Slow sand filter

High school (ages 12+)
Science & Technology

Name:

Date:

Step 1 · Read the article

Open the article and read it at the level above. Then answer the questions below in your own words.

https://smallwhale.org/articles/slow-sand-filter

Write what each word means, using the article.

Do not copy the article. Write two things you learned, the way you would explain them to a friend.

Answers below are taken from the article’s stored facts, so they match what the student read.

1. What is the operational principle?Biological purification via a self-forming biofilm (schmutzdecke) on a sand substrate
2. What is the design parameters?Depth: 1–2 m; Loading Rate: 200–400 L/m²/hr
3. How does a slow sand filter clean water?Water moves slowly through a sand bed where a biofilm of bacteria, fungi, algae, and protozoa lives. The organisms eat the dirty stuff and trap particles, making the water safe to drink.
4. Why do people use slow sand filters?They provide a simple, low‑energy way to make water safe, especially where electricity or advanced equipment is limited. They also help stop diseases like cholera and typhoid.

Substrate: The material or surface on which an organism lives, grows, or obtains its nourishment.
Schmutzdecke: The biologically active layer of microorganisms that forms on the surface of a slow sand filter.
Potable Water: Water that is safe to drink and suitable for human consumption.