Cadmium removal using Cladophora

This work presents results of a feasibility study for removal of heavy metal contaminants from water using aquatic plants. A local strain of Cladophora was used to remove cadmium from a synthetic wastewater. The algae were grown in a laboratory using natural water under the following conditions: pH controlled between 7.8 and 9.0, 18 hrs of light/day, occasional application of plant fertilizer. Cadmium was added to the water in two modes - one time addition of a large dose of heavy metal (concentration 5 mg Cd⁺²/L), and several small, equal doses (each 1 mg Cd⁺²/L), added everyday. Experiments were replicated to verify reproducibility. In all sets, removal of cadmium (in a range of 8 days) varied from 86% to 96%, based on the residual concentration in the water. Percentage of removal calculated from digestion of biomass closely approximated these values (within 20%). High degrees of removal were observed in the first 48 hours. Concentration factors ranged from 1340 to 16,400. Concentration of cadmium (Cd⁺²) was found to be as high as 1.64% of the dried cellmass. The Relative Growth, RG (Final Fresh Weight/Initial fresh Weight) indicated good growth of plant biomass, albeit constant exposure to cadmium.