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Treatment Technology: Fixed Activated Sludge (FAS) Treatment
This technology utilizes an aerobic fixed film process that is a combination submerged attached growth and activated sludge processes. This system is designed to be installed into a two compartment septic tank, where the first compartment provides solids settling, and the second contains the treatment module. Rigid block-type media is submerged within the treatment module, providing surface area for microbial growth. Aeration and wastewater circulation are supplied by a blower unit that pumps air into the center of the block media. Aerated wastewater comes in contact with the rigid block media where nitrification of wastewater is thought to occur. Denitrification is thought to occur in the anaerobic portion of the unit (distal areas away from the active aeration zone). Wastewater transfer through the system is by hydraulic displacement, so wastewater transfer will occur even if the power to the blower unit is lost. Note that treatment of the effluent relies on the function of the blower unit; if the blower power is lost, effluent discharged from the system will likely be of poor quality.
A treatment train incorporating fixed activated sludge treatment
Wastewater exits the home through a gravity-flow building sewer (A) and enters a two-compartment tank (B). A blower (C) supplies air to the advanced treatment portion of the tank, in the second compartment. The first compartment is a septic/trash compartment where solids settle. The second compartment houses the fixed activated sludge unit. Wastewater moves through the unit by gravity displacement, with processed wastewater flowing into the drainfield pump basin (D). A pump located in the drainfield pump basin doses effluent to a shallow narrow drainfield (E).
 
Treatment performance observed for FAS treatment systems in RI
System
BOD5
TSS
TN
% TN Reduction
Fecal Coliform
CFU
Coming soon....
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For more information on fixed activated sludge treatment:
Web Links: This technology is a proprietary device under the trade name MicroFAST® Wastewater Treatment System, manufactured by Biomicrobics Incorporated. For more information on this treatment technology, see the vendor website at www.biomicrobics.com

 

 

Copyright 2006 URI Water Quality Program