Sludge process, extended, activated

Under the high-rate conditions, the fluid remains approximately 2 hours in the aeration basin, and the BOD of feed is reduced between 50 and 70%. When maximum conversion is desired, over 95% of the BOD can be removed. This is termed an extended activated sludge process, and the average residence time is at least 18 hours. The conventional conditions are a compromise, with 90% of the BOD being removed and the fluid being detained around 5 hours.34 Table 16-3 gives the design information for these systems. 

The activated sludge process including multiple-stage, extended aeration, the Unox pure oxygen system, aerated ponds, and other variations. 

Figure 4 Flow diagram for treatment process using activated sludge, extended aeration.

An extended aeration activated sludge process is designed to treat 2000 m day of condensate waste generated from a synthetic organic chemical plant. The system is operating at an organic... 

Over the years, the conventional activated sludge process has been modified to improve or to suit a specific operational condition. Some of the more common modifications are extended aeration process, contact... 

Wong and Maroney [49] reported on a pilot plant comparison of PACT and extended aeration (activated sludge) for treating petroleum rehnery wastewater. Results indicated that although both processes performed similarly in COD removal, only the PACT system yielded an effluent meeting the discharge requirements for whole effluent toxicity reduction. Similar results in toxicity reduction have been reported for wastewaters from other industries [50]. 

Various biological processes have been used with good results, including extended aeration/activated sludge, sequential batch reactors, and biofihn reactors. Anaerobic treatment has not been effective because of high sulfate levels. 

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