Ship emulsified oil
wastewater was used as the research object in this study. The highly efficient
coagulant demulsification degreasing mechanism and
microbubble flotation technology were combined and the effects of
coagulant type and dosage amount on the demulsification of emulsified oil
wastewater were evaluated. The influence of the mixed coagulation effect of pH values, temperature, and hydraulic condition parameters were determined and water intake, air intake, and oil content were regulated. The
coagulant for the demulsification of emulsified oil
wastewater was screened; the dosage was 500 mg L-1, and the removal capacity of the
coagulant was in the following order: polyaluminum
ferric chloride (
PAFC) >
polyaluminum chloride (PAC) > polysilicate
aluminum ferric sulfate (PSAFS) >
alum > Al2(SO4)3 >
polyferric sulfate > FeCl3.
Polyacrylamide (PAM) with added water was used to further reduce the oil content. The
PAFC, PAC, and PSAFS were selected as coagulation-air flotation dynamic test alternative agents. The investment quantities of
PAFC, PSAFS and PAM were 300 mg L-1, 300 mg L-1 and 30 mg L-1, respectively. The stirring time was 5 min, the pH value was 6.5-6.9, the flow rate was 0.25 m3 h-1, the oil content of the emulsified oil
wastewater was 3000-5000 mg L-1 and the effluent oil was stable below 15 ppm. The
microbubble generation device using air flotation effluent was used in the two air flotation treatments to enhance the device efficiency. The air flotation device adopted the structural design of the upper part of the water inlet and the lower part of the micro-air bubble, which can increase the collision probability of the
microbubble and improve the efficiency of oil removal.