Back to: MICROBIOLOGY 400 LEVEL
Welcome to class!
Hello brilliant mind! I’m so glad you’re here again, ready to learn something fascinating and practical. Today, we’re going to look at three key methods used in treating wastewater: the Activated Sludge Process, Trickling Filters, and Lagoons. These methods are used in different parts of Nigeria and the world to clean used water from homes and industries. Just like how we wash dirty clothes in different ways depending on how stained they are, water also needs different treatment processes to become clean and safe again.
Activated Sludge Process, Trickling Filters, And Lagoons
These three methods are part of secondary treatment in wastewater management. They mainly use microbes to break down organic waste in the water. Let’s look at each one in a simple and relatable way.
1. Activated Sludge Process
This is one of the most common methods used in modern sewage treatment plants.
Wastewater is mixed with air (oxygen) in large tanks, which encourages the growth of aerobic bacteria (bacteria that need oxygen).
These bacteria eat the organic waste in the water, turning it into less harmful substances.
After the breakdown, the mixture is sent into a settling tank where the bacteria clump together to form sludge, which settles at the bottom.
The clean water on top is then moved on for further treatment or released safely into the environment.
This process is used in many urban areas in Nigeria where the population is high and the volume of wastewater is large.
2. Trickling Filters
This is a simple and natural-looking method that also uses microbes.
Wastewater is spread over a bed of stones or plastic materials that are covered with a slimy layer of microbes called a biofilm.
As the water trickles over the surface, the microbes in the biofilm feed on the organic matter in the water.
The treated water then drains to the bottom and is collected for further processing or release.
This method is low-cost and easy to manage, making it suitable for small towns or communities with limited resources.
3. Lagoons (Waste Stabilisation Ponds)
Lagoons are large, shallow ponds where wastewater is treated over time with the help of natural sunlight, algae, and microbes.
Wastewater is held in the pond for several days.
Algae produce oxygen through photosynthesis, and aerobic bacteria use the oxygen to break down the waste.
The combination of sunlight, microbes, and time leads to cleaner water.
This method is cheap and eco-friendly and is often found in rural or agricultural areas in Nigeria.
Summary
- These three methods are used in secondary wastewater treatment.
- The Activated Sludge Process uses aerobic bacteria and oxygen in tanks to break down waste.
- The sludge settles, and the clean water is separated.
- Trickling Filters use a bed of stones or plastic covered with biofilm microbes.
- Wastewater trickles over the filter, and microbes remove the organic waste.
- Lagoons or ponds treat water using natural sunlight, algae, and microbes.
- Algae provide oxygen, and bacteria break down the waste over time.
- Lagoons are suitable for rural areas because they are low-cost and natural.
- All three methods help improve water quality and protect the environment.
Evaluation
- How does the activated sludge process clean wastewater?
- What role do algae play in lagoon wastewater treatment?
- Describe one difference between trickling filters and lagoons.
You’ve just gained powerful knowledge about how we use nature and science to keep our water clean and our communities healthy. Keep showing up and learning—you’re building the future, one lesson at a time. Afrilearn is proud of you. See you in the next class!