GLYPHOSATE REMOVAL FROM DRINKING-WATER

Activated-carbon, oxidation, conventional-treatment, filtration, and membrane studies are conducted to determine which process is best suited to remove the herbicide glyphosate from potable water. Both bench-scale and pilot-scale studies are completed. Computer models are used to evaluate the results. The activated-carbon results show that glyphosate adsorbs very strongly in distilled water, but has a much lower capacity in Ohio River water. The jar-test studies with an alum coagulant show that as turbidity is removed, so is glyphosate. The majority of the glyphosate removal occurs as turbidity is reduced below 2 nephelometric turbidity units (NTUs). Powdered-activated-carbon treatment is ineffective. Ultrafiltration membranes and 0.45 mum filters do not remove 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, permanganate, and hydrogen peroxide are less successful. These conventional-treatment and adsorption results are confirmed by pilot-scale studies.