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3 Y i� The 7-day average suspended solids ranged from <5 to 8 mg/L, the 30-day averages ranged from <5 to 6 mg/L and the percent reduction ranged from 96 to,97 percent. As shown in Figure 4, the Clearwater Model CWW450 plant met the requirements of NSF Standard 40 for effluent suspended solids. k . 3.4 pH Over the entire evaluation period, the influent pH ranged from 7.4 to 7.6"(median of 7.5), w e-_ the aeration chamber pH ranged from 7.3 to 7.9 (median of 7.6). 'The effluent pH ranged from 7.5 to 8.1 (median of 7.9) during the evaluation, within the 6 to 9 range required by NSF Standard 40. The pH data for the evaluation are shown in Appendix C. 3.5 Temperature a Influent temperatures over the evaluation period ranged from 11 to 18°C (median of 12°C) while aeration chamber temperatures ranged between 13 and: 20°C (median of 160C). Effluent temperatures ranged between 3 and 19° C (median of I VC). The temperature data are shown in Appendix C. 3.6 Dissolved oxygen Dissolved oxygen (DO) was measured in the aeration chamber and effluent during the evaluation. The aeration chamber DO ranged between 0.6 and 3.9 mg/L (median of 2.0 mg/L), while the effluent DO ranged from 1.3 to 7.1 mg/L (median of 3.7 mg/L). All dissolved oxygen data are shown in Appendix C. 3.7 Color, threshold odor, oily film, foam Three samples of the effluent were analyzed for color, odor, oily film and foam as prescribed in NSF Standard 40. The effluent was acceptable according..to the requirements in NSF Standard 40, with color less than 15 units, non-offensive threshold odor, no visible evidence of oily film and no foam. . 3.8 Noise A reading of the noise level at a distance of 20 feet from the plant was taken while the plant was in operation,using a hand-held decibel meter. The reading, below the 60 dbA required under NSF Standard 40. : .10 Draft Report