Treatment of the effluent from a kraft bleach plant with white rot fungi Pleurotus sajor caju and Pleurotus ostreatus

The final effluents from pulp and paper industry, even after biological treatment, often contain a plethora of unwanted by-products, which confer them colour and toxic characteristics. The aim of this work was to promote degradation of organic matter and remove colour by contacting fungi Pleurotus sajor caju or P. ostreatus with effluents from kraft pulp mill after treatment by an activated sludge process. Absorbance reduction of 57 and 76 % was observed after 14 days of treatment of final effluent with glucose by P. sajor caju, at 400 and 460 nm, respectively. Lower values of absorbance reduction were observed in final effluent with additives and inoculated with the same species (22 to 29%). Treatment with P. ostreatus was more efficient in the effluent with additives, 38.9 to 43.9% of reduction. Higher growth rate of P. sajor caju was observed in the effluent with glucose. Biological treatment resulted in 65-67% reduction of COD after 14 days revealing no differences for each effluent composition and inoculated species. Profiles of composition of organic compounds obtained by GC-MS showed no significant differences between the two effluents treated with P. sajor caju or P. ostreatus, but longer incubation time reflected higher reduction of organic compounds.