Biological Nutrient Removal

Wastewater flows to the 1.52 million gallon aeration basin which provides the environment to promote the growth of the microorganisms necessary for treatment of the wastewater. The microorganisms reduce the wastewater's biochemical oxygen demand (BOD) by feeding on the organic material in the wastewater for growth and reproduction. Another group of microorganisms convert the ammonia of the wastewater to nitrates. The dissolved oxygen levels in the basin are closely monitored and controlled by many rotating partially submerged discs that impart oxygen into the wastewater so that the microorganisms grow and increase in number. The alternating oxygen rich and oxygen deficit zones in the aeration basin transform the nitrate produced from the ammonia to nitrogen gas, which is released to the atmosphere. Phosphorus in the wastewater is removed by adding ferric chloride in the wet well which results in an insoluble compound forming in the aeration basin. Having a large aeration basin with a long detention time results in most of the waste sludge stabilization simultaneously occurring in this basin.
WW Pic 5