[Performance and simulation of intermittent decanted extended aeration treatment plants in a tropical climate]

The paper discusses the design and performance of package sewage treatment plants using the Intermittently Decanted Extended Aeration Process (IDEA-Process) in a tropical climate. This hybrid SBR process has been developed overcome traditional drawbacks associated with the SBR process, such as high Sludge Volume Index, high weir loading rate for decanting, and the need to achieve a better effluent quality, especially in terms of nutrient removal. Three domestic sewage plants in Thailand has been selected for field-testing and results of analyses are presented. The average measured biological removal efficiencies in terms of BOD removal and COD removal are about 95.5% and 90% respectively, and the average total nitrogen removal efficiency is about 90%. A computer model is used to study the performance of IDEA-processes compared to results from laboratory tests. The model experience gained through this research are discussed regarding the limitations of computer models such as ASM 1 (Activated Sludge Model n degrees 1) applied to the IDEA-Process in order to develop a new computer model suitable for design and operation of package treatment plant using IDEA-Process Technology in the future.