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1 A LOW-COST, GREEN TECHNOLOGY FOR ACID MINE DRAINAGE TREATMENT USING A WATER TREATMENT BY-PRODUCT: A PRELIMINARY STUDY Louis Ackah 1, Rajesh Guru 1, Meisam Peiravi 1 and Guilherme Cordeiro 1 Faculty Advisers: Manoj Mohanty 1 and Xingmao “Samuel” Ma 2 1 Department of Mining and Mineral Resources, Southern Illinois University 2 Zachry Department of Civil Engineering, Texas A& M University Illinois Mining Institute (IMI) Annual Meeting 8/26/2015 Presented by: Louis Ackah
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OUTLINE Background Study Area Problem Identification Objectives Methodology Preliminary observations Conclusions 2
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3 BACKGROUND Acid mine drainage (AMD) mostly from abandoned mines poses serious environmental and health problems. AMD results when exposed pyrite (FeS2) reacts with air and water. FeS 2 + 6Fe 3+ + 3H 2 O 7Fe 2+ + S 2 O 3 2- + 6H + It is characterized by a low pH-value and high levels of sulfate and metals. Metals are non biodegradable, they accumulate in the environment. Some metals are carcinogenic, mutagenic, teratogenic and endocrine disruptors while others cause neurological and behavioral changes especially in children (Ali et al., 2013).
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4 BACKGROUND (contd) Different physical and chemical methods used for this purpose suffer from serious limitations like: high cost, intensive labor, alteration of soil properties and disturbance of soil native microflora. Over 12,000 miles of rivers and streams, and 285 sq. miles of lakes/reservoirs are adversely impacted by AMD.
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5 STUDY AREA Location: Tab-Simco is an abandoned coal mine located in the Illinois Basin ≈ 5 miles southeast of Carbondale, Illinois, USA. Geology: Located on a dissected, low plateau underlain by coal-bearing Pennsylvanian System. U/G Mining: 1890 to1955. mined – the 8.2 ft thick Murphysboro Coal and the overlying discontinuous 4.9 ft thick Mt. Rorah Coal. Surface Mining: during the 1960’s and 1970’s in a horseshoe-shaped pattern Location and schematic diagram of Tab- simco site bioreactor system.
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6 PROBLEM IDENTIFICATION The old underground workings are partially flooded with seasonal fluctuations Contains 10.6-20.3 million gallons of acidic, metal-laden water (Smith, 2004). AMD water impacted soil of about 9-acre area was devoid of vegetation and covered with acid salts. Sycamore Creek: impacted with acidic water and metal precipitates.
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Water Treatment Residuals( WTR) WTR are any solid, semisolid, or liquid residue generated (as product) during drinking water treatment processes. Challenge: finding an economical and efficient way to get rid of the residual solids that are filtered out. Current practical disposal/reuse options: Direct land application Stabilization Composting or pelletizing Stream discharge* 7 Al based WTR Fe based WTRCa based WTR Potential for environmental remediation adsorbs heavy metals irreversibly. readily available for free of cost
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Physico-chemical Characterization of WTRs 8 Chemical/Physical Property AL- WTR Ca- WTR Fe- WTR pH6.488.858.3 Electrical conductivity (ms/cm)412.0321.3675.5 Particle density (g/cm 3 )1.542.472.32 Sample FeCaPMgTiAlNaKS Percentage % Al-WTR0.580.360.370.070.01>10.000.020.030.65 Ca-WTR0.6133.010.021.350.000.04 <0.010.12 Fe-WTR2.9215.980.051.770.010.630.010.040.05 Sample CuPbZnCdNiCoMnAsCr ppb (µg/kg) Al-WTR46.235.8447.250.0916.653.655283.0069.605.35 Ca-WTR1.380.369.000.180.600.85202.5018.102.00 Fe-WTR18.247.0426.500.1214.605.852638.509.1520.25 Sample SrLaZrBaScCeGaSnY ppb (µg/kg) Al-WTR76.903.603.40163.850.857.4513.250.853.04 Ca-WTR392.800.801.1096.050.451.000.20<0.11.42 Fe-WTR117.307.553.40126.151.7016.551.901.255.34 Heavy metals content of the dried sludge measured using ICP-MS after extraction with Aqua-regia
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9 To investigate the metal immobilization capability of locally generated water treatment residue (WTR) for the treatment of AMD water. OBJECTIVES Optimize phytoremediation models for passive treatment of AMD and AMD impacted soil, and erosion control of the soil.
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METHODOLOGY: Plug Filter Study (Metal adsorption) Batch adsorption tests were performed with various Al, Ca & Fe WTR treatment mixes to evaluate metal adsorption capacities. Continuous flow filter was designed with the WTR as media to treat AMD water. Metal reduction (adsorption capacity) pH increase Hydraulic conductivity 10
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METHODOLOGY: Proposed phytoextraction/immobilization Metal uptake from AMD Water metal concentration change effects of planting density metal translocation in the plant. 11 Erosion and Metal Leaching Control by WTR and Vetiver/pokeweed optimum residuals mix for plant growth erosion control, adsorption and long- term immobilization of metal ions WTR-AMD soil incubation set up before column study. Two hyperaccumulators: Vetiver grass (Vetiveria zizaniodes L.) Poke weed (Phytolaccae americana) highly tolerant to very acidic, alkaline, saline, and sodic soil conditions.
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PRELIMINARY OBSERVATIONS (SOIL) Incubation test results shows significant increase in soil pH and electrical conductivity 12
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PRELIMINARY OBSERVATIONS (contd) From the Batch test it observed that all the WTRs have various degrees of metal adsorption capabilities. 13 Treat- ment Al conc. (ppm) % Removal Fe conc. (ppm) % Removal Mn conc. (ppm) % Removal Al-WTR307.81-71%44.1489.23405.257.3 Fe-WTR498%0100.00650.031.6 Ca-WTR0100%199.76115.587.8 Al:Fe-WTR125.7330%12.6696.91506.346.7 Al:Ca-WTR7.596%0100.00700.026.3 Control179.5 410 950.0 Hydraulic conductivity of the Ca & Fe based WTRs are lower than the Al-based WTR.
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PRELIMINARY OBSERVATIONS (contd) Hydraulic conductivity of the Ca & Fe based WTRs is lower than the Al-based WTR. In a continuous flow test at 2 flow rates, there was observed loss in filtration rate of the media (plugging) at the higher flow rate. This major operational problem is due to the formation of precipitates and coating of available carbonate minerals. 14
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PRELIMINARY OBSERVATIONS (contd) 15 Initial Conc. = 410 mg/l
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PRELIMINARY OBSERVATIONS (contd) 16 Initial Conc. = 179.5 mg/l Initial Conc. = 950 mg/l
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17 PRELIMINARY CONCLUSIONS Soil incubation tests shows WTR neutralizing capabilities. The analysis of WTRs shows they can be valuable material to facilitate re-vegetation of degraded land/soil. The preliminary study shows that this inexpensive and environmentally friendly approach can effectively treat AMD- impacted water in a continuous flow fashion.
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18 Reference Ali, H., Khan, E., & Sajad, M. A. (2013). Phytoremediation of heavy metals—concepts and applications. Chemosphere, 91(7), 869-881. Behum, P. T., Lefticariu, L., Walter, E., & Kiser, R. Passive Treatment of Coal-mine Drainage by a Sulfate-reducing Bioreactor in the Illinois Coal Basin.
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19 THANK YOU
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