Crude COD characteristics
Dold, P. – Envirosim Associates
(Free)
Characteristics of the influent wastewater have a significant impact on biological phosphorus removal performance, and should be considered in design and operation. A study conducted on crude sewage at the Reading STW demonstrated that the COD fractionation is similar to averages from many studies outside of the U.K. The nitrifier growth rates are favourable; that is important as this essentially sets the STW operating sludge age and the size of a nutrient removal plant. The readily biodegradable COD (RBCOD) fraction is the most important characteristic in determining nutrient removal performance. A higher particulate unbiodegradable
COD fraction increases the required plant volume. If the RBCOD content is low, P removal performance can be supplemented by increasing the size of the anaerobic zone. Typically that reduces nitrogen removal performance.