Monitoring and evaluating the energy consumption of the treatment process at Daugavpils WWTP
Solution to which problem
Daugavpils udens is operating a WWTP, which serves 80 174 PE (according to 2018). About 11 613 m³ of wastewater collected from a combined sewer network are treated daily. Based on the original Soviet style design, the WWTP has been renovated and upgraded. The current treatment process consists of mechanical pre-treatment (screen, aerated grid removal), biological treatment in two lines and sludge dewatering by centrifuges. Phosphorus is removed basically by biological uptake. Chemical removal of phosphorus from wastewater is additional. The nitrification/denitrification process in the biological lines follows a time-based control.
The energy consumption of the total process and of specific units has not been monitored.
Technical conditions
Before the investment was realized, the process control enabled the staff to monitor flows, selected concentrations and setting/configuration of equipment. No information about the energy consumption of the total process and of specific units was available. In case of maintenance works in one of four aeration tanks, which could only be performed in empty tank, the air supply to the other tanks had to be stopped accordingly, since the pipes for air supply were interconnected without any valve.
Implementation
The investment includes installation of 42 energy meters, a server and the evaluation software, enabling ongoing reporting of operation every 10 seconds. Additionally, a valve was added to the pressure air supply, which enables the operation of either line separately in case of maintenance works or extended periods of lower hydraulic loads where capacity of one line would be sufficient.
Result
As a result of the investment, the staff includes the monitored energy consumption to the evaluation of the treatment efficiency. By this, saving potentials will be detected. Measures to decrease the energy consumption are in consideration.