Computer assisted design and flow field analysis of a multi-tube airlift reactor for biological treatment of oily wastewater

The rational design of a bioreactor plays an important role in establishing an efficient biological wastewater treatment process. In this study, a multi-tube parallel airlift reactor (MP-ALR) composed of multiple draft tubes was designed and developed by computational fluid dynamics (CFD), and was applied to oily wastewater treatment. The CFD results showed that the gas holdup and liquid velocity of MP-ALR were higher than those in a traditional airlift reactor (T-ALR), and the flow field distribution of MP-ALR was more uniform. The optimum number of parallel draft tubes was determined to be 3 in the design of a 280 L reactor with a high aspect ratio. The experimental results of using Trichosporon fermentans to treat refined soybean oil wastewater (RSOW) in a 32 L MP-ALR showed that the maximum biomass concentration increased by 2.39 g/L and the chemical oxygen demand (COD) removal was increased by 17.73 % compared with those in T-ALR. The MP-ALR developed in this study not only improves the efficiency of the biological treatment of oily wastewater, but also provides a new idea for the design of bioreactors.