Assessing the economic feasibility of regional deep saline aquifer CO2 injection and storage: A geomechanics-based workflow applied to the Rose Run sandstone in Eastern Ohio, USA

Typical top-down regional assessments of CO₂ storage feasibility are sufficient for determining the maximum volumetric capacity of deep saline aquifers. However, they do not reflect the regional economic feasibility of storage. This is controlled, in part, by the number and type of injection wells that are necessary to achieve regional CO₂ storage goals. In contrast, the geomechanics-based assessment workflow that we present in this paper follows a bottom-up approach for evaluating regional deep saline aquifer CO₂ storage feasibility. The CO₂ storage capacity of an aquifer is a function of its porous volume as well as its CO₂ injectivity. For a saline aquifer to be considered feasible in this assessment it must be able to store a specified amount of CO₂ at a reasonable cost per ton of CO₂. The proposed assessment workflow has seven steps that include (1) defining the storage project and goals, (2) characterizing the geology and developing a geomechanical model of the aquifer, (3) constructing 3D aquifer models, (4) simulating CO₂ injection, (5,6) evaluating CO₂ injection and storage feasibility (with and without injection well stimulation), and (7) determining whether it is economically feasible to proceed with the storage project. The workflow was applied to a case study of the Rose Run sandstone aquifer in the Eastern Ohio River Valley, USA. We found that it is feasible in this region to inject 113 Mt CO₂/year for 30 years at an associated well cost of less than US $1.31/t CO₂, but only if injectivity enhancement techniques such as hydraulic fracturing and injection induced micro-seismicity are implemented.     

Mixing-controlled biodegradation in a toluene plume--results from two-dimensional laboratory experiments

Various abiotic and biotic processes such as sorption, dilution, and degradation are known to affect the fate of organic contaminants, such as petroleum hydrocarbons in saturated porous media. Reactive transport modeling of such plumes indicates that the biodegradation of organic pollutants is, in many cases, controlled by mixing and therefore occurs locally at the plume's fringes, where electron donors and electron-acceptors mix. Herein, we aim to test whether this hypothesis can be verified by experimental results obtained from aerobic and anaerobic degradation experiments in two-dimensional sediment microcosms. Toluene was selected as a model compound for oxidizable contaminants. The two-dimensional microcosm was filled with quartz sand and operated under controlled flow conditions simulating a contaminant plume in otherwise uncontaminated groundwater. Aerobic degradation of toluene by Pseudomonas putida mt-2 reduced a continuous 8.7 mg L(-1) toluene concentration by 35% over a transport distance of 78 cm in 15.5 h. In comparison, under similar conditions Aromatoleum aromaticum strain EbN1 degraded 98% of the toluene infiltrated using nitrate (68.5+/-6.2 mg L(-1)) as electron acceptor. A major part of the biodegradation activity was located at the plume fringes and the slope of the electron-acceptor gradient was steeper during periods of active biodegradation. The distribution of toluene and the significant overlap of nitrate at the plume's fringe indicate that biokinetic and/or microscale transport processes may constitute additional limiting factors. Experimental data is corroborated with results from a reactive transport model using double Monod kinetics. The outcome of the study shows that in order to simulate degradation in contaminant plumes, detailed data sets are required to test the applicability of models. These will have to deal with the incorporation of existing parameters coding for substrate conversion kinetics and microbial growth.     

Long-term geochemical evolution of the near field repository: insights from reactive transport modelling and experimental evidences

The KBS-3 underground nuclear waste repository concept designed by the Swedish Nuclear Fuel and Waste Management Co. (SKB) includes a bentonite buffer barrier surrounding the copper canisters and the iron insert where spent nuclear fuel will be placed. Bentonite is also part of the backfill material used to seal the access and deposition tunnels of the repository. The bentonite barrier has three main safety functions: to ensure the physical stability of the canister, to retard the intrusion of groundwater to the canisters, and in case of canister failure, to retard the migration of radionuclides to the geosphere. Laboratory experiments (< 10 years long) have provided evidence of the control exerted by accessory minerals and clay surfaces on the pore water chemistry. The evolution of the pore water chemistry will be a primordial factor on the long-term stability of the bentonite barrier, which is a key issue in the safety assessments of the KBS-3 concept.In this work we aim to study the long-term geochemical evolution of bentonite and its pore water in the evolving geochemical environment due to climate change. In order to do this, reactive transport simulations are used to predict the interaction between groundwater and bentonite which is simulated following two different pathways: (1) groundwater flow through the backfill in the deposition tunnels, eventually reaching the top of the deposition hole, and (2) direct connection between groundwater and bentonite rings through fractures in the granite crosscutting the deposition hole. The influence of changes in climate has been tested using three different waters interacting with the bentonite: present-day groundwater, water derived from ice melting, and deep-seated brine. Two commercial bentonites have been considered as buffer material, MX-80 and Deponit CA-N, and one natural clay (Friedland type) for the backfill. They show differences in the composition of the exchangeable cations and in the accessory mineral content. Results from the simulations indicate that pore water chemistry is controlled by the equilibrium with the accessory minerals, especially carbonates. pH is buffered by precipitation/dissolution of calcite and dolomite, when present. The equilibrium of these minerals is deeply influenced by gypsum dissolution and cation exchange reactions in the smectite interlayer. If carbonate minerals are initially absent in bentonite, pH is then controlled by surface acidity reactions in the hydroxyl groups at the edge sites of the clay fraction, although its buffering capacity is not as strong as the equilibrium with carbonate minerals. The redox capacity of the bentonite pore water system is mainly controlled by Fe(II)-bearing minerals (pyrite and siderite). Changes in the groundwater composition lead to variations in the cation exchange occupancy, and dissolution–precipitation of carbonate minerals and gypsum. The most significant changes in the evolution of the system are predicted when ice-melting water, which is highly diluted and alkaline, enters into the system. In this case, the dissolution of carbonate minerals is enhanced, increasing pH in the bentonite pore water. Moreover, a rapid change in the population of exchange sites in the smectite is expected due to the replacement of Na for Ca.     

橡胶促进剂M盐废水生物处理技术研究

为探讨微生物技术在橡胶促进剂M盐废水处理中的应用,利用高效优势蘸强化A2O工艺对橡胶促进剂M盐废水进行处理,整个系统运行过程分为污泥的培养与驯化阶段及稳定运行阶段。在稳定运行阶段COD0平均去除率达90．71％,氨氮平均去除率达78．31％。以Mn^2＋、Fe^2＋、Mg^2＋、Ni^2＋为4个影响因子,通过正交实验分析无机离子对橡胶促进剂M盐废水中有机物降解的促进作用。由实验数据的摄差大小可知,各无机离子对优势复合菌降解橡胶有机废水的影响从大到小依次为：Mn^2＋、Fe^2＋、Ni^2＋和Mg^2＋。4种离子最佳质量浓度组合为：0．500mg／L的Mn^2＋、1．00mg／L的Fe^2＋、35．0mg／L的Mg^2＋和0．025mg／L的Ni^2＋。     

啤酒酵母吸附Cu^2＋的模拟实验

研究了啤酒酵母吸附重金属Ｃｕ２＋离子的可行性及反应条件对去除作用的影响．结果表明：用啤酒酵母处理Ｃｕ２＋,在起始浓度ρ０为２０～４００ｍｇ／Ｌ的范围内,吸附量ｗ为２．９８～１２．０３ｍｇ／ｇ,说明用啤酒酵母去除重金属Ｃｕ２＋是可行的．吸附反应在１０～２０ｍｉｎ基本达到吸附平衡．最适反应温度（θ）和ｐＨ分别为１５～２０℃和４．０～６．０,酵母细胞有一最适投加用量．Ｆｒｅｕｎｄｌｉｃｈ吸附等温方程的分析表明,η与重金属离子种类有关,与酵母细胞种类关系较小;ｋ值与酵母种类和重金属离子种类有关．     

蔬菜作物施用耐氨固氮菌的增产效果

研究在小区试验条件下,施用耐氨固氮型的催娩克氏菌和阴沟肠杆菌混合菌剂对蔬菜生长和产量的影响。结果表明,施用耐氨固氮菌可促进蔬菜生长,提高产量并改善品质,供试蔬菜的平均增产率达20％,增产效果明显。     

大气光化学烟雾反应机理比较(Ⅰ)O3和NOx的比较

在相同初始和排放条件下,对四种应用较广的光化学烟雾反应机理(CB4-99,RADM2,RACM,SAPRC99)进行了比较.研究发现对于O3,在低VOCs/NOx时,四种机理模拟结果相关较小,平均相对标准偏差为7%,在高VOCs/NOx时,平均相对标准偏差为26%,差距较大;对于NOx,多数情况下RACM和RADM2的模拟结果较高,CB4-99和SAPRC99的模拟值偏低,其原因主要来源于不同机理中O3的生成对NOx及VOCs的敏感性不同而造成的.在用模式模拟O3和NOx时,应特别注意机理不同而带来的模拟结果差异.     

Zn^2＋对水鳖的毒性作用

研究了不同浓度Zn^2 毒害对水鳖叶片膜脂过氧化作用及其体细胞超微结构的影响。结果表明,随着Zn^2 浓度的增加,叶绿素含量、SOD、CAT、POD活性先后升降,叶绿素a/b值值则逐渐减小,而MDA含量增加,O2^-产生速率也逐渐增大。同功酶分析表明,Zn^2 可以诱导新的POD同功酶,电镜观察发现,低浓度Zn^ 处理下,水鳖叶细胞中核质空泡化,叶绿体膨胀变形,线粒体嵴膨胀,溶酶体、小泡数量增加,且出现了多膜复合体;随着Zn^2 浓度的增加,核质消失,叶绿体和线粒体解体,而根尖分生细胞中则出现了多核仁现象。     

海洋巨藻(Durvilaea potatorum)生物吸附剂对Hg~(2 )的吸附动力学研究

对经特殊的稳定化预处理所得的海洋巨藻 (Durvillaeapotatorum)生物吸附剂对Hg2 的吸附动力学进行了研究 ,报导了不同Hg2 初始浓度、温度以及生物吸附剂平均粒径下动态吸附量与时间的关系 .结果显示 ,各吸附动力学曲线呈优惠型 ;当生物吸附剂平均粒径为 0 .45mm时 ,Hg2 的半饱和时间tS均不超过 6 0min ;Hg2 初始浓度和生物吸附剂粒径越小 ,吸附温度越大 ,达到吸附平衡所需的时间越短 .在测试范围内 ,生物吸附剂的平衡吸附容量与粒径和温度无关 .同时考察了吸附过程中的传质效应并对液膜传质系数kL进行了关联 ,结果表明 :当吸附时间t≤tS时 ,Hg2 的吸附速率为液膜传质控制 ;在测试范围内 ,kL为 0 .0 40 7～ 0 .112cm/s.本研究结果为利用海洋巨藻 (Durvillaeapotatorum)生物吸附剂处理含汞废水的规模化应用提供了一定的依据 .图 5表 2参 11     

纳米TiO2光催化降解有机磷农药的研究

通过实验,探讨了用纳米TiO2光催化处理有机磷农药模拟废水和实际应用的有机磷农药的可行性.实验表明,以测定不同时间PO43-的浓度来衡量有机磷的降解率,并以此来衡量有机磷农药及其中间产物降解的程度是合理的.光催化降解甲胺磷和水胺硫磷的结果,显示了有机磷农药的降解率与其结构有关.实际应用的有机磷农药也可用光催化降解.