Monitoring water quality is essential for maintaining public health and protecting the environment. Among the many indicators used to assess pollution levels, Chemical Oxygen Demand (COD) stands out as one of the most critical parameters. In this article, we’ll explore what COD means, why it matters, and how the ERUN-ST3-J5 Benchtop COD Analyzer provides an efficient and accurate solution for wastewater testing.
Chemical Oxygen Demand (COD) measures the amount of oxygen required to chemically oxidize organic and inorganic matter in water. In simpler terms, it reflects how much oxygen is needed to break down pollutants. The higher the COD value, the more contaminated the water is with organic compounds.
COD is expressed in milligrams per liter (mg/L) and serves as a quick and reliable indicator of the degree of pollution in wastewater.
While COD represents the total oxygen demand for both biodegradable and non-biodegradable substances, Biochemical Oxygen Demand (BOD) measures only the oxygen needed for microbial decomposition. COD testing is faster (taking only a few hours) compared to BOD testing (which takes five days), making COD the preferred method for real-time monitoring and industrial compliance.
For reference:
Clean water: < 30 mg/L COD
Moderately polluted water: 50–150 mg/L COD
Highly polluted water: > 500 mg/L COD
Monitoring COD levels helps ensure compliance with local and international discharge standards. High COD levels indicate excess organic pollutants, which can deplete oxygen in water bodies and harm aquatic ecosystems.
Environmental authorities such as the EPA (U.S. Environmental Protection Agency) and WHO (World Health Organization) have established strict COD limits for industrial and municipal wastewater. Failure to meet these standards can result in heavy fines and reputational damage.
By regularly testing COD, facilities can:
Optimize their treatment processes
Detect system failures early
Prevent the release of harmful substances into the environment
The traditional COD testing method uses potassium dichromate as an oxidizing agent under acidic conditions. The amount of oxygen required to oxidize the sample is determined by measuring the change in dichromate concentration. This method is accurate but involves hazardous chemicals and lengthy digestion.
Modern instruments, like the ERUN-ST3-J5 Benchtop COD Analyzer, adopt sealed catalytic digestion and colorimetric detection. This technique simplifies the process, minimizes reagent exposure, and enhances safety.
The instrument automatically measures absorbance using advanced optics and converts it into COD concentration, ensuring consistent and reliable results.
Several variables can affect the precision of COD measurement:
Sample turbidity and presence of suspended solids
Digestion time and temperature
Reagent quality and handling
Using advanced optoelectronic instruments significantly reduces human error and improves repeatability.
When it comes to accurate and efficient COD testing, ERUN-ST3-J5 stands out as a trusted solution. Developed by Xi’an Erun Environmental Protection Technology Group Co., Ltd., the analyzer integrates sealed catalytic digestion with colorimetric measurement, offering rapid and precise COD readings.
High Measurement Accuracy: Advanced cold light source and narrow-band interference technology ensure precise readings even at low COD concentrations.
Automatic Data Processing: A built-in microcomputer performs intelligent calculations and directly displays COD values in mg/L.
EPA Standard Compliance: The analyzer follows internationally recognized testing methods, ensuring data reliability and regulatory alignment.
The ERUN-ST3-J5 is widely used in:
Environmental monitoring stations
Municipal wastewater treatment plants
Industrial effluent monitoring (chemical, textile, and food industries)
Academic and research laboratories
This versatility makes it a preferred instrument for engineers, environmental scientists, and quality control professionals.
By meeting EPA Standard Methods for COD Testing, ERUN-ST3-J5 guarantees results that are both precise and compliant with international water quality regulations.
The instrument’s automated data processing, intuitive interface, and direct result display help laboratories achieve faster turnaround times and reduce operational costs.
Accurate COD monitoring helps industries better control their wastewater output, thereby minimizing environmental impact and contributing to global sustainability goals.
Unlike conventional COD testers that require multiple manual steps, the ERUN-ST3-J5 Benchtop COD Analyzer offers:
Higher accuracy and repeatability
User-friendly operation with minimal training required
Lower maintenance thanks to robust design and smart diagnostics
Comprehensive after-sales technical support from ERUN’s professional service team
Choosing ERUN not only enhances testing precision but also ensures long-term operational reliability.
COD testing is indispensable for maintaining the balance between industrial development and environmental protection. Understanding what COD in wastewater means and adopting advanced analytical instruments like ERUN-ST3-J5 ensures that every test is accurate, efficient, and compliant.
By integrating innovative optical technology with user-centric design, ERUN continues to empower industries, laboratories, and governments to protect one of our most valuable resources — water.
For more details about ERUN’s water quality analyzers and testing solutions, visit erunwas.com.
