地下水曝气过程中空气流场的数学模拟

地下水曝气（AS）过程中空气流场的数学模拟是现场过程研究的必要手段。利用饱和度与相对渗透率、毛细压力间的关系建立了AS二维非稳态流场的数学模型，用有限元法模拟了复杂流场非稳态二维气相饱和度场、速度场和稳态压力场分布，结果显示气相饱和度随着曝气时间和距曝气井位置的不同而变化。在曝气5 h左右，流场区域稳定。由饱和度的分布确定了空气在地下水中流型为下部U形，上部水平。在本模拟条件下，单井AS的影响区半径为9 m，若修复大面积污染的地下水，宜采用多井曝气的方式，增大其影响区半径。     

多相抽提和强化原位生物修复联合修复技术应用

上海市某地块内的土壤和地下水受1,2-二氯乙烷污染。本案例修复过程中先采用多相抽提技术(MPE)降低土壤和地下水中污染物的浓度，然后通过原位注入零价铁生物强化药剂，实施厌氧强化原位生物修复进一步降低目标污染物浓度。经过60天的多相抽提及注入187吨药剂后，该地块土壤和地下水中1,2-二氯乙烷浓度均达到修复目标。本案例表明，采用多相抽提与强化原位生物修复技术联合修复土壤和地下水中的氯代烃污染物是一种高效可行的技术选择。     

气相抽提与生物通风技术对比研究微生物对苯、甲苯、对二甲苯(BTX)的降解

土壤污染是比较广泛的一种污染.土壤中最严重的污染物是石油类物质的污染,其中苯系化合物(BTX)是最难降解的一类污染物,在治理土壤石油污染中,土壤原位修复中的土壤气相抽提法(SVE)是近年来国外常用的一种方法,随后与微生物降解相结合,产生了生物通风(BV)技术.本文通过实验计算出土壤中污染物BTX的去除作用,生物的降解率分别达到20%、34.4%和38.40%.     

表层土壤轻质油污染的原位通风去除

选取天津滨海地区某地为现场通风试验场址，通过中试试验研究了轻质油污染通风修复方法在该地类型土壤中应用的可行性。在分析了现场通风抽提能力的基础上，以轻质油代表物正己烷为模拟污染物，对抽提过程中抽提尾气正己烷浓度监测，研究了该中试方法去除土壤中轻质油污染物的效果。结果显示，当模拟污染现场抽提过程正己烷初始质量浓度为452．04mg／m^3时，经过89h通风抽提试验后，正己烷质量浓度下降到6．28mg／m^3，抽提后期有较长的拖尾阶段。研究表明该类型土壤使用原位通风法去除轻质油污染效果良好。     

热脱附技术在有机磷农药污染土壤修复过程中的应用研究

天津某农药厂重污染区域土壤中主要以有机磷污染物为主,本文采用在有机氯、石油烃类等污染土壤修复中已广泛使用的热脱附修复技术,通过实验室试验模拟有机磷污染土壤中主要污染物热脱附特征,确立影响土壤有机磷去除效果较佳主导因子及其范围,并进行有机磷污染物去除的热脱附土壤工程修复技术验证试验,为热脱附技术在有机磷污染土壤的修复中推广应用提供技术支持。     

寒区石油污染场地浅层地下水原位增温强化空气扰动修复

原位空气扰动技术（air sparging,AS）常被用在治理地下水与土壤的有机污染,在寒区,由于低温环境,污染物传质过程的多种基本参数受到影响,导致修复结果不理想。本文基于野外原位空气扰动实验结果,以甲苯为代表性污染物,进行室内土柱模拟实验,并构建增温空气扰动下污染物迁移模型,对野外场地增温强化空气扰动效果进行模拟,以预测采用增温方式时寒区污染物的去除效果。结果表明,甲苯的挥发速率与温度之间存在正比例关系;在室内柱实验中,高温注气条件下甲苯浓度衰减速率更快;野外数值模拟中的增温强化空气扰动修复过程中温度传导半径为2~4 m,曝气场污染物去除半径达10 m,比非增温强化条件污染物去除范围扩大3~5 m,进而将去除率有效提高40%~50%。     

寒区石油污染场地浅层地下水原位增温强化空气扰动修复

原位空气扰动技术(air sparging,AS)常被用在治理地下水与土壤的有机污染,在寒区,由于低温环境,污染物传质过程的多种基本参数受到影响,导致修复结果不理想。本文基于野外原位空气扰动实验结果,以甲苯为代表性污染物,进行室内土柱模拟实验,并构建增温空气扰动下污染物迁移模型,对野外场地增温强化空气扰动效果进行模拟,以预测采用增温方式时寒区污染物的去除效果。结果表明,甲苯的挥发速率与温度之间存在正比例关系;在室内柱实验中,高温注气条件下甲苯浓度衰减速率更快;野外数值模拟中的增温强化空气扰动修复过程中温度传导半径为2~4 m,曝气场污染物去除半径达10 m,比非增温强化条件污染物去除范围扩大3~5 m,进而将去除率有效提高40%~50%。     

渤海S油田注水井防膨影响因素研究

阳离子季铵盐聚合物BHFP-02防膨剂长期应用于海上S油田A区块、B区块注水井防膨作业，防膨缩膨效果优异。从历次现场防膨井施工作业效果反馈，44井次防膨作业效果明显，19井次防膨作业效果不明显。历次防膨作业井中挑选效果不明显的3口井，根据防膨井选井依据，对S油田区块岩芯模拟地层水及标准盐水水敏性实验、地层水速敏及煤油速敏性实验及单井注入量、防膨剂耐冲刷性、防膨率实验、单井设计药剂量及油藏单井配注量等，分析不明显防膨井存在的影响因素。结果表明：S油田储层水敏指数为0.43～0.63,属于中偏强水敏，注入水矿化度低于临界矿化度，防膨井储层存在水敏伤害；S油田A区块地层属弱速敏性，B区储层为弱以及中等偏弱的流速敏感，注水速度应控制在临界流速以下，减小速敏对防膨井储层均影响；对注水量高的防膨井，可优化注水频次和提高防膨剂的吸附能力，来保证防膨井效果及防膨有效期。     

生物渗透反应格栅修复甲基叔丁基醚污染地下水的模拟

渗透反应格栅技术(PRB)修复污染地下水的现场模拟是实际工程设计、过程预测及修复效果评价的有效手段.以甲基叔丁基醚(MTBE)为研究对象,在多孔介质流体动力学、传质学、生物降解动力学等基础上,建立了生物渗透反应格栅修复MTBE污染地下水的数学模型.由双柱法的实验结果可知,模型模拟结果与实验数据的平均相对误差为5.74%,说明文中所建模型能够很好地描述MTBE在反应格栅内的降解去除过程;由污染物在格栅及其附近区域的浓度分布可知,由于部分流体从格栅侧面进入,污染物在此流径上得不到充分降解,表现为生物渗透反应格栅系统处理后的地下水区域边缘处的MTBE浓度高于其中心区域浓度,该结果可用于指导现场PRB系统及其附属设施的设计和安装.     

生物通风修复含石油污染物土壤过程

以苯、甲苯和对二甲苯（BTX）为模拟污染物,研究了生物通风原位土壤修复方法去除土壤中石油污染物的效果.用一维生物通风土柱实验和控制实验对比了有生物降解和无生物降解土柱中BTX的去除情况.在通风后期,控制实验中发现了很长的拖尾阶段,污染物不能进一步被有效去除,而生物通风土柱中由于生物降解作用可使土壤中污染物残留浓度更小,修复效率更高.根据实验数据估算得到生物通风过程中苯、甲苯及对二甲苯的生物降解贡献率分别为17.8%, 30.0% 和 32.3%.还用间歇实验探讨了多组分污染物之间的相互影响作用,发现甲苯的降解能够促进对二甲苯和苯的降解,而对二甲苯的存在则增加了甲苯和苯的降解滞后期.     

生物通风过程中单井轴对称受污染区域流场的数值模拟

引 言 土壤污染主要为有机物污染、重金属污染和放射性污染3大类,其中有机物污染最为严重.我国目前大部分油田区和加油站存在储油罐及输送管道泄露的情况,另外加上落地油、含油污水排放等原因,大量有机类污染物进入土层,对土壤甚至地下水造成严重污染[1].     

生物通风修复甲苯污染土壤过程中挥发和生物降解模拟研究

A two-dimensional numerical model is developed to simulate the flow,transport and biodegradation of toluene during bioventing (BV) processes in the unsaturated zones.The simulation for a single well BV system is used to illustrate the effect of air injection rate on remediation efficiency.The air is injected into the vadose zone to create a positive pressure.Simulation results show that air injection rate is a primary parameter governing the dispersal,redistribution and surface loss of contaminant.At injection rates of 81.504 m3·d-1 (Run 1) and 407.52 m3·d-1 (Run 2),the total removed mass of toluene is 169.14 kg and 170.59 kg respectively.Ratios of volatilization to bio-degradation in Run 1 and Run 2 are 0.57︰1 and 0.89︰1,respectively,indicating that lower air injection rate enhances the biodegradation efficiency greatly.Air injection rate should be optimized to meet oxygen demand and to minimize the operational cost.     

层间地下水污染曝气修复的影响带

影响带是开展曝气修复机理研究和工程设计的重要基础,不同场地条件下影响带的型态与形成机制不同。以我国东北地区典型层间地下水污染场地为例,在阐明污染水文地质特征的基础上,开展曝气修复的运行、监测与分析,利用地下水水位、溶解氧、温度等参数的动态变化来反映曝气修复对地下环境的影响,并以之指示曝气影响带的空间分布。进而通过对影响带地下水动态特征的分析,阐明曝气驱替过程中的水流运动过程,量化分析该层间水曝气模式下的水流运动规律。结果表明,在该曝气模式下,影响半径可达9 m,影响区呈倒圆锥状,其中赋存地下水362.04 m³,受曝气驱替作用,影响带内地下水以一定流量向四周流散,该流量随时间递减,连续运行6 h累积流散量为0.97 m³,表明该曝气修复模式下地下水的侧向流散并不显著。     

Electrokinetic remediation of gasoil contaminated soil enhanced by rhamnolipid

Electrokinetic remediation (EKR) has been investigated as one of the best technologies in soil remediation but its applications for organic contaminants have been limited due to low solubility of organics in water and their non-ionic nature. The use of biosurfactants may increase the remediation efficiency by increasing the solubility of organics. The purpose of the introduction of complexing substances is to enhance the EKR process forming complexes and/or increasing the electro-osmotic flow. In this study, the removal of gasoil from a soil using electrokinetic method was investigated in the presence of Rhamnolipid at various concentrations. EKR experiments were undertaken on a gasoil contaminated soil (20,000 ppm). Graphite carbon electrodes were used to provide an electrical direct current (ddp 30–60 V). Results showed that increasing the dose of Rhamnolipid, the efficiency of gasoil removal increased up to 86.7%. Moreover, the lower concentration of the gasoil observed in the liquid phase at the higher concentration of the biosurfactant clearly indicated that the Rhamnolipid addition can enhance gasoil biodegradation.     

Operation of Fixed‐bed Bioreactor for Polluted Surface Water Treatment

Abstract

Dissolved organic matters and ammonia nitrogen are serious contaminants of surface water in Taiwan. These contaminants can interfere with the water treatment process and cause biological instability in the finished water. One solution is to employ a biological treatment stage prior to the conventional water treatment process. A continuous flow biological filter packed with reticulated PU foam was used to remove ammonia nitrogen and organic materials before the conventional water treatment practice. The effect of its operation mode, namely, empty bed contact time (EBCT) and backwash, on the removal efficiencies of ammonia and organic matter was examined. The results suggested that ammonia nitrogen and organic nitrogen can be effectively removed by controlling the operation mode of the biological fixed bed. Efficient ammonia nitrogen removal was achieved upon the combination of the backwash mode with short EBCT or extended EBCT without the backwash. Efficient organic nitrogen and DOC removals were observed at short EBCT without the backwash. This study provides insights into the function of biofiltration, which benefits the design of a fixed‐bed bioreactor for the treatment of polluted surface water.     

考虑储层非均质时注汽井内蒸汽流动规律

稠油热采水平井注蒸汽是一个复杂多变的过程，水平井沿程蒸汽热物性的预测对于储层的均匀动用十分关键。考虑储层渗透率、围压和蒸汽相变等条件的相互耦合影响，建立了预测水平井注汽流动的综合数学模型。与现场测井数据进行对比分析，验证了模型的准确度。模拟结果表明，单一变量条件下，水平井跟部注汽压力越大，注汽井内质量流量和蒸汽干度下降越快，当注汽压力由11 MPa降为8.5 MPa时，配汽距离增加1倍；在水平井相同位置处，跟部注汽干度越高，注汽井内质量流量越大，且蒸汽压力下降越快，注汽干度提高1倍时，压降也几乎增加1倍；跟部注汽流量越大，蒸汽压力下降越快，注汽流量提高1.75倍时压降提高了5.3倍，但管内蒸汽干度下降趋缓；储层渗透率越高，注汽井内的蒸汽干度下降越快。该模型可以为现场注汽提供理论支撑，有效提高配汽效果达到增产降耗。     

Steam flow law in horizontal wells when considering reservoir heterogeneity

Steam injection in horizontal wells for thermal recovery of heavy oil is a complex and changeable process. The prediction of thermal properties of steam along horizontal wells is critical to the uniform production of reservoirs. In this paper, considering the mutual coupling effects of reservoir permeability, confining pressure, and steam phase transition, a comprehensive mathematical model for predicting steam injection flow in horizontal wells was established. Compared with the on-site logging data, the accuracy of the model was verified. The simulation results show that under a single variable condition, the larger the steam injection pressure at the heel, the faster the mass flow and steam dryness decrease. When the steam injection pressure drops from 11 MPa to 8.5 MPa, the steam distribution distance doubles. At the same position, the higher the steam dryness at the heel, the greater the mass flow in the steam injection well, and the faster the steam pressure decrease. Double the steam injection dryness, the pressure drop is almost doubled, but the longer steam injection distance. The larger the steam injection flow at the heel, the faster the steam pressure decreases, and the decrease in the steam dryness in the tube slows down. When the steam injection flow increases by 1.75 times, the pressure drop increases by 5.3 times. The higher the reservoir permeability, the faster the steam dryness decreases. By obtaining the general rules of steam distribution in horizontal wells to provide theoretical support for on-site steam injection, the steam distribution effect can be effectively improved to increase production and reduce consumption.     

A commercial process for the recovery of deodorizer distillates

Summary A continuous system for recovering the organic distillates from the deodorization process has been briefly described. The operation of this system essentially eliminates barometric condenser-water disposal problems since this water is relatively free of organic contaminants. At a nominal cost, which can be economically justified, all deodorizers could be put on a closed-circuit water system. The cooling towers in this system would remain clean and would require little maintenance. The organic materials, which were formerly lost as stream contaminants, would be recovered in a dry form which holds a premium over acidulated soapstock. This system would prove advantageous to the many processors of fatty products who are currently having waste-water disposal problems or who are operating on closed-circuit water systems, where periodic shutdown, cleaning, and maintenance of the cooling tower are required. The system is a major step toward solving the problems which have been so important in the past few years.     

Countercurrent Droplet‐flow‐based mini extraction with pulsed feeding and without moving parts

A countercurrent arrangement of immiscible liquid‐liquid mini contactors based on droplets is described in this article. Mini mixers without any moving parts were used as the contactors. The single stage mini mixer consists of a top and bottom mixing chamber. Both of the mixing chambers have two recirculating channels on either side. In these mini mixers, a liquid was broken up into droplets that dispersed into other continuously flowing liquid, consequently achieving a mass transfer between the two liquids. To realize the countercurrent arrangement, the two liquids were alternately fed into the system from opposite ends by compressed air according to a periodic program. One period consists of the following stages: organic phase feeding stage, droplet aggregation stage I, aqueous phase feeding stage, and droplet aggregation stage II. This continuous countercurrent arrangement is without the defects of continuous countercurrent arrangements based on laminar flows and multiple‐stage countercurrent arrangements based on droplets. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3685–3698, 2016