Laserfiche WebLink
required ratios of limestone and pebble lime for an EPN system to be used as a <br />pretreatment to a sulfate reduction bioreactor system. The EPN system will target pH, <br />aluminum and iron and the SRBR will target zinc and other heavy metals. <br />Methods: <br />Tiger Tunnel MIW was prepared in 8 L batches containing the following chemicals <br />dissolved into de-ionized water: <br />6.972 g of A12(SO4)3 * ~16H2O <br />914.4 mg of CaSO:~ * 1/2 H2O <br />267.2 mg of CuSO4 * SH2O <br />13.82 g of FeSO~ * 7H2O <br />598 mg of MnSO~ * H2O <br />1.09 g of ZnSO~ * 7H2O <br />These compounds were dissolved and mixed in 8 L of deionized H2O and pH was <br />adjusted to 2.3 using ~1 mL of concentrated HZSO~ (using a pH meter to monitor the pH). <br />Experiments were intially designed in batch-type experiments where Synthetic Tiger <br />Tunnel MIW was added to limestone or limestone/pebble lime mixtures. The scale of <br />these experiments consisted of 1500 mL of the synthetic water and 1500 g of <br />limestone or limestone/pebble lime mix such that the water level inside the reaction <br />container was roughly at the same height of the stones. <br />Later, aflow-system was designed using only a constant amount of limestone (3500 g) <br />with synthetic Tiger Tunnel MIW flowed into the reaction vessel at the bottom and then <br />out at top level at the 3500 mL volume level marls (again, keeping the water and stone <br />levels approximately even). Water flowed into this vessel at an average flow rate of 1.82 <br />mL/minute using a peristaltic pump from t = 0 to t = 21 days. <br />The pH and metal analysis of both the starting synthetic MIW, the waters from the batch <br />reactors and the effluent water from the flow-through experiments were analyzed at <br />various time points starting at t=0 to t=21 days. Metals were analyzed using an <br />Inductively Coupled Plasma Atonuc Emission Spectroscopy (ICP-AES) instnunent <br />Results <br />klitial experiments in the batch reactors (non-flow through systems) demonstrated that <br />limestone alone with synthetic Tiger Tunnel MIW took about 0.3-1 days to reach a pH <br />6. However, various nuxtures of limestone and pebble lime (l, 10 and 25% pebble lime) <br />reacted very quicldy and pH went beyond neutral and up to pH = 12. 1% pebble lime to <br />limestone took less than 1 day to reach pH ~ 12 whereas 10 and 25% pebble lime to <br />limestone jumped to pH = 12 almost immediately (Figure 1). The purpose of initially <br />conducting these experiments in a non-flow system was to obtain information of the <br />appropriate basic rock to use for the flow system. Since the pebble lime, even in very <br />Frg~ter~oa EP~-re1x~rt, Jztne ?~, 200<~ 2 <br />