Featured Online COD, Nutrient & Process Electrodes
Explore our flagship continuous analyzers, digital transmitters, and high-temperature electrochemical sensors fabricated in Shanghai for mission-critical environmental protection and process control.
Online COD / TP / TN / NH₃-N Analyzer
Automated dichromate digestion colorimetry instrument featuring high precision microfluidics, auto-zeroing, and scheduled self-cleaning for discharge outfalls.
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TOC-3042 Online Total Organic Carbon Analyzer
High-temperature catalytic combustion oxidation coupled with NDIR detection, correlating directly to continuous industrial COD and BOD organic loads.
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pH5806 High Temperature pH Sensor
Shanghai Brand certified pH electrode built with polymeric gel electrolyte and pressurized annular junction for severe chemical neutralization and bio-fermentation.
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DOG-208FA High Temperature DO Sensor
Polarographic dissolved oxygen electrode built to endure frequent SIP/CIP sterilization cycles in aerobic reactors and high-temperature waste process streams.
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IOT-485-pH Digital Water Quality Sensor
Smart digital sensor integrating an onboard micro-transmitter. Transmits calibrated digital Modbus signals directly to SCADA/DCS networks without external controllers.
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ZDYG-2088-01QX Online Turbidity / TSS Sensor
Infrared 860nm scattered-light sensor equipped with an automatic mechanical wiping wiper. Eliminates bio-fouling in sewage aeration basins and industrial effluents.
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MPG-6099Plus Multi-Parameter Skid Station
Integrated skid panel providing continuous monitoring of COD, residual chlorine, pH, conductivity, DO, and turbidity with centralized display and data-logging.
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Online Silicate & Phosphate SWAS Analyzer
High-accuracy colorimetric monitor designed for steam and water analysis systems (SWAS) in thermal and nuclear power plants, guarding against scaling and corrosion.
Explore SWAS Solutions →Evolution of Chemical Oxygen Demand (COD) Analysis: From Classical Reflux to UV-Vis Optical Telemetry
Chemical Oxygen Demand remains the foundational parameter globally mandated by the US EPA, EU Water Framework Directive, and China MEP for quantifying organic water pollution. Understanding measurement physics is critical for system selection.
1. Standard Dichromate Digestion (Reflux)
Based on standard ISO 6060 and China HJ 828-2017 / HJ/T 399-2007. Organic compounds are oxidized at 165°C using potassium dichromate in concentrated sulfuric acid with silver sulfate as catalyst and mercury sulfate to mask chloride interference.
- Highest correlation with regulatory standards
- Ideal for official regulatory discharge compliance
- Automated wet microfluidics reduce reagent waste
2. UV-Vis Optical Absorption (Reagentless)
Leverages the Lambert-Beer law measuring absorbance at 254 nm where aromatic rings and double-bonded carbon structures absorb UV light. A reference beam at 530 nm or 860 nm compensates dynamically for turbidity and suspended solids.
- Zero chemical reagents, zero secondary hazardous waste
- Real-time response time (<3 seconds)
- Best for process control, aeration dosing, and stormwater
3. High-Temperature Catalytic TOC Surrogacy
Total Organic Carbon analyzers oxidize carbon to CO₂ at 680°C to 950°C. Non-Dispersive Infrared (NDIR) detectors measure the carbon mass, establishing an empirical COD/TOC algorithmic correlation multiplier for the effluent.
- Complete 100% carbon recovery independent of oxidation kinetics
- High reliability in petrochemical and saline media
- Rapid 3 to 5 minute cycle times
Engineering Specification Comparison: COD Analytical Technologies
A transparent guide to specifying the correct online COD hardware platform based on operational constraints, local environmental permits, and total cost of ownership (TCO).
| Evaluation Parameter | Dichromate Digestion Colorimeter | UV254 Spectral Sensor | High-Temp Combustion (TOC/COD) |
|---|---|---|---|
| Governing Standard | ISO 6060, EPA 410.4, HJ/T 399-2007 | DIN 38404-3, ISO 8466 (Spectral) | EN 1484, EPA 415.1, ISO 8245 |
| Measuring Range | 5.0 to 5,000 mg/L (extendable to 50,000 mg/L) | 0.1 to 1,500 mg/L Equiv. COD | 0.1 to 10,000 mg/L Carbon |
| Analysis Cycle Time | 20 to 35 minutes per sample | Real-time continuous (1–5 seconds) | 3 to 7 minutes batch |
| Chemical Reagent Consumption | Potassium dichromate, sulfuric acid, Ag₂SO₄ | Zero reagents (Optical absorption) | Carrier gas (pure air/O₂) & inorganic acid |
| Chloride Masking Capability | Up to 5,000 mg/L Cl⁻ (Standard); 10,000 mg/L (High) | Immune to dissolved salts/chlorides | Specialized high-salt combustion kits required |
| Maintenance Interval | Monthly reagent replenishment & tube inspection | Quarterly optical window wipe / inspection | Monthly catalyst check & carrier gas refill |
| Ideal Plant Application | Municipal discharge outfalls, EPA monitoring stations | Activated sludge aeration basins, river intake | Refineries, ethylene plants, pharma effluent |
What EPC Contractors & Environmental Engineers Require from Chinese Manufacturers
Global procurement managers face recurring risks: sensor fouling, reagent leakage, false EPA alarms, and lack of cross-platform DCS integration. Here is how BOQU solves them at the factory level.
Chloride Ion Interference Mitigation
High Cl⁻ concentrations compete with organic matter during oxidation, creating severe positive measurement bias. BOQU deploys automated dual-stage mercuric sulfate complexation and calibrated titration routines to isolate genuine organic COD loads up to 10,000 mg/L salinity.
Hydraulic Valve & Micro-Pumping Durability
Peristaltic pump tube degradation causes fluid metering inaccuracy and hazardous acid leaks. BOQU analyzers use chemical-resistant precision syringe metering pumps and high-purity PTFE multi-way pinch valves designed for over 1,500,000 continuous actuation cycles.
Automated Self-Cleaning & Digestion Chamber Flushing
Particulate build-up and fat-oil-grease (FOG) coat colorimetric flow cells, causing baseline drift. Integrated ultrasonic transducer agitation and high-pressure chemical backwashing maintain quartz optical window transmittance without manual disassembly.
Cyber-Physical Industrial SCADA Protocols
Instrumentation must communicate seamlessly with existing plant PLCs. BOQU analyzers provide dual isolated 4-20mA current loops, high-voltage relay alarms, standard RS485 Modbus RTU, and optional 4G/5G MQTT wireless modules for cloud telemetry dashboards.
Turnkey Process & Discharge Solutions for Strategic Industries
From corrosive petrochemical cracking plants to ultra-pure pharmaceutical water systems, BOQU configures complete analytical skid packages engineered for rigorous duty cycles.
Petrochemical & Coal Chemical Plants
Refinery effluents contain refractory hydrocarbons, aromatic amines, and volatile phenolics. BOQU delivers explosion-proof Ex d IIB T4 enclosures with heavy-duty sample conditioning skids including coarse cyclone filtration, sample heating, and oil-skimming separation before digestion.
- Continuous COD & TOC hydrocarbon monitoring
- Automatic sludge and oil purge sequence
Municipal Wastewater Treatment (WWTP)
Optimizing biological aeration basins requires continuous organic load profiling. In-situ optical COD/UV254 probes regulate blowers to slash electrical energy consumption by up to 30%, while wet-chemistry analyzers at the final outfall guarantee regulatory discharge compliance.
- Dynamic closed-loop DO & blower automation
- Simultaneous COD, Total Nitrogen (TN) & Phosphorus (TP)
Pharmaceutical & Fermentation Bioprocess
High-strength organic waste generated from broth harvesting and CIP sanitization carries extreme COD fluctuations. BOQU pairs specialized pH5806 sensors and DOG-208FA probes inside fermentation tanks with external outfall COD analyzers for complete facility oversight.
- 130°C steam sterilizable in-line electrodes
- FDA-compliant wetted materials (PTFE & 316L SS)
Audited Production Capabilities: Shanghai Kangqiao & Lingang Facilities
Unlike trading middlemen, Shanghai BOQU Instrument Co., Ltd. operates two state-of-the-art production bases in Shanghai spanning 4,632 m². All electronics assembly, sensor glass-blowing, firmware compilation, and calibration take place in-house.
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Rigorous International Standards & Comprehensive Export Support
We ensure effortless customs clearance, frictionless installation, and flawless compliance audits anywhere in the world.
Accredited Certifications
Production is audited under ISO 9001:2015 Quality Management and ISO 14001:2015 Environmental Systems. Instruments carry CE conformity marks for electromagnetic compatibility (EMC EN 61326-1) and Low Voltage Directive safety. Our pH5806 holds the prestigious Shanghai Brand certification.
48-Hour Pre-Shipment Burn-In & Aging
Zero out-of-box failures: Every COD analyzer and digital sensor undergoes a rigorous 48-hour continuous burn-in cycle in our temperature-controlled aging laboratory. Optical optics, digestion heaters, and fluidic manifolds are wet-tested with standard solutions before receiving final QA dispatch stamps.
Full OEM & ODM Customization
Distributors and skid builders benefit from private labeling, customized measuring ranges, tailor-made GUI firmware, custom immersion pipe lengths, and specialized flow-through sampling skids tailored to your market's exact regional requirements.
Technology Roadmap: The Next Generation of COD Instrumentation
BOQU R&D is pioneering advancements in micro-spectrometry, edge intelligence, and zero-hazardous-reagent instrumentation to lead the water analysis industry into the Industry 4.0 era.
Edge-AI Predictive Calibration
Machine-learning neural models deployed directly inside transmitter firmware continuously evaluate optical degradation and electrochemical slope decay, predicting exactly when preventative maintenance or reagent replacement is needed before measurement errors occur.
Multi-Wavelength Deep-UV Optical Arrays
Moving beyond single-wavelength 254 nm absorption, new deep-UV LED arrays scan from 200 nm to 400 nm continuously. This enables simultaneous separation of nitrate (NO₃-N), organic COD fractions, and humic substances without using toxic chemical reagents.
Cloud Digital Twin Telemetry
Direct cellular MQTT and LoRaWAN integrations allow remote asset tracking across municipal districts. Water plant operators can access real-time diagnostic curves, trigger automated remote calibration, and export cryptographically secure environmental reports from web browsers.
Frequently Asked Questions by Industrial Buyers & Plant Operators
Direct, engineering-backed answers addressing the most critical technical questions encountered during instrument selection and site integration.
How does an online COD analyzer correlate with standard laboratory titration tests?
BOQU online dichromate digestion analyzers follow the exact oxidation chemistry specified by ISO 6060 and China HJ 828-2017 standards (potassium dichromate digest at 165°C with silver catalyst). Because the chemical mechanism is identical to laboratory titrations, standard correlation factors typically achieve an R² value exceeding 0.98 in stable industrial and municipal wastewater streams.
Can online UV254 optical sensors be used for formal environmental regulatory compliance?
Regulatory authorities in most jurisdictions mandate wet-chemical potassium dichromate reflux for official discharge permit reporting. However, UV254 spectral sensors are widely recognized for real-time biological aeration basin control, early warning intake monitoring, and stormwater diversion. Users can calibrate local correlation curves into BOQU optical transmitters to convert UV254 absorbance directly into equivalent COD units.
How does BOQU handle high chloride ion concentrations in industrial chemical waste?
Chloride concentrations above 1,000 mg/L precipitate silver ions and oxidize dichromate, creating false high COD readings. BOQU wet-chemical analyzers feature an automated multi-range mercury sulfate (HgSO₄) complexation dosing mechanism that suppresses chloride interference up to 5,000 mg/L in standard models and up to 10,000 mg/L in our dedicated high-salinity configurations.
What is the typical reagent consumption and routine maintenance frequency?
With automated microfluidic metering, standard reagent sets (1.5L each of oxidant, catalyst, and zeroing standard) last approximately 45 to 60 days under standard 1-hour testing frequencies. Routine maintenance requires less than 20 minutes monthly to replenish reagents and perform an automated two-point standard calibration check.
What output protocols are supported for plant-wide DCS/SCADA integration?
Every BOQU analyzer is equipped with dual isolated 4-20mA analog current loops (standard linear range and alarm), SPDT mechanical relay switches for high/low alarm triggers and pump control, and standard RS485 Modbus RTU serial connectivity. Optional PROFIBUS DP, HART, and wireless 4G/NB-IoT modules are available upon request.
Are custom OEM/ODM packaging, enclosures, and language firmwares available?
Yes. Because BOQU owns its CNC machining, electronics manufacturing, and software engineering facilities in Shanghai, we routinely provide full OEM private branding, custom stainless steel or FRP weatherproof outdoor enclosures, specialized power configurations (110V/220V AC or 24V DC), and multi-lingual user interfaces including English, Spanish, Russian, and French.
Explore Related High-Temperature Sensors & Process Instruments
Browse our specialized high-temperature bio-fermentation sensors, dual-channel controllers, and industrial concentration monitors designed and produced in Shanghai.
High-Temp Fermentation pH Sensor
Designed specifically for antibiotic and biological broth synthesis, withstanding high-pressure steam sterilization and aggressive media without signal drift.
View Sensor Specs →
High-Temp S8 Connector pH Sensor
Featuring a standard PG13.5 thread and S8/K8 electrical connector, this sensor drops directly into existing industrial European and American bioreactor fittings.
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0–130℃ High-Temperature pH Sensor
Utilizes specialized heat-resistant glass formulations and high-density ceramic diaphragms to prevent poisoned electrolyte in harsh chemical process pipelines.
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High-Temp pH Sensor with Built-in Temp
Integrates high-precision Pt100/Pt1000 resistance temperature elements inside the glass bulb for real-time automatic Nernst temperature slope compensation.
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DCA130 Online pH & EC Dual Controller
Simultaneously measures and displays pH and electrical conductivity on a single backlit controller, saving cabinet footprint in RO desalination skids.
View DCA130 Specs →
pHG-2081Pro Industrial pH Transmitter
Heavy-duty aluminum die-cast housing designed for outdoor installation in wastewater neutralization facilities, with PID dosing pump relay controllers.
Explore pHG-2081Pro →
SJG-2083CS Acid & Alkali Concentration Meter
Toroidal electrodeless sensor monitoring chemical dosing concentrations (HCl, H₂SO₄, NaOH, HNO₃) in aggressive chemical CIP sanitization systems.
Explore SJG-2083CS →
Online Residual Chlorine Analyzer
Constant-voltage amperometric sensor system featuring temperature and pH cross-compensation for municipal drinking water disinfection loops.
Explore Chlorine Meter →