Commercial System Design: Organic and Nitrogen Removal

For commercial system design, the organic loading rate is often more critical than the hydraulic.In a biological treatment system, the bacteria in the system with available oxygen first consume the biochemical oxygen demand (BOD5). BOD5 is a measure of the oxygen required by bacteria, chemicals and other organisms to break down organic matter over a five-day period. It is an indicator of the overall strength of the wastewater. If there is additional oxygen available, then nitrification will occur, which is the conversion of ammonium to nitrate. If an appropriate anoxic environment exists post-nitrification, then denitrification will occur. When designing commercial