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Views: 222 Author: Carie Publish Time: 2025-05-07 Origin: Site
Content Menu
● Introduction to Sewage Treatment
● Why Is Sewage Treatment Important?
>> 3. Secondary (Biological) Treatment
>> 5. Tertiary (Advanced) Treatment
● Video: Sewage Treatment Explained
● How Does Sewage Treatment Help the Environment?
● Sewage Treatment Around the World
● Household Practices to Reduce Sewage Pollution
● Sanitation and Disease Prevention
● Careers in Sewage Treatment and Environmental Science
● FAQ
>> 2. Why is sewage treatment necessary?
>> 3. What are the main stages of sewage treatment?
>> 4. How does biological treatment work?
>> 5. What happens to the sludge after treatment?
Sewage treatment is a vital process that removes contaminants from wastewater, making it safe to release back into the environment or reuse. For students in Class 7, understanding sewage treatment means learning about the steps, science, and importance of cleaning the water we use every day. This article will guide you through the basics, stages, and significance of sewage treatment, using simple explanations, diagrams, and videos.
Sewage is the wastewater produced by households, industries, and rainwater runoff. It contains harmful substances like human waste, food scraps, soaps, and chemicals. If released untreated, sewage pollutes water bodies and spreads diseases like cholera and typhoid.
Sewage treatment is the process of removing these harmful substances before the water is returned to rivers, lakes, or reused.
Sewage, also known as wastewater, is a mixture of water and waste materials. It comes from many sources:
- Domestic sewage: Wastewater from homes, including water from toilets, sinks, showers, and washing machines.
- Industrial sewage: Wastewater from factories that may contain chemicals and harmful substances.
- Stormwater runoff: Rainwater that washes dirt, oils, and trash from streets and lands into drains.
Because sewage contains many pollutants, it needs to be treated before it can be safely released into the environment.
- Protects the environment: Untreated sewage pollutes rivers, lakes, and oceans, harming fish, plants, and other wildlife.
- Prevents diseases: Sewage contains harmful bacteria and viruses that cause diseases like cholera, typhoid, dysentery, and hepatitis.
- Conserves water: Treated sewage water can be reused for irrigation, industrial processes, or even drinking after advanced treatment.
- Prevents bad odors and unpleasant sights: Proper treatment reduces foul smells and unsightly waste.
Sewage treatment involves several steps to clean the water effectively. Each step removes different types of pollutants.
Purpose: Remove large objects and grit that can damage equipment or block pipes.
How it works:
- Screens: Large metal bars or mesh screens catch big objects like plastic bags, sticks, rags, and bottles.
- Grit Chambers: These tanks slow down the water flow so heavy particles like sand, gravel, and small stones settle at the bottom.
Purpose: Remove settleable solids and floating materials like oil and grease.
How it works:
- Sewage flows into large tanks called primary clarifiers or sedimentation tanks.
- Solids heavier than water settle at the bottom as sludge.
- Lighter materials like oil and grease float to the surface and are skimmed off.
This process removes about 30-40% of the suspended solids and 25-30% of the organic matter.
Purpose: Remove dissolved and suspended organic matter using microorganisms.
How it works:
- Sewage enters aeration tanks where air is pumped in to provide oxygen.
- Aerobic bacteria and other microorganisms feed on organic waste, breaking it down into harmless substances like carbon dioxide, water, and new bacterial cells.
- The mixture then goes to secondary clarifiers where bacteria settle out as activated sludge. Some sludge is recycled back to keep the bacteria population high, and excess sludge is sent for treatment.
This step removes up to 85-90% of the organic matter.
Purpose: Treat the sludge collected from primary and secondary treatment to reduce volume and make it safe.
How it works:
- Sludge is thickened to remove excess water.
- It undergoes anaerobic digestion, where bacteria break down organic matter without oxygen, producing biogas (mainly methane), which can be used as fuel.
- The remaining sludge is dewatered and dried. It can be used as fertilizer or safely disposed of.
Sludge treatment reduces environmental hazards and recovers energy.
Purpose: Further purify the water to remove remaining nutrients, pathogens, and chemicals.
How it works:
- Filtration: Water passes through sand filters or membranes to remove fine particles.
- Disinfection: Chemicals like chlorine or ozone, or ultraviolet (UV) light, kill remaining bacteria and viruses.
- Nutrient Removal: Processes remove excess nitrogen and phosphorus to prevent algae growth in water bodies.
Tertiary treatment produces high-quality water suitable for reuse or safe discharge.
- Protects aquatic life: Clean water supports fish, plants, and other organisms.
- Prevents eutrophication: Removing nutrients like nitrogen and phosphorus stops excessive algae growth that depletes oxygen in water.
- Reduces greenhouse gases: Proper sludge treatment captures methane for energy use instead of releasing it into the atmosphere.
- Saves water resources: Treated water can be reused for irrigation, industry, or groundwater recharge.
Different countries have different sewage treatment systems depending on their resources and population size.
- Developed countries: Use advanced treatment plants with multiple stages and reuse treated water.
- Developing countries: May have fewer treatment plants; many rural areas rely on septic tanks or simple pit latrines.
- Innovative solutions: Some places use constructed wetlands or natural lagoons to treat sewage using plants and microbes.
You can help reduce sewage pollution by:
- Avoiding flushing non-biodegradable items like plastic, sanitary pads, or medicines.
- Not pouring oils, fats, or chemicals down the drain.
- Using eco-friendly detergents and soaps.
- Conserving water to reduce the volume of sewage produced.
Poor sanitation and untreated sewage cause many health problems:
- Cholera: Caused by bacteria in contaminated water, leading to severe diarrhea.
- Typhoid: Spread through food or water contaminated with sewage.
- Hepatitis A: Viral infection from sewage-contaminated water.
- Dysentery: Intestinal infection causing severe diarrhea.
Proper sewage treatment and sanitation facilities reduce these diseases and improve community health.
If you are interested in protecting the environment and public health, you can consider careers such as:
- Environmental Engineer
- Microbiologist
- Wastewater Treatment Plant Operator
- Environmental Scientist
- Sanitation Specialist
These professionals design, operate, and improve sewage treatment systems to keep our water clean.
Sewage treatment is a crucial process for keeping our water clean and safe. By understanding each stage, following good housekeeping practices, and supporting proper sanitation, we help protect the environment and public health. Clean water is everyone's responsibility! Learning about sewage treatment at a young age helps build awareness and encourages responsible behavior toward water conservation and pollution prevention.
Sewage is wastewater from homes, industries, and rainwater runoff, containing harmful substances like human waste, food scraps, and chemicals.
It prevents water pollution, protects health by stopping the spread of diseases, and allows water to be safely reused or returned to the environment.
The main stages are preliminary (removing large objects), primary (settling solids), secondary (biological treatment), sludge treatment, and tertiary (advanced purification).
Bacteria and microorganisms break down organic waste in the sewage, turning it into harmless substances. This often happens in aeration tanks with pumped-in air.
Sludge is digested by bacteria to produce biogas (used as fuel), and the remaining solid can be dried and used as fertilizer or disposed of safely.
