Biosorption of organochlorine pesticides using fungal biomass

Cladosporium strain AJR(3)18,501 was tested for its ability to sorb the organochlorine pesticide (OCP) pp'-DDT from aqueous media. When pp'-DDT was added to distilled water, ethanol or 1-propanol solutions in excess of its solubility, pp'-DDT was sorbed onto the fungal biomass. Increasing the amount of pp'-DDT in solution by changing the medium composition increased sorbent uptake: pp'-DDT uptake by the fungal biomass was 2.5 times greater in 25% 1-propanol (17 mg of pp'-DDT g(-1) dry weight fungal biomass) than in distilled water. When pp'-DDT was dissolved in 25% 1-propanol (12 mg l(-1)), rapid p,p'-DDT sorption occurred during the first 60 min of incubation. p,p'-DDT in solution was reduced to 2.5 mg l(-1) with the remaining pp'-DDT recovered from the fungal biomass. A number of environmental parameters were tested to determine their effect on pp'-DDT biosorption. As arsenic (As) is prevalent at DDT-contaminated cattle dip sites, its effect on pp'-DDT uptake was determined. The presence of As [As(III) or As(V) up to 50 mg l(-1)] did not inhibit p,p'-DDT uptake and neither As species could be sorbed by the fungal biomass. Changing the pH of the medium from pH 3 to 10 had a small effect on p,p'-DDT sorption at low pH indicating that an ion exchange process is not the major mechanism for pp'-DDT sorption. Other mechanisms such as Van der Waals forces, chemical binding, hydrogen bonding or ligand exchange may be involved in pp'-DDT uptake by Cladosporium strain AJR(3)18,501.