Destruction of alkalinity in aerobic biological wastewater treatment

One of the most interesting areas of research in aerobic biological wastewater treatment is the development of relationships that may be used by the design engineer and treatment plant operator in providing for nitrification. The use of a mathematical model in conjunction with biochemical stoichiometric equations is very useful in gaining insight into biological wastewater treatment systems. The commonly accepted value of 7.14 lb of alkalinity as ${\rm CaCO}_{3}$ destroyed/lb of ${\rm NH}_{3}\text{-}{\rm N}$ oxidized is in error. This is primarily because of incorporation of ${\rm NH}_{3}\text{-}{\rm N}$ into heterotrophic biomass. As a result, a smaller quantity of ${\rm NH}_{3}\text{-}{\rm N}$ is available to be oxidized to ${\rm NO}_{3}\text{-}{\rm N}$. Primary factors affecting alkalinity destruction in a nitrifying activated sludge system are the $\theta _{c}$ of operation and the influent wastewater ${\rm BOD}_{4}$:N:P ratio.