Brown and Caldwell Home Page
Technical Papers RECENT PAPERS    ALL PAPERS

Brown and Caldwell engineers and scientists are technical and thought leaders in the environmental sector. Meet the people who have been advancing innovation for more than 70 years.
Author      Title/Abstract      


Dissolved Air Flotation as Secondary Clarification
Author: Houston Flippin, Larry Cuomo, and Lynn Petersen
Date: 10/12
WEFTEC 2012, New Orleans, LA, Sept. 29 – Oct. 3, 2012

Dissolved Air Flotation (DAF) units have long been used in the food industry to remove fats, oils and grease (FOG), total suspended solids (TSS) and biochemical oxygen demand (BOD). The effluent from the DAF units has often discharged to a downstream activated sludge treatment facility complete with conventional gravity secondary clarification. The activated sludge from these facilities frequently exhibits filamentous sludge bulking requiring large secondary clarifiers, high return activated sludge pumping rates, and supplemental waste activated sludge (WAS) thickening to reduce sludge disposal volumes. This treatment system can be greatly simplified by simply eliminating the primary DAF and conventional gravity clarification and WAS thickening and replacing it with a more robust activated sludge treatment system with DAF as the secondary clarifier. This system is capable of accommodating slug loading and filamentous sludge bulking while discharging effluent BOD, TSS, FOG, and total phosphorus (TP) within pretreatment compliance. Secondly, these systems are capable of discharging WAS concentrations equivalent to or greater than that achieved with traditional WAS thickening. At the same time, these simplified systems occupy a much smaller footprint. A review of the performance and relative costs for two such facilities operated by the Dean Foods Dairy group are described below.

This library contains published materials for which copyrights may be owned by entities other than Brown and Caldwell, but which are stored for limited uses by BC employees. Technical papers authored by BC employees generally may be printed and shared electronically with clients and prospective clients outside BC. Technical papers cannot be sold, and technical papers shared outside BC must have proper attribution of the original sponsoring organization or conference where the paper was presented. This attribution is embedded in each technical paper file when it is loaded into this library. Published articles from magazines or trade journals which are stored in this library are FOR INTERNAL USE ONLY and SHOULD NOT be distributed to clients or others outside BC, without express permission of the copyright owner. For questions regarding copyrights associated with any document in this library, or questions regarding copyrights in general, contact the Legal Department.