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r~ <br />LJ <br />• <br />u <br />Table 4-I Summary of Analytical Results for Nanofilration Pilot Testing (continued) <br />TOXICITY CHARACTERISTIC LEACHING PROCEDURE RESULTS <br />Test B Precipitate <br />Constituent Result RCRA Limit <br /> (rn~) (mg2) <br />Mercury <0.0001 0.2 <br />Arsenic 0.31 5 <br />Barium 0.43 100 <br />Cadmium <0.0001 1 <br />Chromium 0.059 5 <br />Lead <0.001 5 <br />Selenium <0.001 1 <br />Silver 0.021 5 <br />Precipitation testing of the concentrate streams was also conducted during the pilot testing for <br />nanofiltration. The purposes of the precipitation testing were to identify: (1) the reaction time, <br />(2) the optimum pH, (3) the most effective reagents for precipitation of the concentrate stream, <br />and (4) whether the precipitate passed Toxicity Chazacteristic Leaching Procedure (TCLP). As <br />shown in Table 4-1, lazge reductions in TDS and sulfate were possible with cazefu] control of the <br />lime, reagents, and reaction time. The tests showed a 90 percent reduction in sulfate, 70 percent <br />reduction in TDS, a greater than 99 percent reduction in manganese, and 75 percent reduction in <br />calcium. The precipitate passed TCLP criteria as shown in Table 4-1. One operability issue <br />identified in the precipitation testing was the need to move the precipitate immediately after <br />formation because allowing the precipitate to sit overnight resulted in a sludge that hardened to <br />cement-like texture. <br />4.4.3.3 Above-Ground Bioreactor Bench Scale Testing <br />To determine design parameters for anabove-ground bioreactor, a continuous-flow, bench- scale <br />study was initiated. The study consisted of three sepazate fixed-bed anaerobic column units <br />equipped with a sulfide scrubbing mechanism, effluent recirculation, and gas recirculation loops <br />Battle Mountain Resources. lrtc. <br />p:11001671reportslmarchrptllrl6wtrmngfmarch.doc 51 March 11, 1999 <br />