In a sewage treatment plant, there must be the right environment for bacteria and microorganisms. The most essential thing that keeps these tiny helpers alive and working optimally is oxygen—preferably, the amount of oxygen dissolved in the water. This is referred to as dissolved oxygen levels in an STP. It assists operators in knowing how well the treatment process is going and whether any adjustments need to be made. But how is this monitoring done? In this blog, we will discuss How Do You Monitor Dissolved Oxygen Levels In An STP, which measuring equipment is used to measure it, and best practice for monitoring in STPs.
Why Are Dissolved Oxygen Levels Important?
Dissolved oxygen (DO) is the quantity of oxygen gas dissolved in water. In STPs, DO is extremely essential as the aerobic treatment process depends on aerobic bacteria, which need oxygen to break down poisonous organic material in sewage. When oxygen levels fall too low, these bacteria are killed, and the treatment process is slowed or stopped, giving rise to poor-quality water.
The measurement of dissolved oxygen levels in an STP helps operators to:
- Supply aerobic bacteria with adequate oxygen to operate efficiently
- Avoid anaerobic conditions that form odors and toxic gases
- Maintain the overall treatment efficiency and environmental discharge regulations
- Maintaining close monitoring of DO is thus important for the efficient operation of an STP.
Equipment and Techniques to Measure Dissolved Oxygen Levels
There are several routine techniques to monitor dissolved oxygen levels in an STP, each of which possesses its own advantages and typical uses.
1) Electrochemical DO Sensors (Clark-type Electrodes)
One of the more popular and oldest types, the sensor employs the method of measuring the electric current produced by oxygen flow through a membrane. The device is a probe which is inserted directly into water. It has real-time response and is extremely simple to use in the field. But it requires periodic calibration and replacement of the membrane to ensure accuracy.
2) Optical DO Sensors
Optical sensors are more recent and rely on the fluorescence quenching principle. OS have a sensing element whose light intensity is a function of the concentration of oxygen present. It is less affected by water contaminants, require little maintenance, and give stable, fast readings. Optical sensors are increasingly being used in STPs for continuous measurement.
3) Winkler Titration Method
This is an ancient chemical method used mostly in the laboratory. A sample of water is taken from the STP and subjected to reagents, which change color depending on oxygen content. While extremely precise, this method is time consuming and impossible to use for real-time monitoring but useful for standalone verification of sensor outputs.
How is Monitoring Practiced in Reality?
Measuring dissolved oxygen is generally done at some stages during the treatment process, especially in the aeration tanks where oxygen is deliberately introduced to the bacteria.
1) Continuous Monitoring
In the majority of modern STPs, DO sensors are mounted permanently in the aeration tanks. The sensors continuously report the DO levels and send them to a central control system. This allows the operators to react quickly, such as reducing or increasing the airflow to provide the best oxygen levels.
2) Manual Checks
Portable DO meters are also used by operators to perform manual checks with the help of, to double-check sensor readings and verify other plant sections. This provides accuracy and offers confirming information.
3) Data Logging and Analysis
Monitoring data for dissolved oxygen is logged over time, making it feasible to distinguish trends and patterns. This helps to pre-empt trouble, optimize aeration, and improve plant efficiency overall.
Best Practices for Dissolved Oxygen Level Monitoring in an STP
For providing efficient and accurate monitoring of the concentration of dissolved oxygen in an STP, the following should be adopted:
1) Regular Calibration: Sensors must be calibrated regularly as per the guidelines of the manufacturer to guarantee accurate readings.
2) Clean Sensors: Sensors must be cleaned to avoid fouling by algae or sludge that can affect readings.
3) Correct Installation: Sensors must be put in properly mixed areas of aeration tanks to provide representative readings.
4) Backup Verification: Use manual verification at times to confirm sensor precision.
5) Alarm Systems: Issue alarms on low or high DO levels to notify operators immediately of malfunctions.
Implements of these practices enable STPs to regulate oxygen content at an optimal level, offering efficient wastewater treatment.
Conclusion
Monitoring dissolved oxygen levels in an Sewage Treatment Plant is a very essential operation that directly affects the efficiency of wastewater treatment. With correct sensors and methods, operators can keep the oxygen within the limit required, which helps the healthy bacteria to thrive and prevents dangerous conditions. By either continuous electronic sensors or routine manual tests, monitoring dissolved oxygen is a very important aspect of having clean water and saving the environment. Proper monitoring and control of DO allow STPs to operate without any problems, effectively and safely on a daily basis.
Do you need an advice or assistance on selecting the best water and waste water treatment unit? We have solutions for all your problems!
Let us know your problem, our experts will make sure that it goes away.
For an assistance or related query,
Call on +91-9650608473
Or write us at enquiry@netsolwater.com
