Robert Wurm | Badger Meter

| IMAGE 1: A wastewater treatment plant in Central Serbia faced challenges with unreliable, manual water quality testing, prompting the adoption of an advanced monitoring system. (Photo credit: Shutterstock)

The importance of wastewater treatment has risen dramatically in recent times amid increasing concerns over public health and environmental protections. To meet government regulations, treatment facilities have increasingly been overhauled and upgraded to feature complex operational processes involving flow measurement and water quality monitoring systems.

Case Study: Central Serbia Wastewater Treatment Plant

A wastewater treatment plant (WWTP) in Central Serbia faced challenges with unreliable manual testing of water quality parameters, prompting the adoption of an advanced monitoring system.

The activated sludge plant turns leftover sludge into biogas, which is then used to create heat and power for an area populated by 90,000 inhabitants. Previously, wastewater influent was measured at regular intervals through manual, intermittent laboratory tests at the entrance to the plant. However, this method was time-consuming and cost-prohibitive in the long term. With many events and violations occurring within a short time span, it was all too easy for them to go undetected. Operators were increasingly finding that their current systems were unreliable and ineffective, as they provided no real way to predict events and prevent inevitable damage ahead of time.

A solution for monitoring wastewater influent to support smooth, efficient operation—and to verify that any water discharged from the plant into the Morava River met required standards—would help to protect the health of surrounding communities and the local environment.

Combined Flow, Level & Water Quality Monitoring

With an initial objective of improved water quality and flow monitoring at the plant, the basis of the proposal was formed around the continuous online measurement of chemical oxygen demand (COD), total suspended solids (TSS), acidity (pH), conductivity and temperature. These vital parameters would be measured alongside flow level and velocity.

A noncontact radar flow meter was installed to provide continuous measurements of flow level and velocity. Water quality sensors were also installed to monitor the critical parameters of COD, TSS, conductivity, pH and temperature for the project. The sensors all connect via a central data terminal, which transmits the information to the plant’s supervisory control and data acquisition (SCADA)/energy management system (EMS).

With continuous monitoring of vital parameters, the WWTP staff can generate accurate and actionable data in real-time. The system highlights any changes in the condition of the wastewater as they are happening and alerts operators, which allows preventative action to avoid incidents and large-scale damage to be taken immediately.

The measurement of these analytical parameters alongside those of flow, velocity and level provide valuable, actionable data, enabling improved management of the wastewater treatment plant while providing enhanced protection against incidents such as extreme chemical and biological pollution and the buildup of sludge and sand deposits.

After preliminary discussions with the end user, it was recognized that the plant would also benefit from an expanded system that integrated the data processing of other existing networks, such as the aeration systems and pump stations. These additional functionalities, alongside the flow and water quality measurement system, allowed for the creation of an enhanced energy management system that enabled substantial savings on operational costs to be achieved.

Designing a Continuous Wastewater Monitoring System

This challenging installation comprises three main parts: the automatic analyzing station, the main collector flow measurement system and the SCADA/EMS system. The automatic analyzing station was built and installed 2,000 meters from the plant, a distance that provides adequate time to respond to incidents and avoid pollution events. Incorporating both the system for monitoring water quality and an industrial computer featuring a versatile terminal for data acquisition and control, the station is equipped with Internet of Things (IoT) functionality. It is capable of spectral analysis and can control stations and sensors of up to 64 parameters.

The station is responsible for the automatic operation of the water quality sensors, mechanical and compressed air probe cleaning systems and sampling systems. It also integrates signals from the noncontact flow measurement system, located on the main flow collector pipe, and communicates remotely via the data terminal with the SCADA/EMS system housed in the main operator center at the treatment plant. This connectivity enables preventative action and helps safeguard critical system functions, supporting plant optimization and long-term performance.

The automatic analyzing station also houses the water quality monitoring sensors. Mounted within flow cells, the sensors have been adapted for automatic air cleaning, simplifying their operation and maintenance.

The advanced flow meter forms a vital component of the main collector pipe flow measurement system. Installed above the water level, this monitor measures both flow velocity and level to determine the flow rates within the plant. Continuous monitoring is carried out using Doppler technology, meaning the sensors do not have to be submerged, further lessening the need for ongoing maintenance as the threat of sensor fouling and sediment buildup is removed. Data is taken from the monitor and transmitted back to the con::cube within the automatic analyzing station. The enhanced data logging provides plant operators with a clear view of wastewater flow and supports improved plant functionality.

| IMAGE 2: Water quality sensors monitor the critical parameters of COD, TSS, conductivity, pH and temperature. (Images 2-4 courtesy of Badger Meter)

| IMAGE 3: Enhanced data logging and SCADA/EMS system compatibility provides a clear view of wastewater flow and allows for improved plant functionality.

Reducing Pollution Events & Improving Energy Efficiency

Since its installation in July 2021, the system has demonstrated that it can efficiently operate without interruption in extremely challenging conditions, continuously measuring and analyzing key parameters of completely unprepared wastewater. The continuous and accurate data streams have allowed for more effective plant management and enhanced energy efficiency, while the ability to detect events ahead of time and perform preventative action has been vital to the operation of the plant.

With 65 pollution events being avoided within the first six months of installation, it is evident that this installation could be instrumental to the future success of the wastewater treatment plant. The success of this project may influence others in the region, increasing the standards of health for local communities, protecting the flora and fauna of the native environment and improving the water quality of the Morava River for future generations.

| IMAGE 4: A noncontact flow meter can provide continuous measurement of flow level and velocity.

Robert Wurm is director of sales and international business development with Badger Meter. He may be reached at rwurm@badgermeter.com. For more information, visit badgermeter.com.

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Cover Series Wastewater