PDF_ Nopal as Natural Coagulant

European Joint Master in Water and Coastal Management 2009

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APAPAPAPPPPPLICATION OF A NATURAL COAGULANT LICATION OF A NATURAL COAGULANT LICATION OF A NATURAL COAGULANT LICATION OF A NATURAL COAGULANT

DERIVDERIVDERIVDERIVEEEED FROM Opuntia sD FROM Opuntia sD FROM Opuntia sD FROM Opuntia sssssp. IN WATER TREATMENTp. IN WATER TREATMENTp. IN WATER TREATMENTp. IN WATER TREATMENT

bybybyby

José Miguel García MorenoJosé Miguel García MorenoJosé Miguel García MorenoJosé Miguel García Moreno

European Joint Master in Water and Coastal ManagementEuropean Joint Master in Water and Coastal ManagementEuropean Joint Master in Water and Coastal ManagementEuropean Joint Master in Water and Coastal Management

March 2009 March 2009 March 2009 March 2009


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Research GuidesResearch GuidesResearch GuidesResearch Guides

Dr.DanieDr.DanieDr.DanieDr.Daniel Prats and Dr.Pedro Varó l Prats and Dr.Pedro Varó l Prats and Dr.Pedro Varó l Prats and Dr.Pedro Varó

Research coResearch coResearch coResearch co----GuideGuideGuideGuide

Dr. Angel Del Valls Casillas Dr. Angel Del Valls Casillas Dr. Angel Del Valls Casillas Dr. Angel Del Valls Casillas

Author has been financially supported by Erasmus MundusAuthor has been financially supported by Erasmus MundusAuthor has been financially supported by Erasmus MundusAuthor has been financially supported by Erasmus Mundus


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This Master Thesis was carried out in the Water Institute and The

Chemical Technology Centre of Alicante University (UA), as part of

the master program “Erasmus Mundus: Water and Coastal

Management” of Cadiz University. The author was supported by

Erasmus Mundus and Spanish Government scholarships.


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STATEMENTSTATEMENTSTATEMENTSTATEMENT

I heI heI heI herererereby declare that this work has been carried out by me aby declare that this work has been carried out by me aby declare that this work has been carried out by me aby declare that this work has been carried out by me and the thesis has been composed by nd the thesis has been composed by nd the thesis has been composed by nd the thesis has been composed by

me and has not been submitted for any other degree or professional qualification.me and has not been submitted for any other degree or professional qualification.me and has not been submitted for any other degree or professional qualification.me and has not been submitted for any other degree or professional qualification.

This work is presented to obtain a masters degree in water and coastal management.This work is presented to obtain a masters degree in water and coastal management.This work is presented to obtain a masters degree in water and coastal management.This work is presented to obtain a masters degree in water and coastal management.

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José Miguel García MorenoJosé Miguel García MorenoJosé Miguel García MorenoJosé Miguel García Moreno


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D. ANGEL DEL VALLS CASILLAS, Profesor Titular del Departamento de Química-Física de

la Universidad de Cádiz , D DANIEL PRATS RICO, Director del Instituto del agua de la

Universidad de Alicante y PEDRO JOSE VARÓ GALVÁN , como sus directores.

HACEN CONSTAR:

Que esta Memoria, titulada APLICATTION OF A NATURAL

COAGULANT DERIVADED FROM OPUNTIA SP. IN

WATER TREATMENT, presentada por D. José Miguel García

Moreno, resume su trabajo de Tesis de Master y, considerando que

reúne todos los requisitos legales, autorizan su presentación y

defensa para optar al grado de Master en Gestión del Agua y

Costera.

Cádiz, Mayo de 2009

________________________________ ________________________________

Dr. Daniel Prats Rico Dr. Pedro José Varó

------------------------------------------------------------------------------------------------------------------------------------------------------------

Dr. Ángel Del Valls Casillas


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ACKNOWLEDGEMENTSACKNOWLEDGEMENTSACKNOWLEDGEMENTSACKNOWLEDGEMENTS

I am deeply indebted to Pedro José Varó Galvan, Doctor of Chemical Engineering at Alicante

University, without his benevolent commitment and constant support this project would not

have been possible.

Also thank to Dr. Daniel Prats Rico, director of water Institute of Alicante University, for

investing trust in me and for providing all the necessary materials for the experimental work.

My deepest gratitude to Dr. Ángel Del Valls Casillas and Prof. Alice Newton, coordinators of

this master program for allowing me to participate in this adventure.

Thanks to all the colleagues of Alicante University, who I have annoyed this year with a thousand

questions, doubts, reflections and favours. Thanks to friends’ for helping me and thanks to

everybody with whom my path has crossed at this great University.

My best wishes go to the Master colleagues; all the experiences we have shared throughout this

year have been very enriching

Thanks to Carmen Lopez the real motor of this Master.

Last thank to my Parents for being as they are, and for shaping me as I am; thanks to my

brothers, thanks to my girlfriend for enduring this with me and of course thanks to Pachamama

for showing me my way in life.


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SYNOPSISSYNOPSISSYNOPSISSYNOPSIS

The following study is an experimental approach to the possible uses of Opuntia ssp. for water

treatment.

In this investigation the properties of a dry and liquid extracts of Opuntia Ficus Indica were

evaluated as primary coagulant and coagulant aids in synthetic and “true” water samples by jar

test method.

There is ancestral evidence for the use of several cacti for water clarification. Recent authors have

investigated the properties of Opuntia ssp., obtaining excellent results.

Opuntia plants have an enormous potential for application on both local and commercial levels,

as a cheap alternative with large socioeconomic benefits.

The biological characteristics of this plant allow it to be applied for the integration of water

management, environmental control and economic development of arid areas.

Is necessary a thorough research of its coagulation properties and the compromise of institutions

to develop this new ecological alternative able to reduce the actual social, economic and

environmental disequilibrium.


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TABLE OTABLE OTABLE OTABLE OF CONTENTSF CONTENTSF CONTENTSF CONTENTS

Contents Contents Contents Contents Page No Page No Page No Page No....

Aim of the work Aim of the work Aim of the work Aim of the work 9999

1. 1. 1. 1. ---- Introduction Introduction Introduction Introduction 10 10 10 10

1.1. -The natural resource (Opuntia ficus indica) 14 14 14 14

1.2. - Nopal as natural coagulant 18181818

2. 2. 2. 2. ---- MethodologyMethodologyMethodologyMethodology 21212121

2.2. - Coagulant extraction 21 21 21 21

2.3. - Water model 23232323

2.4. - Work method 24 24 24 24

2.5. - Experimental objectives 26 26 26 26

3. 3. 3. 3. ---- Results Results Results Results 27 27 27 27

3.1. - Turbidity removes 27272727

3.2. - Potabilization parameters remove 33333333

3.3. - Waste water parameters remove 34 34 34 34

4. 4. 4. 4. ---- Discussion Discussion Discussion Discussion 36363636

5. 5. 5. 5. ---- Conclusion/The future Conclusion/The future Conclusion/The future Conclusion/The future 41 41 41 41

6. 6. 6. 6. ---- References References References References 43 43 43 43

7. 7. 7. 7. ---- Scientific paperScientific paperScientific paperScientific paper 48 48 48 48

8888---- Appendix Appendix Appendix Appendix 60 60 60 60


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Aim Aim Aim Aim of the studyof the studyof the studyof the study

The principal objective of this Master project is evaluating the properties of nopal mucilage in

the water treatment.

The research focuses on:

- Study the qualities of two different Opuntia ssp. extracts as primary coagulants and

flocculants aids in synthetic waters experiments and in drinking and waste water samples.

- Encouraging about the use of Opuntia ssp. in an integrated develop project for water

management and socioeconomic grow of arid places around the world.


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1.1.1.1.----INTRODUCTIONINTRODUCTIONINTRODUCTIONINTRODUCTION

One of the more important Challenges of the modern World is to make human development

economically and environmentally compatible; directing their efforts towards social equality.

Water is vitally important in this process because it is used in a variety of ways at many different

levels, producing social, spatial and organizational problems.

Growing population, increase in economic activity and industrialization has not only created an

increased demand for fresh water but also resulted in severe misuse of this natural resource.

According to a survey conducted by UNEP (2º United Nations World Water Development

Report ), 20% of the world’s population lacks access to safe drinking water and 50% of the

world’s population lacks access to safe sanitation. Polluted water is estimated to affect the health

of about 1200 million people and contribute to the death of 15 million children under the age of

five every year.

Water resources all over the world are threatened not only by over exploitation and poor

management but also by ecological degradation.

With increased industrial growth and urbanization, the volume of domestic and industrial

effluent, agricultural waste and urban runoffs is steadily growing. Water bodies have an inherent

capability to dilute the pollutants which enter into the system, however, the indiscriminate

dumping of untreated sewage and chemical wastes directly into rivers, lakes, and drains have

made these water bodies unable to cope up with the pollutant load.

It is necessary to recognise water as a limited resource and to encourage the application of clean


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technologies which reduce negative environmental impact and assist in the development of poor

countries.

In this sense the use of biological methods for water treatment is a fair and efficient way to

support the ecologic control of residues and increase access to drinking water in rural places.

Natural water treatment systems are designed to take advantage of the physical, chemical, and

biological processes that occur in the natural environment when water, soil, plants, micro-

organisms and the atmosphere interact (Metcalf & Eddy 3º Edition).

Natural treatment systems include, among others: land treatment, floating aquatic plants,

constructed wetlands, solar irradiation, natural coagulants, microbiological degradation and active

carbon.

The investigation and development of new ecofriendly technologies are being implemented in

both small and large scale ventures.

Natural materials have been used in traditional domestic water treatment for centuries. Many of

these plants and other biological substances have been investigated as natural coagulants, proving

their capacity to reduce turbidity, co-precipitated metals and pathogen reduction (Table 1).

Unfortunately the application of these new technologies is limited to NGO projects and pilot

plants. There is not yet a clear interest from companies and government for the commercial

development of these methods.

Of all the plant material investigated, the seeds of Moringa oleifera are one of the most effective

sources as a primary coagulant for water treatment (Sutherland, 1994, Ndabigengesere, 1998).


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Species Species Species Species Natural CoagulantNatural CoagulantNatural CoagulantNatural Coagulant ReferenceReferenceReferenceReference Opuntia ficus indica Mucilage Kirchmer Cliff J. 1975

Marine algae All Hauc A. 1964

Corn, potatoes , yucca, wheat Starch of Seed or Roots Gyulla Marrtton 2001

Beans Seeds Bulusu K.R.1974

Agave Saponins M. Madrid 2007

Acacia (samaena saman) Sap G.Gonzales et al. 2006

Moringa oleifera Seeds Sutherland, G. et all, 1994 , Ndabigengesere, et all 1998

Calotropis Procera Latex Okonko 2007

Cactus latifaria Mucilage Diaz A. et al.1999

Nirmali Plant Seeds Bulusu 1965

Microorganims

Variable Al-Shahwani, M.F et all, 1989

Kurane, R., Takeda, K. 1986

Table 1. - Natural coagulants review in bibliography

This tree is native of Northern India but is actually distributed throughout tropical climates

around the world. The traditional use of M. oleifera seeds for domestic water treatment is

common practice in rural areas of some developing countries. The dried seeds are shelled, crushed

and sieved. A seed powder is mixed with turbid water that produces positively charged water-

soluble proteins. These proteins bind to the suspended particles forming large agglomerated

solids, which then sink.

Pilot scale and full-scale water treatment plants using M. oleifera seeds are successfully operating

in Malawi. Also NGOs are implementing “Moringa sand filters” successfully for household

water potabilisation in India and Africa, helping to improve the quality of water and the lives of

local communities (RAWDP).

Synthetic Coagulants also act to electrostatically distort the colloids suspended in water,

producing its precipitation and consequently removing turbidity. Aluminium is the coagulant


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used most widely in water and wastewater treatment globally. The annual world production of

aluminium approached approximately 28 million metrics in 2003 (AAC, 2005). Spain annually

consumes about 200,000 tonnes of chemical coagulants involving an outlay of 30,000 million

euros (Kemitra report, Spanish Ministry).

More than the economic cost, this enormous volume of chemical compounds involves a high cost

in different ways; toxicological problems of treated sludge, the energy consumption for its

synthesis and distribution, the economic dependence of developing countries; and most seriously,

problems for human health (Normatov I. , 2002). Studies of different scholars advise the risk of

introducing aluminium into the environment and report that the remnants of alum after

coagulation may induce Alzheimer’s disease (Letterman, 1990, McLauchlan D. R., 1995).

In other ways, biocoagulants are a renewable resource; have a low cost production, are available

locally, have possibilities of industrial and local application, are innocuous and contribute to rural

growth (Biron M. 2003).

However, the use of biocoagulant is very limited; the tendency towards sustainable development

and social equilibrium make necessary the gradual abandonment of synthetic products and the

generalist the use of natural coagulants (Chen YC & Xiao J., 1997).

Only through agreement between public organisations and private companies is it possible to

make these changes.


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1.1.1.1.1.1.1.1.----The natural resource (Opuntia ssp.)The natural resource (Opuntia ssp.)The natural resource (Opuntia ssp.)The natural resource (Opuntia ssp.)

The genus opuntia is the largest under the Cactaceae family with more than 250 endemic species

from Central America. The Opuntia ssp. chosen as natural coagulant source for this project was

Opuntia ficus indica, also named chumbera in Spain, cactus pear in North America and nopal in

Mexico.

Picture 1.- Opuntia ficus indica

The nopals are succulent plants which grow up to 3-5 metres, many times in a dense and tangled

structure. It´s recognized by its green thick long pads that look like sports rackets. They grow

one linked to the next and can be considered as both leaves and stalks. The plant surface is

covering by spines which help to conduct water, reduce water loss, and protect the succulent

tissue from herbivores and other predators (Mondragon C., 1995).

Nopals are strong plants with not much water and nutrient requirements, are highly adaptable


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and propagate easily. After the American conquest, it was very treasured by explorers for its

properties and introduced to Europe, Asia, Australia and Africa where it rapidly adapted to

various environments (Barbera, G. et all, 1992).

Opuntia is the most widely distributed genus of cacti, Species of this genus are the most northern

ranging of cacti, occurring to 56° Northern latitude in British Columbia and Canada (Areces A.,

2004) and are also some of the most frost-tolerant cacti.

Different cultures know different uses for this plant, being especially appreciated for its

organoleptic and medicinal properties. In developing countries where it is present, nopal

represents an important economic and nourishing resource.

The fruit, named higo chumbo in Spain and Tuna in Mexico, is very rich in sugars and typically

is dried for use during the winter. Its uses include: syrup (“tuna” honey), fermented and un-

fermented drinks and also the skin as a food colouring, even its seed can be ground and used as

flour.

The use of Opuntia as a vegetable crop is less popular. Only the young leaves of the nopal

(nopalitos) are appreciated as a vegetable in Mexico for its nutritional aspects. They are typically

cooked as a green vegetable or marinated as part of a salad. Nopal leaves present a general

composition of 87% water, 1% protein, 0.1% fat, 1.3% ash, 1.1% crude fibre, and 5.4%

carbohydrates (Loayza D.et all, 2007) being also an excellent forage for livestock in arid climates

(E. Órnelas, 2007).

Moreover in Mexico and South America it is used to treat numerous maladies and researchers are

interested in its medicinal use.


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Preparations of nopal are variously considered anti-diabetic, anti-inflammatory, analgesic,

galactogogue, hypoglycemic, antiviral and anti-oxidant. Preparations have been used to regulate

weight, blood sugar, increase fibber intake and facilitate childbirth and are used in the treatment

of asthma, fatigue, liver injury following alcohol abuse, diarrhea, dysentery, dyspnoea, gastritis,

colitis, gonorrhoea and syphilis, hypercholesterolemia, measles, nosebleeds, obesity, snakebite,

sore throat, virginities, and inflammation of the eyes, among other disorders (Feugang, J. M,

2006, Duke, J. A. et all, 2002, Martínez, M, 1999).

The wide variety of uses involves a big industry for nopal commercialisation. This market of

nopal moves millions of euros and produces millions of tonnes for different applications as food,

medicines, cosmetics, pigments and as a paint additive.

Table 2. - Alimentary products, subproducts and additives obtained from tunas and leaves of nopal, Source: Saenz 2000; Corrales and Flores 2003.

Within the nopal industry the tuna market is the larger; in 2000 it obtained a volume of

973,400 tonnes. Mexico provides 44% of the total, Tunisia 13%, Argentina 8%, Italy7% and

Sub products Products

Tuna Leaves Tuna and Leaves

Juice and nectars Juice Seed oil

Jam , gel and jelly Pickle and brine Leave mucilage

Fruit and dried sheet Jam and jelly Pigments from peel and fruit

Edulcorant Flour Dietary fibber from leaves

Alcohols , wine and vinegar Alcohol

Canned fruit Compote

Fruit and pulp freezer Sauce

Nopalitos


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South Africa 4% along with over 30 producing countries. The area cultivated around the world

is estimated to reach 1,114,000 hectares (SAGARPA).

All the time more countries are integrating the nopal in different ways and uses, for commercial

application or for internal supply.

Picture 2. - Some commercial products made with nopal

The nopal requires only that it be planted and left to grow on its own, without fertilizer or

watering. The high efficiency of converting water in nopal biomass produces a high productivity

value. For example a nopal fruit crop can generate production of 20 tonnes per hectare annually

and produce up to 50 tonnes of dry material with the potential use as a natural coagulant.


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Picture 3.- Nopal leaves ready to grown

The biological characteristics of nopal and the socioeconomic repercussions of its possible uses in

water treatment make it an excellent candidate for this study.

1.2.1.2.1.2.1.2.----Nopal as Natural Coagulant.Nopal as Natural Coagulant.Nopal as Natural Coagulant.Nopal as Natural Coagulant.

Historically, there is evidence to suggest the use of cactus mucilage for water clarification.

Opuntia ssp. and cactus latiferi mucilage respectively were used by Chilean and Venezuelan

indigenous peoples for centuries to remove pathogens and turbidity of surface water (Diaz A. et

all.1999, Sutherland, J.P. et all 1990).

The ability of cactaceae to retain water under such unfavourable climatic conditions is due to the

water-binding capacity of mucilage, which involves the consequent coagulation properties (Mindt

L. et all, 1975). When it is mixed with water or other fluids, forms a sticky and slippery gel

which has the capacity to catch the suspension particles and carry them to the bottom.

Experiments suggest that the coagulation mechanism of opuntia ssp. is not by charge


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neutralization like metallic salts, instead it occurs by adsorption and bridging mechanisms (Miller

S. et all, 2008).

Mucilage is a slimy storage substance mainly in the parenquima tissue of leaves. It is composed of

55 sugar residues, mostly L-arabinose, D-galactose, L-rhamnose, D-xylose, and galacturonic acid,

although proportions can vary with different factors such as age, ambient conditions, species or

extraction method (Amin E.S. et all,1970).

Nopal has been considered a potential source of an industrial hydrocolloid gum. Also the

mucilage has been extracted and evaluated as dietary fibre, digestive, paint additive or emulsion

agent (Saenza C. et all,2003, Sáenz, 1997, Garti N. , 1998)

First coagulation experiments were carried out in 70s but the promising results fell into oblivion

(Kirchmer, Cliff J., 1975). In the last few years different scholars have returned to this research

and the nopal coagulant properties are starting to be revealed (Jingdong Zhang et all ,2005, , N.

Quezada,2004 , López, E., 2000, P. Miretzky 2007, Young K. et all, 2006).

Some considerations about this research are described below:

-In comparative experiments with Moringa oleifera and Al2 (SO4)3, nopal extract presents a

similar capacity to remove turbidity in synthetic and real waters.

-Temperature has slight influence on the coagulation effect of nopal.

-The coagulation activity of Nopal is greatest in basic Waters .

-Nopal coagulation produces significant reductions of metals (As, Pb, Fe, Al, and Mg).


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-Possible DOQ and coliform removal.

Results suggest that nopal has a great potential for water treatment. It is necessary to undertake

deep investigation for a better understanding of the coagulation qualities of nopal and in this way

to develop cheap and efficient commercial substances which can minimise the use of synthetic

coagulants.


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2.2.2.2.----METHODOLOGYMETHODOLOGYMETHODOLOGYMETHODOLOGY

The effectiveness of opuntia ssp. as a primary coagulant and flocculant aid in water treatment was

compared with Al2 (SO4)3 by jar test method. Properties of the dry and liquid extract obtained

from fresh nopal leaves and were tested in four different water models. This water models were;

Kaolin clay suspension, a pre-potable water source and industrial and urban wastewaters.

Turbidity was the parameter measured to obtain the optimal work dose and calculate coagulation

activities. From the supernatant of each optimal jar other key parameters were measured relating

to every water model. Data collected was used to calculate the removal efficiencies of each

parameter.

The present work was performed in the laboratories of the Water Institute and the Chemical

Technology Centre of Alicante University.

2.1.2.1.2.1.2.1.----Natural coagulant extractionNatural coagulant extractionNatural coagulant extractionNatural coagulant extraction

Nopal mucilage extraction is abundantly reported in the bibliography . It is possible to obtain the

pure mucilage using organic solvents; however the data states which easy extraction methods also

obtain excellent results of turbidity removal (Jingdong Zhang et all 2005). Natives used the

water after boiling fresh opuntia leaves for water clarification, in our case the mucilage was

extracted by maceration and desiccation.

A Liquid extract is more easy and fast to extract but has a short life span and therefore could

possibly be used for a low scale application; on the other hand the dry extract needs an oven to


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control the temperature but is easier to transport and conserve and therefore its character is suited

to a more industrial application.

Leaves of Opuntia ficus indica were collected around the University of Alicante and two different

extracts were obtained through the following methods:

- Dry Extract (DE)

Dry coagulant was prepared by hand cutting of fresh nopal leaves. The skin and other superficial

tissue was scored and only the internal mucilaginous component was used. It was cut into strips

approx. 1cm in width and dried in an oven at 65 ºC over 72 hours. Samples were then ground in

a coffee grinder to obtain particles with less than 300 µmetres diameter. This white powder was

stored at 4ºC preserving its properties for more than two months.

The output was 2% of dry powder per 100 grams of fresh leaves.

- Liquid Extract (LE)

Gummy coagulant was prepared by maceration. Entire leaves were cut into strips 1cm in width

and mixed with the same volume of tap water. After 24 hours it was filtered through a nylon

material to obtain a transparent slime soluble in water.

The liquid was stored at 4ºC preserving its properties for no more than 3 days.

The output was 200ml of coagulant for every 100 grams of fresh leaves.


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2.2.2.2.2.2.2.2.----Water modelWater modelWater modelWater model

Jar test experiments were realised with four different water models:

-Synthetic turbidity models were prepared by the addition of kaolin clay (KAOLIN CH-N PRS,

3TQ) into tap water to provide a turbidity of 75 and 200 NTU. Tap water characteristics are

collected in appendix 1.

-Real waste water was recollected from the entry of Benidorms and Elda water treatment plants.

Both residual Waters were collected after the sieve and before any physicochemical treatment.

Water samples were stored at 4ºC for a maximum of two days before the experiments.

Elda waste water treatment plant receives a high industrial charge while the Benidorm plant

receives a higher urban charge, which implies that both water samples had very different

physicochemical characteristics.

-A potable water source was collected from Amadorio reservoir. This is situated in the

Villajoyosa municipality, has a surface area of 103 hectares and a capacity of 16 hm³ with

recreational and cropping use.

The characteristics of “true” water models follow:

Elda wastewaterElda wastewaterElda wastewaterElda wastewater ValueValueValueValue Turbidity 235 NTU

Conductivity 3,11 mS

pH 7,81

Suspension Solids 754 mg/l

DQO 1095 mg/l

DBO 507 mg/l

Benidorm wastewaterBenidorm wastewaterBenidorm wastewaterBenidorm wastewater ValueValueValueValue Turbidity 106 NTU


pH 7,75


DQO 460 mg/l

DBO 293 mg/l

Amadorio Reservour Amadorio Reservour Amadorio Reservour Amadorio Reservour ValueValueValueValue Turbidity 13 NTU

Conductivity 485 µS

pH 8,63

Fecal Streptococcus 110 UFC /100ml

Fecal Coliforms 1920UFC/100ml


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2.3.2.3.2.3.2.3.----Work MethodWork MethodWork MethodWork Method

The experimental method to measure the efficiency of nopal extracts for water treatment in the

different water models was designed based on the removal of turbidity.

The Residual turbidity tests were carried out according with ASTM jar test standard method.

Coagulants were added to six water samples (1000 ml) and stirred at 125 rpm for 2 minutes and

next the speed was reduced to 70 rpm for 20 min. After the agitation, stirring was stopped and

the samples would stand for 20 min.

Turbidity of the supernatant were recorded in triplicates and measured using a calibrated

turbidymeter.

In each jar test experiment one of the six jars received no treatment, serving as a control for

comparison of the turbidity reduction for all other jars. Coagulation activity was calculated using

the equation defined in the bibliography (Okuda 2001):

(Residual turbidity control - Residual turbidity sample)

Coagulation activity = -------------------------------------------------------------- x 100

(Residual turbidity control)

Dry extract, liquid extract and Aluminium were compared as primary coagulants.

The dry extract was previously diluted in distilled water for a correct mix.

For flocculation tests were aided a low optimal dose of aluminium and the nopal extracts at the

same time before starting the agitation.


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A total of 25 experiments analysed the flocculation and coagulation properties of nopal in

synthetic and real water without ph correction.

The water samples analysed in experiments had an approximate temperature of 20 ºC.

In “true” water experiments only the supernatant of the jar with the more effective reduction of

turbidity was used to measure the key parameters of every water model. The key parameters for

wastewater were DQO, DBO and Suspension Solids; and for pre-potable water were fecals

Streptococcus and fecals Coliforms.

Next are collected the techniques and instruments used for the analysis of parameters:

DQO-----------------------Kit LCK 114 CSB/COD/DCO, HACH LANGE S.L.U. Appendix 3.

DBO----------------------- Biochemical Oxygen Demand sensor set determination systems, Velp

Scientifica. Appendix 4.

Microorganisms-----------Chromocult Coliform Agar ES (Enhanced Selectivity), Merck

Microbiology Manual 12th Edition. Appendix 5.

Suspension solids---------- APHA-AWPCF 2540 Normalized methods for analyses of drinking

and residual water, Díaz de Santos, Madrid (1992).

pH--------------------------CRISON basic 20

Conductivity-------------- CRISON micro CM 2200

Turbidity------------------ Merck turbiquant 1500 IR


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2.4.2.4.2.4.2.4.----Experiment ObjectivesExperiment ObjectivesExperiment ObjectivesExperiment Objectives

-Obtain optimal work dose and coagulation activities in every water model for both nopal

extracts.

-Determine the flocculation efficiency of nopal in the interaction with aluminium sulphate.

-Analyse the key parameters for every water model and determine the potential of both extracts

for possible small and large applications.


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3.3.3.3.----RERERERESULTSSULTSSULTSSULTS

3.1.3.1.3.1.3.1.----Turbidity removesTurbidity removesTurbidity removesTurbidity removes

The efficiency of turbidity remove at optimal dosages of both extracts in each water model is

presented in next table.

Table 3.Turbidity removal of water models

The turbidity reduction was approx. 90% and 75% in kaolin synthetic suspensions and pre-

potable water samples respectively. In residual water the output was dependent on the type of

extract and the charge of the water. Liquid extract did not perform well and the maximum

turbidity reduction for the dry extract reached 40% when applied to urban wastewater.

Both extracts worked better as primary coagulant than as coagulant aid. The activity of

aluminium sulphate when applied together with nopal was increased by a maximum of 15%.

EffectEffectEffectEffect of of of of NopalNopalNopalNopal when when when when used to treat Sused to treat Sused to treat Sused to treat Synthetic waterynthetic waterynthetic waterynthetic water....----

The effectiveness of nopal to reduce the turbidity in synthetic clay solutions absent of natural

organic matter is similar to Aluminium sulphate.

Nopal as primary coagulant reduces the turbidity between 88% and 98%, however, as flocculant

aid; it does not produce a significant increase in the flocculation activity.

Turbidity Removal %

Synthetic water

75NTU

Synthetic water

200 NTU

Pre-potable

water

Urban

Wastewater

Industrial

Wastewater

Dry Extract 88 90 75 40 19

Liquid Extract 92 98 76 8 12

Control + Al 74 93 45 42 44

Dry Extract + Al 89 96 59 46 48

Liquid Extract + Al 96 98 42 38 4


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Turbidity removal in Synthetic water at Optimal dosages Turbidity removal in Synthetic water at Optimal dosages Turbidity removal in Synthetic water at Optimal dosages Turbidity removal in Synthetic water at Optimal dosages

0102030405060708090100

Dry Extract Liquid Extract Control + Al Dry Extract+Al

Liquid Extact+Al

Rem

oval %

Initial turbidity 75

Initial turbidity 200

Graphic 1.-Turbidity Removal at optimal dosages in synthetic water

The optimal work dosages of the dry extract (DE) are around 20 mg/l at initial turbidity of 200

NTU and 10 mg/l at 75 NTU. The optimal work dosage of liquid extract (LE) is 0,2 ml/l

with independence of the initial turbidity.

Low dosages of nopal coagulant tended to induce a strong initial reduction of turbidity whereas

higher dosages tended towards a gradual increase of turbidity in the profile.

Synthetic water treated with Liquid ExtractSynthetic water treated with Liquid ExtractSynthetic water treated with Liquid ExtractSynthetic water treated with Liquid Extract

0102030405060708090100

0 0,2 0,4 0,6 0,8 1

Concentration ml/l

Turbidity NTU

75 NTU

200 NTU

75 NTU + Al

200 NTU + Al

Graphic 2.-Turbidity reduction profile in synthetic water treated with LE


29292929

Only the liquid extract reduced the turbidity at values lower than 5 NTU; this is related to the

residual turbidity generated by the liquid extract. In Experiments incorporating tap water

(turbidity less than 0,1 NTU) and the optimal work dosages of nopal extracts, the levels of

residual turbidity increase at 6 NTU when water was treated with the DE; and at 2 NTU when

treated with the LE. The different residual turbidity of the extracts is related to the extraction

method.

Synthetic water treated with Dry ExtractSynthetic water treated with Dry ExtractSynthetic water treated with Dry ExtractSynthetic water treated with Dry Extract

0102030405060708090100

0 10 20 30 40 50 60

Concentration mg/l

Turbidity NTU

75 NTU

200 NTU

75 NTU + Al

200 NTU + Al

Graphic 3.-Turbidity reduction profile in synthetic water treated with DE

In the case of the LE the maceration process produced a pure mixture made up of water and the

mucilage without the presence of pigments or other plant materials. However, in the DE small,

but significant, amounts of cuticle and other tissues of the plant are present in the final dust.

These residues have dissolution problems and produce an increase in the basal turbidity level.

The nopal extract doesn’t produce conductivity changes in the solution but instead produces a

Light basify of the water.

The results are comparable with the previous kaolin experiments collated in the bibliography.


30303030

Effect of Nopal Effect of Nopal Effect of Nopal Effect of Nopal on potable water sourceon potable water sourceon potable water sourceon potable water source....----

Both extracts work better as primary coagulants than as flocculant aids.

When applied alone both extracts reduce the turbidity at levels less than 3 NTU, that is, they

concede with the levels permitted by the Spanish drinking water normative. In this case, the

optimal dosages were 0,3 ml/l and 6 mg/l for the LE and DE respectively.

Pre-potable water treated with liquid extract Pre-potable water treated with liquid extract Pre-potable water treated with liquid extract Pre-potable water treated with liquid extract

024

681012

1416

0 0,5 1 1,5 2

Concentration ml/l

Turbidity

Liquid Extract

Liquid Extract+ Al(1ppm)

Graphic 4. Turbidity reduction profile in pre-potable water treated with LE

As an aluminium aid, both nopal extracts do not produce a positive turbidity reduction.

Pre-potable water treat with Dry ExtractPre-potable water treat with Dry ExtractPre-potable water treat with Dry ExtractPre-potable water treat with Dry Extract

0

5

10

15

0 5 10 15 20 25 30 35

Concentration mg/l

Turbidity

Dry Extract

Dry Extract + Al(1ppm)

Graphic 5. Turbidity reduction profile in pre-potable water treated with DE


31313131

Effect of Nopal when Effect of Nopal when Effect of Nopal when Effect of Nopal when used to treat industrial wastewater.used to treat industrial wastewater.used to treat industrial wastewater.used to treat industrial wastewater.----

It is no possible to reduce the turbidity more than 20%. The best results arise when the DE is

applied as the primary coagulant. When combined with the aluminium the DE does not produce

any change from the initial turbidity reduction while the LE increases the turbidity until reaching

initial levels.

Industrial Wastewater treated with Liquid extractIndustrial Wastewater treated with Liquid extractIndustrial Wastewater treated with Liquid extractIndustrial Wastewater treated with Liquid extract

0

50

100

150

200

250

0 0,5 1 1,5 2

Concentration ml/l

Turbidity NTU

Liquid Extract

Liquid Extract Al (50ppm)

Graphic 5. Turbidity reduction profile in Industrial water treated with LE

Industrial Wastewater treated with Dry extractIndustrial Wastewater treated with Dry extractIndustrial Wastewater treated with Dry extractIndustrial Wastewater treated with Dry extract

0

50

100

150

200

250

0 50 100 150 200

Concentration mg/l

Turbidity NTU

Dry Extract

Dry Extract Al(50 ppm)

Graphic 6. Turbidity reduction profile in Industrial wastewater treated with DE

Although these experiments do not clearly remove turbidity, in all experiments the nopal

mucilage formed big flocs which quickly acquire an intense black colour.


32323232

Effect of Nopal Effect of Nopal Effect of Nopal Effect of Nopal when when when when were used to treat Urban wastewater.were used to treat Urban wastewater.were used to treat Urban wastewater.were used to treat Urban wastewater.----

Again, there exist clear differences in the behaviour of the DE and LE. The LE does not produce

any significant reduction of turbidity and increases it when applied together with aluminium.

In this case, the DE reduces the initial turbidity charge by almost half but does not produce

changes when is applied as a flocculant aid.

Urban wastewater treated with Nopal Liquid Extract Urban wastewater treated with Nopal Liquid Extract Urban wastewater treated with Nopal Liquid Extract Urban wastewater treated with Nopal Liquid Extract

0

20

40

60

80

100

120

0 0,5 1 1,5 2

Concentration ml/L

Turbidity

Liquid Extract

Liquid Extract + Al

Graphic 7.Turbidity reduction profile in Urban waste water treated with LE

Urban Wastewater treated with Nopal Dry Extract Urban Wastewater treated with Nopal Dry Extract Urban Wastewater treated with Nopal Dry Extract Urban Wastewater treated with Nopal Dry Extract

0

20

40

60

80

100

120

0 50 100 150 200

Concentraction mg/l

Turbidity

Dry Extract

Dry Extract + Ale

Graphic 8.Turbidity reduction profile in urban waste water treated with DE

The maximum turbidity remove was 40% when the DE was apply as primary coagulant in an

optimal dosage of 50 mg/l.


33333333

3.2.3.2.3.2.3.2.----PotabiliPotabiliPotabiliPotabilizzzzation parametersation parametersation parametersation parameters remove remove remove remove

To determine the potabilization properties of nopal were analysed its capacity to reduce the fecal

streptoccocus and coliform charge from the Amadorio reservoir.

Removal efficiences in Pre-potable waterRemoval efficiences in Pre-potable waterRemoval efficiences in Pre-potable waterRemoval efficiences in Pre-potable water

0

20

40

60

80

100

Dry Extract 6 mg/l

Liquid Extract0,4 ml/l

Control + Al(2ppm)

Dry Extract 6 mg/l + Al

Liquid Extact0,4 ml/l +Al

Sample

Rem

oval % Turbidity renoval

Fecal coliforms renoval

Fcal Streptococus renoval

Graphic 9.-Removal efficiencies of pre-potable water key parameters at optimal dose

The DE achieved the best results in reduction of the fecal streptococcus by 81% and the fecal

coliforms by 45%. The LE has a similar capacity to remove turbidity but the microbiological

reduction is more limited.

Fecal coliforms are reduced when Aluminium sulphate is applied; behaving similarly to both

nopal extracts although for the fecal streptococcus is less effective.

Once again, the combined effect of aluminium with the natural coagulant does not achieve the

results obtained when they are applied separately.

Any way the initial microbiological charge was too high and the results obtained are unacceptable

for the levels established by the Spanish drinking water normative.


34343434

3.3.3.3.3.3.3.3.----WasteWasteWasteWaste water water water water parameters remove parameters remove parameters remove parameters remove

To test the effectiveness of nopal in waste water treatment some key parameters of this process

were analysed (DQO, DBO, Suspended solids).

Although both residual waters have different characteristics, results can be interpreted as a whole.

Industrial Wastewater removal eficience at optimal dosagesIndustrial Wastewater removal eficience at optimal dosagesIndustrial Wastewater removal eficience at optimal dosagesIndustrial Wastewater removal eficience at optimal dosages

0

10

20

30

40

50

60

70

80

Dry Extract 50 mg/l


Control + Al(50 ppm)



Rem

oval %

Turbidity

DQO

Suspension solids

DBO

Graphic 9.-Removal efficiencies of key Waste water key parameters

In any case it was possible to reduce the DQO and DBO by more than 25%, however, the

suspended solids were notably reduced specially in the case of the DE treatment. Its achieved a

maximum output of 58% when were applied as primary coagulant for both waste water samples.

In general nopal work better with urban waste water than the industrial waters.

The LE is not successful in producing a clear reduction of the parameter analysed, even when is

applied together with aluminium produces a negative influence.


35353535

Urban wastewater removal eficiences at optimal dosagesUrban wastewater removal eficiences at optimal dosagesUrban wastewater removal eficiences at optimal dosagesUrban wastewater removal eficiences at optimal dosages

0

10

20

30

40

50

60

70

80

Dry Extract 50 mg/l


Control + Al(50ppm)

Dry Extract 50 mg/l

Liquid Extact0,4 ml/l

Rem

oval %

Turbidity

DQO

Suspension solids

DBO



36363636

4.4.4.4.----DISCUSSION DISCUSSION DISCUSSION DISCUSSION

The results obtained from this research suggest that nopal is a better primary coagulant than the

flocculation aid of aluminium sulphate. Suspension solids reduction is the key parameter in this

process and is related to the action mechanism of the nopal mucilage.

Miller S., 2008, demonstrated by z potential experiments that the nopal mucilage action

mechanism takes place through processes of adsorption and bridging; in place of the charge

destabilisation of synthetic coagulants. This supposes that the suspension solids can be caught

physically by the mucilage but the diluted solids which form a colloid can only be removed by

charge neutralization.

When the mucilage is rough inside the water sample, it disperses and the suspension solids adhere

to the mucilage surface, producing a posteriori co-precipitation and consequent removal of

turbidity. Also, in theory, these action mechanisms could combine with and therefore remove

some metals, parasites, microorganisms and other non diluted substances as current research

suggests.

After a minute of agitation the mucilage is dispersed into a multitude of fine strands which

become intensely coloured, depending on the sample; for kaolin suspension the mucilage becomes

a yellowish colour, in pre-potable water it becomes red and in wastewater, black.

There is no clear relation between the colour strain and the turbidity reduction. In the case of

waste water treated with the LE the floc formed have a similar appearance to the DE, however

both extracts have very different behaviour relating to the turbidity and suspension solid

reduction.


37373737

It is clear from this report that there exists a direct relationship between the nopals mucilage

action mechanism, suspension solids removal and reduction of turbidity in water treatment.

In synthetic water experiments kaolin is distributed throughout the sample in the form of

suspension solids producing all the total turbidity. The nopal performance upon the clay particles

depends of the initial turbidity and nopal dosage applied.

In all the previous experiments using kaolin synthetic water and the optimal dosages of nopal; a

turbidity reduction of greater than 90% was achieved; in water samples with low, medium and

high turbidity.

In the case of waste water, it is probable that diluted solids produce mostly of turbidity and

nopal only can reduce a lowest part of turbidity generated by suspension solids. Moreover diluted

chemicals, organic matter, soaps, oils and other substances could interact in the coagulation

properties of the nopal.

Generally in water analysis, DQO and DBO are the measurements used to evaluate the diluted

chemical and organic compounds.

In these coagulation experiments either one of these two parameters were reduced by the nopal

action by more than 25%, although nopal was able to reduce the suspension solid by almost

60% in urban and industrial wastewater.

The turbidity was reduced up to a maximum of 40% for the urban waste water and 19% for the

high industrial charge water when the DE was applied as primary coagulant.

The LE does not produce a significant reduction of any parameter; something happened and

decreased its coagulation capacity.


38383838

Recognizing that one of the factors which affects the coagulant capacity of nopal is the charge of

the diluted solids within the samples; it is necessary to examine which parameters are affecting to

this process.

It is very interesting to research about the floc formed during the nopal coagulation process and

to clarify more detailed information about the action of the nopal mechanism and what

substances it is able to remove. From these premises it would be possible to develop new theories

and practical applications for every specific type of water and therefore reduce reliance upon

synthetic coagulants.

Other factors, for example: ph, temperature and alkalinity can also change the coagulation

qualities of nopal. In our case the samples from this study were obtained from a region with

highly alkaline water and possibly can be an important factor in the low output obtained.

Picture 4.-Floc formed after nopal treatment in Synthetic water ,

Initial turbidity of 200 NTU Picture 5. - Floc formation after nopal treatment in wastewater experiments.


39393939

In theory the aluminium sulphate generates small flocs which could be easily attached to the

nopal mucilage increasing its coagulation capacity. However, to the contrary, there was no clear

relation in these experiments. The DE did not produce a significant increase in the removal of all

the factors analysed and the LE generated a negative effect.

It is necessary to study if there are any determining factors in the application of the nopal as a

flocculant, for example, the moment of addition, the agitation velocity or additional water

characteristics.

In pre-potable water experiments there was a significant reduction of microorganisms but not up

to levels permitted by the drinking water normative because of the high initial charge. It could be

interesting determine the microorganisms and parasites removal capacity of nopal in controlled

experiments and other fresh water systems.

The LE could be a better way to apply the nopal in water clarification because it is easier to

produce at a local scale; on the other hand, the DE obtained better results in wastewater

treatment and is also easier to transport and store, which implies it may be better suited for

application in large scale application.

In many arid regions of the world where the nopal is present the turbidity of fresh water is made

up of clay and slime, rendering water non-potable. Theoretically this is an ideal situation to apply

the nopal, as a first step towards water clarification. Moreover it has been shown that nopal is

totally innocuous and has the capacity to reduce pathogens.

In developing countries the integration of nopal crop and nopal water treatment could produce

enormous socioeconomic benefits.


40404040

An increase in drinking water quality and the possibility of natural and sustainable residual water

treatment systems would be sure to produce an increase in the quality of life of rural developing

populations; in addition encouraging a sustainable environmental management system for

preventing further degradation of natural systems.

Nopal is a resource highly productive and beneficial , the combination of water management and

nopal crops in an integrated develop project program for rural communities is a objective very

plausible and one of the possibilities open with this new material.

We have the possibility to redress ecological and social imbalances in the world, through the

introduction of new and socially empowering clean technologies; an obligation of this age.

Deep research is necessary and the compromise of governments and corporations to generalise the

use of this beneficial, effective and ecofriendly technique.


41414141

5.5.5.5.----CONCLUSIONSCONCLUSIONSCONCLUSIONSCONCLUSIONS/THE FUTURE/THE FUTURE/THE FUTURE/THE FUTURE

In general both nopal extracts worked better as primary coagulants than as aluminium sulphate

aids.

As a primary coagulant, nopal is able to remove over 90% turbidity in kaolin clay suspensions.

In pre-potable water experiments, it reduced fecal streptococcus and fecal coliforms to a

maximum of 81% and 45%, respectively.

In waste water experiments nopal did not produce a clear DQO or DBO reduction. Suspension

solids were reduced by up to 58% and the removal of 40% of turbidity occurred when the DE

was applied to urban waste water. LE was not successful in treating waste water.

The promising results obtained and the biological characteristics of this plant demonstrate its

exciting potential for integration into sustainable water management programmes of both

developed and developing countries. It appears to offer an excellent alternative to synthetic

coagulants and also harbours the possibility of promoting empowering socioeconomic grown of

arid regions worldwide.

At this point, it is necessary to increase the current body of knowledge we have on the

coagulation properties of nopal; and for future research to build upon the numerous lines of

questioning begun here, for example:


42424242

• Further research into nopal’s mucilage properties and its mechanism action.

• More information on which metals it is able to remove; enabling satisfactory water

potabilisation and industrial waste water treatment.

• Further research into varying types of waste water and how nopal’s effects upon them

differ.

• Studies into the potabilisation possibilities of different fresh water sources.

• Study the output of nopal as flocculant aid with other synthetic coagulants and in

different mix conditions.

• Further studies into the output of nopal; how as a flocculant it aids with other synthetic

coagulants; and which differing combinations promote optimum results.

• Research into the combined usage of nopal and Moringa oleifera.

• Pilot plant scale experimentation.

• Nopal application as a previously step for sand filters treatment in water clarification.

• The development of a project focusing on the integration of nopal crops into the water

management of rural communities.


43434343

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48484848

APAPAPAPPPPPLICALICALICALICATION OF A NATURAL COAGULANT DERIVTION OF A NATURAL COAGULANT DERIVTION OF A NATURAL COAGULANT DERIVTION OF A NATURAL COAGULANT DERIVEEEED FROM D FROM D FROM D FROM

Opuntia sOpuntia sOpuntia sOpuntia sssssp. IN WATER TREATMENTp. IN WATER TREATMENTp. IN WATER TREATMENTp. IN WATER TREATMENT

José Miguel García Moreno

Erasmus Mundus master program

May 2009

--------------------------------------------------------------------------------------------------------

Abstract

The following study is an experimental approach about the possible use of Opuntia ssp. for water

treatment.

In this investigation the properties of the dry and liquid extracts of Opuntia Ficus Indica were

evaluated as primary coagulant and coagulant aids in synthetic and “true” water samples by jar

test method.

There is ancestral evidence for the use of several cacti for water clarification. Recent authors have

investigated the properties of Opuntia ssp., obtaining excellent results. The biological

characteristics of this plant allow it to be applied on both local and commercial levels, as a cheap

alternative with large socioeconomic benefits.

In experiments with Synthetic Kaolin suspensions, nopal extracts remove more than 90% of

turbidity; however the effectiveness of coagulation was reduced in “true” water sample

experiments. For pre-potable waters the maximum effectiveness was about 75%; urban waste

water reached 40% and high industrial charge waste water did not exceed 20%.

In general nopal extracts worked better as primary coagulant than as a coagulation aid of

aluminum sulfate.

Analysis of the other measured parameters suggests that the nopal mucilage works well to reduce

suspension solids but not dissolved solids. In addition, total fecal coliforms and streptoccus were

reduced by 45% and 81% respectively in the pre-potable water samples.

------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------


49494949

1.1.1.1.----IntroductionIntroductionIntroductionIntroduction

One of the more important Challenges of the modern World is to make human development

economically and environmentally compatible; directing their efforts towards social equality.

Water is vitally important in this process because it is used in a variety of ways at many different

levels, producing social, spatial and organizational problems.

Growing population, increase in economic activity and industrialization has not only created an

increased demand for fresh water but also resulted in severe misuse of this natural resource.

According to a survey conducted by UNEP(2º United Nations World Water Development

Report ), 20% of the world’s population lacks access to safe drinking water and 50% of the

world’s population lacks access to safe sanitation. Polluted water is estimated to affect the health

of about 1200 million people and contribute to the death of 15 million children under the age of

five every year.

It is necessary to recognise water as a limited resource and to encourage the application of clean

technologies which reduce negative environmental impact and assist in the development of poor

countries.

In this sense the use of nopal for water treatment is a fair and efficient way to support the

ecologic control of residues at local and industrial level and is an excellent resource to increase

access to drinking water in rural places and contribute to it socioeconomic development.

1.1.1.1.1.1.1.1.----The natural resource (Opuntia ssp.)The natural resource (Opuntia ssp.)The natural resource (Opuntia ssp.)The natural resource (Opuntia ssp.)

The genus opuntia is the largest under the Cactaceae family with more than 250 endemic species

from Central America. The Opuntia ssp. chosen as natural coagulant source for this project was

Opuntia ficus indica, also named chumbera in Spain, cactus pear in North America and nopal in

Mexico.

The nopals are succulent plants which grow up to 3-5 metres, many times in a dense and tangled

structure. It’s recognized by its green thick long pads that look like sports rackets. They grow one

linked to the next and can be considered as both leaves and stalks. The plant surface is covering


50505050

by spines which help to conduct water, reduce water loss, and protect the succulent tissue from

herbivores and other predators (Mondragon C. 1995).

Nopals are strong plants with not much water and nutrient requirements, are highly adaptable

and propagate easily. After the American conquest, it was very treasured by explorers for its

properties and introduced to Europe, Asia, Australia and Africa where it rapidly adapted to

various environments (Barbera, G. et all 1992,).

Different cultures know different uses for this plant, being especially appreciated for its

organoleptic and medicinal properties. In developing countries where it is present, nopal

represents an important economic and nourishing resource.

Nopal leaves present a general composition of 87% water, 1% protein, 0.1% fat, 1.3% ash,

1.1% crude fibre, and 5.4% carbohydrates (D. Loayza et all 2007) being also an excellent forage

for livestock in arid climates (E. Órnelas, 2007).

Moreover in Mexico and South America it is used to treat numerous maladies and researchers

are interested in its medicinal use.The nopal market moves millions of euros and produces

millions of tonnes for different applications as food, medicines, cosmetics, pigments and as a

paint additive.

The biological characteristics of nopal and the socioeconomic repercussions of its possible uses in

water treatment make it an excellent candidate for this study

1.2.1.2.1.2.1.2.----Nopal as Natural Coagulant.Nopal as Natural Coagulant.Nopal as Natural Coagulant.Nopal as Natural Coagulant.

The ability of cactaceae to retain water under such unfavourable climatic conditions is due to the

water-binding capacity of mucilage, which involves the consequent coagulation properties (Mindt

L., et all ,1975). When it is mixed with water or other fluids, forms a sticky and slippery gel

which has the capacity to catch the suspension particles and carry them to the bottom.

Experiments suggest that the coagulation mechanism of opuntia ssp. is not by charge

neutralization like metallic salts, instead it occurs by adsorption and bridging mechanisms (Sarah

Miller et all, 2008).


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In the last few years different scholars have returned to this research and the nopal coagulant

properties are starting to be revealed (Jingdong Zhang et all 2005, N. Quezada,2004 , López, E.

2000, Miretzky P. 2007, Young K. et all, 2006).

Some considerations about theses research are described below:

-In comparative experiments with moringa oleifera and Al2 (SO4)3, nopal extract presents a

similar capacity to remove turbidity in synthetic and real waters.

-Temperature has slight influence on the coagulation effect of nopal.

-The coagulation activity of Nopal is greatest in basic waters .

-Nopal coagulation produces significant reductions of metals (As, Pb, Fe, Al, Mg).

-Possible DOQ and coliforms removal.

2.2.2.2.----MethodologyMethodologyMethodologyMethodology

The effectiveness of opuntia ssp. as a primary coagulant and flocculant aid in water treatment was

compared with Al2 (SO4)3 by jar test method. Properties of the dry and liquid extract obtained

from fresh nopal leaves and were tested in four different water models. This water models were; a

Kaolin clay suspension, a “true” pre-potable water source, an industrial water source and urban

wastewater.

Leaves of Opuntia ficus indica were collected around the University of Alicante and were

obtained a dry (DE) and liquid extract (LE) were obtained for the experimentation.

Dry coagulant was prepared by hand cutting of fresh nopal leaves. The skin and other superficial

tissue was scored and only the internal mucilaginous component was used. It was cut into strips

approx. 1cm in width and dried in an oven at 65 ºC over 72 hours. Samples were then ground in

a coffee grinder to obtain particles with less tham 300 µmetres diameter. This white powder was

stored at 4ºC preserving its properties for more than two months.


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Gummy coagulant was prepared by maceration. Entire leaves were cut into strips 1cm in width

and mixed with the same volume of tap water. After 24 hours it was filtered through a nylon

material to obtain a transparent slime soluble in water.The liquid was stored at 4ºC mantening its

properties for no more than 3 days.

Jar test experiments were realised with four different water models: Synthetic turbidity models

were prepared by the addition of kaolin clay (KAOLIN CH-N PRS, 3TQ ) into tap water to

provide a turbidity of 75 and 200 NTU; “true” waste water was recollected from the entry of

Benidorms (urban charge) and Elda water treatment plants (industrial charge) ; a potable water

source was collected from amadorio reservoir.

The characteristics of all real water models follow:

The experimental method to measure the efficiency of nopal extracts for water treatment in the

different water models was designed based on the removal of turbidity .

The Residual turbidity tests were carried out according with ASTM jar test standard method

Coagulants were added to six water samples (1000 ml) and stirred at 125 rpm for 2 minutes and

next the speed was reduced to 70 rpm for 20 min. After the agitation, stirring was stopped and

the samples would stand for 20 min.

Turbidity of the supernatant were recorded in triplicates and measured using a calibrated

turbidymeter.

Elda wastewaterElda wastewaterElda wastewaterElda wastewater ValueValueValueValue Turbidity 235 NTU


pH 7,81


DQO 1095 mg/l

DBO 507 mg/l

Benidorm wastewaterBenidorm wastewaterBenidorm wastewaterBenidorm wastewater ValueValueValueValue Turbidity 106 NTU


pH 7,75


DQO 460 mg/l

DBO 293 mg/l

Amadorio Reservour Amadorio Reservour Amadorio Reservour Amadorio Reservour ValueValueValueValue Turbidity 13 NTU

Conductivity 485 µS

pH 8,63

Fecal Streptoccocus 110 UFC /100ml

Fecal Coliforms 1920UFC/100ml


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In each jar test experiment one of the six jars received no treatment, serving as a control for

comparison of the turbidity reduction for all other jars. Coagulation activity was calculated using

the equation defined in the bibliography (Okuda 2001):

(residual turbidity control - residual turbidity sample)

Coagulation activity = -------------------------------------------------------------- x 100

(residual turbidity control )

Dry extract (previously diluted in water for a correct mix ), liquid extract and Aluminium were

compared as primary coagulants.

In real water experiments only the supernatant of the jar with the more effective reduction of

turbidity was used to measure the key parameters of every water model. The key parameters for

wastewater were DQO, DBO and Suspension Solids; and for pre-potable water were fecals

streptococcus and fecal coliforms .

3.3.3.3.----ResultsResultsResultsResults

The efficiency of turbidity reduction at optimal dosages of both extracts in each water model is

presented in next table.

Table1.Turbidity removal of water models

In all the cases turbidity reduction was around 90% in kaolin synthetic suspensions. The

optimal work dosages of the dry extract (DE) are around 20 mg/l at initial turbidity of 200

Turbidity Removal %

Synthetic water

75NTU

Synthetic

water 200

NTU

Pre-potable

water

Urban

Wastewater

Industrial

Wastewater

Dry Extract 88 90 75 40 19

Liquid Extract 92 98 76 8 12

Control + Al 74 93 45 42 44

Dry Extract + Al 89 96 59 46 48

Liquid Extact + Al 96 98 42 38 4


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NTU and 10 mg/l at 75 NTU. The optimal work dosage of liquid extract (LE) is 0,2 ml/l

with independence of the initial turbidity.

In pre potable water both extract reduce the turbidity more than 75 % until remains values less

than 3 NTU.

Turbidity reduction with Liquid extract Turbidity reduction with Liquid extract Turbidity reduction with Liquid extract Turbidity reduction with Liquid extract

0

50

100

150

200

250

0 0,2 0,4 0,6 0,8 1 1,2

Concentration ml/L

Turbidity NTU Synthetic water 75 NTU

Synthetic water 200 NTU

Prepotable water

Urban wate water

Industrial waste water

Graphic 1. Turbidity reduction in the water models treated with LE

In waste water LE doesn’t produce any effect, while DE only obtains good results treating urban

waste water. An optimal dose of 50 mg/L of DE produced 40 % of turbidity remove.

Turbidity reduction with Dry extractTurbidity reduction with Dry extractTurbidity reduction with Dry extractTurbidity reduction with Dry extract

0

50

100

150

200

250

0 10 20 30 40 50

Concentration mg/l

Turbidity NTU Synthetic water 75 NTU

Synthetic water 200 NTU

Pre-potable water

Urban waste water

Industrial waste water

Graphic 2. Turbidity reduction in the water models treated with DE


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For other side there isn’t a clear increase of flocculation activity when aluminium and nopal were

added together. In any case could be increased the flocculation activity more than 15 %.

The DE achieved the best results in reduction of the fecal streptococcus by 81% and the fecal

coliforms by 45%. The LE has a similar capacity to remove turbidity but the microbiological

reduction is more limited.

Removal efficiences in Pre-potable waterRemoval efficiences in Pre-potable waterRemoval efficiences in Pre-potable waterRemoval efficiences in Pre-potable water

0

20

40

60

80

100

Dry Extract 6 mg/l


Control + Al(2ppm)



Sample

Rem

oval % Turbidity renoval

Fecal coliforms renoval

Fcal Streptococus renoval

Graphic 3. Removal efficiencies of key parameters in pre-potable water

Fecal coliforms are reduced when Aluminium sulphate is applied; behaving similarly to both

nopal extracts although for the fecal streptococcus is less effective.

Urban wastewater removal eficiences at optimal dosagesUrban wastewater removal eficiences at optimal dosagesUrban wastewater removal eficiences at optimal dosagesUrban wastewater removal eficiences at optimal dosages

0

10

20

30

40

50

60

70

80

Dry Extract 50 mg/l


Control + Al(50ppm)

Dry Extract 50 mg/l

Liquid Extact0,4 ml/l

Rem

oval %

Turbidity

DQO

Suspension solids

DBO



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In any case it was possible to reduce the DQO and DBO by more than 25%, however, the

suspended solids were notably reduced specially in the case of the DE treatment. Its achieved a

maximum output of 58% when were applied as primary coagulant for both waste water samples.

In general nopal work better with urban waste water than the high indusrial charge waters.

Industrial Wastewater removal eficience at optimal dosagesIndustrial Wastewater removal eficience at optimal dosagesIndustrial Wastewater removal eficience at optimal dosagesIndustrial Wastewater removal eficience at optimal dosages

0

10

20

30

40

50

60

70

80

Dry Extract 50 mg/l


Control + Al(50 ppm)



Rem

oval %

Turbidity

DQO

Suspension solids

DBO

Graphic 5.-Removal efficiencies of key waste water parameters

The LE is not successful in producing a clear reduction of the parameter analysed , even when is

applied together with aluminium produces a negative influence.

4.4.4.4.---- Discussion Discussion Discussion Discussion

Suspension solids reduction is the key parameter in this process and is related to the action

mechanism of the nopal mucilage.

It is clear exists a direct relationship between the nopal mucilage action mechanism , suspension

solids removal and reduction of turbidity in water treatment.

In synthetic water experiments kaolin is distributed throughout the sample in the form of

suspension solids producing all the total turbidity. The nopal performance upon the clay particles

depends of the initial turbidity and nopal dosage applied.


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In all the previous experiments using kaolin synthetic water and optimal dosages of nopal; a

turbidity reduction of greater than 90% was achieved; in water samples with low, medium and

high turbidity.

In the case of waste water, it is probable that diluted solids produce most of turbidity and nopal

only can reduce a lowest part of turbidity generated by suspension solids. Moreover diluted

chemicals, organic matter, soaps, oils and other substances could interact in the coagulation

properties of the nopal.

In this way DQO and DBO remove experiment doesn’t produce a output higher than 25 %.

The LE does not produce a significant reduction of any parameter; something happened and

decreased its coagulation capacity.

The results obtained from this research suggest that nopal is a better primary coagulant than the

flocculation aid of aluminium sulphate.

However the theory says that aluminium sulphate generates small flocs which could be easily

attached to the nopal mucilage increasing its coagulation capacity. However, to the contrary,

there was no clear relation in these experiments. The DE did not produce a significant increase in

the removal of all the factors analysed and the LE generated a negative effect.

In pre-potable water experiments there was a significant reduction of microorganisms but not up

to levels permitted by the drinking water normative because of the high initial charge. It could be

interesting determine the microorganisms and parasites removal capacity of nopal in controlled

experiments and other fresh water systems.

In many arid regions of the world where the nopal is present the turbidity of fresh water is made

up of clay and slime, rendering water non-potable. Theoretically this is an ideal situation to apply

the nopal, as a first step towards water clarification. Moreover it has been shown that nopal is

totally innocuous and has the capacity to reduce pathogens.

In developing countries the integration of nopal crop and nopal water treatment could produce

enormous socioeconomic benefits.


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An increase in drinking water quality and the possibility of natural and sustainable residual water

treatment systems would be sure to produce an increase in the quality of life of rural developing

populations; in addition encouraging a sustainable environmental management system for

preventing further degradation of natural systems.

Nopal is a resource highly productive and beneficial , the combination of water management and

nopal crops in a Integrated develop project program for rural communities is a objective very

plausible and one of the possibilities open with this new material.

We have the possibility to redress ecological and social imbalances in the world, through the

introduction of new and socially empowering clean technologies; an obligation of this age.

Deep research is necessary and the compromise of governments and corporations to generalise the

use of this beneficial, effective and ecofriendly technique.

5.5.5.5.----Conclusion /the futureConclusion /the futureConclusion /the futureConclusion /the future

The promising results obtained and the biological characteristic of this plant ,convert to it in a

excellent resource susceptible to be integrated in a water management plan for develop and

developing countries. Could be an alternative to reduce the use of synthetic coagulants and also

promote the socioeconomic grown of arid regions.

At the moment is necessary to increase the knowledge which we have about the coagulation

properties of nopal and develop the numerous research lines opened for a future:

• Further research into nopal’s mucilage properties and its mechanism action.

• More information on which metals it is able to remove; enabling satisfactory water

potabilisation and industrial waste water treatment.

• Further research into varying types of waste water and how nopal’s effects upon them

differ.

• Studies into the potabilisation possibilities of different fresh water sources.


59595959

• Study the output of nopal as flocculant aid with other synthetic coagulants and in

different mix conditions.

• Further studies into the output of nopal; how as a flocculant it aids with other synthetic

coagulants; and which differing combinations promote optimum results.

• Research into the combined usage of nopal and Moringa oleifera.

• Pilot plant scale experimentation.

• Nopal application as a previously step for sand filters treatment in water clarification.

• The development of a project focusing on the integration of nopal crops into the water

management of rural communities.


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APPENDIX 1.APPENDIX 1.APPENDIX 1.APPENDIX 1.---- Water characteristic of Alicante tap water used for synthetic water .


61616161


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APPENDIX APPENDIX APPENDIX APPENDIX 2.2.2.2.---- Amadorio reservoir water characteristics .


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APPENDIX 3APPENDIX 3APPENDIX 3APPENDIX 3.- DQO kit identification


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APPENDIX 4APPENDIX 4APPENDIX 4APPENDIX 4. DBO analysis method


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APPENDIX 5APPENDIX 5APPENDIX 5APPENDIX 5.- Microbiological analysis method


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APPENDIX 6APPENDIX 6APPENDIX 6APPENDIX 6.- Microbiological analysis

Parte Analítico

Resultados Microbiológicos

Silvia Gabriela Avilés Robles Especialista Técnico IUACA

DATOS GENERALES E IDENTIFICACION

MUESTRA REMITIDA POR: JOSE MIGUEL GARCIA MORENO.

DENOMINACION DE LA MUESTRA: NUMERICA SUCESIVA 1,2,3,4,5,6

DESCRIPCION DE LOS ENVASES RECIBIDOS: BOTELLAS DE CRISTAL BOROSILICATADO ESTERILES DE 1 L DE CAPACIDAD CON CAMARA DE AIRE.

FECHA DE RECEPCIÓN: 24 de marzo de 2009

FECHA DE FINALIZACIÓN: 26 de marzo de 2009

Muestra Parámetro Métodos Resultados Unidades 1 Coliformes Fecales Filtro de Membrana (FM) 1920 u.f.c/100mL

Estreptococos Fecales Filtro de Membrana (FM) 110 u.f.c./100 mL 2 Coliformes Fecales Filtro de Membrana (FM) 1050 u.f.c/100mL Estreptococos Fecales Filtro de Membrana (FM) 20 u.f.c./100 mL 3 Coliformes Fecales Filtro de Membrana (FM) 1200 u.f.c/100mL

Estreptococos Fecales Filtro de Membrana (FM) 45 u.f.c./100 mL 4 Coliformes Fecales Filtro de Membrana (FM) 1155 u.f.c/100mL Estreptococos Fecales Filtro de Membrana (FM) 69 u.f.c./100 mL 5 Coliformes Fecales Filtro de Membrana (FM) 920 u.f.c/100mL

Estreptococos Fecales Filtro de Membrana (FM) 51 u.f.c./100 mL 6 Coliformes Fecales Filtro de Membrana (FM) 1123 u.f.c/100mL Estreptococos Fecales Filtro de Membrana (FM) 62 u.f.c./100 mL


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THANK YOU , I HOPE YOU ENJOY AND LEARN WITH MY WORK.

GOOD LUCK.


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