Statistical Evaluation of Rapid Biochemical Oxygen Demand Test for Monitoring Municipal Wastewater Quality
The conventional standard methods for measuring wastewater quality include the 5-day biochemical oxygen demand (BOD5) and carbonaceous BOD (CBOD5). This thesis presents an alternative wastewater quality test that requires much less time to achieve valid results. This research addresses the precision and statistical validity of an alternative methodology consisting of a two-phased testing approach: an enhanced total adenosine triphosphate (E-tATP) process and percent confirmatory bacterial reduction (%CBR) process that evaluates the aggressiveness of heterotrophic aerobic bacteria (HAB) communities as a means to determining the overall wastewater quality. Primary influent (PI) and final effluent (FE) samples from two municipal wastewater treatment plants (WWTPs) in Saskatchewan were collected between September and December of 2012 for analysis using the proposed E-tATP and %CBR techniques. Results indicated that the E-tATP and %CBR methods can be completed in between 0.25 to 28 hours, significantly less than the typical 5-day test. The mean values of measured ATP for the E-tATP test ranged from approximately 24 000 to 79 000 pg/ml for PI, and 3 000pg/ml to 19 000 pg/ml for FE. The relative standard deviation (RSD) of the means ranged from 8.5 to 10.3% and 8.1 to 27.1%, for PI and FE, respectively. The analysis of the %CBR data also indicates that bacterial metabolic activity was directly impacted by incubation temperature (tested at 20, 22, and 28°C). Both E-tATP and %CBR results were significantly different among the months of September, November, and December in 2012, thus indicating the test is sensitive to detect the effect from changes in climate during fall and early winter seasons on wastewater. Moreover, analysis of the E-tATP and %CBR methods demonstrated they were statistically repeatable and reliable across all 180 E-tATP and 576 %CBR tests that were performed. The relationship between average values from the 15-minute E-tATP test and average %CBR values resulted in an R2 value of 0.898 based on exponential regression. These results indicate that a more practical approach to monitoring and managing wastewater discharge in a more timely fashion is available to wastewater regulators, managers and operators.
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Faculty of Graduate Studies and Research, University of Regina