Water may look clear and calm on the surface, but what happens beneath it determines the health of aquatic ecosystems, treatment processes, and overall water quality. One of the most critical yet often overlooked factors is dissolved oxygen (DO).
Dissolved oxygen refers to the amount of oxygen gas present in water. It is essential for aquatic life, biological treatment processes, and the natural balance of water systems. Whether in ponds, lakes, rivers, aquaculture facilities, or wastewater treatment plants, maintaining adequate dissolved oxygen levels is key to sustainable water management.
What Is Dissolved Oxygen?
Dissolved oxygen is oxygen that has mixed into water from the atmosphere or through mechanical and biological processes. Unlike oxygen bubbles you can see, dissolved oxygen exists at a molecular level and is measured in milligrams per litre (mg/L) or parts per million (ppm).
Oxygen enters water in several ways:
- Diffusion from the air at the water surface
- Photosynthesis by aquatic plants and algae
- Mechanical aeration or oxygenation systems
The amount of dissolved oxygen water can hold depends on factors such as temperature, pressure, salinity, and biological activity. Cooler water generally holds more oxygen, while warm, stagnant, or polluted water often has lower DO levels.
Why Dissolved Oxygen Matters
Dissolved oxygen plays a vital role in keeping water systems functional, healthy, and balanced.
Supporting Aquatic Life
Fish, invertebrates, and beneficial microorganisms all rely on dissolved oxygen to survive. When DO levels drop too low, aquatic organisms experience stress, reduced growth, or mortality. Prolonged low oxygen conditions can lead to fish kills and biodiversity loss.
Preventing Anaerobic Conditions
Low dissolved oxygen creates anaerobic environments where harmful bacteria thrive. These conditions often result in foul odours, sludge buildup, blackened sediments, and the release of gases such as hydrogen sulfide and methane.
Improving Water Quality
Adequate oxygen supports aerobic bacteria that naturally break down organic matter. This process helps reduce nutrients, minimise sludge accumulation, and prevent excessive algae growth. Well-oxygenated water is clearer, cleaner, and more stable.
Enhancing Wastewater Treatment
In wastewater treatment, dissolved oxygen is essential for biological processes that remove organic pollutants, ammonia, and nutrients. Insufficient oxygen reduces treatment efficiency and increases operational issues, while stable oxygen levels improve system performance and compliance.
Maintaining Balanced Ecosystems
Healthy dissolved oxygen levels contribute to balanced ecosystems by supporting beneficial microorganisms and preventing dominance by harmful algae or bacteria. This balance is especially important in ponds, lakes, and irrigation systems where water quality directly impacts surrounding environments.
What Happens When Dissolved Oxygen Is Too Low?
Low dissolved oxygen, also known as hypoxia, can cause several serious issues:
- Fish stress or death
- Increased algae blooms
- Strong odours and poor water clarity
- Accumulation of organic waste and sludge
- Reduced efficiency in treatment systems
These problems often reinforce each other, making recovery more difficult without intervention.
How Dissolved Oxygen Can Be Improved
Improving dissolved oxygen levels requires the right approach based on water conditions and system requirements. Common methods include:
- Aeration systems that circulate and oxygenate water
- Destratification to prevent stagnant layers
- Advanced oxygenation technologies that improve gas transfer efficiency
At IGS Water, we focus on practical, energy-efficient solutions that enhance dissolved oxygen without adding complexity or excessive operating costs. Our technologies are designed to improve oxygen distribution, support biological processes, and deliver measurable improvements in water quality across a wide range of applications.
Dissolved Oxygen and Sustainable Water Management
Maintaining optimal dissolved oxygen levels is not just about fixing problems when they arise. It is a proactive step toward long-term water sustainability. Proper oxygen management reduces chemical use, lowers energy consumption, minimises maintenance, and supports healthier ecosystems.
By understanding and managing dissolved oxygen effectively, industries and communities can protect water resources while improving performance and environmental outcomes.
