[en] This study proposes the application of Eichhornia crassipes roots biomass to remove cobalt and zinc ions from solution, aiming its application to effluent treatment. The efficiency of adsorption and the percent of removal were checked as a function of pH and contact time. The plants, for biomass production, were collected at the Billings reservoir in São Bernardo do Campo, located in the Southeast of São Paulo Metropolitan Region. The biomass obtained was subjected to the chemical activation process by the treatment with HCl 0.1 molL^-1 in order to increase its surface area. The concentrations of cobalt and zinc, present in the adsorbent, before and after the adsorption experiments were determined by the instrumental neutron activation analysis (INAA) technique. Results showed that the pH of the solution must be adjusted after the addition of the biomass. The contact time for maximum removal of both ions is between 20 and 30 min. (author)