Abstract

Paper industry produces large volumes of wastewater causing environmental pollution due to con-taining high levels of organic matter. In the present study, native yeasts of one of the paper and cardboard recycling industries wastewater were isolated and identified, and their efficiency in the wastewater bioremediation was investigated. In this experimental study, after sampling, the yeast strains of the wastewater were isolated and identified. After preparing the yeast suspension, exper-iments were performed on the main sample of the wastewater and the modified samples with pH 5, 6, and 7, dilution of 25 and 50, and incubation time of 48 and 96 h. The efficiency of these yeasts in removing chemical oxygen demand (COD) was also investigated. The results showed that this industrial wastewater contains high levels of turbidity and COD. Two types of yeast, including Candida glabrata and Candida albicans, were identified. The optimal pH for C. albicans was 6 and for C. glabrata was 5. According to the results of the experiments, COD removal efficiency by these yeasts was 71 and 81.8, respectively, at incubation time of 96 h and dilution of 25 of the wastewater at optimal pH. It seems that according to the characteristics of these isolated yeast species and their ability to remove COD, they can be considered as an economic and eco-friendly option for the treat-ment of the mentioned industrial wastewater.