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Alternating intermittent aeration activated sludge

The intermittent aeration activated sludge process, where aerobic and anoxic phases are created in the same reactor, will be modified for nitrogen control to ensure compliance with stringent nutrient limits in sensitive coastal areas.

The majority of existing activated sludge plants are designed for organic carbon removal. However the effective control of nutrient discharges to sensitive coastal areas that are likely to initiate or enhance eutrophication is now required. For nitrogen control, the Intermittent Aeration Activated Sludge (IAAS) process, where aerobic and anoxic phases are created in the same reactor in an engineered time sequence by simple oxygen supply control, is currently evaluated as one of the best available alternatives. It exhibits distinct advantages over conventional, single stage pre or post denitrification systems, as it eliminates the need for external intermittent aeration. The total cycle time thus includes an aerated time, where nitrification is allowed to proceed with ammonia nitrogen consumption and nitrate nitrogen build up; the opposite takes place during the following anoxic phase characterized by an anoxic time. Consequently, effluent concentrations fluctuate between minimum and maximum levels under cyclic pseudo-steady state conditions determined by the operation parameters of the system. The IAAS process can be modified to Alternating Intermittent Aeration Activated Sludge (AIAAS) process by using spatial sequence besides temporal sequence in aeration to decrease the fluctuation of effluent ammonia and nitrate concentrations. Keywords: activated sludge, nitrogen removal, process design.
Acronym: 
AIAAS
Project ID: 
3 005
Start date: 
25-02-2003
Project Duration: 
35months
Project costs: 
710 000.00€
Technological Area: 
Biotreatment / Compost / Bioconversion
Market Area: 

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