Effect of Enteromorpha polysaccharides on coagulation performance and kinetics for dye removal

The effect of Enteromorpha polysaccharides (Ep) as a new coagulant aid on coagulation performance and kinetics was investigated for synthetic dye wastewater treatment. Color removal efficiency was used to evaluate coagulation effects and meanwhile zeta potential was measured to analyze coagulation mechanism. Floc growth kinetics and re-growth characteristics were investigated by photometric dispersion analyzer (PDA) in terms of floc growth rate, size, strength and reversibility. Results showed that coagulation aid effect of Ep was notable. When Ep was used in combination with alum coagulants, the color removal could be apparently improved, and the optimal solution pH range was 6.0–8.0 for coagulation efficiency. The growth rate and average size of flocs formed by aluminum sulfate-Ep were larger than those by aluminum sulfate in steady-state after floc growth phase, and meanwhile the distribution of floc size had a wider range. In addition, the former was also stronger and had a better recoverability than the latter.