Slow sand filtration water treatment plants
Practical Action
TITLE
OBJECTIVE
MATERIAL
METHOD
TIME
INTRODUCTION
DEVELOPMENT
EVALUATION
REVISION
The filtration process
The participants will be capable of describing, in their own words,
what happens when the water seeps through the sand, why the water
level increases over time and why cleaning is necessary.
Whiteboard, felt pens, adhesive tape, flip charts and a drawing of a
slow filter, with no written information
A talk followed by a discussion with questions and answers
An hour and a half
Explain why the operators need to know what is happening in the
filtration process and the operations required for it to work properly.
1) Discuss the biological filtration mechanism
2) Explain what the characteristics of the sand should be and
why
3) Explain what ‘load loss’ means
4) Ask questions to check whether the participants have
understood
5) Allow questions
1) Give the participants a drawing of the filter and ask them to
explain what occurs in the sand bed
2) Ask questions like what ‘load loss’ means and how it affects
the filtration operation, or when it is necessary to clean the
filter.
Revise any parts that the participants were unsure of.
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