In this paper, a new method is proposed for the remediation of contaminated groundwater. The method is based on fuzzy inference and risk evaluation. The effectiveness of the presented method is assessed in numerical simulations. The main results of the study are as follows: 1) A pump-and-treat control algorithm was proposed by using the fuzzy inference and the human health risk calculation model, 2) It was found that applying the proposed algorithm was likely to reduce the pumped quantity, and 3) It was found that the proposed model can be used to notify residents of the human health risk; the model is based on the ASTM RBCA model for residents. A new fuzzy control system for contaminated groundwater can be used as a useful model for characterising the effects of contaminants on human health and providing helpful information on the human risk assessment of the contaminated groundwater site. 相似文献
Extracting aqueous solutions with or without additives are employed to solubilize contaminants in soil. Since water solubility is the controlling removing mechanism, additives are used to enhance efficiencies. These additives can reduce the time to treat a site compared to the use of water alone. Additives must be of low toxicity and biodegradable. The research in this area has focussed mainly on halogenated volatile organic compounds (VOCs) and is still quite limited for metal removal. Additives include surfactants, organic and inorganic acids, sodium hydroxide, which can dissolve organic soil matter, water-soluble solvents such as methanol, displacement of cations with nontoxic ones, complexing agents such as EDTA, acids in combination with complexing agents or oxidizing/reducing agents. Cationic, anionic and nonionic surfactants are particularly used for soil washing or flushing. They contain both hydrophobic and hydrophilic portions, making them ideal for solubilization of hydrophobic compounds. Numerous studies have indicated that surfactants enhance recoveries of non-aqueous phase liquids (NAPLs). There have also been indications that pretreatment of soil with surfactant washing to solubilize hydrophobic compounds such as PAHs enhances biodegradation of these contaminants. A few in situ field studies have been performed with surfactants. Large-scale treatment has been done mostly for organic removal. Soil pH, soil type, cation exchange capacity (CEC), particle size, permeabilities and contaminants all affect removal efficiencies. High clay and organic matter contents are particularly detrimental. Understanding the chemistry of the binding of the contaminant and the hydrogeology of the site are very important. Once the water is pumped from the soil, it must be extracted and then treated to remove the hydrocarbons and metals. Several technologies exist such as sodium hydroxide or sodium sulfide precipitation, ion exchange, activated carbon adsorption, ultrafiltration, reverse osmosis, electrodialysis and biological processes. Recycling of the surfactants is desired to decrease treatment costs.
This paper will provide an overview of the laboratory research, field demonstration and full-scale application of surfactants for the remediation of contaminated soil. The majority of pilot scale in situ flushing tests, particularly in the United States, have involved the use of surfactants and co-solvents. There are only a few full-scale projects however. Recent laboratory scale efforts by the authors concerning the use of biosurfactants, biologically produced surfactants, to enhance the removal of copper, cadmium and zinc from contaminated soils and sediments are discussed. Three types of biosurfactants were evaluated for their effectiveness. They included a lipopeptide called surfactin from Bacillus subtilis, a rhamnolipid from Pseudomonas aeruginosa and a sophorolipid from Torulopsis bombicola. The results indicated the feasibility of removing the metals with the anionic biosurfactants even though the exchangeable fractions were not significant. 相似文献
Lead (Pb), as an environmental hormone, acts as an estrogen in animal and human bodies, and its environmental pollution can result in many procreant anomalies, such as maladjustment of incretion, weakening of procreation function and descending of genital immunity. Experiments on pot-growth of paddies and corns in this study indicated that these crops did not show any macro-toxic symptoms in the observed contents of Pb added (0-4000 mg/kg) in soils. However, lead in soils can be easily absorbed by crops and accumulated in the different parts of plants. Statistical analysis showed that Pb contents in the crops are strongly positively correlated to the Pb contents in soils. In the crops, the Pb contents of roots are highest, tens to thousands of times those of straws and seeds. It is suggested that the root is a barrier of Pb absorbed by straws and seeds. Based on this fact, Pb pollution in soils can be gradually reduced by planting crops and subsequently removing the roots from the soil. This biotechnology may be used in environmental remediation, which embraces the quality of sustainable agricultural economy and a healthy environment. 相似文献