Efficient Emission Measurement for the New EU Wastewater Directive
Wastewater treatment plants are increasingly in the focus of climate protection, as they emit significant quantities of nitrous oxide (N2O) and methane (CH4). These gases are produced primarily in the biological treatment stage when aeration is not operating at optimum levels.
With the upcoming EU Wastewater Directive, emission monitoring is now becoming a mandatory focus for all operators. What is required now are reliable, traceable measured values and unrestricted data sovereignty over operational data.
This is precisely where the Off-Gas System from Fresenius Umwelttechnik comes in: A turnkey complete solution captures emissions directly at the basin. The system provides meaningful key figures – without any detour through a cloud or subscriptions.
The Complete System of the Gas Dome 300 at a Glance
Five Perfectly Coordinated Components for Outdoor Use
The system is designed as a closed unit for demanding outdoor use directly at the clarification basin. Everything comes preconfigured from a single source – from sampling to the final measured value.
- Floating Hood (Off-Gas Hood): Floats on the basin surface and captures the rising gas over a defined area.
- Gas Analysis System GA320: Reliably measures the relevant greenhouse gases in the configuration for wastewater treatment plants (N2O, CH4, CO2) with integrated humidity compensation.
- Flow Measurement: Captures as an independent device the exact volume flow of the entire off-gas on its way to the analyzer.
- Condensate Separator: Reliably keeps moisture out of the gas path and protects the sensitive measurement technology from failures.
- Outdoor Cabinet: The weatherproof, heated, and temperature-controlled housing accommodates all the technology directly on-site at the basin.
The Floating Hood as the Core Component
Maximum Precision Instead of Distorted Measurement Results
The off-gas hood of the Gas Dome 300 is placed directly on the water surface and held stably in position via ropes or a fixed bridge. A surrounding skirt dips into the water and perfectly seals the measurement chamber laterally.
The decisive advantage: Ambient air cannot distort or artificially dilute the sensitive gas analysis at any time. Unlike edge extraction systems, only the gas that actually emerges from the surface is captured.
Secure Gas Transport to the Measurement System
Reliable Sample Preparation Under Harsh Conditions
A robust hose leads from the floating hood to the analysis system in the outdoor cabinet. Along this path, the entire emerging off-gas flows through the installed flow meter, which precisely captures the volume flow.
From this main flow, the GA320 extracts via a bypass only the partial volume required for the actual measurement. An internal pump draws in the gas and passes it through sample gas filters and condensate separators.
This ensures that a clean, dry gas continuously reaches the analyzer. The emission measurement remains absolutely reliable and low-maintenance even under humid and warm conditions above the basin.
Flow Measurement and Its Real Added Value
Why Concentration Values Alone Are Not Sufficient
Pure concentration data does not answer the critical question: How much greenhouse gas does the basin actually release? A high concentration at low gas flow can mean less emission than a moderate concentration at high gas flow.
Only the combination of measured concentration and volume flow transforms a density value into a true emission indicator. The flow meter transmits this value via an analog signal directly to the GA320.
The system automatically calculates the emission rate from the mass concentration, volume flow, and hood area. The result is output as an area- and time-based value.
The Three Decisive Advantages of the Emission Rate
- Transferability: Based on the defined area, the measurement point can be precisely extrapolated to the entire basin.
- Comparability: Measurement points, basins, and plants can be directly compared over time, independent of hood size.
- Control Relevance: Operators can immediately see whether optimizations to aeration effectively reduce actual climate gases.
Important for operators: The calculation is performed entirely in the GA320 and transmitted directly to the control system (PLC). No additional software or regulatory emission calculator is required.
Your Advantages at a Glance
- Complete System from a Single Source: Perfectly coordinated components from sampling to calculation.
- Representative Measurement Results: Direct capture at the surface without any distortion from ambient air.
- Direct PLC Connection: Emission rates are transmitted to the control system without detours through additional software.
- Full Data Sovereignty: No cloud requirement, no subscription – all sensitive measurement data remains securely in your hands.
- Low-Maintenance Gas Analysis: Calibration-free, self-referencing NDIR measurement method in a robust, heated outdoor cabinet.
Contact us for your individual solution for greenhouse gas monitoring and discover for yourself the advantages of the Fresenius Off-Gas System!
