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The WaterCAMPWS
Cen
ter for Advanced Materials for Purification of Water with Systems

University of Illinois at Urbana
-
Champaign




Media
Filtration






Teacher’s

Guide





The WaterCAMPWS
Center for Advanced Materials for Purification of Water with Systems

STEM Educational Curriculum Supplement

1


Curriculum Connection
:
Biology, Chemistry, or Environmental Sciences

Bloom’s Taxonomy:

Grade Level
:
9
-
12


Topic
:
Media

Filtration

for Water Treatment

Lesson Duration
:
Approximately 1.5

hours


Purpose

F
iltra
tion
refers to the process of separating a mixture by a filter. It

is

part of our everyday life.
Filters are used fo
r coffee making, draining food,

and
cleaning

water.
The purpose of this lab is to
demonstrate the use of media filtration, a process that

is widely used by water treatment plants for
purifying drinking water.
This lab begins
with

having students
add a coagulant to a synthetic
muddy water that leads to particle aggregation and sedimentation. They will then
create a

packed
sand column as th
e filter
, which will
be
used to filter
the water
.
Alternatively, the students will also
be asked to filter the water through a cotton cloth which acts as a filter media.
By comparing the
clarity

of the incoming and product waters, the effect of media fil
tration can be demonstrated.

The
students will also be asked to use the column to filter a dye solution. The lack of change in color
should indicate what the filter is not designed for, which can lead to discussions on other water
treatment processes for

specific removal of other contaminants.



Learning Goals and Objectives

1.

Students will learn key vocabulary associated with
filtration, including

turbidity
,

coagulation
,
flocculation, sedimentation, contaminant, disease, filter,
microorganism,

bacteria,

virus,
protozoa
.

2.

Students
will
develop an understanding of drinking water treatment.

3.

Students will be introduced to the principles that govern filtration processes.


Benchmarks and Standards

Illinois State Learning Standards:



11.A.3a

Formulate hypotheses

that can be tested by collecting data.



11.A.3b

Conduct scientific experiments that control all but one variable.



11.A.3d

Explain the existence of unexpected results in a data set.



11.A.3f

Interpret and represent results of analysis to produce findings.



11.A.3g

Report and display the process and results of a scientific investigation.



11.A.4a

Formulate hypotheses referencing prior research and knowledge.



11.A.4b

Conduct controlled experiments or simulations to test hypotheses.



11.A.4e

formulate alterna
tive hypotheses to explain unexpected results.



11.A.3a Formulate hypotheses that can be tested by collecting data.



11.A.3c Collect and record data accurately using consistent measuring and recording techniques and media.



11.A.4c Collect, organize and an
alyze data accurately and precisely.



11.B.4e

Develop and test a prototype or simulation of the solution design using available materials, instruments
and technology.



11.B.4f

Evaluate the test results based on established criteria, note sources of error an
d recommend
improvements.



11.B.4g

Using available technology, report to an audience the relative success of the design based on the test
results and criteria.



13.A.4b

Assess the validity of scientific data by analyzing the results, sample set, sample siz
e, similar previous
experimentation, possible misrepresentation of data presented and potential sources of error.



13.B.3b

Identify important contribution to science and technology that have been made by individuals and groups
from various cultures.



13.B.
3f

Apply classroom developed criteria to determine the effects of policies on local science and technology
issues



13.B.4a

Compare and contrast scientific inquiry and technological design as pure and applied sciences.



13.B.4d

Analyze local examples of re
source use, technology use or conversation programs; document findings;
and make recommendations for improvement.


NSES

Standards:
In grades 9
-
12, students will learn:


The WaterCAMPWS
Center for Advanced Materials for Purification of Water with Systems

STEM Educational Curriculum Supplement

2



Content A

Abilities necessary to do scientific inquiry & understandings about scientif
ic inquiry.



Content B

Structure and properties of matter, motions and forces, and interactions of energy and matter



Content C


Interdependence of organisms and behavior of organisms



Content D

Origin and evolution of the earth system



Content E


Abilities
of technical design and understandings about science and technology



Content F

Personal and Community health, population growth, natural resources, environmental quality, natural
and human induced hazards, and science and technology in local, national and
global challenges



Content G

Science as a human endeavor, nature of scientific knowledge



Teaching A

Plan an inquiry
-
based science program for their students



Teaching B

Guide and facilitate learning



Teaching D

Design and manage learning environments that

provide students with the time, space and resources
need for learning science.



Teaching E

Develop communities of science learners that reflect the intellectual rigor of scientific inquiry and the
attitudes and social values conducive to science learning.



The WaterCAMPWS
Center for Advanced Materials for Purification of Water with Systems

STEM Educational Curriculum Supplement

3

Materials and Equipment

Water:



Muddy water prepared by mixing ~1tbsp of gardening soil in 1L of water



2

mg/L methyl orange dye solution



For Rapid s
and filtration
:


Materials required for this lesson are (for
each group of students
):



60ml plastic syrin
ge

(as the column
)



Sand



Gravel

or
l
izard litter



Clamp and stand



Alum (Al
2
(SO
4
)
3
.14H
2
O)
(1 g/L)



Turbidity meter (if available)



0.5
L of muddy water



0.5
L of 2

mg/L methyl orange dye solution



Glass rod



500 ml beaker x
2



50 ml beaker x 2


For Cloth Filtration:


Materials required for this lesson are (for
each group of students
):



Cotton cloth



Alum (Al
2
(SO
4
)
3
.14H
2
O)
(1 g/L)



Turbidity meter (if available)



0.5L of muddy water



0.5L of 2

mg/L methyl orange dye solution



Glass rod



500 ml beaker x 2



250 ml beaker x 2



The WaterCAMPWS
Center for Advanced Materials for Purification of Water with Systems

STEM Educational Curriculum Supplement

4

Introduction

Filtration

is a
process

used
extensively
in drinking water treatment. Its major objective is to
remove particulate contaminants that may cause health and/or asthetic concerns. Contaminants
tackled

by filtration include inorganic particles s
uch as silt and clay, as well as microorganisms such
as
planktons,
bacteria and protozoa.
Turbidity
, which refers to the amont of light scattered by the
particles in a water sample,

is
a widely used measure

for the presence
of particulate contaminants.

W
hile it is a non
-
specific measurement, the reduction of turbidity has been used as an indicator for
the effectiveness of processes such

as
coagulation and filtration. This is because high
turbidity removal

should indicate at least partial
removal of micro
organisms that are of health
concern, particularly when they are associated
with particles.


Microorganisms of co
ncern to drinking water
include
:


Cryptosporidium parvum

(protozoa)

Giardia lamblia

(protozoa)

Legionella

(bacteria)

Adenovirus (virus)






**Does not include Bangladesh, Pakistan

and other countries










4,610


Keep in mind that

media

filtration

by itself

is rarely used as
the
method for particle removal in
drinking water treatment. It is commonly applied in conjunction with
coagulatio
n
,
flocculation
,
and
sedimentation
.
Direct filtration

refers to the process of
coagulation

and flocculation followed
by media filtration.
Conventional filtration

is a similar process, with the additional step of
sedimentation after flocculation.


Coagula
tion


This is a process that destabilizes the suspended particles in water by chemical known as
coagulants
. The surface charge of most particles in water is negatively charged, and therefore,
the tendency for particles to aggregate upon collision is relat
ively low. When
alum
(
Al2
(
SO
4
)
3
.14H
2
O), the most common coagulant
, dissociates in water, it forms a series of
complexes with water,
such as

Al
(OH)
2+
, Al
7
(OH)
17
4+
, Al
13
(OH)
34
5+
, and Al
2
(OH)
2
4+
. These
positively charged species attach to the particles and
neutralize the surface charge. Because of
this, when these neutral particles collide, they aggregate into larger particles (flocs) and eventually
settles out from the water due to their considerable weights.

The addition of coagulants also lead
to a high
er tendency for the particles to attach to the sand grains in the filter, as discussed later.

In a water treatment plant, coagulant addition is usually followed by flocculation, a process that
enhance
s

particle collision (and thus coagulation) by gentle a
gitation.

The flocs are then removed
from the water by gravity, known as sedimentation.

THE GLOBAL IMPACT OF CHOLERA


Cholera is caused by

the bacterium Vibrio cholera. People become infected after eating food or drinking

water
that has been contaminated by the feces of infected persons.


Control of cholera

is a major problem in several Asian countries as well

as in Africa. In the year 2000,

some 140,000 cases resulting in approximately 5000 deaths were officially notified to W
orld Health

Organization. Africa accounted for 87% of these cases.


The WaterCAMPWS
Center for Advanced Materials for Purification of Water with Systems

STEM Educational Curriculum Supplement

5

Rapid sand Filtration


Filtration with sand as the media can be further divided into
rapid sand filtration and slow sand filtration. Since they
operate with differe
nt mechanisms, this handout will focus
only on rapid sand filtration. For more information on slow
sand filtration, please check the website listed below.
The
schematic of a typical sand filter is shown
on the right
. Raw
water enters from the top and as

it percolates through the
sand media by gravity, particulate matters are entrapped in
the sand media. The cleaned water exits thorugh the
bottom.


T
he sand used in a sand filter has size of about 0.5 mm.
P
articulate matters
are entrapped by two mechan
isms:
mechanical straining, if the particle is bigger than the smallest opening through which the water
flows; and physical adsorption, which refers to attachment of particulate matters to the sand
media.

Keep in mind that the efficiency of both mechanis
ms are enhanced by coagulations, which
leads to 1. the formation of bigger flocs and 2. particles with their surfaces neutralized.



Mechanisms of filtration. (source:
http://ewr.cee.vt.edu/environmental/teach/wtprimer/rapid/rap
id.html
)





To get an idea of the size of the unit of measure, 2 micrometers, check out the example at the web site:

http://www.cellsaliv
e.com/howbig.htm


List of drinking water contaminants and their MCLs (maximum contaminant levels)

http://www.epa.gov/safewater/mcl.html#mcls


On Line Resources:

Water Quality Report for the Unive
rsity of Illinois, Urbana/Champaign

http://www.fs.uiuc.edu/sc/ecs/pdf/2003wqr.pdf


Emergency Disinfection of Drinking Water

http://www
.epa.gov/safewater/faq/emerg.html


What is
Cryptosporidium parvum

http://www.cdc.gov/ncidod/dpd/parasites/cryptosporidiosis/factsht_cryptosporidiosis.ht
m


An introduction to slow sand filtration

http://ewr.cee.vt.edu/environmental/teach/wtprimer/slowsand/slowsand.html



Sand
Influent
Effluent
Underdrain
system
Sand
Influent
Effluent
Underdrain
system
Sand
Influent
Effluent
Underdrain
system

The WaterCAMPWS
Center for Advanced Materials for Purification of Water with Systems

STEM Educational Curriculum Supplement

6

Cloth Filtration


This refers to filtration of water by means of a cloth filter. While it is not commonly used in water
treatment plants in developed regions such as the United
S
tates, it has been widely used
as a
point
-
of
-
use treatment in developing regions such as rural India and Bangladesh. In such
treatment,
w
ater is poured through
a
cloth that is folded over a few times.

Results have shown
that not only is the

water visibly cleaner, it also has dramatically r
educed numbers of disease
-
causing bacteria.


Activities

1.

Present the introduction to this lab, or some other materials appropriate to

media

filtration
.

2.

Prepare “muddy” water by m
ixing gardening soil in water (0.5
L for each group).

3.

Prepare the

2

mg/L

methyl
orange dye solution (0.5L for each group).

4.

Prepare coagulant by dissolving 1g of alum into 100 ml of water. That would give a
concentration of 10g/L as alum. The muddy water requires 150 mg/L of alum to coagulate,
so each group requires 7.5 ml. You may
want to have the right volume in a beaker for the
students to use.

Adaptation:

If time is limited, do
the muddy water only
.

5.

Divide the lab materials on the bench space depending on the number of groups.

6.

Divide the students into groups.

7.

Have the students a
dd the coagulants and mix the water by a glass rod, rapidly for 10
seconds then gently for 30 seconds.

8.

Have the students
wait for about 10 minutes and
observe the change in water. How does
the clarity of water change?


9.

For filtration with

the sand co
lumn
:

a.

Have the students

build the sand column

by adding wizard litter or gravel up to the
5ml mark
.
Then have them add sand to the 50 ml mark.
Assistances may be
needed.

b.

Have the students pour the muddy water slowly into the column, and collect the
efflu
ent from the bottom

with a 50 ml beaker
.

c.

Ask the students to describe the appearance of muddy water and filtered water. If
turbidity meter is available, have the students measure the turbidity of both waters.

10.

For filtration with cloth filter:

a.

Have the stu
dents
fold a piece of cloth 4 times. Have them use the cloth to cover a
250
-
ml glass beaker. Assistance maybe needed.

b.

Have the students pour the muddy water slowly into the column, and collect the
effluent in the beaker.

c.

Ask the students to describe the
appearance of muddy water and filtered water. If
turbidity meter is available, have the students measure the turbidity of both waters.

11.

Filtering the methyl orange dye solution
:

a.

Have the students pour the methyl orange dye solution slowly
through either th
e
column or cloth
, and collect the effluent from the bottom.

b.

Ask the students to compare the color of the influent and effluent.

12.

Have the students clean up their area after the experiment is completed.

13.

Conclude the lab with a discussion of their results.



Conclusion


With remaining time, have some of the groups share their
results
. Collect the
lab books

at the
end.





The WaterCAMPWS
Center for Advanced Materials for Purification of Water with Systems

STEM Educational Curriculum Supplement

7


Assessment

The
lab book

should provide an assessment tool for this lesson.


Glossary of Terms


Coagulant


A
chemical that destabilizes

suspended particles in water by neutralizing their surface
charges, which leads to aggregation upon collision.


Coagulation



A process
of

increasing the tendency of small particles in water to
aggregate by

means of neutralizing the surface charge of the

particles with
chemical known as
coagulants (
such
as Al
3
+

or Fe
3+

salts).


Filtration



A process of separating a mixture (water and solid) by a filter.


Flocculation



A

process
that enhances coagulation by agitating the chemically
-
treated water.


Sedime
ntation



A process
of particle removal from water by gravity
.


Turbidity



A non
-
specific measure of the amount of particulate material in water. Measured by
detecting the amount of light scatted by particles in a sample. Used as indictors

of

drinking
w
ater
quality and efficiency

of coagulation and filtration processes.