Reliable open-channel flow measurement in wastewater treatment

In wastewater treatment plants, open-channel flow measurement is essential for process monitoring, reporting and regulatory compliance. By using Micropilot FMR20B radar sensors and FlexView FMA90 control unit for reliable flow calculation, visualization and totalization, operators benefit from stable and traceable flow data, even under demanding conditions such as foam, turbulence, changing weather conditions and varying flow profiles.

The implemented solution provides highly reliable and accurate flow measurement for wastewater applications. 80 GHz radar technology ensures stable level measurement, supporting reliable flow calculation even in the presence of foam, turbulence and changing environmental conditions.

Clear visualization and integrated flow totalizers support transparent reporting and facilitate compliance with regulatory requirements. Reduced maintenance effort, remote access to measurement data and cybersecurity features based on IEC 62443 principles support efficient and secure plant operation. As a result, operators benefit from traceable flow data, minimal downtime and reliable, audit-ready plant operation.

In wastewater treatment plants, inflow and outflow are measured in open channels where flow conditions vary continuously and systems are directly exposed to environmental influences. Outdoor conditions such as rain, wind, intense sunlight, snow, temperature fluctuations, condensation and changing surface conditions can affect conventional measurement technologies.

In addition, typical wastewater influent and effluent conditions can cause foam, turbulence and debris accumulation, depending on operating conditions, particularly during low-flow periods. Further challenges arise from fluctuating flow conditions and backwater effects, requiring reliable conversion of nonlinear level measurements into precise flow values. At the same time, operators must ensure long‑term measurement stability and dependable flow totalization for documentation, reporting and compliance with regulatory requirements.

A simple start to smarter control for wastewater treatment plants can be achieved with a non‑contact, radar‑based flow measurement solution tailored to the site conditions. Micropilot FMR20B continuously measures the water level in the open channel using its focused beam angle. The measurement remains stable even in the presence of foam, turbulence and environmental influences.

Protective accessories, including flooding protection tubes and weather shields for Micropilot FMR20B and an optional weather protection cover for FlexView FMA90, help protect the measurement setup against flooding and condensation, supporting reliable operation throughout the year. The measured level is transmitted to FlexView FMA90, which performs flow calculations using pre-programmed linearization curves, freely configurable linearization tables and predefined flume or weir geometries. While simple flow calculations can be performed directly in the sensor, FlexView FMA90 adds value through centralized visualization, totalization, event logging and data management, making it ideal for advanced monitoring tasks.

FlexView FMA90 enhances the sensors and brings every insight into clear view by visualizing level, flow rate, totalized flow, alarm states and trends directly at the measurement point or via remote access. It converts nonlinear level signals into flow values, continuously totalizes flow volumes and supports data and event logging for traceable process documentation. With support for up to two level inputs, FlexView FMA90 can perform sum, difference and ratio calculations while also enabling backwater detection through an additional level input where required. For example, flow measurements from two open channels can be combined and displayed as a total flow value.

Operators can access all relevant data through the integrated web server and Wi‑Fi interface, reducing the need for manual readings and on‑site intervention. This setup supports reliable documentation, transparent reporting and stable long‑term operation in demanding wastewater applications.