A novel integrated ozone-SBR-ozone process for treatment of baker’s yeast wastewater

The wastewater which released from fermentation industries containing a high organic matter with a dark color is the major source of soil and aquatic pollution. The aim of this study was to evaluate an integrated ozonation and sequencing batch reactor (SBR) processes for the treatment of molasses wastewater. This study was conducted in three series (pre-ozonation, SBR, and post-ozonation) glass reactor. While pre- and post-ozonation reactors were operated with ozone doses from 0.1 to 1 g O 3 /g COD, and for SBR, hydraulic detention times (HRT) of 12–60 h were used. Different pH from 7.5 to 11 was examined in the process. According to the results, pre-ozonation of baker’s yeast wastewater with optimum operational conditions of ozone dose of 0.6 g O 3 /g COD and pH 10.5, has removed 31.74% and 88.31% COD and color, respectively. In the SBR process, maximum COD removal rate (52%) was achieved during 36 h aeration time. Due to increasing readily biodegradable intermediate compounds in pre-ozonation step, the ratio of the BOD 5 /COD was increased from 0.37 to 0.59 in the next biological reactor. In addition, optimum ozone concentration in post-ozonation step was obtained 0.5 g O 3 /g COD. The overall removal efficiencies of COD and color in whole operational status for the combination process of ozone-SBR-ozone were obtained 80% and 88%, respectively. This process might be suitable for treating high strength baker’s yeast wastewater in terms of COD and color removal.