Pilot study on the effect of removing anion-surfactant by general coagulation-settlement process

Due to the overseas application of anion-surfactant (LAS) in civil and industrial use, water pollution problem becomes more increasingly serious. It is necessary to study the effect of removing anion-surfactant by general water supply process. The coagulant Al₂(SO₄)₃, PAC, FeCl₃, PFS and non-ion PAM were adopted in the experiment. Results indicated that coagulation could remove about 20–40% of LAS in water, and there was a positive correlation between dosage and elimination effects before the maximum removal effect was reached. However, at different coagulations, the maximum elimination and the corresponding dosage were quite different. When the water quality condition was the same, iron-coagulation was much better in removing turbidity, organisms and LAS than aluminium-coagulation. A correlation between the amount of LAS and organism removed was found in our test, which was much closer than between LAS and turbidity. This indicated most LAS was combined with other organic matters in water. That was to say the removal of LAS and other organic matter was concordant, which was significant to the removal of LAS. Water temperature and pH has much effluence on the wiping off of LAS. Both lower pH and higher temperature are propitious to remove LAS.