ASSESSMENT OF BIOREMEDIATION FOR TREATMENT OF ARSENIC IN MINE PIT WATER
Rafi, Saif Al
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Contamination of arsenic (As) in ground water and surface water is a widespread problem throughout the world. Industrial development and increase of anthropogenic activities such as mining are an issue of concern due to their pollution of the environment. Because of its toxicity to human and environmental health, remediation of As-contaminated water has become a high priority and a number of As treatment technologies have been developed. Common treatment technologies for As treatment are coagulation, oxidation, filtration processes, electrochemical methods, adsorption, phytoremediation, and bioremediation. Common difficulties with conventional treatment techniques may include the potential production of toxic by-products, limited efficiencies, operational difficulties, and high capital and operation/maintenance costs. Bioremediation may be used to promote the growth of indigenous water and wastewater bacteria, such as sulphate reducing bacteria (SRB), to remove As from these matrices in an effective and environmentally friendly manner. The goal of thesis was to investigate and assess the As bioremediation potential for mine pit water at in situ temperature (8 °C) using molasses as a carbon source. Six sets of experimental batch reactors were prepared including positive controls, negative controls, and molasses amended reactors. A problem with determining As speciation is the need for advanced analytical instruments for the analysis that are not readily available. Thus, suitable sample processing and storage procedures are vital to preserve the species from the time of sampling to analysis. To assess these processing and storage procedures, three methods were used: (1) no acid; (2) ethylene diaminete tetra acetic acid (EDTA); and (3) 2% nitric acid (HNO3). An ion-exchange method was used for the separation of arsenite (As(III)) and arsenate (As(V)) prior to inductively coupled plasma mass spectrometry (ICP-MS), while other metal(loid)s and bacteria were determined using ICP-MS and MiSeq 16S rRNA V4 analyses, respectively. Results showed that iron reducing bacteria increased the As release rate from waste rock over time leading to higher aqueous concentrations in molasses treatment reactors. For the preservation, it was found that filtered samples stored at 4 °C without acidification provided the best results for maintaining appropriate As speciation. Overall, using molasses as a carbon source led to increased As solution concentrations which was not the anticipated outcome. Thus, bioremediation of As in mine pit water needs further investigation and optimization.
DegreeMaster of Science (M.Sc.)
DepartmentCivil and Geological Engineering
CommitteeChang, Wonjae; Lindsay, Matt; Abdelrasoul, Amira
Copyright DateMay 2020