磁性壳聚糖改善污泥脱水性能的研究

采用天然壳聚糖为原料,戊二醛为交联剂,Fe₃O₄为磁核制备磁性壳聚糖,以改善污泥脱水性能.考察了磁性壳聚糖投加量、污泥pH值、调理时间对磁性壳聚糖改善污泥脱水性能的影响,探讨了磁性壳聚糖的作用机理,并通过响应面法研究了磁性壳聚糖和CPAM复配处理污泥对污泥脱水性能的影响.结果表明,保持污泥pH值为6.8时,经20mg/L的磁性壳聚糖调理30min后,污泥比阻（SRF）和含水率（MC）分别由原污泥的13.8×10¹²m/kg和98.7%降低至4.8×10¹²m/kg和75.5%,说明磁性壳聚糖明显改善了污泥脱水性能.响应面实验所拟合的响应值为污泥SRF的二次模型P（Prob>F）<0.05、R²=0.98>0.90,响应值为污泥MC的二次模型P（Prob>F）<0.05、R²=0.95>0.90,表明模型显著,且实验设定变量之间的相关性较好.根据响应值的分布情况,确定污泥脱水的最佳条件为磁性壳聚糖18mg/L、CPAM26mg/L、调理时间27min,相应SRF和MC分别为3.3×10¹²m/kg和59.5%,污泥脱水效果较单独采用磁性壳聚糖或CPAM时得到了明显的提高.     

Association of emergency room visits for respiratory diseases with sources of ambient PM2.5

Previous studies have reported associations of short-term exposure to different sources of ambient fine particulate matter(PM_(2.5)) and increased mortality or hospitalizations for respiratory diseases. Few studies, however, have focused on the short-term effects of source-specific PM_(2.5) on emergency room visits(ERVs) of respiratory diseases. Source apportionment for PM_(2.5) was performed with Positive Matrix Factorization(PMF) and generalized additive model was applied to estimate associations between source-specific PM_(2.5) and respiratory disease ERVs. The association of PM_(2.5) and total respiratory ERVs was found on lag4(RR = 1.011, 95%CI: 1.002, 1.020) per interquartile range(76 μg/m~3) increase.We found PM_(2.5) to be significantly associated with asthma, bronchitis and chronic obstructive pulmonary disease(COPD) ERVs, with the strongest effects on lag5(RR = 1.072,95%CI: 1.024, 1.119), lag4(RR = 1.104, 95%CI: 1.032, 1.176) and lag3(RR = 1.091, 95%CI: 1.047,1.135), respectively. The estimated effects of PM_(2.5) changed little after adjusting for different air pollutants. Six primary PM_(2.5) sources were identified using PMF analysis, including dust/soil(6.7%), industry emission(4.5%), secondary aerosols(30.3%), metal processing(3.2%),coal combustion(37.5%) and traffic-related source(17.8%). Some of the sources were identified to have effects on ERVs of total respiratory diseases(dust/soil, secondary aerosols, metal processing, coal combustion and traffic-related source), bronchitis ERVs(dust/soil) and COPD ERVs(traffic-related source, industry emission and secondary aerosols). Different sources of PM_(2.5) contribute to increased risk of respiratory ERVs to different extents, which may provide potential implications for the decision making of air quality related policies, rational emission control and public health welfare.     

无机复合调理剂对污泥脱水性能的影响

针对污泥的固化填埋或建材化利用等后续处置方式,采用FeCl3与生石灰、粉煤灰两种骨架构建体为主要成分的无机复合调理剂对市政污泥进行调理.通过污泥真空抽滤、离心脱水及比阻测定实验,分别确定FeCl3、生石灰、粉煤灰的优化投加量为2.0 g.L-1、20.0 g.L-1、30.0 g.L-1.在优化投加量下,污泥比阻可降到...     

Filtration of Lignin from a Lignocellulose-Based Ethanol Pilot Plant

Abstract An increasing demand for bio-based vehicle fuels and impending harsher regulations of CO2 emissions are driving the development of a second generation of ethanol fuel processes. These processes will increase yields and make new feedstocks available, as they are designed to handle lignocellulosic materials such as wood. In order to achieve a sound financial economy of such a process, as well as an acceptable degree of energy efficiency, it is of the utmost importance that the lignin produced has a high dry content. An experimental study was conducted on lignin slurry from a pilot plant in the north of Sweden, in which the lignin slurry was filtered, pressed, and characterized. The dewatering was evaluated with the classical filtration equation by determining the average specific filtration resistance of the filter cakes. Compared with previous work, relatively low values of the specific filtration resistance were obtained. It is probable that the low values were an effect of the high amount of cel...     

天然气汽车加气站压缩机房火灾爆炸事故故障树分析

压缩天然气汽车加气站压缩机房具有高压、易泄漏、易爆炸等危险性特点。根据其运行的实际情况,对压缩机房火灾爆炸事故原因运用故障树进行了深入分析,提出了压缩机房火灾爆炸事故预防对策。     

Bi5O7I/g-C3N4Z型异质结的常温沉淀制备及其光催化性能研究

以Bi（NO₃）₃·5H₂O、KI和g-C₃N₄为前驱体,采用常温沉淀法制备Bi₅O₇I/g-C₃N₄Z型异质结复合光催化剂,表征其光吸收性能、微观形貌、光生电子-空穴的分离效率等特性,研究新型光催化剂对RhB的可见光催化降解性能,探讨其可见光催化过程活性基团种类以及作用机理.结果表明：利用沉淀法合成Bi₅O₇I/g-C₃N₄的条件为：Bi（NO₃）₃·5H₂O、KI和g-C₃N₄的投加量分别为4.85g、1.66g和1.61g,乙二醇的用量为50mL,反应液的pH值为12,反应搅拌速度为200r/min,反应温度为25℃.Bi₅O₇I/g-C₃N₄异质结无杂相生成且纯度高,异质结复合发生在g-C₃N₄的（002）晶面和Bi₅O₇I的（203）晶面,但g-C₃N₄和Bi₅O₇I的化学结构未受影响.Bi₅O₇I/g-C₃N₄呈三维纳米花瓣形貌结构,为光生电子-空穴的迁移提供了大量的接触位点.Bi₅O₇I的g-C₃N₄掺杂改性使其光催化活性显著增强,其光吸收边缘由425nm红移至462nm,Bi₅O₇I/g-C₃N₄的能带排列结构与Z型异质结匹配,促进了光生电子-空穴的分离.其光电流密度（11.5mA/cm）约为g-C₃N₄和Bi₅O₇I对应值的2.66倍和1.47倍.Bi₅O₇I/g-C₃N₄对罗丹明B的可见光催化降解率为93.9%,显著高于g-C₃N₄（58%）和Bi₅O₇I（49.7%）的降解效果,其光催化氧化活性主要来自羟基基团、超氧基团和光生空穴等中间态自由基.     

MAP法沉淀回收装置的运行条件优化研究

采用一种简易的MAP回收装置,研究了间歇运行条件下反应时间和曝气量对MAP法除磷效果的影响,确定出最佳反应时间为90 min,最佳曝气量为1.2 L/min,相应的除磷率可达98.26%,沉淀回收率为74.54%。当增加一个漏斗形隔板分离反应区和沉淀区并连续运行时,除磷率和沉淀回收率分别为92.11%和63.66%。当不投加镁盐和铵盐而仅调控实际污泥脱水滤液的pH值为9.8时,其连续运行的平均除磷率和MAP回收率分别可达95.16%和70%,运行性能比较稳定。     

新型改性聚丙烯酰胺的合成及对污泥调理效果的研究

采用原位聚合法,在聚丙烯酰胺的聚合过程中引入金属离子进行改性,合成了一种新型改性聚丙烯酰胺.通过正交实验确定了改性聚丙烯酰胺的最佳合成条件.红外图谱显示,该聚丙烯酰胺是一种具有特殊结构的有机高分子化合物.以污泥脱水率和污泥比阻为考察指标,研究了改性聚丙烯酰胺对污水处理厂剩余活性污泥脱水性能的影响,结果表明,在每1000...     

基于CFD的污泥脱水机房恶臭扩散分布规律研究

污泥脱水机房是污水处理厂恶臭污染最严重的处理单元之一，其恶臭污染危害工作人员和周边居民身体健康。为研究脱水机房恶臭扩散分布规律，运用计算流体动力学（computational fluid dynamics, CFD）理论并采用其商用软件FLUENT对脱水机房主要恶臭污染物之一的硫化氢扩散分布进行数值模拟。案例研究了3种典型情景下的硫化氢扩散分布。结果表明，不同通风条件对脱水机房硫化氢扩散分布影响较大。在进行脱水机房设计时，应将脱水机布置于夏季最多风向的下方向，并靠近排风口，使恶臭污染物在最短的路径上排除出去，还应考虑机房其他布置，使工作人员经常接触和经过的地方位于低浓度区。     

CPAM调质浓缩污泥脱水的影响因素及其机理研究

污水处理厂剩余污泥的处置是当前业界的热点。研究了阳离子聚丙烯酰胺(CPAM)调质浓缩污泥脱水的一些影响因素，如药剂投加量、污泥pH值、环境温度、搅拌条件等。同时，还对污泥絮凝脱水机理进行了一定的探讨。研究表明：阳离子聚丙烯酰胺(CPAM)作为浓缩污泥脱水剂，在优化投加量下、污泥pH值在5.0～7.5、低速搅拌时，有较好的脱水效果。环境温度对污泥的脱水效果也有一定的影响，夏天处理优于冬天处理。