The German standard ATV-DVWK-A 131 (now superseded by DWA-A 131) provides with secondary clarification, nitrification, and denitrification. It applies to municipal wastewater treatment plants serving >1,000 population equivalents (PE). The standard emphasizes:
[ f_D = \fracD_reqr_D \cdot X_MLSS \cdot \theta ] atv dvwk a 131 epdf top
Sets permitted sludge volume loading rates and determines required tank depths . Associated Tools and Accessibility The German standard ATV-DVWK-A 131 (now superseded by