Treatment of Dairy Wastewater with Pretreatment Techniques and Sequencing Batch Reactor for the Removal of Pollutants: Kinetics and Optimization

Abstract

In order to remove pollutants like BOD, COD, TKN, TP, TSS, sulphates, chlorides, oil and grease effectively, this study outlines the treatment of dairy effluent by employing the advanced oxidation process (AOP) as pretreatment method with a sequencing batch reactor. It also describes the impact of aeration time and bacterial mass concentration (MLSS) in the sequencing batch reactor for pollutant removal. The high percentage of nutrient contents can be removed by the sequencing batch reactor (SBR), which only needs a single tank for the entire treatment procedure. The pretreatment technique of a combination of ozone and AOP was introduced into the dairy effluent to increase the removal efficiency of pollutants. In this research, the optimal conditions for ozone were a pH of 10, a reaction time of 5 minutes, and an amount of H2O2 of 10 mL/L. The experiments were conducted in the 4 L Plexiglas reactor and the analysis was carried out for different aeration times of 4, 6, 8, 12, 16 and 24 h at the different MLSS concentrations of 2100, 2400, 2900, 3200, 3700 and 4200 mg/L after the addition of ozone and hydrogen peroxide. In this analysis, the higher percent removal of BOD, COD, TKN, TP, TSS, sulphates, chlorides, oil and grease was obtained for the MLSS of 2100 mg/L at the aeration time of 16 h. The percent removal of above pollutants for the above MLSS concentration was in the order of 99.8%, 99.6%, 76.7%, 99%, 99.3%, 34%, 46% and BDL, respectively. The GC-MS analysis was carried out to find the level of contaminants present in the raw and treated water. Further, the sludge analysis was done for the wasted sludge to find its characteristics and its uses. This study suggests that at low MLSS concentrations, a large percentage of pollutants can be removed.