The performance achieved by the operation parameters

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Unformatted text preview: ffer from one WWTP to another, and this may be, the expected one. as expected, a result of design, operation or both. It was • The UASB reactors showed good BOD and COD removal also observed that none of the WWTPs that presented efficiencies and a poor performance regarding TSS, FC removal efficiencies above the upper limit reported by and nutrients, in terms of the reference ranges reported the literature were operating within the usual design and in the literature. The performance achieved by the operation parameters. Table 10 | UASB reactors followed by post treatment (UASB þ Operating conditions of the WWTPs with significantly different performances Mean performance above the usual Mean performance below the usual % overloaded % overloaded Technologies Parameter % underloaded % underloaded FP Ls HRT – – – – 0 0 0 0 AP þ FP Ls HRT Lv HRT 0 0 0 0 33 0 33 0 50 0 0 0 0 100 50 50 AS F/M ratio HRT HLR SLR 0 0 33 67 0 100 33 0 33 33 50 50 17 33 17 0 UASB Upflow velocity HRT – – 100 100 0 0 0 0 55 S. C. Oliveira & M. von Sperling | Performance of wastewater treatment technologies POST) was the closest one with the expected values from Journal of Water, Sanitation and Hygiene for Development | 01.1 | 2011 ACKNOWLEDGEMENTS the literature. The authors would like to thank FINEP, FAPEMIG, CNPq, SABESP, COPASA, FEAM, USP and municipalities for Influence of the operational conditions • their support and cooperation during the course of the In general, the influence of the loading conditions research. was very small and scattered in all the treatment processes. • A single variable or a group of variables could not be used to explain the differentiated performances among all the WWTPs. The contribution and influence of each variable seemed to differ from one WWTP to another and, as expected, this is likely to be a combination of multiple design and operational aspects. Final remarks The purpose of the paper was to present a diagnosis of the wastewater treatment reality in a developing country, reflecting actual operating conditions. If this portrays the existing reality, care should be taken in not considering that the expected performance of the treatment technologies will always be within the range obtained. From the literature and from results from some of the plants investigated, the expected performance may be higher than the overall performance achieved. This shows that improvements in the current situation are possible, thus serving as an incentive to designers and plant operators. In view of the results, it is evident that each WWTP should be evaluated individually to justify either good or poor performances, since they result from several factors. The designer and operator are required to have a broad and integrated knowledge of each system, involving not only the implications of the applied hydraulic and organic loads, but also factors not always directly measurable. Specific characteristics of each influent, microbiolog...
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