WTW TresCon COD-3250 Online Chemical Oxygen Demand (CODCr) Analyzer
| Brand | WTW |
|---|---|
| Origin | Germany |
| Model | TresCon COD-3250 |
| Instrument Type | Online Analyzer |
| Measurement Principle | Potassium Dichromate Digestion Method (Online) |
| Wavelength | 610 nm |
| Measurement Range | 20–1500 mg/L (extendable to 5000 mg/L) |
| Accuracy | ±10% of reading for ≥30 mg/L |
| Repeatability | ≤3% |
| Limit of Detection | 5 mg/L |
| Cycle Time | 35 minutes |
| Batch Capacity | 1 sample per cycle |
Overview
The WTW TresCon COD-3250 is a fully automated online chemical oxygen demand (CODCr) analyzer engineered for continuous, unattended monitoring of wastewater and surface water in environmental compliance and process control applications. It implements the standardized potassium dichromate digestion method—recognized by ISO 6060, DIN 38409-H41, and EPA Method 410.4—as a robust, reference-grade analytical platform. In operation, the instrument aspirates sample and reagent under controlled negative pressure, mixes them in a sealed high-temperature reaction chamber (175 °C), and completes complete oxidation of organic matter over a defined digestion period. The resulting colorimetric change—proportional to the COD concentration—is quantified via a precision photometric system operating at 610 nm. This optical measurement is calibrated against NIST-traceable standards and corrected for turbidity interference using dual-beam referencing, ensuring metrological integrity across variable matrix conditions.
Key Features
- True online operation with fully automated sampling, reagent dosing, digestion, cooling, and photometric analysis—no manual intervention required between cycles.
- Negative-pressure aspiration eliminates direct contact between peristaltic pump tubing and aggressive reagents or samples, significantly extending maintenance intervals and reducing consumable costs.
- Integrated thermally stabilized digestion module maintains precise 175 °C temperature control within ±1 °C, critical for reproducible Cr(VI) reduction kinetics and complete organic oxidation.
- High-stability dual-beam optical path with LED light source and matched photodiodes ensures long-term photometric drift <0.5% per month, even under ambient temperature fluctuations.
- Touchscreen HMI with intuitive workflow navigation, multi-language support (EN/DE/FR/ES), and configurable alarm thresholds for out-of-spec events, low reagent level, or system fault.
- Onboard automatic calibration and diagnostic routines—including blank verification, standard check, and valve/pump actuation tests—support GLP-compliant operational validation.
Sample Compatibility & Compliance
The TresCon COD-3250 is validated for use with municipal wastewater, industrial effluents (including textile, food processing, and chemical manufacturing streams), surface water, and influent/effluent channels in WWTPs. Its digestion protocol meets regulatory acceptance criteria under ISO 6060:1989, DIN EN 15922:2012, and China’s HJ 399–2017 standard for CODCr. The system architecture supports audit-ready data integrity: all measurements, calibrations, alarms, and service logs are time-stamped, user-identified, and stored locally with optional encrypted export. When integrated into validated IT infrastructure, it satisfies FDA 21 CFR Part 11 requirements for electronic records and signatures via optional audit trail enablement and role-based access control.
Software & Data Management
Data acquisition and remote supervision are managed through WTW’s proprietary TresCon Control Center software (v3.2+), compatible with Windows-based SCADA environments and Modbus TCP/RTU protocols. Each measurement event generates a structured dataset including raw absorbance values, temperature logs, digestion time stamps, calibration history, and QC flag status. Historical data is exportable in CSV or XML formats compliant with LIMS integration standards (ASTM E1482, ISO/IEC 17025). Optional cloud connectivity enables secure remote diagnostics, firmware updates, and predictive maintenance alerts based on cumulative pump revolutions and reagent consumption trends.
Applications
- Real-time compliance monitoring at discharge points subject to EU Urban Wastewater Treatment Directive (91/271/EEC) or US Clean Water Act NPDES permits.
- Process optimization in activated sludge systems, where rapid COD feedback informs aeration control and nutrient dosing strategies.
- Trend analysis for early detection of upstream contamination events—e.g., accidental chemical spills or sanitary sewer overflows—in combined sewer networks.
- Long-term water quality assessment in river basins and reservoirs, supporting national reporting under UNECE Water Convention frameworks.
- Verification of tertiary treatment efficiency in membrane bioreactor (MBR) and advanced oxidation installations.
FAQ
What regulatory standards does the TresCon COD-3250 comply with?
It conforms to ISO 6060, DIN 38409-H41, EPA Method 410.4, and HJ 399–2017 for CODCr determination.
Can the analyzer operate unattended for extended periods?
Yes—designed for 30-day autonomous operation with standard reagent packs and scheduled self-diagnostics.
Is remote configuration and data retrieval supported?
Yes, via Ethernet-connected TresCon Control Center software with Modbus TCP, OPC UA, or MQTT interface options.
How is calibration traceability maintained?
Using certified potassium hydrogen phthalate (KHP) standards traceable to NIST SRM 1012; onboard calibration verification occurs before each measurement cycle.
What maintenance tasks require operator intervention?
Reagent cartridge replacement, waste bottle emptying, and quarterly optical window cleaning—no routine alignment or lamp replacement needed.
