Carbon, Nitrogen, and Phosphorous Removal, Basics and Overview of Technical Applications

Used water consists largely of organic carbon, either as a solution or particulate matter. Apart from organic compounds, nitrogen and phosphorus also number among the main used water constituents. The overall objective of biological treatment is to reduce these dissolved and particulate biodegradable constituents to an extent that prevents them from inducing a further deterioration in the receiving waters and its communities. This biological treatment is carried out by different groups of microorganisms, but it is bacteria that are primarily responsible for the conversion processes, and depending upon how the biomass exists in the reactor, biological treatment can be divided into suspended and attached growth. Hybrid processes represent a new chapter in biological used water treatment and combine the benefits of both suspended and attached growth processes. Three different types of biochemical processes can occur as used water is treated: carbon, nitrogen, and phosphorus removal. In order to remove these pollutants, various reactor’s configuration and combination of anaerobic, anoxic, and aerobic conditions are required. This chapter deals with these conversion processes and basic removal mechanisms, and process schemes and treatment methods are also described.