污水污泥在富氧环境下燃烧特性的实验研究

采用综合热分析仪研究了空气气氛和富氧气氛下污水污泥和煤的燃烧曲线,分析比较氧浓度对污泥燃烧特性参数的影响,并计算得到各工况下的动力学参数。结果表明：随着氧浓度增加,污泥燃烧DTG曲线向低温区移动,着火温度和燃尽温度均降低,综合燃烧指数大大提高,污泥燃烧特性得到改善。可用两段一级反应动力学模型来较好的描述污泥的主要燃烧过...     

恶臭假单胞菌降解苯酚的动力学研究

研究了恶臭假单胞菌（Pseudomonas putida LY1）利用苯酚作为唯一碳源和能源时的生长动力学特性。通过对该菌株在不同温度、pH和初始苯酚浓度下的生长和降解情况的研究,可知该菌株在温度为25℃左右、pH为中性和偏碱性的条件下具有更高的降解活性。细菌的生长动力学过程符合基质抑制型的Haldane方程,可利用该...     

聚合氯化铝污泥对磷的吸附动力学及热力学

聚合氯化铝污泥（polyaluminium chloride sludge,PACS）是指以聚合氯化铝（PAC）为混凝剂的城镇给水厂在生产过程中所产生的污泥。采用批量吸附实验考察了PACS对磷的吸附动力学及热力学行为。结果表明,吸附反应发生1 h后,PACS对磷的吸附量达到平衡吸附量的75%～90%,随后PACS对磷的...     

氢氧化镁对水中As（Ⅲ）的吸附作用

以氢氧化镁为吸附材料,通过单因素实验分别考察了氢氧化镁投加量、pH、温度、吸附时间对吸附效果的影响。研究了氢氧化镁对As（Ⅲ）的吸附热力学和动力学特性,并对作用机理进行了探讨。结果表明：在砷初始浓度为0.5～100 mg/L之间,温度为25℃,pH为3,氢氧化镁投加量为0.5～4 g,吸附时间为1 h的条件下,氢氧化镁...     

锐钛矿-金红石混合晶型TiO2降解气相苯

用溶胶-凝胶法并通过控制煅烧温度合成不同晶相比的混合晶型纳米TiO_2,在紫外光光照下降解气相苯。考察了苯初始质量浓度、紫外灯光照强度和催化剂加入量对苯去除率的影响;探究了光催化降解气相苯的动力学特征。结果表明:450℃煅烧制备的催化剂降解苯效率最高,此催化剂金红石相质量分数为6.30%;在苯初始质量浓度为74.39 mg/m~3、催化剂加入量为7 g、光照强度为2.18 klux的最佳条件下反应84 min,苯去除率达99.73%;光催化降解率与光照强度之间符合0.5级动力学特征;当催化剂加入量为3 g时,单位时间单位质量催化剂降解苯的质量最多;苯的光催化降解反应均符合一级动力学方程。     

化工园区生化出水氯代烃污染物的臭氧氧化降解

以化工园区污水处理厂生化出水为背景水样,考察了臭氧氧化对2,4,6-三氯酚、氯苯、1,2-二氯苯、对硝基氯苯、四氯酞酸5种特征氯代烃污染物的降解效果,并对其降解动力学进行了分析。实验结果表明:臭氧对2,4,6-三氯酚和氯苯的降解效果最好,反应30 min时的去除率均接近100%,其次为1,2-二氯苯和对硝基氯苯,反应30 min时的去除率分别为95.7%和36.0%,最差为四氯酞酸,反应30 min时的去除率仅为8.9%;臭氧对2,4,6-三氯酚和对硝基氯苯的降解符合零级动力学方程,对氯苯和1,2-二氯苯的降解符合一级动力学方程,对四氯酞酸的降解符合二级动力学方程。     

针铁矿对Pb~(2+)的吸附特征及影响因素研究

通过恒温振荡平衡法研究了Pb~(2+)在针铁矿上的等温吸附和吸附动力学特征,探讨了吸附的影响因素.结果表明:(1)随Pb~(2+)平衡浓度和pH的增大,针铁矿对Pb~(2+)的吸附量逐渐增大.(2)针铁矿对Pb~(2+)的等温吸附可用Freundlich和Langmuir方程较好地拟合.(3)在相同温度和pH下,随离子强度的提高,针铁矿对Pb~(2+)的吸附量增大.(4)在相同离子强度和pH下,针铁矿对Pb~(2+)的吸附量总体随温度升高而增大.针铁矿对Pb~(2+)的吸附是自发进行的吸热反应.(5)针铁矿吸附Pb~(2+)的过程可分为初始的快吸附和随后的慢吸附2个阶段.pH影响吸附反应快慢,随pH增大吸附速率增大;随着pH的增大,达到平衡吸附的时间缩短.吸附动力学方程用Elovich方程拟合最佳.     

壳聚糖/纳米CdS复合颗粒可见光光催化降解猩红B动力学研究

采用仿生矿化法制备了壳聚糖/纳米CdS复合颗粒光催化剂,并用于可见光光催化降解猩红B染料模拟废水,研究了猩红B初始浓度、pH、催化剂投加量和催化剂重复使用次数等因素对猩红B光催化降解的影响.X射线衍射(XRD)分析表明,壳聚糖能有效负载CdS纳米微晶.采用Langmuir-Hinshelwood模型描述壳聚糖/纳米CdS复合颗粒可见光光催化降解猩红B反应动力学行为,在猩红B初始质量浓度较低(≤20 mg/L)时,光催化降解过程符合假一级动力学方程.降低猩红B初始浓度和溶液pH都可显著增大光催化降解速率常数;催化剂投加量小于0.7 g/L时,光催化降解速率随其增加而增大,但催化剂投加量过大会使光催化降解速率减小;催化剂重复使用第5次时,猩红B光催化降解速率常数仍为第1次使用时的63.4%.     

Numerical analysis of water and solute transport in variably-saturated fractured clayey till

This study numerically investigates the influence of initial water content and rain intensities on the preferential migration of two fluorescent tracers, Acid Yellow 7 (AY7) and Sulforhodamine B (SB), through variably-saturated fractured clayey till. The simulations are based on the numerical model HydroGeoSphere, which solves 3D variably-saturated flow and solute transport in discretely-fractured porous media. Using detailed knowledge of the matrix, fracture, and biopore properties, the numerical model is calibrated and validated against experimental high-resolution tracer images/data collected under dry and wet soil conditions and for three different rain events. The model could reproduce reasonably well the observed preferential migration of AY7 and SB through the fractured till, although it did not capture the exact depth of migration and the negligible impact of the dead-end biopores in a near-saturated matrix. A sensitivity analysis suggests fast flow mechanisms and dynamic surface coating in the biopores, and the presence of a plough pan in the till.     

Incorporating layer- and local-scale heterogeneities in numerical simulation of unsaturated flow and tracer transport

This study characterizes layer- and local-scale heterogeneities in hydraulic parameters (i.e., matrix permeability and porosity) and investigates the relative effect of layer- and local-scale heterogeneities on the uncertainty assessment of unsaturated flow and tracer transport in the unsaturated zone of Yucca Mountain, USA. The layer-scale heterogeneity is specific to hydrogeologic layers with layerwise properties, while the local-scale heterogeneity refers to the spatial variation of hydraulic properties within a layer. A Monte Carlo method is used to estimate mean, variance, and 5th, and 95th percentiles for the quantities of interest (e.g., matrix saturation and normalized cumulative mass arrival). Model simulations of unsaturated flow are evaluated by comparing the simulated and observed matrix saturations. Local-scale heterogeneity is examined by comparing the results of this study with those of the previous study that only considers layer-scale heterogeneity. We find that local-scale heterogeneity significantly increases predictive uncertainty in the percolation fluxes and tracer plumes, whereas the mean predictions are only slightly affected by the local-scale heterogeneity. The mean travel time of the conservative and reactive tracers to the water table in the early stage increases significantly due to the local-scale heterogeneity, while the influence of local-scale heterogeneity on travel time gradually decreases over time. Layer-scale heterogeneity is more important than local-scale heterogeneity for simulating overall tracer travel time, suggesting that it would be more cost-effective to reduce the layer-scale parameter uncertainty in order to reduce predictive uncertainty in tracer transport.