Optimizing dissolved oxygen concentration in a climate changing environment to alleviate energy consumption in the aerobic bioreactor: application of particle swarm optimization algorithm

The conventional activated sludge process, aerobic bioreactor (ASPAB) is globally applied for wastewater purification. The ASPAB yields optimal inorganic and organic matter removal efficiency. However, tons of energy are used up throughout this process owing to the air blowers/pumps that operate non-stop in an effort to maintain dissolved oxygen (DO) concentration in the ASPAB. The objective of this research is to optimize DO concentration to minimize oxygen used in the ASPAB, which will decrease the operation of air blowers/pumps, as a result, less energy is consumed. DO concentration model was optimized using the PSO algorithm. As a result of optimization techniques, a 36.3% difference between the optimized (1.54766 mg/L) and measured (2.43 mg/L) DO concentration was obtained. This resulted in a 47.156% energy consumption decrease between the optimized (0.0288 kWh/m³) and measured (0.0545 kWh/m³). The decrease in energy consumption was realized by applying high wastewater temperature (31 °C) in the ASPAB, which enhanced microbes’ growth (3.8824 g/L), at low airflow supply (2.0953 L/min), and less hydraulic retention time (1.2678 h), without COD concentration effluent violation (46.4564 mg/L) in the ASPAB. In conclusion, the ASPAB should function at 1.54766 mg/L DO concentration, which will result in a reduced amount of energy consumption, without compromising the growth and survival of microbes.