Municipal water treatment plants need reliable nitrate data at the denitrification stage to optimize carbon dosing and prevent discharge violations. But traditional grab sampling and lab analysis are too slow to catch rapid process shifts. At a 500,000 m³/d municipal plant in China, operators needed continuous nitrate monitoring at the denitrification tank effluent — and they needed it in an underground facility where access is limited.
The Challenge
Denitrification depends on precise carbon dosing and stable anoxic conditions. The nitrate concentration at the tank effluent tells operators whether the process is performing as designed. Without real-time data, adjustments are based on yesterday’s numbers, not current conditions.
In a fully underground plant, manual sampling is difficult and time-consuming. Reagent-based analyzers add consumable costs and maintenance requirements. The plant needed a monitoring solution that could operate continuously with minimal intervention.
The Solution: Full-Spectrum Sensing
A full-spectrum sensor was installed directly in the denitrification tank effluent channel. The sensor measures nitrate-nitrogen in real time using ultraviolet-visible absorption spectroscopy — no reagents, no sampling, no lag.
| Параметр | Capability |
| Nitrate-nitrogen | Real-time, reagent-free |
| COD/TOC | Same platform, configurable |
| Цвет | Optional |
| Техническое обслуживание | Self-cleaning brush available |
The same optical platform can be configured for COD, TOC, and other parameters, making it a scalable investment for plants with multiple monitoring points.
Real Data from the Site
The chart shows nitrate-nitrogen concentrations over a two-week period, with values ranging from approximately 3 to 8 mg/L. Diurnal fluctuations are visible in the trend, consistent with hydraulic and biological cycles. Operators used this continuous data to adjust carbon dosing in real time — something grab sampling could not support.
Installation & Maintenance
The sensor probe is installed directly in the effluent channel, with the optical path submerged in the process stream. The local control cabinet provides real-time display and data output. Maintenance is minimal: periodic cleaning of the optical window, with self-cleaning brush options available for extended intervals.
Заключение
Real-time nitrate monitoring at the denitrification tank effluent gives operators the data they need to optimize carbon dosing and maintain process stability. Full-spectrum sensing delivers this data without reagents, without sampling lag, and with low maintenance — even in underground facilities where access is limited.
Related applications: nitrate and TOC monitoring in watersheds, COD monitoring in sewage networks.
If you are evaluating online nitrate monitoring for your denitrification process, contact us to discuss your application and see how full-spectrum technology can fit your facility.