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Amazing And Reliable Insights Gathered From Dissolved Oxygen Sensors

  • 26 September 2023
  • ckearns

By Emily Newton

Dissolved oxygen sensor monitoring is critical to making wastewater plants run smoothly and within regulations. Here are some fascinating things people can learn by looking at data from these devices.

Whether The Current Aeration Is Sufficient

Wastewater treatment plants need appropriate aeration so aerobic bacteria can use the resultant oxygen to break down organic matter. One of the advantages of this method is it relies on the microorganisms in water for pollutant removal. Then, wastewater plant managers can become less reliant on chemicals that can become toxic in inappropriate quantities.

Some aeration systems take up to eight hours to remove contaminants. However, people must also continually monitor the processes and equipment to check the aeration levels. Dissolved oxygen sensors help with that.

Colorado’s Edgemont Ranch is a highly data-driven wastewater treatment facility and employees know oxygen content determines how well bacteria-based pollutant removal methods work. That facility is like many others because it uses blowers to provide the necessary aeration, separate liquids and solids, and suspend bacteria.

At Edgemont Ranch, the dissolved oxygen sensor probes connect to a smartphone app that allows for monitoring precise levels at any time. Additionally, the system automatically starts the blowers once the statistics reach a point warranting it. The blowers used at one of the plant’s basins activate once the levels hit 0.8 parts per million, making the whole setup much more energy efficient1.

The plant’s decision-makers initially invested in their high-tech system after Colorado instituted stricter effluent limits. They committed to spending money on a long-term fix that required substantial upfront costs but will allow the plant to continue operating within regulations.

How Wastewater Treatment Plants Affect Nearby Waterways

Wastewater’s high nutrient content can harm local waterways and ecosystems. When organic matter breaks down in sewage systems, ammonia gets discharged. Besides having directly poisonous effects, the ammonia can deplete oxygen, harming the fish that need it to survive.

A research team from Canada’s University of Waterloo examined what happened when the cities of Waterloo and Kitchener upgraded their wastewater treatment systems. They chose a nitrification system that turns ammonia into other types of nitrogen. Both those locations are along the Grand River, which drains into Lake Erie.

Since excessive nitrogen can negatively impact dissolved oxygen levels, the researchers used sensors to see if the nitrification programs moved things in the other direction. Before changing their systems, the two wastewater plants had ammonia discharges of more than 90 metric tons every month2.

Within a year, the Kitchener plant had reduced its ammonia output by 80%. Part of this research also involved using dissolved oxygen sensor monitoring to learn more about the impact on the area’s fish. Oxygen levels fluctuate during the day — when plants produce oxygen — and the night hours — when oxygen consumption occurs. The researchers relied on dissolved oxygen sensors to study the metabolic balance of organisms producing versus using oxygen.

Before the nitrification efforts started, the data showed the river was most biologically active during the summer. Its nighttime oxygen levels during that season were insufficient to support the ecosystem on 90% of the days studied. However, once nitrification began and the researchers concluded the study, only 6% of the days had oxygen levels that could not sustain the most sensitive aquatic creatures. This research improved the Grand River’s health and showed authorities from the wastewater plants their upgrades paid off to support a more eco-friendly, responsible future.

The Positive Changes Caused By New Investments

As today’s leaders set industrial production goals, they increasingly rely on data-driven best practices3.  Doing so can identify how the facilities fall short of others in the area or highlight instances of above-average performance. Digging into data is also important when executives want to reach broad but measurable goals that will ultimately protect the bottom line.

That was the case at Italy’s Alto Seveso wastewater plant. The facility’s leaders wanted to increase energy efficiency while being mindful of how the operations affected the nearby Seveso River. During dry weather, about 90% of the river’s flow comes from wastewater discharge4. Decision-makers set goals to optimize resource usage and reduce input load variations that cause pollutant peaks. Meeting those milestones required several upgrades, including a dissolved oxygen sensor monitoring system that connects to adaptable submersible mixers to prevent tank sedimentation.

Another benefit of the selected mixers is they can reduce the airflow in specific sections of the vessel to reduce energy consumption. The plant’s previous system had mechanical surface aerators without variable settings that used more energy and had limited oxygen regulation capabilities. The updated blowers cut energy consumption by 40%.

The upgrades collectively caused annual energy savings of 640,000 kilowatt-hours or 20%, compared to the previous system. Although the dissolved oxygen sensors were relatively small parts of an advanced setup, they were vital in providing continuous measurements that affected other aspects of the plant. Then, leaders could compile data that showed them the results of their investments and how much closer they got to achieving their goals.

Progress Toward The Remediation Of Identified Problems

Wastewater treatment plant leaders must research and thoughtfully choose the most appropriate equipment for their needs. For example, UV membrane filter systems typically have 0.01-micron membranes, while nanofiltration systems feature 0.001 pores5. A detailed study can reveal which filtration systems to use in different areas of a plant. Besides finding the best equipment for a productive facility, these decision-makers must remain mindful of how internal processes may affect the surrounding community.

In May 2023, officials from the Michigan Department of Health and Human Services identified a municipal wastewater treatment plant and paper mill as significant contributors to hazardous levels of hydrogen sulfide affecting Kalamazoo’s Northside neighborhoods6.

Part of the proposed remediation plan involved a dissolved oxygen sensor monitoring system to assess the frequency and ranges associated with the facility’s wastewater clarifier. Officials believe the setup will enable a significant drop in hydrogen sulfide levels. Other aspects require installing permanent oxygen injection and wet scrubber control systems. Increased amounts of oxygen will also restrict the hydrogen sulfide formation, decreasing the likelihood it reaches problematic levels.

Once those updates occur, the involved parties must resubmit remediation documentation to authorities for approval. After that, representatives from Michigan’s Department of Environment, Great Lakes and Energy will continually receive data from the plant’s sensors to gauge the progress.

However, outside of this specific case, a dissolved oxygen sensor monitoring system could help leaders become more proactive about issues before regulatory authorities learn of them. Data-logging devices allow facility managers to establish baseline conditions and track deviations. Many modern products give real-time readings, allowing prompt investigations of possible problems.

Dissolved Oxygen Sensor Monitoring: Essential For Wastewater Operations

These real-world examples show why today’s wastewater management professionals must prioritize using dissolved oxygen sensor monitoring equipment in their facilities. These sensors support other systems in a plant, giving users dependable data to shape their decisions and avoid preventable problems.

Making the most of the provided insights is even easier when people take specific steps to increase the information’s accessibility. That may mean setting up a system to send real-time push notifications to smartphones or connecting the dissolved oxygen probes to a cloud-based platform so that people can monitor processes from anywhere.

No matter how leaders choose to depend on dissolved oxygen sensors in their plants, they should always be open to changing processes based on what the data shows. That approach facilitates continuous improvement based on improved visibility.

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