable" sludge [Water Res. 35 (5) (2001) 1358]. Reported water content in bio-sludge was commonly about 80-90% wt after dewatering process. The EPS and the form of water in sludge influences the structure of sludge. Adding cationic fluctuations can change the form of water in sludge and increase the velocity of dewatering process, but has little influence on the final water content. According to Bien's work [Water Sci. Technol. 36 (4) (1997) 287], a combination of ultrasound or other method could agglomerate the sludge, improve the activities of biomass [Ultrasonics 38 (2000) 711; Ultrasonics 40 (2002) 25], enhance anaerobic process [Water Sci. Technol. 36 (11) (1997) 155; Water Sci. Technol. 36 (11) (1997) 121; Water Res. 35 (8) (2001) 2003; Water Sci. Technol. 36 (12) (1997) 117] and decrease over 10% final water content of sludge. The mechanisms of ultrasonic influence on sludge are not very clear, but the application of ultrasound to industrial process is relatively easy and possible.     

Using low intensity ultrasound to improve the efficiency of biological phosphorus removal

Low intensity ultrasound can produce various effects on biological materials, such as stimulating enzyme activity, cell growth, biosynthesis, etc., which may improve the efficiency of enhanced biological phosphorus removal (EBPR). We adopt total phosphorus (TP) and dehydrogenase activity (DHA) as indicators to confirm the feasibility of applying low intensity ultrasound in EBPR. Single-factor experiments and orthogonal test were conducted in batch anaerobic/oxic (A/O) process simulation to study the influence of ultrasonic intensity and exposure time in the EBPR process. The results showed that the optimal ultrasonic parameters were 0.2 W/cm² and 10 min under which condition the TP concentration in the effluent was 35–50% lower than that of the control (without ultrasonic irradiation). Changes of sludge activities after ultrasonic irradiation were examined. The improvement of sludge activity by ultrasound took 4 h after irradiation to reach the peak level, when an increase above 50% of DHA has been achieved by ultrasonic irradiation, and the enhancing effects induced by ultrasound disappeared in 16 h after irradiation. A tentative mechanism of biological phosphorus removal enhancement stimulated by ultrasound was discussed based on these phenomena.     

Ultrasonic treatment on activated sewage sludge from petro-plant for reduction

In this essay, the influences of low frequency ultrasound (20 kHz) on dewater ability and anaerobic digestion behaviors of activated sewage sludge, obtained from Yangzi Water Treatment Plant, Yangzi Petrochemical Corporation, were discussed. Ultrasound pretreatment could enhance the filtration progress and decrease the moisture content of the sludge from 99% to 80%. Together with flocculant, the ultrasound pretreatment decreased the specific filtration resistance (SFR) of the sludge from 3.59 x 10(12) m/kg to 1.18 x 10(12) m/kg and saved about 25-50% of the flocculant dosage. Bound water of the sludge was measured by dilatometer. After 2-4 min treatment of ultrasound under intensity of 400 W/m(2), the bound water of sludge decreased from 16.7 g/g (dry base) to above 2.0 g/g (dry base). Ultrasound pretreatment could also enhance digestion and reduce digestion time. To the same resolution ratio, such as 49%, the digestion time of sludge with ultrasound pretreatment was 7 days less than that without ultrasound. Proper ultrasound pretreatment could also improve the dewater ability of the digested sludge, the final moisture of which was 73.7%.     

Concomitant degradation of bisphenol A during ultrasonication and Fenton oxidation and production of biofertilizer from wastewater sludge

Degradation of bisphenol A (BPA), an endocrine disruptor, from wastewater sludge (WWS) has attracted great interest recently. In the present study, the effects of different pre-treatment methods, including ultrasonication (US), Fenton's oxidation (FO) and ferro-sonication (FS) was assessed in terms of increase in solubilization of WWS and simultaneous degradation of BPA. Among US, FO and FS pre-treatment, higher suspended solids (SS), volatile suspended solids (VSS), chemical oxygen demand (COD) and soluble organic carbon (SOC) solubilization (39.7%, 51.2%, 64.5% and 17.6%, respectively) was observed during a ferro-sonication pre-treatment process carried out for 180 min, resulting in higher degradation of BPA (82.7%). In addition, the effect of rheological parameters (viscosity and particle size) and zeta potential on the degradation of BPA in raw and different pre-treated sludges were also investigated. The results showed that a decrease in viscosity and particle size and an increase in zeta potential resulted in higher degradation of BPA. BPA degradation by laccases produced by Sinorhizobium meliloti in raw and pre-treated sludge was also determined. Higher activity of laccases (207.9 U L(-1)) was observed in ferro-sonicated pre-treated sludge (180 min ultrasonic time), resulting in higher removal of BPA (0.083 μg g(-1)), suggesting concomitant biological degradation of BPA.     

Ultrasound assisted method to increase soluble chemical oxygen demand (SCOD) of sewage sludge for digestion

The aim of this study was to clarify the possibilities to increase the amount of soluble chemical oxygen demand (SCOD) and methane production of sludge using ultrasound technologies with and without oxidising agents. The study was done using multivariate data analyses. The most important factors affected were discovered. Ultrasonically assisted disintegration increased clearly the amount of SCOD of sludge. Also more methane was produced from treated sludge in anaerobic batch assays compared to the sludge with no ultrasonic treatment. Multivariate data analysis showed that ultrasonic power, dry solid content of sludge (DS), sludge temperature and ultrasonic treatment time have the most significant effect on the disintegration. It was also observed that in the reactor studied energy efficiency with high ultrasound power together with short treatment time was higher than with low ultrasound power with long treatment time. When oxidising agents were used together with ultrasound no increase in SCOD was achieved compared the ultrasonic treatment alone and only a slight increase in total organic carbon of sludge was observed. However, no enhancement in methane production was observed when using oxidising agents together with ultrasound compared the ultrasonic treatment alone. Ultrasound propagation is an important factor in ultrasonic reactor scale up. Ultrasound efficiency rose linearly with input power in sludge at small distances from the transducer. Instead, ultrasound efficiency started even to decrease with input power at long distances from the transducer.     

An investigation of mechanisms for the enhanced coagulation removal of Microcystis aeruginosa by low-frequency ultrasound under different ultrasound energy densities

There is a lack of studies elaborating the differences in mechanisms of low-frequency ultrasound-enhanced coagulation for algae removal among different ultrasound energy densities, which are essential to optimizing the economy of the ultrasound technology for practical application. The performance and mechanisms of low-frequency ultrasound (29.4 kHz, horn type, maximum output amplitude = 10 μm) -coagulation process in removing a typical species of cyanobacteria, Microcystis aeruginosa, at different ultrasound energy densities were studied based on a set of comprehensive characterization approaches. The turbidity removal ratio of coagulation (with polymeric aluminum salt coagulant at a dosage of 4 mg Al/L) was considerably increased from 44.1% to 59.7%, 67.0%, and 74.9% with 30 s of ultrasonic pretreatment at energy densities of 0.6, 1.11, and 2.22 J/mL, respectively, indicating that low-frequency ultrasound-coagulation is a potential alternative to effectively control unexpected blooms of M. aeruginosa. However, the energy density of ultrasound should be deliberately considered because a high energy density (≥18 J/mL) results in a significant release of algal organic matter, which may threaten water quality security. The specific mechanisms for the enhanced coagulation removal by low-frequency ultrasonic pretreatment under different energy densities can be summarized as the reduction of cell activity (energy density ≥ 0.6 J/mL), the slight release of negatively charged algal organic matter from cells (energy density ≥ 1.11 J/mL), and the aggregation of M. aeruginosa cells (energy density ≥ 1.11 J/mL). This study provides new insights for the ongoing study of ultrasonic pretreatment for the removal of algae via coagulation.     

Influence of ultrasonication and Fenton oxidation pre-treatment on rheological characteristics of wastewater sludge

The effect of ultrasonication and Fenton oxidation as physico-chemical pre-treatment processes on the change of rheology of wastewater sludge was investigated in this study. Pre-treated and raw sludges displayed non-Newtonian rheological behaviour with shear thinning as well as thixotropic properties for total solids ranging from 10 g/L to 40 g/L. The rheological models, namely, Bingham plastic, Casson law, NCA/CMA Casson, IPC Paste, and power law were also studied to characterize flow of raw and pre-treated sludges. Among all rheological models, the power law was more prominent in describing the rheology of the sludges. Pre-treatment processes resulted in a decrease in pseudoplasticity of sludge due to the decrease in consistency index K varying from 42.4 to 1188, 25.6 to 620.4 and 52.5 to 317.9; and increase in flow behaviour index n changing from 0.5 to 0.35, 0.62 to 0.55 and 0.63 to 0.58, for RS, UlS and FS, respectively at solids concentration 10–40 g/L. The correlation between improvement of biodegradability and dewaterability, decrease in viscosity, and change in particle size as a function of sludge pre-treatment process was also investigated. Fenton oxidation facilitated sludge filterability resulting in capillary suction time values which were approximately 50% of the raw sludges, whereas ultrasonication with high input energy deteriorated the filterability. Biodegradability was also enhanced by the pre-treatment processes and the maximum value was obtained (64%, 77% and 73% for raw, ultrasonicated and Fenton oxidized sludges, respectively) at total solids concentration of 25 g/L. Hence, pre-treatment of wastewater sludge modified the rheological properties so that: (1) the flowability of sludge was improved for transport through the treatment train (via pipes and pumps); (2) the dewaterability of wastewater sludge was enhanced for eventual disposal and; (3) the assimilation of nutrients by microorganisms for further value-addition was increased.     

Intensified recovery of lipids,proteins, and carbohydrates from wastewater-grown microalgae Desmodesmus sp. by using ultrasound or ozone

This study evaluates the effect of ultrasound and ozone pretreatments for the subsequent recovery of Desmodesmus sp. biocomponents—lipids, proteins, and carbohydrates—using a response surface methodology. Both pretreatments impact on the recovered lipids quality, solvent waste production and extraction time is analysed for process intensification purposes. For ultrasound pretreatment, independent parameters were energy applied (50–200 kWh/kg dry biomass), biomass concentration (25–75 g/L), and ultrasonic intensity (0.32 and 0.53 W/mL). While for ozone pretreatment, independent parameters were ozone concentration (3–9 mg O₃/L), biomass concentration (25–75 g/L), and contact time (5–15 min). In the case of ultrasound pretreatment, recovery yield reached 97 ± 0.4%, 89 ± 3%, and 73 ± 0.6% for proteins, carbohydrates and lipids respectively. Given process required: energy applied of 50 kWh/kg dry biomass, 75 g/L of biomass concentration, 0.32 W/mL of ultrasonic intensity, and 56 min of time process. Ultrasound caused high cell disruption releasing all proteins, thereby obviating downstream processing for its recovery. Ozone pretreatment recovery yield was 85 ± 2%, 48 ± 1.4%, and 25 ± 1.3%, for carbohydrates, lipids and proteins respectively, under the following conditions: 9 mg O₃/L of ozone concentration, 25 g/L of biomass concentration, and 5 min of contact time that depicts an energy consumption of 30.64 kWh/kg dry biomass. It was found that ultrasound and ozone pretreatments intensified the lysis and biocomponents recovery process by reducing solvent consumption by at least 92% and extraction time between 80% and 90% compared with extraction of untreated biomass biocomponents. Both pretreatments improve the composition of the recovered lipids. It was noted that the yield of neutral lipids increased from 28% to 67% for ultrasound pretreatment while for ozone pretreatment from 49% to 63%. The method used for lipid extraction may also have an effect but here it was kept constant.     

Ultrasound-enhanced coagulation for Microcystis aeruginosa removal

Source water eutrophication has caused serious problems in drinking water supplies, with enhanced coagulation widely used to remove the resulting algae. This paper investigates the use of sonication to improve the removal by coagulation of Microcystis aeruginosa, a common species of toxic algae. The results show that sonication significantly enhances the reduction of algae cells, solution UV254, and chlorophyll a without increasing the concentration of aqueous microcystins. The main mechanism involved the destruction during ultrasonic irradiation of gas vacuoles inside algae cells that acted as ‘nuclei’ for acoustic cavitation and collapse during the “bubble crush” period, resulting in the settlement of cyanobacteria. Coagulation efficiency depended strongly on the coagulant dose and sonication conditions. When the coagulant dose was 0.5 mg/l, 5 s of ultrasonic irradiation increased algae removal efficiency from 35% to 67%. As further sonication enhanced the coagulation efficiency only slightly due to better mixing, optimal sonication time was 5 s. The most effective sonication intensity was 47.2 W/cm², and the highest removal ratio of M. aeruginosa was 93.5% by the sonication–coagulation method. Experiments with reservoir water showed that this method could be successfully applied to natural water containing multiple species of algae.     

Synthesis of nano-β-CD@Fe3O4 magnetic material and its application in ultrasonic treatment of oily sludge

The extraction process of Tarim oil field in Xinjiang is accompanied by a large amount of oily sludge generation, which seriously restricts the progress of oil and gas development and causes serious pollution to the environment due to its large production, complex composition, and difficult treatment. Nanomaterials combined with ultrasound have been demonstrated to be a promising method for the disposal of hazardous oily sludge. In this paper, a magnetic material Nano-β-CD@Fe₃O₄ was prepared by hydrothermal method and surface modification method. Nano-β-CD@Fe₃O₄ can be intelligently enriched at the oil–water interface and oil-solid interface, and it can be stably dispersed to form nanofluid under the action of ultrasound. Nano-β-CD@Fe₃O₄ can cause changes in oil composition when it is exposed to ultrasound, resulting in the decrease of viscosity and increase of fluidity. The experimental results of treating oily sludge in Xinjiang Tarim showed that the best treatment effect was achieved when the concentration of Nano-β-CD@Fe₃O₄ was 0.5 %, the ultrasonic frequency was 60 Hz and the temperature was 60℃. This solution can reach 90.17 % oil removal efficiency within 45 min, and the secondary oil removal efficiency of Nano-β-CD@Fe₃O₄ recovered by magnetic separation could still reach 85.65 %. This efficient oily sludge treatment method proposed in our study provides valuable information for the development of oily sludge treatment technology.