The Effect of Point-of-Use Water Treatment Methods on Water Quality

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The Effect of Point
-
of
-
Use Water Treatment Methods on Water
Quality


Maeve Givens


Takoma Park Middle School 2011
-

12


Abstract

The purpose of this experiment was to discover the most effective Point
-
of
-
Use

(POU) method
at

increas
ing

water quality.
This
was achieved by testing phosphate, dissolved oxygen (DO), and turbidity levels
in water before and after applying POU methods. The POU methods that were tested were flocculation and
disinfection, chlorination and filtration, and solar disinfection (SODIS)
.

The original hypothesis was: i
f three
POU methods
are tested to
improve water quality,
then the most effective
method w
ould

be flocculation and
disinfection.

To perform the experiment
,

water was obtained from Sligo Creek.
The phosphate, turbidity, and
DO
levels
in the water
were tested immediately with a water testing kit.
F
ive bottles were filled and put aside.
Chlorine
and a flocculent were added to two separate containers filled with water.
A control was tested
with

no
POU method

being
used
. After a
waiting

process
, the
treated
water
’s
phosphate, turbidity, and DO levels

were
measured
.
The results
found that
flocculation reduced turbidity and phosphate dramatically.
Flocculation

decreased turbidity by 89% and phosphate by 50%

on average
.
SODIS

and chl
orination increased DO by 26%

on average
, while flocculation increased
DO only
by 15%. No method proved best in all
categories
, but
flocculation
was the most effective in general. This investigation could prove
useful

in improving the lives of
many people
in rural areas
who lack clean drinking water. Millions of people die every year from
this
water
quality
issue, and
POU methods could
be a viable solution
. Key terms include:

water quality, Point of Use,
turbidity
.


Introduction and Review of Literature

The purpose of this experiment is to find the
most effective POU method at removing phosphate
and
turbidity, while incre
asing DO levels. The
researcher

expect
s

to learn the best POU method
that will increase water quality in rural areas. The
testable question is:
How do different POU methods
reduce the amount of turbidity

and phosphate, and
increase DO

in unsafe water? This research is being
conducted to help find a solution to the problem of
lack of access to clean water in rural areas. Millions
of people in developing countries die each year
from lack of clean drinking water which is a real
world issu
e this investigation addresses.


The hypothesis is: If
three POU methods
are
tested to reduce

phosphate and turbidity, while
increasing DO,
then the most effective

method will
be flocculation and
disinfection.

The dependent
variables are t
he amount of
ph
osphate

and turbidity
removed from th
e water after treatment method.
Another dependent variable is the increase in the
amount of DO in water that has been treated. The
independent variable is the different type of POU
methods
to be used
which include: floc
culation and
disinfection, chlorination and filtration, and SODIS.
The amount of DO is expected to increase, while
the amount of phosphate and turbidity is expected to
decrease in water after being treated with any of the
POU methods.

Dissolved oxygen is
the amount of gaseous
oxygen dissolved in water, and will
be
measured in
parts per million (ppm). Oxygen gets into the water
through diffusion from the surrounding air, by rapid
movement, and as a byproduct of photosynthesis.
High levels of DO indicate goo
d water quality,
while high levels of phosphate
are

detrimental to
water quality. Phosphate levels will be measured in
ppm. Turbidity will be measured in Jackson
Turbidity Units (JTU). Turbidity is the
cloudiness
of the water due to sediment and other smal
l solid
particles
.

The researcher

believe
s

the most effective POU
method will be the flocculation and disinfection
system. This

system will use a Purifier of W
ater
(PUR) packet, which when mixed with water will
clump harmful substances and turbidity parti
cles
together. These clumps will be easily removed
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when passed through a filter. This process will
remove any excess turbidity and substances, just as
when hot water is filtered through ground coffee.
The water becomes coffee, but does not have any
extra c
offee particles thanks to the filter. Currently
at the University of Maryland, Allen P. Davis is
conducting an experiment where he uses a
bioretention system

to remove

runoff from bodies
of water entering the Chesapeake Bay. This is
similar to the floccula
tion and disinfection system
because it removes harmful substances to increase
water quality.

This system is a real life application
proving that the
flocculation and disinfection
system can be

expected to be effective
in the real
world
.

Currently there
are numerous researchers
conducting programs and experiments to help solve
the issue of water pollution. Researchers and
organizations from the Center for Disease Control
and Prevention (CDC) and the University of
Maryland are currently con
ducting several

investigations. These programs could prove vital in
finding an efficient solution for water filtration.

The CDC’s Global Water, Sanitation, and
Hygiene program works to prevent water diseases
related with water supplies. They dev
eloped a
Water Safety Plan

(WSP),

a program where water
is
tracked

from whe
re

it is taken to whe
re

it is
consumed. The WSP

insure
s

procedures are taken
to remove any dan
gers in the water
in order
to
guarantee a high
er

quality

of water. The

WSP’s
objective is to help stakeholders improve the quality
of drinking water and maintain health regulations.
This plan is being implemented all over the globe. If
this plan is a success
, the
n it could help
find

a
feasible
method to prevent water polluti
on.

The research, “Bio
-
Filtration System Promises
Less Chesapeake Pollution” is being performed by
Allen P. Davis from the University of Maryland and
his team. By designing a bioretention system which
is a series of rain gardens, or bands of plants which
filters storm runoff before it enters the Chesapeake
Bay. The system allows the removal of
phosphorous, nitrogen, and other urban pollutants
from water runoff, by the bands of greenery acting
as a sponge, and absorbing the pollutants. Though
the research i
s not directly related to water
filtration, if it is proven
to be
effective
then
a
similar system could be implemented to remove
bacteria in drinking water, with a slightly different
design.

These two programs could be useful in finding
an effective way t
o filter bacteria and other diseases
out of drinking water. These investigations could
also be used in future research
related
to water
filtration

as a foundation
.

There are several experiments and
investigations which have been conducted by
researchers t
o improve and research basic or low
technology water treatment systems. These include
projects which were conducted by USAID in the
Hy
giene Improvement Project, Mark

D
.

Sobsey
from the University of North Carolina, University
of South Florida, Georgia Inst
itute of Technology,
Stoney Brook U
niversity, and many others which

will be discussed
below
. All of these experiments
use different techniques including teaching villagers
to treat water, ceramic filters, and using green
chemistry.

The USAID Hygiene Impro
vement Project
(HIP) conducted a program which aimed to reduce
diarrheal disease by promoting hygiene
improvements including th
e treatment of water on a
house
hold level. This pro
ject was conducted from
2004
-
201
1. HIP conducted trials in developing
countrie
s such as Peru, Ethiopia, and Madagascar.
The program taught local communities how to be

more

sanitary. In 2007 HIP began using chlorine
-
based water treatment, instead of local water
treatments in a small town. Significant
improvements were noticed right a
fter installation.
The program was a success, and found that teaching
communities to use treat water made a major
impact.

Mark
D. Sobsey at the University of North
Carolina performed an investigation on the
microbiological effectiveness of ceramic filters

for
water systems in Cambodia. The purpose of the
experiment was to evaluate the performance of two
ceramic filters that were d
esigned

to remove
waterborne pathogenic microbes. The experiment
was performed by using rainwater and surface water
containing t
he bacteria Escherichia Coli and
bacteriophage MS2, in which filters were tested to
see how much of the bacteria were removed from
the water. Eight filters were tested, which were all
ceramic water purifiers (CWP); four with AgNO
3

(silver nitrate) treatmen
t and four without silver
(Ag). The results were that both filters were able to
reduce bacteria microbes; E. coli was reduced
around 99% of the time, while bacteriophage was
only reduced 90
-
99% of the time. Based on these
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results the author believed that t
his
approach is
a
possible solution for sustainable drinking water
treatment.

The experiment “
Removal of Sediment and
Bacteria from Water Using Green Chemistry” was
conducted by the University of Florida. The
researchers found that the best methods for wa
ter
treatment accepted
and used
are those which use
indigenous materials. Researchers extracted
two
fractions of mucilage gum from the
Opuntia ficus
-
indica

cactus. They then tested to see if it would
work as a treatment against sediment and bacterial
contamination. The removal rate was 97% to 98%
for high bacteria concentration. They found that the
cactus demonstrated water purification skills, but is
also a
ffordable and easily obtainable.

Researchers at the Georgia Institute of
Technology conducted research on “
Fate and
Transformation of C
60

Nanoparticles in Water
Treatment Processes.”

The investigation addressed
the objective of removing and transforming
model
carbon nanomaterials with water treatment systems.
Several experiments established that C60 colloidal
aggregates were eliminated sufficiently by
coagulation, flocculation, sedimentation and
filtration processes. They concluded that the
previously men
tioned processes were capable of
removing C60, but the efficiency depended on
water quality.

The Department of Chemistry at Stoney Brook
University conducted the experiment, “
Ultrafine
Polysaccharide Nanofibrous Membranes for Water
Purification.” The res
earchers employed
ultrafine
polysaccharide nanofibers 5 to 10 nm in diameter,
such as cellulose and chitin, as a barrier in thin
-
film
nanofibrous composite membranes to be used in
water filtration. This system rejected 99.5% of
bacteria. Researchers say th
at these low cost
materials and performance rate could be very useful
in water purification.

Ghislaine Rosa, Laura Miller, and Thomas
Clasen performed the study


Microbiological
Effectiveness of Disinfecting Water by Boiling in
Rural Guatemala.” They cond
ucted a 5 week study
in 45 households in Guatemala, where 71.2% of
stored water met guidelines for safe drinking water,
and 10.7% fit into an accepted low risk category.
The study proved that boiling made a considerable
impact on the microbiological qualit
y of drinking
water, but water that has been boiled and then
stored was not always free of contaminations.

These experiments and investigations which
have been conducted by researchers helped improve
water treatment systems
, and influenced this
investigat
ion
.

All of these experiments use different
techniques, but
addressed

the issue of water
purificati
on

in an effective way
.


Materials and Methods

There were many materials used in this
experiment. When testing the POU methods
,

forty
liters of water from
Sligo Creek were needed for
each trial. For the chlorination method, one bucket
of chlorine bleach
,

which was a hypochlorite
solution
, was needed

and it

costs three dollars. The
SODIS method required five clear plastic soda
bottles which were two liters each, but had virtually
no cost. Five buckets were needed to transport the
water from the
Sligo
Creek to the experiment
location. Each bucket was plastic
and held ten liters
of water, and
each
cost approximately
twenty five

dollars. Eight one by one meter pieces of cloth
were used as a filtering device. Each piece of cloth
was 100% thick c
otton, and cost approximately five

dollars. Five PUR packet were nee
ded, and were
used as a flocculent. Each packet cost .035 dollars.
A syringe that was five milliliters was also needed.
One wood spoon was needed for mixing. Lastly two
water testing kit
s

from the
GREEN water
monitoring kit

brand was used, and cost
approxi
mately 40 dollars. These were all the
materials used in the experiment.

There was a series of procedures followed in
this experiment during the trials. First the
researchers gathered
40 liters of water from Sligo
Creek, 10 liters for each POU method.
The
y did this

by placing the 4 plastic buckets in the water at the
edge and fill
ing

them with water.
They then took

a
20 ml sample from each of the 4 buckets.
Next the
researchers m
easure
d

the phosphate, turbidity, and
DO

levels from each sample, using the wat
er testing
kit.
For clarification
,

they became

familiar with the
testing kit and read through the directions provided
in the kit thoroughly

before beginning
.
They found
that s
teps for using the kit may vary depending on
the brand.

Afterwards they recorded
the data and
any observations.

They first tested the SODIS method. They
took

one bucket and use
d

this to fill the 5 clear soda
bottles.

Next they s
eal
ed

the bottles and sh
ook

them
thoroughly for about 3 minutes.

The researchers
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then p
lace
d

the

bottles

out
side so that they
were
sitting vertically, and verified
that the bottles
were
in a spot which received

direct sunlight.

They then
left

the bottles there for 8 hours and test
ed

the other
methods. When the 8 hours
passed, they
measure
d

the phosphate,
DO

and
turbidity content of 20 ml of
the water with the water testing kit.
Then they
recorded the data and any observations.


The researchers then tested the chlorination
and filtration method.
Using the syringe,

they
measure
d

and dr
ew

4 ml of chlorine bleach an
d
add
ed

the bleach to the second bucket.
T
he water
was then stirred
for 5 minutes, and
the researchers
wait
ed

30 minutes.

They p
lace
d

the c
loth over an
empty bucket and two researchers held it in place.
A
nother
researcher

pour
ed

the water from the
original bucket
of water
through the cloth into the
empty bucket.

They t
est
ed

a 20ml sample of the
water in the new bucket

for the
phosphate,
DO

and
turbidity

levels
.
They
then
recorded the data and
any observations.

The flocculation

and disinfection method
was tested next. The PUR packet was opened, and
the contents of the packet were poured into one of
the buckets filled with untested water.

The
researcher s
tir
red

the wa
ter in the bucket for 5
minutes, and waited for
10 minutes

whi
le the water
sat.

Clumps
formed

from the
substances

settled at
the bottom.
T
he water
was then poured
through the
cloth into a second empty bucket.

The cloth was
being held by two researchers over the empty
bucket, while the third poured the filled bucket
through the cloth.

The
second bucket
was covered
and
the water sat

for 30 minutes
. This was done so
the hypochlorite (disinfectant) wa
s allowed to
inactivate the microorganisms.
The researchers then
t
est
ed

a 20ml sample from the second bucket

and
measured

the
phosphate,
DO

and turbidity

levels
.
They
then
recorded the data and any observations.


Lastly
,

the control was tested. Before testing
the control the researchers w
ait
ed until all other
methods we
re completed.

They t
est
ed

20m
l of water
from the last b
ucket of water, the only untested
bucket. They measured
phosphate,
DO

and turbidity
content. They
then
recorded the data and any
observations
.
Lastly they verified

that the results
from each method were recorded in the data table,
and that the following th
ings were noted and
recorded: phosphate,
DO
, and turbidity content
before purification, and phosphate,
DO
, and
turbidity after purification.
They repeated this entire
process three more times, for a total of four trials
for each method, starting with obtaining water at
Sligo Creek.

Results

Many trends can be found based on these
results. In general, the amounts of
DO

increased,
the phosphate levels decreased, and the turbidity
decreased
when implementing

POU
treatment
methods. One trend that
can be found

in the data
from the control method was that
the amount of
turbidity, phosphate, and
DO

in the water
was

unchanged
throughout

the experiment.
But, t
he
flocculation method showed an increase in
DO

of
15%, a decrease in phosphate by
50%

and a
decrease in turbidity by 89%.

The chlorination method co
mpared to the
untreated water

showed an increase in
DO

of 26%,
a decrease

in phosphate by 12.5%, and a decrease in
turbidity by 75%. The
SODIS

method compared to
the untreated water
showed an increase in
DO

of
26%, a decrease in phosphate by 44%, and a
decrease in turbidity by 64%. The chlorination and
SODIS

performed best for
DO
, with an average of 6
ppm, 0.5 ppm better that flocculation.

Flocculation performed best for phosphate,
with only 1 ppm of phosphate, 0.125 better that
SODIS
. Flocculation also performed best at
reducing turbidity, with an average of 3.75 JTU of
turbid
ity, 5 JTU less that chlorination. The worst for
all 3 dependent variables was the control or the
untreated water
, with 35 JTU of turbidity, 4.75 ppm
of
DO
, and 2 ppm of phosphate. Overall, the
dependent variable with the widest range was
turbidity.
DO

and

Phosphate were similar between
the independent variables.


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Graph 1
:

The effect of different POU methods
before and after being used on amounts of
Phosphate and
DO

in water



Graph 2:

The effect of different POU methods
before and after being used on amounts of
Phosphate and DO in water.


Discussion and Analysis

The research that was conducted tested the
effect of different Point
-
of
-
Use (POU) methods on
the amount of turbidity, phospha
te, and dissolved
oxygen

(DO)

in water which had

not been purified.
The original hypothesis was that
if
different POU
methods
were tested to

reduce phosphate and
turbidity

and increase dissolved oxygen levels
,

then
the most effective method would be
the
fl
occulation
and disinfection system.
The three POU methods
tested were chlorination and filtration, flocculation
and disinfection, and solar disinfection (SODIS).
The chlorination and filtration system used was
chlorine bleach being put into the unpurified
water
and then being filtered through cloth. The
flocculation and disinfection system used was a
Purifier of water (PUR) packet, which is commonly
used system in rural areas. Lastly the SODIS system
was created by filling several plastic bottles with
water

and leaving them in the sun.

The results obtained during the experiment
mainly support the hypothesis.
Based on the

data,
the PUR packet

was the
most effective method at
removing turbidity. The flocculation method
removed on average 31.25 JTU (Jackson Tu
rbidity
Unit), while the chlorination method removed only
26.25 JTU and the Solar Disinfection (SODIS)
method removed 23.25 JTU. When
the f
locculation
method
was used,
only 3.75 JTU remaine
d;

while
when using chlorination
,

8.75 JTU remained and
with
SODIS 11.75 JTU remained. Flocculation
removed 5 JTU
more
on aver
age
than any other
method, which suggested that flocculation was the
best method.


But, w
hen
the methods were tested on
removing Phosphate from water, the chlorination
method was most effect
ive. This method left only
.75 ppm (parts per million) of Phosphate on
average, while the SODIS method left 1.125 ppm of
Phosphate. The flocculation method left 1ppm of
Phosphate in the water. Before the POU methods
were tested
,

there was on average 2 ppm
of
Phosphate in the water. The chlorination method
was able to remove 1.25 ppm of Phosphate from the
water, which is .25 ppm of Phosphate more than
any other method.



When
the methods were tested for
increasing Dissolved Oxygen (DO) levels in water,
the S
ODIS method performed the best, while
chlorination and flocculation performed equally.
0
2
4
6
Flocculation
Chlorination
SODIS
Control
2

2

2

2

4.75

4.75

4.75

4.75

1

0.75

1.125

2

5.5

5

6

4.75

Amount in Water(ppm)

POU methods

Amount of Phosphate and Dissolved Oxygen in
water before and after

After Dissolved
Oxygen
After
Phosphate
Before
Dissolved
Oxygen
Before
Phosphate
0
20
40
Flocculation
Chlorination
SODIS
Control
35

35

35

35

3.75

8.75

12.5

35

Amount of Turbidty(JTU)


POU Methods

Amount of Turbidity in water before and
after

After
Before
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SODIS had on average 6 ppm of DO in the water
after using the POU method, while the other two
POU methods had on average 5.5 ppm of DO.
Before testing any POU

methods, t
he DO levels
w
ere on average 4.75 ppm

in the water.


Though none of these POU methods
performed the best in all three categories for water
quality, flocculation and disinfection was
the
best
on average. The PUR packet

removed the most
turbidity, the seco
nd most amount of phosphate on
average, and increased the DO the second most. The
PUR packet removed 31.25 JTU of turbidity, 1 ppm
of phosphate, and increased the DO levels by .75
ppm on average. Therefore, the flocculation method
was the most efficient me
thod, supporting the
original hypothesis. The study by Allen P. Davis
supports this result because his experiment is testing
the effectiveness of a bioretention system on runoff
into the Chesapeake. This study shows that using a
filter to remove waste is

very efficient. The
flocculation method also uses a filter to remove the
clumps of harmful substances that have formed.
But, the results show that all of the POU methods
are acceptable water treatment
methods
because
they all improved water quality.

The

results
of the experiment occurred

due
to

the

properties of the substances used in the
methods. Flocculation is defined as the causing
of
aggregation or coalescing

into small lumps or loose
clusters
. Therefore when the PUR packet was used,
it caused the t
urbidity in the water to coalesce. The
clumps formed from the flocculation were then
filtered out, reducing the water of turbidity
dramatically. The same dramatic reduction did not
occur when using the other methods because neither
method clumped the turbi
dity together
to make

the
dirt

easy

to filter. SODIS increased the DO levels
the most because when the bottles were closed, air
remained. The air then diffused into the water,
which created higher dissolved oxygen levels when
using SODIS. Chlorination dec
reased phosphate
levels the most because chlorine kills bacteria and
algae, which thrive on high phosphate levels. By
eliminating the organisms that contain phosphate,
the chlorination method decreased phosphate levels.

Each method has specific properties
that are
responsible for the results which occurred.

There were several problems encountered
during the experiment. The first was that the costs
of the water testing packets were expensive and
could not be bought in large quantities. This forced
the numbe
r of trials to be decreased so that the
experiment was on budget. Weather conditions
were also a problem encountered during the
investigation. During the first trial there were severe
winds which made measuring turbidity, phosphate,
and dissolved oxygen di
fficult. And during the
second trial it began to snow, causing the collection
of water from Sligo Creek to be very complicated
because of the freezing temperatures. This problem
was solved by performing the remaining trials in
warmer weather on days when t
he temperature was
above 50 degrees.

There were some possible sources of error
when gathering the data. For example, it is possible
that due to human error there was not
exactly
10
liters of water in each bucket, but
an amount
slightly over or under

10 li
ters
. Also the testing of
phosphate, DO, and turbidity could have had errors,
such as the testing ta
blets not fully being dissolved
.
Another
possible
source of error was that the
sample size was not large enough to get precise
results. With more trials a single method might have
emerged to be the most effective in all three
categories of water quality.


The experiment has many related possible
improvem
ents and potential experiments. An
improvement or new experiment could be to study
the effect of different POU methods and
purification systems that were not used in this
experiment. These methods include sand filtration,
ceramic filtration, and boiling. A
nother
improvement to the experiment could be to also test
bacteria levels in water. A related experiment could
see how certain plants around or in the body water
effect the water quality. Additionally, a researcher
could test methods with different water

sources
instead of just one. A related study could test
purification methods on a large
r

scale. Several
different villages in a rural area with one water
source could all use different POU methods to see
the real world application of the methods. This
exp
eriment has many related investigations and
potential improvements to enhance the experiment.


Acknowledgements

Thank you to all the people who helped while I was doing my
experiment at the
Sligo
Creek in the cold. Thanks to everyone
who drove me to Sligo

Creek.




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Retrieved from United States Agency
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