Motor oil removal from wastewater by continuous froth flotation

Abstract

Froth flotation is a surfactant-based separation process which is suitable for treating a dilute oily wastewater. The objective of this study was to investigate the effects of certain opreational parameters on the separation performance of continuous froth flotation to remove motor oil water. A branched alcohol propoxylate sulphate, sodium salt (Alfoterra 145-5PO), was used in both the phase behavior and froth flotation studies. The effects of surfactant concentration and NaCl concentration, where the minimum surfactant concentration can form the middle phase in microemulsion systems, or critical microemulsion concentration, were studied. From the microemulsion diagram, the critical microemusion concentration (CuC) was found to be 0.5 wt.% Alfoterra. After that, the continuous froth flotation experiments were performed to investigate the efficiency of motor oil removal from water using Alfoterra 145-5PO. The effects of surfactant concentration, hydraulic retention time and air bubble size distribution on foam characteisticand froth flotation performance were also investigated. The results showed that the system with 0.5 wt.% Alfoterra, 5 wt.% NaCl, and 30 min HRT gave the maximum oil removal (61.5%)