Unformatted text preview: e range of discharge standards. mainly operating results of individual treatment plants. In However, the pure availability of a technology is not by itself Brazil, and also in most developing countries, there are sufﬁcient, because it should be cost-effective, appropriate very few consolidated reports on the existing performance, to the local conditions and affordable. While developed based on an evaluation of operating records of a large countries, in general, have extensive sewerage networks and number of treatment plants. In this context, it is believed a high degree of sewage treatment and industrial wastewater that this study is of great relevance to the wastewater control, most developing countries have inadequate sewerage treatment sector, since it evaluates the actual behaviour systems and simply use watercourses as open sewers. of 166 full-scale wastewater treatment plants in operation doi: 10.2166/washdev.2011.022 38 S. C. Oliveira & M. von Sperling | Performance of wastewater treatment technologies in Brazil, providing information on the performance of six Journal of Water, Sanitation and Hygiene for Development | 01.1 | 2011 Inﬂuence of the operational conditions treatment processes in terms of efﬂuent quality and removal
efﬁciency. Due to the climatic, social and economic diver- The operational conditions were evaluated to verify the sity of the region investigated, the results obtained are existence of a relationship between design and operational likely to be representative for other developing regions. parameters and the performance of the treatment plants. The treatment technologies most widely used in warm Typical design and operational parameters recommended climate regions are evaluated here. The observed results of by the technical literature are listed in Table 1 and show efﬂuent concentrations and removal efﬁciencies of the broad ranges, in view of the diversity of characteristics of constituents BOD (biochemical oxygen demand), COD the inﬂuent and climatic conditions in the region under (chemical oxygen demand), TSS (total suspended solids), study. The hydraulic retention time (HRT) was included in TN (total nitrogen), TP (total phosphorus) and FC (faecal the evaluation of almost all units, not because it is an explicit or thermotolerant coliforms) are compared with the typical design parameter, but because this variable could be calcu- expected performance reported in the literature. The treat- lated for all units and also because it reﬂects in a ment technologies selected for the study are: (i) septic simpliﬁed way loading conditions. Based on these typical tank þ anaerobic ﬁlter (ST þ AF), (ii) facultative pond (FP), ranges, the plants were classiﬁed as underloaded (actual (iii) anaerobic pond followed by facultative pond (AP þ FP), BOD load less than the minimum of the recommended (iv) activated sludge (AS), (v) UASB reactor without post- range), normally or usually loaded (BOD load within the treatment (UASB) and (vi) UASB reactor followed by several range) and overloaded (BOD load higher than the maxi- post-treatments...
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