NTA Level 4 • Semester 1 • PST04102

Water Treatment Methods

Disease Control and Prevention • Source Session/Topic 8

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Session 8: Water Treatment Methods

Total Session Time: 60 minutes + 2 hours Assignment

Prerequisites

• None

Learning Task

By the end of this session students are expected to be able to:

• Explain Water Treatment Methods

Resources Needed:

• Flip charts, marker pens, and masking tape

• Black/white board, chalk and whiteboard markers

• Computer and LCD Projector

SESSION OVERVIEW

SESSION CONTENTS

STEP1: Presentation of Session Title and Learning Task (5 minutes)

READ orASK students to read the learning tasks and clarify

ASK students if they have any questions before continuing

STEP 2: Water Treatment Methods (40 minutes)

|Activity: Small Group Discussion ( 20 minutes) |

| |

|DIVIDE students into small manageable groups |

| |

|ASK students to discuss on the following question |

|What are the methods used for treatment of contaminated water? |

| |

|ALLOW students to discuss for 10 minutes |

| |

|ALLOW few groups to present and the rest to add points not mentioned |

| |

|CLARIFY and SUMMARIZE by using the contents below |

The following are common methods for treating contaminated water

(Purification)

• Filtration

• Disinfection

• Boiling

Filtration

• Purification through sand reduces the bacterial content of the water by

85% to 90%

• The two types of filters commonly used in community water supply are:

o Slow sand filter

o Rapid (Pressure) filter

Slow filter

• Requires little operational maintenance skills

• Applicable in rural areas

• Needs attention regularly because it is liable to become a breeding

place for bacteria and water contamination

Home-made sand filter

• Filtration which is done when raw water passes through a fixed depth of

arranged sand medium

• All the suspended matter in water is dropped by the first few top layers

of the sand grain

• The clean water is collected at the bottom of the medium

• It can be used in containers like barrels of steel or concrete or clay

pots

• The home-made sand filter can be used effectively in combination with

chlorination

Disinfection

• It is killing of the organisms causing diseases

o There are different methods used to disinfect water supplies, e.g.

chlorination, silver treatment, ultra-violet radiation

Water Chlorination

• It is the final safe guard of the quality of water

o The Chlorine should be applied in the water system in such a way that

good mixing of the chlorine with water is ensured

Boiling

• Simplest way to treat a small quantity of water for at least 20 minutes

• This will kill the organism and render the water harmless

• Boiled water is tasteless but it is a safe rule to follow that all

drinking water should be boiled to disinfect it

STEP 6: Key Points (5minutes)

• Water purification can be done by boiling, disinfection and filtration

• A properly constructed and carefully maintained sand filter can remove

most of the substances that cause turbidity and odour

• It is important to prevent water from contamination

STEP 7: Evaluation (5 minutes)

• What are the methods of treating contaminated water?

• Why is it important to treat contaminated water?

STEP 8: Assignment (5 minutes)

|Activity: Take Home Assignment (10 minutes) |

| |

|DIVIDE individual assignment |

| |

|ASK the students to work individually on the following Assignment |

|Prepare a list of common methods used to treat water in their |

|household. |

| |

|ALLOCATE time for students to do the assignments and submit |

| |

|REFER students to recommended references |

References

Basset W.H. (1992). Clay’s Handbook of Environmental Health (16th ed).

London: Chapman and Hall

Nyamwaya, D. (1994): A Guide to Health Promotion through Water and

Sanitation, Nairobi: AMREF

Subi, S. (2008).Environmental Health Hand Book for Clinical Officer

Students. Kilosa, Tanzania.

Wood, C. H. (1997). Community Health (2nded). Nairobi: AMREF

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