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Chapter I

INTRODUCTION

Background of the Study

Manila Bay is one of the best natural harbors of the world because of its appropriate geography

and in turn, it has become one of the premier international gateways to the countrys political, economic,

and social centers. With this strategic importance, many manufacturing industries are now found here

and the bay is now home to tanneries and jewelry making, electronics, and plastic industries among

others. These changes in human activity have change the natural environment of the area is now facing

various threats: over population, pollution discharges, and ecosystem deterioration. One particular threat

is the extinction of important marine life, which live in the area due to overexposure to the contaminants

caused by human activity.

Certain conditions in our waterforms make them suitable for sustaining marine life. If these

standards arent met, less and less marine life will survive our waters up to the point that the area

becomes biologically dead: when oxygen levels are so low that it cant support life anymore. Less

marine life will result to more consequences both environmentally and economically. If the water is

severely polluted, it needs to be restored so that it can sustain marine life.

The alarmingly increasing damages wrought on to its ecosystem results in socio-economic losses

estimated at an average of Php 4 billion yearly: 48% of which (Php 1.92 billion) accounts for fishermen

due to red tide. These economic losses will eventually be worse if no action is taken to prevent them;

they also reflect the urgency of the situation with regards to our environment.


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The fact that the Philippines is one of the megadiverse countries in the world due to its

tremendous amount of resources means that some of them might not be consumed properly. One such

example are crab shells which, after the meat of crabs are eaten, are only used as decorations or

ornaments. In addition to this, potassium alum or tawas is also very popular, but only for use as a

deodorant. There are studies that have shown that components in crab shells and potassium alum may be

used to help in reducing pollutants in our waters.

This inspired our group to go beyond that aesthetic aspect of crabs and made a treatment where

crabs and potassium alum can be used to remove contaminants from the seawater at Manila Bay. The

study compares three areas of the bay and how much lead will be reduced once they undergo the

treatment. This study can help the Department of Environment and Natural Resources, the Department

of Science and Technology, and the Department of Health in creating innovative ways to help in

cleaning our waters and promoting a healthy environment for everyones benefit.

This study was aimed to:

General Objectives

Determine if chitin and/or aluminum sulfate can be used to lessen the lead content of water inManila Bay.

Specific Objectives

Observe and determine the physical characteristics of water samples from Manila Bay usingpH, and temperature tests.

Improvise a filtering process that includes the use of chitin and potassium alum for thetreatment process.


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Measure and analyze the lead content of the said samples both before and after thetreatments.

Significance of the Study:

Metals are found in the environment all around the world, mostly because of human activities.

Industrial activities have led to very high heavy metal concentrations on the environment, which are in

general significantly higher than those in the Earths crust, which presents the lurking dangers of

exposure of organisms to such contaminants, not only decreasing marine biodiversity, but exposing

human beings and cause harmful effects on them.

Lead, in particular, us a very poisonous metal regardless of intake and affects every organ in the

body. It mainly affects the nervous system, and long-term exposures can lead to weakness in joints, and

severe damage to the brain and kidneys. It also causes harmful effects to marine life, which may lead to

eventual extinction, and serious losses in resources may occur if such an event may happen.

Manila Bay is a natural harbor which serves the Port of Manila. It facilitated commerce and trade

between the Philippines and its neighboring countries and became a gateway for commerce and trade

between the Philippines and its neighboring countries. According to theManila Bay Coastal Strategyby

PEMSEA, Manila Bay provides many uses for the community: employment, income, services. More

than 50% of the countrys products come from it: fishing and aquaculture, manufacturing, shipping,

agriculture, mining, quarrying, and tourism.


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Additionally, the UNDP Regional Programme on Building Partnerships in Environmental

Management for the Seas of East Asia (PEMSEA) stated that the Manila Bay has an annual economic

value of Php 8 billion at its lowest. Today, it faces a serious environmental threat: pollution. With

industrialization, overexploitation of its resources is now causing pollution and destruction of habitats,

increase of pollution, and the death of marine life because of the uncontrolled contamination of the bay.

The destruction of marine life in an ecosystem can cause many catastrophic damages

environmentally, economically, and aesthetically. Using the concept of the food chain, with the

extinction of one species, there will be a chain reaction, and many other organisms will be depleted of

food and eventually, we too will be affected with this decline.

With this study, new methods of treating lead-contaminated water can be explored, particularly

with the use of materials which are usually disposed of after consumption (e.g. crab shells). The study

can help avoid wastage of materials by recycling, and help save resources which communities,

especially the poor living near the bay, may make use of in order help save the environment without the

need to spend too much, and in the future, restore the economic balance in our country because our

natural resources will have been restored and benefitting our country by promoting the conservation of

our environment.

Scope and Delimitation:

The researchers collected samples from three areas of Manila Bay: the coastline at Roxas

Boulevard in Manila City, one from a point deeper than the coastline, and a point near the center of the

bay to be used as subjects for the testing. The the location of the collection was at Roxas Boulevard


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across Aristocrat and Maxs Restaurants on January 26,2013 at 1:13 pm, 1:01 pm, and 1:07 pm for the

coast, off-shore, and deep shore locations, with respective distances of 0 m, 60 m, and 110 m off-coast.

A filter process using chitin was used to pour the water through to remove contaminants or

impurities from the water. Potassium aluminium sulfate (tawas) will be acquired from the supermarket

for use in this study. The budget used for this study was estimated to be around Php 700 800. To

determine its lead content, samples were sent to the laboratory for analyzing to determine the amount of

lead content present before and after the treatment process. The water samples will be subjected to 2

tests to determine their physical characteristics: pH test, and temperature test before and after being

subjected to the purification process. The study will use the same 3 samples for the tests to determine

their water quality. Furthermore, the thermometer can take measurements up to one decimal place.

(0.1.To determine the quantity of lead concentration of the samples used in the study, an Atomic

Absorption Spectrophotometer was used in UP Diliman, Quezon City using mg/L (milligrams per liter)

as a unit of measurement. It is commonly used as a unit of concentration for liquids to measure to

amount of a certain chemical or substance per volume of water, which is appropriate for this study

which deals with water quality.

Finally, the researchers focused on the effect of the chitin and potassium alum in terms of the

percentage of decrease in the lead content of the collected water samples. The researchers were not

focused on determining changes, temperature, or the maximum limit of reduction of lead content

percentages for the water samples. Furthermore, the nitrite, nitrate and ammonium, and phosphates were

measured only to attain an overview of the condition of the bay at the time of collection, these

information are not necessarily intended to significantly determine the lead concentration.


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Chapter II

REVIEW OF RELATED LITERATURE

Water is one of the most important resources to most life in our planet, especially for us humans.

Biologically speaking, water makes up approximately 70% of adult humans. Almost all industries use

water in one way or another, and to top it all of, it practically makes three fourths of our planet.

However, with the advent of the Industrial Revolution, problems with water pollution have

arisen and have worsened today. Water pollution is defined as a body of water that is "adversely affected

due to the addition of large amounts of materials" (Krantz, 1996). This means that when a body of water

is not anymore suitable for its original purpose, it is deemed "polluted". There are multitudes of ways

wherein this can happen. One example is a direct form of pollution, such as an oil spill. According to

studies made by the World Water Assessment Programme in 2003, an estimated 2 million tons of

sewage, industrial, and agricultural waste is thrown into our worlds water. Furthermore, this problem

also affects inland life: globally, 24% of mammals and 12% of birds connected to inland waters have

been considered threatened.

Many factors may point to evidences of water pollutions, some of which are nitrites, nitrates and

ammonium, and phosphates. Nitrates and nitrites are some of the chemicals that are produced during the

nitrogen cycle and are predominantly used for fertilizers and food preservatives, respectively.

Meanwhile, ammonium is a polyatomic ion that is formed when ammonia reacts with a base; and

phosphate is another polyatomic ion which is a salt of phosphoric acid.


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meters, which resulted in an estimated mean pH of 8.34, which is higher in alkalinity in comparison to a

neutral 7 for water in normal conditions.

Instead of expensive treatments, the use of biological materials is a good alternative to reduce

lead in seawater. One such example is chitin: it is the second most common organic compound in nature

and is a polysaccharide, forming the basis of hard shells of crustaceans, such as crabs. Pastor (2004) said

that chitin has applications in pharmaceutical, biomedical, food, agricultural, paper, cosmetic and textile

industries, as well as in chromatography. Additionally, Domard and Muzzarelli (2000) said that

considerable amounts of chitin are used for water treatments. The application of chitin and chitosan in

water treatment focuses mainly in coagulation-flocculation processes to remove organic residues,

suspended solids, amino acids and dyes. Lontoc, Mendoza, Rasco, Salvador, Yap (2003) said could be

obtained as a powder after dissolution of calcium and studies have shown it to have potentials in treating

basic and acidic water treatment. According to a study by Peiselt da Silva, K.M., et al., one of the most

important properties of chitin is removing is its ability to remove metal ions. This is supported by

Muzzarelli, R.A.A., et al., who said that their structure allows excellent complexation capacity with

metal ions, particularly transition and post-transition metals.

Furthermore, chitin has been proven to remove heavy metals by Saravanan, et. al., of

Sathyabama University, India. The essentiality of removal of heavy metals was discussed, along with

adsorption studies have been used to remove Cr (VI) from aqueous solutions using chitin composites. It

was suggested that chitin can be used to remove heavy metals to attain a more favorable quality of

water. A similar study was made by D. Zhou, et al., of the Wuhang University in China with the


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adsorption of metals in aqueous solutions by chitin. It was proven that chitin can effectively adsorb lead

(II), cadmium (II), and copper (II) ions. This was influenced by the properties of metal ions, specifically

electronegativity.

Additionally, potassium alum may also be a possible solution to this problem. According to

Anne Marie Helmenstine, Ph.D. of About.com, is also known as potash alum or tawas, in the Philippines

and is a mineral salt. It is also known as simply alum. It was known to have been used in Roman times

as for water purification. It's chemical formula is KAl(SO4)2. It can be used to bond to impurities in

water and settle them at the bottom, and this type of water purification is known as coagulation.

A past study was made by Johnson, Girinathannair, Ohlinger, Ritchie, Teuber, and Kirby and

published in 2008, which made use of alum, other mineral salts and ferric chloride to test their efficiency

in the removal of heavy metals in wastewater through coagulation. Different analytical methods were

used such as jar tests, total suspended solids analyses, and the use of spiking solutions. The study

showed a 95% removal efficiency in lead, 79% in copper, 57% in zinc, and 17% in nickel. Alum and

ferric chloride increased the removal of total suspended solids as well as the optimum settling,

specifically from 45 minutes to 25 minutes.

With the pollution present at Manila Bay, many risks and challenges are present for the

communities, which thrive through it especially fishermen, which have the water resources as their most

important and vital source of income. According to the Manila Bay Coastal Strategy, the economic and
http://chemistry.about.com/bio/Anne-Marie-Helmenstine-Ph-D-7815.htmhttp://chemistry.about.com/bio/Anne-Marie-Helmenstine-Ph-D-7815.htm


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social losses brought by deterioration of the Bay waters and consequent decline in economically

important resources are felt most by the fisherfolks, particularly those who depend on subsistence

fishing.

With these problems, the researchers will conduct tests for this study which will involve mainly

the biochemical oxygen demand and the dissolved oxygen of the water. refers to the amount of oxygen

that would be consumed if the organics in one liter of water were oxidized by bacteria and protozoa.

When BOD levels are high, dissolved oxygen (DO) levels decrease because the bacteria are consuming

the oxygen that is available in the water. Since less dissolved oxygen is available in the water, fish and

other aquatic organisms may not survive.


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Chapter III

METHODOLOGY

Materials/Equipment:

Quantity Specifications Description of Material

3 500 mLwater samples from manila

bay

500 mL Wilkins distilled water

5 pcs. locally available crab and shrimp shells

50 gacquired from the

supermarket

potassium aluminium

sulfate (tawas)

500 mL 4% concentration sodium hydroxide solution

500 mL 4% concentration hydrochloric acid solution

20 g Activated charcoal

80 g N/A sand

1 pc. medium-sized basin

4 pcs. 400 mL-capacity beakers

1 pc. 50 mL-capacity beaker

1 pc. porcelain bowl

4 pcs. iron tripods

4 pcs. glass funnels

1 pc. glass stirring rod

3 Glass jars

1 medium basin

12 pcs. N/A universal pH indicators

1 pc. aquarium thermometer1 pc. glass Graduated cylinders

1 pc. Small-sized Water container

May vary*Laboratory-use

(preferably latex)Gloves


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General Procedure / Treatment:

PREPARATION OF MATERIALS

A. Acquisition of water samplesWater samples were collected from the coastlines of Manila bay: fifteen 500 mL samples

from each location: one from the coastline, one from a point deeper than the coastline, and a

point near the center of the bay, for the three tests. Nine of which were used for the physical

tests, 3 of which were used as control samples and were tested before the treatment process, and

three of which were used for the treatment.

B. Creation of Acid and Base SolutionsIn order to attain a 4% concentration of hydrochloric acid, 8.33 mL of a 12 M solution

was added to 1000 mL of distilled water and stirred. Afterwards, 4 g of sodium hydroxide was

added to 1000 mL of distilled water to attain a 4% sodium hydroxide solution. Solutions with pH

of 2 and 12 were recorded for the hydrochloric acid solution and sodium hydroxide solution.

C.Extraction of ChitinCrab and shrimp shells were collected, washed, air-dried, and ground. To remove the

protein residues, 50 g each of the powdered crab shells were treated with 500 mL of the NaOH

solution. It will be stirred as a mixture for 30 minutes, decanted and the solid particles washed

with distilled water. 500 mL of HCl solution will then be added. The mixture was stirred for 30

minutes. The solid particles obtained after filtration was the chitin. It was air-dried and weighed.

30 grams of chitin were yielded by 50 grams of chitin.


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THE FILTER PROCESS

20 g of activated charcoal, 5 g of chitin, 80 g of sand and 80 g of pebbles were placed in

coffee filters which were shaped like cones were placed funnels and secured in tripods.

Afterwards, the assigned 500 mL samples for testing will be poured through the filters to another

basin separately then the three samples will be subjected to the three tests to monitor changes the

samples.

Afterwards, 10g of potassium aluminum sulfate (alum or tawas) will be added to each of

the 500mL mixtures and, it will then be stirred and left for 60 minutes. The water will then be

decanted to remove any settled substance at the bottom.

TESTING

A. Chemical Testing

The 500mL samples from each location will be sent to a laboratory to analyze for the lead

content of the water samples. An AAS (Atomic Absorption Spectrophotometer) was used to

measure the concentrations of lead in the water samples. Furthermore, additional factors were

tested and measured particularly, the averages and standard deviations of nitrate, nitrite and

ammonium, and phosphate concentrations.

B.Physical Testing

Aside from the laboratory tests, the samples will be subjected to three tests in order to

determine the quality of the water samples. They will be tested before, in-between (after the

pouring through the filter), and after the purification process.


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If you spill acid or base on the lab bench top or on the floor, treat it immediately. If it is

an acid, first neutralize it with baking soda. If it's a base, you can neutralize it with some vinegar,

which is dilute acetic acid. In any case, clean up the area thoroughly after it has been neutralized.

One must also be careful with handling laboratory equipment since these are usually

made of glass. Use glassware that is without defect and has smooth edges. Glassware should

have no cracks, chips, or scratches. In particular, be wary of star cracks that can form on the

bottom of beakers and flasks. Any glassware with such cracks should be properly disposed of

immediately.


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Chapter IV

RESULTS AND DISCUSSION

A. Chemical Testing

These are the results of the chemical tests which were performed on the water samples

before and after they were poured through the filters. Concentrations for the first table are

measured in micromolar (M), while the unit of milligrams per liter (mg/L) is used in the second

table.

Lead Concentrations

Location of Sample Before Treatment After Treatment Percentage ofRemoval

Coast 0.735 mg/L 0.694 mg/L - 5.58 %

Off-shore 0.583 mg/L 0.531 mg/L - 8.92 %

Deep shore 0.534 mg/L 0.487 mg/L - 8.80 %

Dissolved Inorganic Nitrogen, Nitrite and Ammonium, and Phosphates

Sample Nitrate

Nitrite and

Ammonium Phosphates

Before

Average 0.10 M 8.00 M 0.92 M

Standard Deviation 0.16 M 1.35 M 0.34 M

After

Average 0.11 M 7.82 M 0.90 M

Standard Deviation 0.14 M 1.23 M 0.31 M

As seen in the data illustrated above, the lead concentrations of the samples decreased by

a significant amount in all of the samples. Additionally, the nitrate is the only factor which

increased in its value among the variables and the standard deviation decreased, which means the


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values became more consistent. However, the other variables did not change as drastically as the

nitrite content of the samples.

B.Physical Testing

These are the results of the physical tests performed on the water samples. For the

samples tested before the treatment, the average pH was calculated from the three trials to be

compared:

pH Test

Location of Sample Before Treatment After Treatment

Coast 6.33 4

Off-shore 7.67 4

Deep shore 6.00 4

Temperature Test

Sample Trial 1 Trial 2 Trial 3Coast 28.3C 27.8C 28.3C

Off-shore 28.9C 27.8C 30.0C

Deep shore 28.7C 28.3C 27.2C

The results show a drastic change in the pH of the samples, which all became acidic after

the exposure of the water samples to the treatment process. On the other hand, the temperature

readings show that the offshore part of the bay is generally warmer in comparison to the other

parts of the bay.


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Other observations

When filtering the water samples through the filter processes, the resulting water seemed

to be hazy compared to that of the original samples, especially after they were poured through

the sand. Furthermore, the chitin after the acid treatment became more brittle, and had a less

vibrant orange color compared to normal crab shells. Furthermore,

Analysis of Data

Chemical Tests

The results show that chitin and potassium alum are effective in the removal of lead

concentrations in the water. In general it showed a decrease in the concentrations ranging from

approximately 5-9%. Despite having the highest concentration of lead, the water from the coast

reduced the least percentage of contaminants out of the three areas.

As seen in the graph, the overall trend of the lead concentrations as the depth increases is

clearly lower. As it was stated in Chapter II, chitin was mentioned to have good complexation

properties especially with transition and post-transition metals. Furthermore, lead, being a metal,

Coast Offshore Deep shore

Before 0.735 0.583 0.534

After 0.694 0.531 0.487

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Concentrations(inmg/L)

Lead Content of Water


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means that it has high electronegativity. Consequently, this means that it will gain electrons more

easily, and because of this electronegativity, lead will have a greater attraction towards the chitin,

and the complexation and adsorption properties of chitin contributed to the further removal of the

lead content of the water samples. Furthermore, the potassium alum helped by bonding the

impurities, with the lead and settled them at the bottom.

The factors of nitrate, nitrite and ammonium, and phosphates were measured in order to

determine the condition of the bay at the time of the collections. According to Mr. Garcia, the

data suggested that Manila bay was highly eutrophicated and was due to the high concentration

of nitrogen in the bay. This might be due to the fact that Manila bay is highly polluted, with not

just lead, and the pollution consequently caused it to get too much nutrients. After the treatment,

along with the reduction of the lead content, the contaminants also decreased but only in small

amounts.

Physical Tests

In terms of the pH, the samples clearly became more acidic after the water samples were

treated. In chapter II, it was mentioned that one of the solutions that companies use to remove

metals was by changing the pH of the solution and precipitating out the metal after treating it

with other chemical. The changes the chitin brought onto the pH of the samples combined with

the properties of the potassium alum in treating the water, seemed to have contributed in

reducing the lead content of the samples.


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On the other hand, in comparison to the other areas of the bay, the offshore part was seen

to have the highest temperature in general among the areas tested. For this, many factors could

have affected how the temperature behaved, especially current weather patterns, and other

outside factors which can change the temperature of the water before the collection process. The

reason why the temperature is not collected for samples after exposure to the filter process is that

by that time, the temperature will already be controlled and will no longer exhibit readings that

reflect Manila bay in its natural state.


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In the results given, the concentration of lead decreases as the depth increases. In the

findings, the offshore showed the greatest percentage of reduction of contaminants. Along with

all the other data given in the experiment, the researchers conclude that chitin and potassium

alum are both feasible ways to reduce the lead content of seawater, particularly that of Manila

Bay.

Recommendations

For the filter process, it is recommended to have three trials as well to be able to properly

compare the data received. Only one sample per location was used because of the lack of time

and the availability of the testing center could not allow the researchers to do so. Furthermore, if

one is only focused on getting the lead content of the water, it is optional to get the data for

nitrate, nitrite and ammonium, and phosphate content, one may use it if he/she wants to relate the

conditions of the pollution of the water to the metal concentration.

Since chitin and potassium alum were proven to be able to reduce the lead contaminant in

this study, more research should be given in finding other feasible materials which are suitable

for removing heavy metal contaminants (e.g. tilapia scales).

Finally, future experiments should also be done for other metals like cadmium, zinc,

chromium, etc. in order to determine if chitin and potassium alum will become feasible in

removing such metal contaminants.


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BIBLIOGRAPHY

20 Interesting and Useful Water Facts. AllAboutWater.org. 1 Dec. 2012

.

Biological Oxygen Demand (BOD)Overview. 2 Dec. 2012 < http://www.polyseed.com/mis

c/BODforwebsite.pdf>.

Gorme et. al. The Water Quality of the Pasig River in the City of Manila, Philippines: Current

Status, Management and Future Recovery. [CERIC]

. 2010. 30 Sept. 2012 .

Helmenstine, Anne Marie. What is Alum?. About.com. 30 Nov. 2012

Impacts of Ammonia. Colorado State University. 20 Feb. 2013

.

Jacinto, G.S., Azanza, R.V.,Velasquez, I.B. and Siringan, F.P.(2006)."Manila Bay:

Environmental Challenges and Opportunities" in Wolanski, E.(ed.) The Environment inAsia Pacific Harbours. pp. 309-328, Dordrecht, The Netherlands: Springer, 2006

Johnson, Pauline D. et al., (2008). Enhanced Removal of Heavy Metals in Primary Treatment

Using Coagulation and Flocculation Water Environment Research,pp. 472-476

Krantz, D, & Kifferstein, B. (1996). Water pollution and society.

Lontoc, Vir Angelo et al., Water Purifying Abilities of Natural Filters, Puritabs, and Boiling.

Bato Balani for Seniors, 2003, Volume 23 pp. 16-18

Manila Bay: Refined Risk Assessment. PEMSEA Technical Information Report No. 2004/01.

Global Environment Facility / United Nations Development Programme / InternationalMaritime Organization Regional Programme on Building Partnerships in Environmental

Management for the Seas of East Asia (PEMSEA). 2004. 1 Dec. 2012

.
http://chemistry.about.com/od/moleculescompounds/f/What-Is-Alum.htmhttp://chemistry.about.com/od/moleculescompounds/f/What-Is-Alum.htm


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Muzzarelli, R.A.A. & Tubertini, O. (1969). Chitin and chitosan as chromatographic supports

and adsorbents for collection of metal ions from organic and aqueous solutions and

seawater. Talanta,16(12), 15711577.

Nielsen, Danielle. The Importance of Rewriting Storm Water Regulations Water Pollution.

21 Feb. 2013 .

Nitrate and Nitrite. 20 Feb. 2013 .

An Overview of Manila BayManila Bay Costal Strategy, 2002. 25 Nov. 2012

.

Peiselt da Silva, K.M. & Pais da Silva, M.I. (2004). Copper sorption from diesel oil on chitin

and chitosan polymers. Coll. and Surf. A: Physicochem. Eng. Aspects,237(13), 1521.

Phosphorus. City of London, Ontario Canada. 20 Feb. 2013

.

Precautions. Clackamas Community College. 30 Nov. 2012

.

Rangel-Mendez, Jose Rene, Barrios, Vladimir Alonso Escobar and Davila-Rodriguez, Jose Luis

(2010. Chitin Based Biocomposites for Removal of Contaminants from Water: a Case

Study of Fluoride Adsorption in Magdy Elnashar (Ed.Biopolymers, ISBN: 978-953-307-

109-1, Rijeka, Croatia: InTech, 28 Sept. 2010

Rivera, Blanche. UN study says Manila Bay worth P8 billion.Inquirer. 20 June 2006. 2 Dec.

2012 .

Saravanan, et al.,(2012. Sorption studies on heavy metal removal using chitin/bentonite

biocomposite., 2012 Elseiver B.V.,

Sustainable Development and Management of Manila Bay: A Focus on Water Quality.
https://sites.google.com/a/brvgs.k12.va.us/water-pollution/home/research-paperhttps://sites.google.com/a/brvgs.k12.va.us/water-pollution/home/research-paperhttp://www.emb.gov.ph/mbemp/dloads/mbcs%2002mvw.pdfhttp://dl.clackamas.cc.or.us/ch105-05/precauti.htmhttp://www.pinoyexchange.com/forums/showthread.php?t=261861http://www.pinoyexchange.com/forums/showthread.php?t=261861http://dl.clackamas.cc.or.us/ch105-05/precauti.htmhttp://www.emb.gov.ph/mbemp/dloads/mbcs%2002mvw.pdfhttps://sites.google.com/a/brvgs.k12.va.us/water-pollution/home/research-paperhttps://sites.google.com/a/brvgs.k12.va.us/water-pollution/home/research-paper


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PEMSEA. May 2006. 1 Dec. 2012 .

Water quality facts and statistics. UN WATER. 1 Dec. 2012

.

Wright, David A. and Welbourn, Pamela (2002). Environmental Toxicology.Cambridge

University Press, Cambridge, U.K.

Zhou D., et al., (2004) Cellulose/chitin beads for adsorption of heavy metals in aqueous

solution. Wuhan University, China.

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