Efficiency of microbubble production using surfactants for the treatment of oily water by flotation

Abstract

Microbubble flotation is a process for the treatment of oily water that requires attention to the variables of the oil removal process. In the present study, experimental designs were applied to a microbubble generation and measuring unit. The factors selected for optimization of the microbuble production were water flow rate, airflow rate, pH, and surfactant concentration. The response variables were dynamic Sauter diameter (DSD), static Sauter diameter (SSD), and microbubble haze height (MHH). Factor planning (central composite rotational design) was used to determine the behavior of the microbubbles in the absence of surfactant as the collector (fluid dynamic planning) as well as in the presence of the synthetic surfactant sodium dodecyl sulfate (chemical planning) or a microbial surfactant produced by the bacterium Pseudomonas cepacia (biological planning). Motor oil (200mgL−1) was added to the best assay of each type of factor planning. The results indicated that the assays with the chemical surfactant were the best conditions compared with the assays without surfactant and with the biosurfactant. The addition of the oil reduced the Sauter mean diameter of the microbubbles to a minimum of 14μm. Therefore, the 71 assays enhanced microbubble production efficiency, enabling better oily water treatment in flotation systems.