Lesson Notes By Weeks and Term v5 - Grade 9

Lesson Video

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Performance objectives

• Design a basic solar-powered water purification system.
• Explain the science behind solar disinfection and filtration.
• Identify appropriate materials and tools for a prototype.
• Evaluate the system's potential community impact.

Lesson summary

This week, we dive into the practical application of our technological knowledge through integrated projects. Integrated technology projects are crucial because they mirror real-world problem-solving scenarios. In South Africa, tackling challenges like access to clean water, efficient energy use, and improved communication requires a combination of technological skills. Learning to integrate different technological concepts and skills is vital for future innovators and problem-solvers who can contribute meaningfully to our communities and the nation's development.

Lesson notes

What is an Integrated Technology Project? An integrated technology project combines various technological principles, skills, and knowledge from different areas to create a solution for a specific problem. It requires you to think holistically and apply what you've learned in a practical way. This contrasts with isolated exercises focusing on one skill at a time.

Our Project: Solar-Powered Water Purification System Many rural communities in South Africa lack access to clean and safe drinking water. Waterborne diseases are a significant health concern. Our project aims to provide a simple, affordable, and sustainable solution using solar energy – a resource abundant in South Africa. The system will utilize two primary methods: Solar Water Disinfection (SODIS): This method uses sunlight to kill harmful bacteria and viruses in water. UV-A radiation from the sun damages the DNA of these microorganisms, rendering them harmless.

Filtration: This process removes larger particles and sediments from the water, making it clearer and more aesthetically pleasing.

Components of the System: Water Source: A container to collect raw water (e.g., a bucket, borehole).

Pre-Filter (Sediment Filter): A coarse filter (like cloth or gravel) to remove large debris and sediment.

SODIS Container: A transparent plastic bottle (PET plastic is ideal) filled with pre-filtered water.

Elevated Platform: A structure to elevate the SODIS container to maximize sunlight exposure.

Filtration System: A multi-layer filter with sand, gravel, and charcoal to remove finer particles and improve taste.

Collection Container: A clean container to collect the purified water.

Scientific Principles: Solar Radiation: The sun emits electromagnetic radiation, including UV-A, UV-B, and UV-C. UV-A is the most effective for SODIS because it penetrates deeper into the water. The intensity of solar radiation varies depending on the time of day, season, and location. In South Africa, solar radiation is generally high, making SODIS a viable option.

UV-A Radiation and Microorganisms: UV-A radiation damages the DNA of bacteria, viruses, and protozoa, preventing them from reproducing and causing illness.

Filtration: Filtration relies on physical separation. Different layers of filter media (sand, gravel, charcoal) have varying pore sizes, trapping particles of different sizes.

Sand Filtration: Removes suspended solids and turbidity.

Gravel Filtration: Removes larger particles and provides support for the sand layer.

Charcoal Filtration: Removes odors, tastes, and some chemicals. Charcoal adsorbs these impurities onto its surface.

Materials and Tools: Transparent PET plastic bottles: Recycled bottles are a cost-effective option.

Coarse cloth or gravel: For the pre-filter. Sand, gravel, charcoal: For the filtration system.

Containers: For collecting raw and purified water.

Wooden planks or bricks: For building the elevated platform.

Tools: Scissors, knife, measuring tape, gloves (for handling materials).