The Efficiency of Sophorolipids for Removal of Arsenic from Mine Tailings

Fereshteh Arab, Catherine N. Mulligan

In the proceedings of: GeoRegina 2014: 67th Canadian Geotechnical Conference

Session: Geoenvironmental Engineering

ABSTRACT: Mine tailings are one of the main sources of dissolved arsenic in ground water. In the present study, an investigation was conducted on the efficiency of sophorolipids at different concentrations and pH levels, to remove arsenic and heavy metals from mine-tailings. Furthermore, the effect of sophorolipids on the speciation of arsenic, and the effect of sophorolipids on different fractions through sequential extraction of the mine tailing specimen was investigated. Following treatment of the specimen with a solution of 1% sophorolipids at pH 5, the percentage of mobilization of arsenic associated with the specimen was as follows: 44.6% from water-soluble, 37.4% from exchangeable, 27.0% from carbonates, 60.2% from oxide/hydroxides, 56.4% from organic and 24.2% from residual. The results from this study help to develop a sustainable and environmentally friendly solution for the remediation of mine tailings. RÉSUMÉ Les résidus miniers sont l'une des principales sources d'arsenic dissous dans les eaux souterraines. Dans la présente étude, une enquête a été menée sur l'efficacité de sophorolipides à différentes concentrations et différentes niveaux de pH pour éliminer l'arsenic et les métaux lourds à partir des résidus des mines. En outre, l'effet des sophorolipides sur la spéciation de l'arsenic, et l'effet des sophorolipides sur différentes fractions de médias par extraction séquentielle de l'échantillon de résidus miniers ont été étudié. Après traitement avec une solution de pH 5, contenant 0,1% de sophorolipides, les pourcentages de la mobilisation de l'arsenic associés à des fractions différentes de l'échantillon sont les suivants : 44,6% des solubles dans l'eau, 37,4% d'échangeable, 27,0% des carbonates, 60,2% des oxydes / hydroxydes, 56,4% des matières organiques et de 24,2% des résiduels. Le résultat de cette étude contribue à développer une solution durable et respectueuse de l'environnement pour l'assainissement des résidus miniers. 1 INTRODUCTION Arsenic contamination has affected millions around the world (Smith et al. 2000). In countries like Bangladesh and Canada, arsenic is a natural contaminant for ground water. Arsenic is naturally present in a variety of rocks and minerals including sulfides, oxides and hydroxides. Arsenic pollution can also be anthropogenic. Mining, smelting, pesticides, combustion of coal, wood treatment, and industrial pollution all contribute to the presence of high levels of arsenic in the environment (Nordstrom, 2002). The range of arsenic present in natural waters can vary considerably from region to region, ranging anywhere from 0.5 µg/L to 5000 µg/L. Arsenic is a potent poison and is considered a primary pollutant in water due to its high toxicity (Smith & Rahman 2000). Arsenic has been considered a carcinogen by various environmental protocols and exposure to a high levels or even long term exposure to lower levels of arsenic is linked to numbers of short term or long term health problems and some forms of birth defects. Arsenic V is known to have properties that interfere with cellular metabolism, and arsenic III can interfere with enzyme function and impair protein function for DNA repair, thereby increasing the frequency of genetic mutations and cancer in biological organisms (Mazumder et al. 1998). The maximum level of inorganic arsenic recommended for soil in a residential area is 32 mg/kg and for a commercial area is 640 mg/ kg of the soil's dry weight (Environment Agency, 2009). Contamination can have a variety of implications for a population given the extent of exposure in the population. Some common adverse health effects associated with long-term exposure to arsenic include: skin lesions, skin cancer, internal cancers such as bladder, kidney, and lung cancer, neurological effects, hypertension and cardiovascular disease, pulmonary disease, peripheral vascular disease, and diabetes mellitus (Morales & Chen 2000; Smith et al. 2000). Some common sources of arsenic exposure are contaminated food and water. Arsenic, even at high concentrations, has no odor, taste, or color when dissolved in water, and is only determined to be present through laboratory testing. 1.1 Problem statement: Arsenic is found in gold mineral deposits in the form of arsenopyrite. Mine tailings are considered to be environmental contamination sources (Dushenko et al. 1995). For example, it has been estimated that the mine tailings from the past mining activities at Giant mines, Yellowknife contain a quarter-million tonnes of arsenic, which are deposited into nearby Great Slave Lake. Reports have indicated that heavy metals and arsenic

RÉSUMÉ: FFICIENCY OF SOPHOROLIPIDS FOR REMOVAL OF ARSENIC FROM MINE TAILINGS Fereshteh Arab and Catherine N. Mulligan Department of Building, Civil, & Environmental Engineering Œ Concordia University, Montreal, Quebec, Canada

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Fereshteh Arab; Catherine N. Mulligan (2014) The Efficiency of Sophorolipids for Removal of Arsenic from Mine Tailings in GEO2014. Ottawa, Ontario: Canadian Geotechnical Society.

@article{GeoRegina14Paper264,author = Fereshteh Arab; Catherine N. Mulligan,title = The Efficiency of Sophorolipids for Removal of Arsenic from Mine Tailings,year = 2014}