A study of influent quality estimation of municipal wastewater treatment plants

Wastewater treatment plants (WWTPs) in Beijing are currently undergoing reconstruction and expansion as part of the upgrading of WWTPs. The analysis of influent quality is important for WWTP design as a basic condition for evaluating the treatment process,. The influent quality of two existing WWTPs in Beijing was investigated using probability theory and mathematical statistics. The measured data values matched well with the standard normal distribution curve, but had a better consistency with the standard log-normal distribution. Therefore, the reference data for influent quality is presented separately according to a different probability guarantee. The results clearly show that the actual influent quality is generally higher than the current design value.