Removal and degradation of glyphosate in water treatment: a review

Glyphosate is a broad spectrum, non-selective herbicide, widely used for the post-emergence control of annual and perennial weeds in a variety of applications. Although of low toxicity, its presence in drinking water is undesirable and can cause drinking water compliance failure in the EU if found at concentrations >0.1 μg L⁻¹. Treatment methods such as ozonation and activated carbon are currently used for pesticide degradation and removal. This article provides a review of the reported efficiency in removal and degradation of glyphosate and aminomethylphosphonic acid (AMPA) by some commonly employed treatment options. Additional experiments have been carried out where knowledge gaps have been identified. Oxidants used in water treatment, particularly Cl₂ and O₃, are highly effective in degrading glyphosate and AMPA. Removal by coagulation and activated carbon is ineffective as a barrier against contamination in drinking water. UV treatment is also ineffective for glyphosate and AMPA degradation but the combination of UV/H₂O₂ provided significant degradation of glyphosate, but not AMPA, under the conditions investigated. UV/TiO2 treatment can degrade significant amounts of glyphosate but the irradiation time needed is long. Removal or degradation by bank filtration, slow sand filtration, ClO₂ and membranes is variable but can provide significant removal under the right conditions.