Predominance of Attached Versus Suspended Growth in a Mixed-Growth, Continuous-Flow Biological Reactor Treating Primary-Treated Petrochemical Wastewater

摘要

In this study, a laboratory-scale continuous-flow, mixed-growth biological treatment process, based on the integrated fixed-film activated sludge (IFAS) process, was configured using granular activated carbon as the attached-growth media. With potential to degrade target organics, the application of this process for treating the petrochemical industry wastewater may provide a flexible, more efficient, and inexpensive replacement for the activated sludge and other biological treatment processes. The laboratory-scale IFAS configuration was experimented to evaluate the process ability to enhance the biodegradation process utilizing both suspended growth and attached growth, to evaluate its ability to remove nitrogen and phosphorous, and to identify conditions of predominance of attached versus suspended growth. Ratios of attached to suspended growth reached 3 at steady-state conditions; the laboratory-scale flow-through column reached a steady-state operation in 1-2 h, promising smaller tank volumes on a large-scale application. The organics' removal rates were found to be sensitive to higher initial concentrations and higher hydraulic loading within the range tested in this work. However, nitrogen and phosphorous removal rates were low, and it was mainly attributed to the low total phosphorous-to-chemical oxygen demand ratio representing the bottleneck for upscaling this process.