Bolivar is the largest wastewater treatment plant in Adelaide. An average of 135 million litres of household and industrial wastewater enters the Bolivar plant each day. The plant is composed of four parallel primary sedimentation tanks, 4 aeration tanks with a total hydraulic retention time (HRT) of 18 h (including 12 h of aeration and 6 h of no aeration), eight 40 m diameter secondary settling tanks and six stabilisation lagoons.