High Organic Wastewater Monitoring & Process Control

Food and beverage wastewater often contains high concentrations of sugars, starches, proteins and other biodegradable organics. This creates a high COD/BOD load that can fluctuate significantly between production batches.

At a beverage plant in Wuxi, Jiangsu, online monitoring was introduced not only to check wastewater quality, but to use organic-load data as an input for biological process control and internal carbon reuse.

The operating logic was:

High COD Wastewater → Carbon Monitoring → Biological Process Control → Carbon Reuse → Stable Effluent

High COD Wastewater as a Process Variable

At the Wuxi beverage plant, production wastewater contained high concentrations of biodegradable organic matter. The challenge was not simply high COD, but variable organic loading.

When influent conditions change faster than laboratory or manual sampling can capture, aeration, recirculation and carbon dosing can lag behind the actual biological treatment demand.

The project therefore installed online COD monitoring at key points around the equalization and biological treatment stages to continuously track changes in incoming organic load.

APURE identifies COD as an important parameter for describing organic load, while online multiparameter systems can combine COD with parameters such as pH and ammonia nitrogen for process monitoring.

Carbon Monitoring Drives Biological Process Control

The value of the monitoring system comes from turning COD data into operating information.

Online COD measurements indicate how the organic load entering biological treatment is changing. The project combined this information with ammonia nitrogen and pH monitoring, giving operators a more complete basis for adjusting the treatment process.

The control relationship becomes:

COD Load
↓
Organic Carbon Availability
↓
Biological Treatment Status
↓
Aeration + Recirculation + Carbon Adjustment

Ammonia nitrogen monitoring is particularly relevant around nitrification and denitrification processes, while continuous online data can be integrated into process-control systems for alarms and operating adjustments.

From Wastewater Load to Internal Carbon Reuse

The more distinctive part of this project was carbon reuse.

Instead of treating high-COD influent only as a load that had to be removed, real-time COD data helped operators identify when the wastewater itself could provide organic carbon for the biological process.

According to the project record, high-organic wastewater was used as an internal carbon source for denitrification, reducing the need for externally purchased carbon sources such as sodium acetate.

This changes the operating concept from:

High COD → Remove It

to:

Measure COD → Understand Carbon Availability → Use Carbon Where the Process Needs It

The project reported an approximately 20% annual reduction in external carbon-source purchasing costs after implementing this approach.

Project Results: Stable Effluent with Lower Carbon Input

The project record reports that effluent COD and ammonia nitrogen remained consistently within the applicable local discharge requirements during the reported operating period.

More importantly, the monitoring system connected influent conditions directly with biological treatment decisions. Operators could use COD, ammonia nitrogen and pH data to support carbon dosing, aeration and recirculation adjustments instead of relying primarily on delayed sampling results.

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