Removal of glyphosate from aqueous environment by adsorption using water industrial residual

This study investigated the glyphosate adsorption by water treatment residual (termed as alum sludge) in dewatered form (DAS) and liquid form (LAS). Batch adsorption tests were carried out with DAS at different pH, particle size and DAS mass. Standard jar tests were conducted with LAS at two different concentrations (3 g/l and 5 g/l) for glyphosate adsorption. Thereafter, the glyphosate-enriched LAS (after adsorption tests) was subjected to sludge conditioning procedure with polymer LT25 as conditioner to explore any possible further glyphosate reduction. The results indicate that alum sludge has the high adsorption capacity of 85.9 mg/g for DAS and 113.6 mg/g for LAS. This demonstrated the potential of the alum sludge to be an efficient and cost-effective adsorbent for glyphosate removal in comparison with other adsorbents, such as soils, humic substances, clay minerals, and layered double hydroxides (LDH). The polymer conditioning of the glyphosate-enriched LAS cannot bring about the further glyphosate reduction in the supernatant of the dewatered LAS. Overall, this study promotes the beneficial reuse of alum sludge in wide range of pollutant control in environmental engineering.