The application of a micro-algal/bacterial biofilter for the detoxification of copper and cadmium metal wastes.

In the present study the potential of a biofilter containing a mixture of dried micro-algal/bacterial biomass for removing heavy metals (Cu(2+), Cd(2+)) from dilute electroplating waste was tested. The biomass was produced in an artificial stream using the effluent of a municipal waste water treatment plant as a nutrient source, with the additional benefit of reducing phosphorus and nitrogen loadings. Baseline batch experiments determined that optimum adsorption for both metals (80-100%) were achieved with the deionized-H(2)O conditioned biomass at initial pH 4.0. Other biosorption variables (contact time, initial metal concentration) were also tested. Biosorption data were fitted successfully by the Langmuir model and results showed a high affinity of the used biomass for both metals (q(max) 18-31 mg metal/g.d.w). Flow-through column experiments containing Ca-alginate/biomass beads showed that metal adsorption depends also on flow-rate and volume of treated waste. Desorption of both metals with weak acids was very successful (95-100%) but the regeneration of the columns was not achieved due to the destabilization of beads.