Chlorella

Chlorella is a tiny, single-celled green microalga that lives in water and makes its own food using photosynthesis.

• Why it is green: It contains chlorophyll (the same green pigment found in leaves), which helps it capture sunlight to make food and release oxygen.
• Why people use it as a supplement: Chlorella is rich in proteins, vitamins, and minerals, so it is sometimes dried and sold as tablets or powder.
• How it helps in water purification: When grown in wastewater, chlorella can take up dissolved nutrients (like nitrogen and phosphorus) and can also help reduce some pollutants, making the water cleaner.
• Real-life picture: Think of chlorella as a “mini underwater plant” that both makes oxygen and can act like a natural cleaner by absorbing unwanted substances from water.
• One useful nuance: Chlorella helps in cleaning water best when conditions are right (enough light, suitable temperature, and proper mixing), because it needs to keep photosynthesising to grow and do its job.

Because it supports oxygen production and can help clean water, chlorella is a good example of how microscopic organisms can be useful in everyday life.