The paper analyses the performance of the wastewater treatment plants considering the influence of the design and operational parameters. Four different treatment technologies have been investigated, comprising the following processes: facultative pond, anaerobic pond + facultative pond, activated sludge, UASB reactors without post treatment. The objective of the research was to verify the influence of the loading conditions, plant's size and the operational quality (indicated by monitoring frequency) on the effluent quality. The results showed that a consistent relationship between performance and design and operational parameters does not exist. The contribution and influence of any variable differs for each plant. This situation may be a result of design, operation or both.
Effluent quality; performance evaluation; wastewater treatment
