Treatment of pulp mill wastewater by Cryptococcus podzolicus and solar photo-Fenton: A case study

Abstract This study evaluated a combination of biological and physical–chemical processes for pulp mill wastewater (PMW) treatment. Biological tests were performed with various yeasts to find out their capacity for growth at different temperatures in the effluent under study. Of the 8 yeast isolates, Cryptococcus podzolicus (AGG 691) proved to be the most appropriate for the aims pursued. After 32 h of incubation, the AGG 691 monoculture had removed 68% of the chemical oxygen demand (COD) and 27% of total polyphenols (TP). This was followed by evaluation of a physical–chemical polishing step. First, coagulation/flocculation was evaluated. Since this was found to be ineffective, two Advanced Oxidation Processes (AOPs), dark-Fenton and solar photo-Fenton, were then studied. Solar photo-Fenton experiments were performed with 10, 20 and 50 mg/L concentrations of Fe 2+ . Although all the solar photo-Fenton experiments showed over 90% dissolved organic carbon (DOC) removal, the experiment with 10 mg Fe 2+ /L was selected as the best treatment option considering the lowest consume of iron and H 2 O 2 . Treatment with Cr. podzolicus (AGG 691) yeast followed by solar photo-Fenton was able to ensure that pulp mill wastewater discharged into natural waters met legal requirements.