4.4. SR 03-20-2017 - Laserfiche WebLink

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Table 3.2: Bench -Scale Effluent Chlorination Testing Results Sample UV Chlorine Final UV UVT Percent Transmittance Concentration Transmittance (%) Increase (%) (mg/L Cl) 44.5 0 44.6 0.22% 44.5 2 46.4 4.09/ 44.5 3 47.4 6.12% 44.5 4 48 7.29/ 44.5 6 48.8 8.81% 44.5 8 49.7 10.46% 44.5 10 50.5 11.88% 44.5 14 51.1 12.92% 44.5 18 51.2 13.09% 44.5 24 51.3 13.26% 44.5 30 51.5 13.59% 44.5 50 50.5 11.88/ 44.5 100 47.7 6.71/ From Table 3.2 the sample UV transmittance was approximately 44.5%. The chlorine doses ranged from 2 mg/L to 100 mg/L as chlorine. Initially, the UV transmittance began to increase with each dose of chlorine indicating the chlorine was removing species that were hindering the transmittance. The peak transmittance occurred with a chlorine dose of 30 mg/L at 51.5%. However, with a dose of 50 mg/L of chlorine the UV transmittance dropped to 50.5%. The chlorine dose was doubled to 100 mg/L and another drop in transmittance was observed. This test results show that the chlorine does remove color (or recover transmittance) but only up to a certain level. The leachate color cannot be completely removed by this method. One possible theory is that the chlorine will initially oxidize particles and other substances in the water that hinder the transmittance. With higher chlorine doses, instead of oxidizing the substances, the chlorine will react with them and create new substances that will hinder the transmittance. Leachate can contain many different organic substances that are able to react with chlorine at the higher doses. Based on small-scale bench test at Elk River, an optimum dose of chlorine is 18 to 20 Prepared by: Bolton & Menk, Inc. Results and Discussion Waste Management/Elk River Leachate Pilot Study I T21.109643 Page 14