Wastewater treatment is one of critical issues faced by water utilities,and receives more and more attentions recently.The energy consumption modeling in biochemical wastewater treatment was investigated in the study via a general and robust approach based on Bayesian semi-parametric quantile regression.The dataset was derived from a municipal wastewater treatment plant,where the energy consumption of unit chemical oxygen demand (COD) reduction was the response variable of interest.Via the proposed approach,the comprehensive regression pictures of the energy consumption and truly influencing factors,i.e.,the regression relationships at lower,median and higher energy consumption levels were characterized respectively.Meanwhile,the proposals for energy saving in different cases were also facilitated specifically.First,the lower level of energy consumption was closely associated with the temperature of influent wastewater,and the chroma-rich wastewater also showed helpful in the execution of energy saving.Second,at median energy consumption level,the COD-rich wastewater played a determinative role in the reduction of energy consumption,while the higher quality of treated water led to slightly energy intensive.Third,the higher level of energy consumption was most likely to be attributed to the relatively high temperature of wastewater and total nitrogen (TN)-rich wastewater,and both of the factors were preferably to be avoided to alleviate the burden of energy consumption.The study provided an efficient approach to controlling the energy consumption of wastewater treatment in the perspective of statistical regression modeling and offered valuable suggestions for the future energy saving.