Experimental investigation has been made on the removal of phenol from waste water by liquid membrane technique employing both batch and continuous operations. A mathematical modeling developed for a water-in-oil (w/o) emulsion drop has been found in a reasonable correlation with experiments.
The effects of system variables, such as phenol concentration in the feed, surfactant concentration, film thickness of oil phase, concentration of sodium hydroxide, volume ratio of feed to sodium hydroxide solution and mixing intensity, were analyzed.
The appropriate operating conditions, as obtained from bench-scale experiments for the waste water feed with 1,000 ppm phenol, are that the concentration of sodium hydroxide and surfactant is one weight percent respectively and the volume ratio of surfactant solution to aqueous sodium hydroxide solution is unity and that the stirring is made at 200 rpm.
For the continuous operation, the level of phenol concentration can be lowered from 1,000 ppm to below 5 ppm, which is the upper limit in the environmental protection act, by using the emulsion solutions with 1 wt.% of sodium hydroxide for the ten times more volume of waste water and with 0.5 wt.% of sodium hydroxide for the six times more volume of waste water.
The capital cost for the two-stage continuous system handling one hundred and fifty thousand gallons of waste water per day has been estimated and compared with that for the traditional solvent extraction system.
