C oliveira m von sperling performance of wastewater

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Unformatted text preview: concentrations and removal efficiency. 49 Figure 6 S. C. Oliveira & M. von Sperling | | Performance of wastewater treatment technologies Journal of Water, Sanitation and Hygiene for Development Relationship among Ls, HRT, flow, monitoring index and effluent BOD concentration and BOD removal efficiency – secondary facultative ponds. | 01.1 | 2011 50 Figure 7 S. C. Oliveira & M. von Sperling | | Performance of wastewater treatment technologies Journal of Water, Sanitation and Hygiene for Development Relationship among Ls, HRT, flow, monitoring index and effluent BOD concentration, BOD removal efficiency – anaerobic ponds. | 01.1 | 2011 51 Figure 8 S. C. Oliveira & M. von Sperling | | Performance of wastewater treatment technologies Journal of Water, Sanitation and Hygiene for Development | 01.1 | 2011 Relationship among F/M, HRT (aeration tank), HLR, SLR (secondary clarifier) and effluent BOD concentration, BOD removal efficiency – activated sludge. Note: The symbol ⊗ represents one WWTP that had a hydraulic loading rate outside the axis scale (HLR ¼ 5 m3 m2 hÀ1). 52 Figure 9 S. C. Oliveira & M. von Sperling | | Performance of wastewater treatment technologies Journal of Water, Sanitation and Hygiene for Development | 01.1 | 2011 Relationship among flow, monitoring index and effluent BOD concentration, BOD removal efficiency – activated sludge. Note: The symbols ⊗ and ⊕ represent WWTPs that have influent flow equal to 194,000 and 605,000 m3 dÀ1, respectively, therefore outside the axis scale. substantially the performance of the aeration tanks, results confirmed by the statistical tests. The same behav- Investigation on the causes of the variability of the performance within the same treatment technology iour was observed in the secondary clarifier, considering the HLR and SLR applied. The statistical tests showed An extensive study was performed for the determination of that the great difference between the influent flows did the WWTPs that presented a performance significantly not influence significantly the plants’ performance, con- different from the average performance achieved by the sidering the effluent quality. The mean and median WWTPs within their process, and for the verification of effluent concentrations of BOD, COD, TSS, TN, TP and possible causes that could justify such behaviour. Statistitests of Kruskal–Wallis FC from the treatment plants operating at overloading cal were not significantly higher than those operating at comparison of mean ranks for all groups were used to followed by multiple usual or underloading conditions. verify the existing difference in the percentage of BOD removal efficiency among the WWTPs of the four treat- UASB reactor ment processes. Table 9 presents the total number of WWTPs in each Figure 10 presents the relationship between effluent BOD treatment technology and the number and percentage of concentration and BOD removal efficiency and the fol- WWTPs that had performances significantly different from lowing variables: upflow velocity (v), hydraulic retention those achieved by the treatment technology, accordi...
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