Removal of cadmium (Cd) from low quality water by bentonite applied in the soil

Abstract

The present study investigated the removal of cadmium from low quality water by bentonite applied in the soil using with the plants test radish, corn and sugar beet. The experiments were carried out in a greenhouse, with a completely randomized design with four replications. The experimental units were plastic pots with a capacity of 5 kg for beets and radish; and for corn in plastic pots with 14 kg. The soil was mixed with increasing doses of bentonite equivalent to 0; 30; 60 and 90 t ha-1. The sowing was done directly on the pot, leaving two plants per pot after thinning. They have been irrigated with poor quality water with a concentration of 0.2 mg L-1 Cd. Plants of radish, corn and beet were harvested at 30, 60 and 90 days, respectively, separated in shoot and roots and placed in air circulation oven. The data were submitted to analysis of variance. The present study led to demonstrate that application of bentonite in soil irrigated with poor quality water had a significant positive effect on development of radish, corn and beet crops, ie, influenced at 1% probability the dry biomass of roots of radish, corn and beet and the dry biomass of shoot of the corn. Generally the bentonite promoted the retention of cadmium in the soil, evidenced by the reduction of the concentration and/or accumulation of this metal in the shoot and roots of radish, corn and beet. Bentonite favored the reduction of bioaccumulation and translocation factors of cadmium thereby increasing the concentration of this element in soil in relation to the plants and in shoot in relation to root, except of corn.