Wastewater treatment plants (WWTPs)
can account for up to 1% of
a country’s energy consumption. Meanwhile, WWTPs have high
energy-saving potential. To achieve this, it is necessary to establish
appropriate energy consumption models for WWTPs. Several recent models
have been developed using logarithmic, exponential, or linear functions.
However, the behavior of WWTPs is non-linear and difficult to fit
with simple functions, particularly for non-numerical variables. Thus,
traditional modeling methods cannot effectively describe the relationship
between water and energy in WWTPs. Therefore, a machine learning method
was adopted in this study to investigate the energy consumption in
WWTPs; a novel energy consumption model with a non-numerical variable
(discharge standard) for WWTPs was developed using the random forest
algorithm. The model can also predict the energy consumption of WWTPs
after upgrading discharge standards. We found that the unit electricity
consumption of WWTPs exhibited an average increase of 17% after the
effluent discharge standard was increased from class I B to class
I A (as per China’s classification). The correlation coefficient
of the model was 0.702. Thus, the developed model can provide a better
understanding of energy efficiency in WWTPs.