Exploring hydropower options at a wastewater treatment plant - a case study

Abstract

In the intensified search for more renewable energy generating opportunities, this study looks at the hydropower potential at the discharge point of a wastewater treatment plant. A comparison of the energy yield is drawn between installing the hydropower scheme at the discharge point of the wastewater treatment plant, against implementing it in the river in which the plant is discharging. The resultant energy potential of the two sites is compared to indicate the maximum possible energy yield. The specific site conditions were obtained, and the calculated flow characteristics are used in conjunction with prior literature to determine suitable turbine options. The obtained results show that the hydropower scheme at the wastewater plant generates more power than the scheme at the river. The Archimedes screw turbine was also found to be the best-suited turbine at the outflow of the wastewater treatment plant. The turbine at the plant generates 7.9 kW and 9.8 kW powers for the low and high-efficiency turbines, respectively, while the waterwheel only produces an average of 4.5 kW. This study proves that a hydropower system can be implemented successfully at a wastewater treatment plant with a head of 1.5 m. Conclusively, the potential energy yield found serves to give authorities and prospective owners early indication if there is merit in hydropower projects. If economically viable turbines are designed, hundreds of wastewater treatment plants can be retrofitted to generate many gigawatt-hours per year.