waste water management
5 Minutes
Wastewater management for kids: learn how sewage water is treated through four main stages in a treatment plant. An English science lesson.
- How river pollution affects living beings and causes diseases
- Screening and primary stages to remove floating and settled waste
- Using bacteria and chlorine in secondary and tertiary stages
What this lesson teaches
Wastewater management is the process of purifying dirty sewage water from homes and towns through several cleaning stages so it does not pollute rivers and can even become drinkable again. Untreated sewage carries household garbage, factory waste, and harmful substances that spread disease and turn natural waterways black.
The problem of river pollution
Rivers begin in mountain streams and flow toward the sea, providing drinking water, food, and habitats for living beings. When humans dump untreated sewage, factory waste, and plastic trash into them, the water turns black and causes severe diseases. Wastewater treatment plants clean this dirty water before it mixes into nature, protecting human health and river ecosystems.
Screening and primary treatment
- In the screening stage, filters with large holes trap floating items like plastic bottles, plastic covers, and household trash, which a conveyor belt carries away.
- In the primary stage, sewage water sits undisturbed in a tank so that heavy materials such as sand and small stones settle to the bottom.
- Lighter waste, including oil, toilet waste, cut milk packets, and chocolate wrappers, rises to the surface of the tank.
- The waste settled at the bottom and the waste floating on top are both removed before sending the water forward.
Secondary treatment with bacteria
In the secondary stage, the wastewater flows into another tank where microorganisms called bacteria are introduced. Microorganisms are tiny living organisms that are invisible to the naked eye. Just as bacteria use sugar in milk to turn it into curd, these added bacteria feed on invisible, harmful chemicals in the sewage as their food source. As the bacteria feed and multiply, the toxic chemicals in the water decrease until the sewage water becomes clean of chemical waste.
Tertiary treatment and disinfection
- The water cannot be used immediately because it still contains a very high number of living bacteria.
- In the tertiary stage, a filtration process strains the water to filter out these microorganisms.
- A chemical called chlorine is added to the filtered water to kill any remaining bacteria that managed to escape the filter.
- The purified water is then clean enough to be sent safely back into the river or used again for drinking.