Treatment of Wastewater Containing Carbohydrates using Pichia Saitoi Culture

Treatment of wastewater containing carbohydrates by Pichia saitoi growing on beet molasses was investigated in a well-mixed continuous tank as an alternative to bulking control.The yeast strain that used in this work was isolated from non-alcoholic beverage industrial wastewater, with a view on TOC removal compared with other strains in previous study.In this research the isolated yeast showed high COD and TOC removal at three hydraulic retention times, HRT= ۴۸, ۲۴ and ۱۸ hours.Maximum COD and TOC reductions were obtained at HRT=۴۸ hours, which were ۹۶% and ۸۸%, respectively.The influent COD and TOC were ۲۵۰۰ and ۱۴۸ mg/l, respectively.The pH maintained for synthetic wastewater was about ۹.The changes of pH within the aeration tank at each HRT was monitored.Effects of organic loading rate (OLR) on COD and TOC reduction efficiencies were studied in this work.Aeration rate was between ۰.۲-۰.۲۵ vvm, which was very low in comparison to the other studies.This yeast strain had high settling ability (maximum SVI was observed at ۶۰ ml/g) and also high F/M ratios (maximum of F/M was ۲.۹ kg COD/kg MLSS.day).