Application of ULS-03GP in Liquid Level Monitoring of Sewage Treatment Plant: From "Frequent Inspection" to "Unattended"

March 24, 2026

The regulation pool and sludge pool liquid level monitoring in wastewater treatment plants have long faced challenges such as wet corrosion, foam interference and 24-hour continuous operation. In an intelligent renovation project, a municipal wastewater treatment plant fully adopted ULS-03GP ultrasonic liquid level sensor, replacing the original floating ball switch and pressure liquid level meter, achieving remote monitoring and automated interconnection of liquid level data, and significantly improving operational efficiency.

Project Background
The wastewater treatment plant has a daily treatment capacity of 50,000 tons and a total of 12 liquid level monitoring points covering inlet regulation ponds, biochemical ponds, diversion ponds and sludge concentration ponds. Before the transformation, liquid level detection mainly relied on mechanical floating ball switches and input pressure sensors, and there were the following pain points:

The floating ball switch has been soaked for a long time, the cable is ageing, there are frequent lags, and the error alarm rate is as high as 15%.
The input sensor probe is easily wrapped in sludge and requires manual cleaning every week, and the maintenance work is heavy.
The liquid level signal is only switched, and cannot be continuously monitored for variable frequency interaction with the pump.
ULS-03GP Resolution

1. Contactless installation to completely eliminate the mounting problem
   The sensor is installed on the top of the pool bracket, and the probe emits ultrasonic waves vertically down, without direct contact with sewage and sludge, which completely avoids the problem of sensor pollution and corrosion. After the renovation, the frequency of probe cleaning was reduced to once a quarter, and the operational workload was reduced by 80%.
   Anti-foam algorithm ensures signal stability
   A large amount of foam is often present on the surface of biochemical pools, and traditional ultrasonic sensors are prone to "return wave loss."The adaptive echo analysis algorithm of ULS-03GP can identify the real echo of foam layer and liquid level, and output liquid level data stably when the foam thickness is ≤ 20cm.
2. Lora + Wifi networking to achieve centralized monitoring
   All sensors are connected to the PLC system of the central control room through Lora, and the liquid level data is displayed on the monitor screen in real time. The system automatically controls the pump start and stop and adjusts the frequency according to the level value, enabling the full automatic operation of "low level stop pump, high level open pump, over limit alarm.
3. Weather resistance design adapts to outdoor environment
   The sensor casing has rain- and UV-resistant properties, and it has operated continuously for 12 months under outdoor open-air installation conditions without ageing or sealing failure.
   Project results
   Error alarm rate: reduced from 15% before the renovation to less than 1%
   Cost of manual maintenance: approximately 40 hours of inspection and cleaning work per month
   Energy consumption optimization: Under variable frequency interconnection control, the comprehensive energy consumption of the booster pump is reduced by about 12%.
   System reliability: 12 months of continuous operation without failure
   The head of equipment at the plant responded:“The biggest value of ULS-03GP is that we truly realize "unattended." Now you only need to look at the data in the central control room, the number of field runnings is drastically reduced, and the accuracy of liquid level control is much greater than ever.”
   Application expansion
   Based on the successful experience of this project, the model has been applied to sewage treatment plants and industrial waste water treatment projects around the country. In addition, ULS-03GP also shows good adaptability in chemical storage tank level interlocking, automatic water supply for agricultural irrigation and other scenarios.
   epilogue
   ULS-03GP ultrasonic liquid level sensor with non-contact, maintenance-free, highly reliable features, is helping more and more industrial users to achieve liquid level management of digital and intelligent. To learn more about industry application cases or to apply for field testing, please contact us.