Recovery of hydrocarbons and heavy metals from contaminated soils and wastes

在过去和今天，土地受到石油碳氢化合物(如汽油、柴油、原油和沥青)和重金属的污染。这种污染是意外泄漏和不当废物处理做法的结果，并对环境、公众健康和经济构成威胁。土壤中存在的污染物可能会进入水中，污染我们饮用的水和我们用于农业或娱乐目的的水。污染物也可能进入我们呼吸的空气中。污染物也可能被植物吸收，从而进入食物链，污染我们吃的食物。最后，受污染的土地也造成了经济负担，因为清理污染土地是一种经济责任，而未使用的土地则是收入的损失。加拿大有数千个受污染的地点，世界各地有数十万个受污染的地点必须清理。 除了受污染的土壤外，还有许多其他受污染的废物，既含有石油碳氢化合物，也含有重金属。这种废物的一个例子是油砂尾矿，即从油砂中提取沥青后产生的尾矿。这些尾矿含有残留的沥青、其他碳氢化合物和重金属，必须进行清理，以保护周围环境，并在未来几年不留下受污染的尾矿。 为了清理这些受污染的土壤和废物，迫切需要能够以经济高效的方式有效、快速地清理石油碳氢化合物和重金属的创新技术。超临界流体萃取(SFE)是一种可能处理这些类型的污染物质的技术。超临界流体萃取是一种使用超临界流体作为溶剂的溶剂萃取过程。超临界流体是指压力和温度高于其临界压力和温度的任何流体。最常用的超临界流体之一是二氧化碳，因为它无毒、不可燃、容易获得，而且相对便宜。二氧化碳还具有相对容易达到的临界温度和压力，使其成为许多应用的良好超临界流体选择，即使是大规模的。 该提案概述了一项研究计划，该计划将在实验室和中试规模上调查超临界二氧化碳从受污染的土壤和废物中提取石油碳氢化合物和重金属的效率。实验将考察压力、温度、固体含量、固体(土壤)类型和水分等重要参数对污染物萃取量的影响。预计这些结果将提供重要的信息，从而设计出一种超临界流体萃取系统，能够有效地清理加拿大和世界各地许多受重金属和石油烃污染的土壤和废物。

In the past and still today, land is contaminated with both petroleum hydrocarbons (such as gasoline, diesel oil, crude oil and bitumen) and heavy metals. This contamination is a result of accidental spills and improper waste disposal practices and poses a threat to the environment, public health and the economy. Contaminants present in soil may move into the water, contaminating the water we drink and the water we use for agricultural or recreational purposes. Contaminants may also move into the air we breathe. Contaminants may also be taken up by plants and thus find their way into the food chain, contaminating the food we eat. Finally, contaminated land also poses an economic burden because their cleanup represents an economic liability and unused land represents a loss in revenue. There are thousands of contaminated sites in Canada and hundreds of thousands of contaminated sites around the world that must be cleaned up. In addition to contaminated soils, there are many other contaminated wastes that contain both petroleum hydrocarbons and heavy metals. An example of such a waste is oil sands tailings i.e. tailings that are produced after the extraction of bitumen from oil sands. These tailings contain residual bitumen, other hydrocarbons and heavy metals and must be cleaned up in order to protect the surrounding environment and to not leave a legacy of contaminated tailings for years to come. To clean up these contaminated soils and wastes, innovative technologies that can clean up both petroleum hydrocarbons and heavy metals effectively, quickly, in a cost-effective manner are desperately needed. Supercritical fluid extraction (SFE) is a technology that could potentially deal with these types of contaminated materials. SFE is a solvent extraction process that uses a supercritical fluid as a solvent. A supercritical fluid is any fluid that is at a pressure and temperature above its critical pressure and temperature. One of the most commonly used supercritical fluids is carbon dioxide, owing to the fact that it is non-toxic, non-flammable, readily available and relatively inexpensive. Carbon dioxide also has a relatively easily achievable critical temperature and pressure, making it a good supercritical fluid of choice for many applications, even at a large scale. This proposal outlines a research program which will investigate the efficiency of supercritical carbon dioxide, on both a laboratory-scale and pilot-scale, at extracting petroleum hydrocarbons and heavy metals from contaminated soils and wastes. Experiments will investigate the effect of important parameters, such as pressure, temperature, solids content, solids (soil) type and water content, on the amount of contaminant extracted. It is expected that the results will provide important information that will lead to the design of a SFE system that can effectively clean many heavy metal and petroleum hydrocarbon contaminated soils and wastes in Canada and around the world.