Study of coagulating/flocculating characteristics of organic polymers extracted from biowaste for water treatment

Abstract

The aim of this research was to evaluate the coagulating/flocculating characteristics of three natural polymers: green plantain peel starch, orange peel pectin and tamarind seed extracts in three solutions (water, sodium chloride and ammonium acetate), for the purification of raw natural water with turbidity of 5,32 NTU. Natural polymers did not present coagulant activity due to the low turbidity of raw natural water. However, they showed flocculant activity in combination with aluminum sulfate. The optimal combinations of aluminum sulfate [mg/L] + natural polymer [mg/L] were: 50+0,2 for starch, 60+0,06 for pectin, 60+0,6 for tamarind extract in water, 60+0,5 for tamarind extract in sodium chloride and 60+0,2 for tamarind extract in ammonium acetate. Removal values of turbidity and color were about 87% and 92%, respectively. Residual sludge exceeded the maximum permissible limits for discharging to the sewer system. In addition, it showed a toxic effect on the mitotic activity of onion roots with an IC50 of 0,5 to 2%.

Keywords

• coagulation/floculation
• floculant aid
• natural polymers
• water purification.