A flexible aeration strategy based on the removal of COD and MLSS in treating tomato paste wastewater

The influent chemical oxygen demand (COD) of tomato paste wastewater changes with the quality of the raw material without any evident trend. The required aeration also changes irregularly during treatment. If the actual aeration rate is set at maximum and does not change, the treating cost increases. Thus, an adaptable aeration strategy based on simple data, such as the removal of COD and mixed liquor suspended solids (MLSS), must be established. The plug-flow activated sludge system of Shihezi Tianye Tomato Products Co., Ltd., was used to establish the relationship between the theoretical aeration rates and the removal of COD and MLSS in different regions. The calculation bases of the theoretical aeration rates at different COD loadings were determined. A flexible aeration strategy based on the removal of COD and MLSS was used to analogically calculate and compare the actual aeration patterns from 2010. The proposed method can decrease aeration rate by 8%.