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Degradation Characteristics of Influent Solids and the Effect on Industrial Activated Sludge Design
Author: Thomas R. Steinwinder, T. Houston Flippin and Victor J. Boero
Date: 10/12
WEFTEC 2012, New Orleans, LA, Sept. 29 Oct. 3, 2012

Understanding and correctly accounting for influent volatile suspended solids (VSS) degradation is important for representative modeling and successful design of industrial wastewater treatment plants (WWTPs). The key factors for evaluating the degradation characteristics of influent VSS are the first-order rate coefficient of biodegradable VSS (bVSS) reduction (KP) and the degradable fraction of the influent VSS (fx). From these values the non-biodegradable VSS (nbVSS) concentration can be determined as well as the remaining bVSS at a given sludge age (C). The objective of this study was to develop the Kp and fx values for a variety of industrial wastewaters using a bench-scale test and associated model. The results of the bench-scale testing exhibited a wide range of degradation characteristics indicating the importance of generating wastewater-specific parameters for industrial WWTP design. The Kp values were observed to range from 0.023 day-1 (Landfill Leachate A) to 0.095 day-1 (Municipal wastewater). The fx values were observed to range from 0.65 (Landfill Leachate A) to 0.97 (Municipal wastewater). Using the KP and fx values, the influent VSS contribution to mixed liquor volatile suspended solids (MLVSS) in a hypothetical WWTP was modeled. The results indicated influent VSS fractions of MLVSS in the range of 29 percent for municipal to 63 percent for landfill leachate. This research identifies a simple method for establishing the key values for influent VSS degradation behavior. In addition, the resulting data set provides a comparison of VSS degradation kinetics as well as a resource for other wastewater professionals.