GLYPHOSATE REMOVAL FROM DRINKING-WATER

Activated-carbon, oxidation, conventional-treatment, filtration, and m embrane studies are conducted to determine which process is best suite d to remove the herbicide glyphosate from potable water. Both bench-sc ale and pilot-scale studies are completed. Computer models are used to evaluate the results. The activated-carbon results show that glyphosa te adsorbs very strongly in distilled water, but has a much lower capa city in Ohio River water. The jar-test studies with an alum coagulant show that as turbidity is removed, so is glyphosate. The majority of t he glyphosate removal occurs as turbidity is reduced below 2 nephelome tric turbidity units (NTUs). Powdered-activated-carbon treatment is in effective. Ultrafiltration membranes and 0.45 mum filters do not remov e glyphosate in Ohio River water even though the effluent turbidity is reduced below 0.2 NTU. The oxidation results indicate that glyphosate is easily destroyed by chlorine and ozone. Chlorine dioxide, permanga nate, and hydrogen peroxide are less successful. These conventional-tr eatment and adsorption results are confirmed by pilot-scale studies.