Final report

i
FABRICATION AND CHARACTERISATION OF
CERAMIC FILTER CANDLES FOR DOMESTIC WATER
PURIFICATION
A PROJECT REPORT
Submitted by
SRIDHAR PRASAD P (2012301020)
UDAYA SANKAR S (2012301025)
in partial fulfilment for the award of the degree
of
BACHELOR OF TECHNOLOGY
IN
CERAMIC TECHNOLOGY
DEPARTMENT OF CERAMIC TECHNOLOGY
A.C COLLEGE OF TECHNOLOGY
ANNA UNIVERSITY::CHENNAI 600 025
MAY 2016

ii
ALAGAPPA COLLEGE OF TECHNOLOGY
ANNA UNIVERSITY : CHENNAI – 6000025
BONAFIDE CERTIFICATE
Certified that this project report “FABRICATION AND CHARACTERISATION
OF CERAMIC FILTER CANDLES FOR DOMESTIC WATER
PURIFICATION” is the bonafide work of “SRIDHAR PRASAD P
(2012301020) and UDAYA SANKAR S(2012301025)” who carried out the project
work under my supervision.
EXTERNAL GUIDE INTERNAL GUIDE
Dr. V. Viswabaskaran Dr. S. Manisha Vidyavathy
Managing Director Associate Professor
VB Ceramic Consultants Department of Ceramic Technology
Kottivakkam A.C. College of Technology
Chennai - 600041 Anna University
Chennai - 600025

iii
ACKNOWLEDGEMENT
We express our sincere thanks to Dr. K. KALAICHELVAN, Professor and
Head of the Department of Ceramic Technology for providing us this opportunity to
undergo this particular project.
We express our deep sense of gratitude and indebtedness to our project
External Guide Dr. V. VISWABASKARAN, Managing Director, VB Ceramic
Consultants for their precious guidance and constant support throughout the project.
It is indeed a pleasure to mention about DR. S. MANISHA VIDYAVATHY
our project Internal Guide who is always been patient enough to make us understand
the complexities of the project and relentlessly support us throughout the project
We express our sincere thanks to Dr. N. R. SRINIVASAN and
Mr.MANOHAR, for their valuable suggestions and help.
We wish to thank all the staff members of Department of Ceramic
Technology, Parents and Friends for their encouragement and help to carry out this
successfully.
SRIDHAR PRASAD P
UDAYA SANKAR S

iv
ALAGAPPA COLLEGE OF TECHNOLOGY
ANNA UNIVERSITY : CHENNAI – 600025
ABSTRACT OF THE PROJECT WORK
Degree and Branch : B.Tech Ceramic Technology
Month and Year of Submission : May 2016
Title of the Project : “FABRICATION AND
CHARACTERISATION OF
CERAMIC FILTER CANDLES
FOR DOMESTIC WATER
PURIFICATION”
Name of the Student : P.SRIDHAR PRASAD
And Roll Number 2012301020
S.UDAYA SANKAR
2012301025
Name and Designation of : Dr. S. MANISHA VIDYAVATHY
Internal Guide Associate Professor
Department of Ceramic Technology
Name and Designation of : Dr. V. VISWABASKARAN
External Guide Managing Director
VB Ceramic Consultants

v
ABSTRACT
Ceramic candles are hollow cylindrical forms placed into the bottom of a
container. Water seeps through the ceramic candle and falls into a lower container,
which is fitted with a tap at the bottom. Units often use more than one candle because
the flow rate through one candle can be slow. A lid is placed on top of the filter to
prevent contamination. This system both treats the water and provides safe storage
until it is used. They are usually made from local clay mixed with a combustible
material like sawdust, rice husks or coffee husks. When the candle is fired in a kiln,
the combustible material burns out, leaving a network of fine pores through which
the water can flow through. The main aim of this work is to prepare a ceramic candle
with increased porosity by altering its tri axial composition and by adding a small
percentage of pore forming agents. This study is intended in observing the properties
of the newly prepared ceramic candle and characterizing it.
Date : SRIDHAR PRASAD.P
Place : Chennai - 25 UDAYA SANKAR.S

vi
CHAPTER
NO.
TITLE PAGE NO.
ACKNOWLEDGEMENT iii
ABSTRACT V
LIST OF TABLES vii
LIST OF FIGURES ix
LIST OF ABBREVIATIONS AND
SYMBOLS
X
1 INTRODUCTION 1
1.1 CERAMIC WATER FILTER 1
1.1.1 Ceramic Filter Candles 4
1.1.2 Fine Pores Of Ceramic 6
1.1.2.1 Surface Filtration 7
1.1.2.2 Depth Filtration 7
1.2 EFFECTIVENESS OF CERAMIC
FILTERS
8
1.3 PRODUCT AND MARKET 8
1.4 APPLICABILITY 9
1.5 BENEFITS OF USING CERAMIC
FILTERS
9
1.6 DRAWBACKS OF CERAMIC FILTERS 10
1.7 OBJECTIVES OF THE PROJECT
1.8 SCOPE OF THE PROJECT
10
11
2 LITERATURE REVIEW 12

vii
3 EXPERIMENTAL WORK 22
3.1 RAW MATERIALS 22
3.2 MINEROLOGY
3.2.1 Ball clay
3.2.2 China clay
3.2.3 Quartz
3.2.4 Feldspar
3.2.5 Sodium carbonate and Sodium
silicate
22
22
23
24
24
25
3.3 BATCH COMPOSITION 26
3.4 BODY PREPARATION
3.4.1 Mixing
3.4.2 Slip Preparation
3.4.3 Slip Casting
3.4.4 Drying
3.4.5 Firing
28
30
30
30
31
32
3.5 TESTING
3.5.1 Linear Shrinkage
3.5.2 Bulk Density and Apparent Porosity
33
33
33
3.6 CHARACTERISATION
3.6.1 Total Dissolved Solids
3.6.2 Scanning Electron Microscope
34
34
36

viii
4 RESULTS AND DISCUSSION
4.1 PHYSICAL PROPERTIES OF SAMPLE
TRIALS
4.2 TOTAL SHRINKAGE
4.3 BULK DENSITY
4.4 WATER ABSORPTION
4.5 APPARENT POROSITY
4.6 TOTAL DISSOLVED SOLIDS
4.7 SEM ANALYSIS
37
37
38
39
40
41
42
43
5 CONCLUSION 44
REFERENCES

ix
LIST OF TABLES
TABLE
NO
TITLE PAGE NO.
1.1
General Strengths and Weaknesses of Ceramic
Water Filters
5
1.2 Size of common Pathogens in Water 6
3.1 Batch 1 Composition 26
4.1 Initial & Final Thickness, Dry weight,
Suspended weight, Soaked Weight of Sample
Trials
37
4.2 Total Shrinkage of Samples 38
4.3 Bulk Density of Samples 39
4.4 Water Absorption of samples 40
4.5 Apparent porosity of Samples 41

x
LIST OF FIGURES
FIGURE
NO.
TITLE PAGE NO.
1.1 Types of Ceramic water Filter Elements 2
1.2 Ceramic Water Filter System and Media 3
1.3 Ceramic Filter Candles 6
3.1 Flow Sheet for Body Preparation 29
3.2 Slip Preparation using Planetary Mill 30
3.3 Slip Casting 31
3.4 Drying at 60ºC in Oven 32
3.5 Dried Sample 32
3.6 Firing at 1060ºC in Furnace 32
3.7 Fired Sample 32
3.8 TDS value for various types of water 35
4.1 Total Shrinkage variation graph of Samples 38
4.2 Bulk Density variation graph of Samples 39
4.3 Water Absorption variation graph of Samples 40
4.4 Apparent Porosity variation graph of Samples 41
4.5 TDS value graph of unfiltered and filtered water 42
4.6 Sample 4 SEM Micrograph 43
4.7 Sample 5 SEM Micrograph 43

xi
LIST OF SYMBOLS AND ABREVIATIONS
LS : Linear Shrinkage
TDS : Total Dissolved Solids
SEM : Scanning Electron Microscope
mm : Millimeter
µm : Micrometer
⁰C : Degree Celsius
g : gram
mg/l : Milligram/Litre
ppm : Parts per million
g/cc : Gram per cubic centimeter

1
CHAPTER 1
INTRODUCTION
1.1 CERAMIC WATER FILTER
According to World Health Organization (WHO) over 99.8% of
death caused by poor quality of drinking water in the developing countries
strongly suggesting a need of safe (free from physical, chemical and
biological contaminations) and adequate amount of drinking water. In
order to improve water quality, various water treatment techniques (bio
sand filter, ceramic filters, boiling water, solar disinfection) are in common
practice at household level of many developing countries where centralized
water treatment systems are limited. Among many options for household
water treatment methods, ceramic filter candles are one of the promising
techniques for the developing countries. The fact is that ceramic filter
candle can be manufactured by local ceramists using locally available
materials that not only make it affordable but also make it an attractive
point-of-use treatment technology. Moreover, this type of filter can be used
in different forms such as candle, pot and disc. It physically eliminates
colloidal particles (which make water turbid), odour and microorganisms
including pathogens. Performance of this filter is normally evaluated based
on water flow rate, removal of pathogens, reduction on chemical
contaminants including turbidity and odour.
Ceramic water filters have been used in various places around the
world as a means of treating drinking water at the household level. Some
examples include the Potters for Peace Filtron (Nicaragua), the TERAFIL
terracotta filter (India), and the candle filter (India, Nepal, Bangladesh,
Brazil, etc).Fig 1.1 Shows the different types of Ceramic water filters.

2
Ceramic water filters can be categorized according to various key
parameters:
1. Shape (e.g.: candle element, disk, pot)
2. Type of clay (e.g.: white kaolin, red terracotta, black clay, etc)
3. Combustible material (e.g. : sawdust, flour, rice husk, etc).
Figure 1.1 Types of Ceramic Water Filter Elements
Ceramic water filters can also be described by their functions:
1. Microbial removal (e.g.: Pottters for Peace Filtron)
2. Chemical contaminant removal such as arsenic and iron (e.g.:Kolshi
Filter for arsenic)
3. Secondary contaminant removal like taste and odor (e.g: Katadyn
Gravidyn ceramic candle filter with activated carbon).

3
Other key variables that influence the properties of ceramic water filters
include:
1. Use of additional materials in production (e.g.: grog, sand,
Combustible materials,)
2. Firing temperature
3. Mode of production (e.g.: hand mold, wheel, mechanical press).
The entire unit is often defined in terms of two components as shown
in Fig 1.2 : the filter element or media through which water passes and
the filter system which houses the media, usually consisting of an upper
and lower storage vessel for holding water.
Figure 1.2 Ceramic Water Filter System and Media

4
Table 1.1 General Strengths and Weaknesses of Ceramic Water Filters
Strengths Weaknesses
 Relatively cheap to manufacture and
produce;
 The ceramics trade is well
established in many countries;
 Materials (clay, sawdust, rice,
husk…) are often readily available;
 If designed and used properly, can
remove up to >99% of indicator
organisms and reduce turbidity to
below World Health Organization
guideline values.
 Very slow filtration rates. (Typically
ranging between 0.5 and 4 L/day)
 Filter maintenance and reliability
depends on the user – herein lies
many non technical social issues;
 Breakage during distribution or use
can be a problem since ceramic
filters are often fragile;
 Requires regular cleaning;
 The rate of production as
implemented in countries such as
Nicaragua and Nepal has tended to
be relatively slow;
 It is difficult to maintain consistency
(quality control is an issue).
1.1.1 Ceramic Filter Candles
Ceramic candles as shown in Fig 1.2 are hollow cylindrical forms
placed into the bottom of a container. Water seeps through the ceramic
candle and falls into a lower container, which is fitted with a tap at the
bottom. Units often use more than one candle because the flow rate through
one candle can be slow. A lid is placed on top of the filter to prevent

5
contamination. This system both treats the water and provides safe storage
until it is used. In
stationary use, ceramic candles have mechanical, operational and
manufacturing advantages over simple inserts and pots. Filter candle
allows sturdy metal and plastic receptacles to be used, which decreases the
likelihood of a sanitary failure. Since their filter area is independent of the
size of the attachment joint, there is less leakage than other geometries of
replaceable filter, and more-expensive, higher-quality gaskets can be used.
Since they are protected by the upper receptacle, rather than forming it,
they are less likely to be damaged in ordinary use. They are easier to
sanitize, because the sanitary side is inside the candle. The no sanitary part
is outside, where it is easy to clean. They fit more types of receptacles and
applications than simple pots, and attach to a simple hole in a receptacle.
They also can be replaced without replacing the entire upper receptacle,
and larger receptacles can simply use more filter candles, permitting filter
manufacture to be standardized. If a filter in a multi filter receptacle is
found to be broken, the filter hole can be plugged, and use can continue
with fewer filters and a longer refill-time until a replacement can be
obtained. Also, standardizing the filter makes it economical to keep one or
a few filters on hand. Ceramic candles are usually made from local clay
mixed with a combustible material like sawdust, rice husks or coffee husks.
When the candle is fired in a kiln, the combustible material burns out,
leaving a network of fine pores through which the water can flow through.
In Out
Fresh water Drinking water

6
Figure 1.3 Ceramic Candle Filter
1.1.2 Fine Pores of Ceramics
Pathogens and suspended material are removed from water through
physical processes such as mechanical trapping and adsorption.
The sizes of the pores that let the water go through the ceramics are very
fine. The sizes of these pores differ.
Table 1.2 Size of common Pathogens in water
Viruses
Smallest and most complex
to remove
0.02 – 0.10 µm
Bacteria Most dominant 0.5 – 5 µm
Protozoa May be able to form cysts 4 – 20 µm

7
Due to the small size of the pores and the thickness of the ceramics
(length of the pore channels) two physically distinctive phenomena help
to remove the particles and bacteria:
1. Surface filtration or Sieving and
2. Depth Filtration.
1.1.2.1 Surface Filtration
A surface filter can be visualized as a screen that is covered with
particles that are too large to pass through. Surface filtration is also known
as sieving or dead end filtration. Generally it is thought that this type of
filtration is only applicable for particles larger than the largest size of the
pores.
Direct Interception (Sieving): Particles that are larger then the pore size
cannot pass. The retention of particles will be absolute.
Bridging: Smaller particles may be too small to be intercepted however
two particles hitting the obstruction at the same time will form a bridge
across the pore adhering to each other. Bridged particles may not plug the
pore creating even smaller pore gradually forming a “filter cake”. This cake
creates a finer filtration for subsequent interception at the cost of decreased
flow rate and eventually no flow rate.
Inertial Impaction: Due to their inertial mass particles cannot follow the
water flow. These particles hit none porous surface barrier. The particles
become captured while the water flows around the barrier.
1.1.2.2 Depth Filtration
Depth Filtration is the physical phenomenon that lets particles
Helminths / Worms
Derive sustenance at host’s
expense
40 – 60 µm

8
penetrate the ceramic filter and get captured throughout the depth of the
candle wall. There are several ways in which particles/bacteria will be
captured in the depth of the filter wall.
Labyrinth (& inertial impaction): Particles intercepted within the ceramic
depth can be much smaller than the pores. This is because particle laden
water has to navigate through intricate maze of labyrinths. The path
through the filter twists and turns through sharp angles due to complicated
ceramic structure and so the particles.
Cluster formation: Small particles can combine with other particles to
form a cluster of particles large enough to become trapped as a group or
individual in dead end cavities. This process is comparable to the bridging
process mentioned before.
Adsorption: Weak Van der Waals forces attract the small particles to the
ceramic causing them to be adsorbed onto the wall of the ceramic.
1.2 EFFECTIVENESS OF CERAMIC FILTERS
Ceramic candle filters are effective in removing bacteria, protozoa,
helminths and turbidity from water. It also removes some viruses and iron
and taste, smell and colour of water are improved. The effectiveness of the
filter also depends on the production quality, the initial water quality, and
the handling practices of users. Highly turbid or iron containing water may
plug candle pores easily so that container and candle need to be cleaned
more frequently. In this case, the water should be pre‐settled before
pouring it into filter. It is recommended to use raw water with less iron
(<0.3mg/L) and turbidity (<5NTU).
1.3 PRODUCTION AND MARKET
Candle filters can be manufactured at a local level and contribute
to the development of local commerce. Local production process

9
provides financial supports to household and voluntary labours. However,
the production of ceramic filters is a lengthy process and a quality control
process is required to ensure candle filter‘s effectiveness. Quality can be
affected by variations in clay composition across geographic regions.
Variability in weather conditions also makes long‐term production
planning difficult, and lack of storage can complicate storage of filters.
The fragility of ceramic filters can make their transport difficult. Supply
chain and market availability for replacement of candles and taps is
required. Filters typically come with illustrated instructions in market.
1.4 APPLICABILITY
Ceramic candle filters are easy to set up and operate, cheap and
effective in removing bacteria, protozoa, helminths and turbidity from
water. It also removes some viruses and iron and taste, smell and colour of
water are improved. But due to the limited flow rate (i.e. 1‐2liter/hour) and
storage capacity, filters are only suitable for small families, organizations
or school classroom. It is suitable where drinking water is little turbid
(<5NTU) and contaminated and with little iron (<0.3mg/L). In the case of
too high turbidity, water can be presettled. Chlorinated water should not be
used in candle filters! Except for clay, filter containers of other materials
are easy to transport and handle.
1.5 BENEFITS OF USING CERAMIC FILTERS
• Cheap, simple and easy to use and clean.
• Removes pathogens, turbidity and suspended solids.
• Somewhat effective for the removal of viruses and iron.
• Improves taste, smell and colour of water.

10
• Can be constructed with locally available material.
• Keeps water cold and safe.
• Long life if the filter remains unbroken  
• Proven reduction of diarrheal disease incidence in users
• Durable, easy to move and transport (except clay pot).
1.6 DRAWBACKS OF CERAMIC FILTERS
 Lower effectiveness against viruses
 Does not remove all the pathogens
 Does not remove chemical contaminants and colour
 Highly turbid or iron containing water plugs candle pores
 Low flow rate
 Ceramic candle and clay container is not easy to transport due to its
fragility and heavy weight
 Quality control difficult to ensure in local production
 A lower flow rate of 1- 3 liters per hour in non- turbid waters.
 Filters and receptacles need to be regularly cleaned, especially when
using turbid source waters.
 Lack of residual protection can lead to recontamination if treated water
is stored unsafely.
1.7 OBJECTIVE OF THE PROJECT
 To prepare a ceramic candle at a low cost for domestic water
purification.
 To increase the porosity of the ceramic candle by altering its triaxial
composition and by adding pore forming agents such as bleached
wheat flour, rice flour, coffee powder, sago, poppy seed.

11
 To characterize its properties and calculate the TDS of the water used
with this sample.
1.8 SCOPE OF THE PROJECT
 By effective increase in porosity of the ceramic candles, there will be
a significant removal of pathogens, turbidity and suspended solids.
 By effectively utilizing the pore forming agent as a component to
produce ceramic candle filters and thereby reducing the cost of natural
raw materials used in ceramic candle preparation.
 In addition to cost, by recycle and reuse of these non-biodegradable
wastes, we can save the environment from landfills and ecological
damage.

12
CHAPTER 2
LITERATURE REVIEW
Eva Gregorova et al 2006 explains that starch has gained remarkable
popularity as a pore forming agent in ceramic technology, obviously due
to the absence of hygiene and ecological concerns, easy handling and
processing (including defect free burnout), the easy commercial
availability in arbitrary amounts, low cost and controlled quality, the
rounded shape with well defined aspect ratio (usually close to unity without
any scatter) and the well defined size distributions for each starch type.
Apart from its universal function as a pore forming agent, starch can serve
as a body forming agent in a new shaping technique called Starch
Consolidation Casting (SCC), due to its ability to swell in water at elevated
temperatures, thus enabling ceramic green bodies to be fabricated by slip
casting of suspensions with starch into non porous molds. (e.g. metal
molds).
Eva Gregorova et al 2006 explains that poppy seed is a potentially
interesting and unique pore-forming agent (PFA) for use in ceramic
technology, due to its large size (around 1 mm), narrow size distribution,
constant shape (kidney-like), appropriate density and easy availability.
Porous alumina ceramics have been produced using commercially
available poppy seed in combination with a new ceramic shaping technique
called starch consolidation casting. After shaping and drying the ceramic
green bodies were fired at 1570 °C with a heating rate of 2 °C/min,
resulting in porous alumina bodies with a bulk density of
2.50 ± 0.03 g/cm3
, a total porosity of 37.6 ± 0.8% (open porosity

13
32.4 ± 0.9%, closed porosity 5.2 ± 0.3%) and a linear shrinkage of
14.1 ± 0.2%. As expected, the pore size exhibits a bimodal distribution,
corresponding closely to the original size of the pore-forming agents.
Eva Gregorova et al 2009 explains that wheat starch can be used for the
preparation of porous alumina ceramics via the SCC (starch consolidation
casting) process, resulting in porosities ranging from > 20% to approx.
50% (using nominal starch contents of 10 – 50%, v/v), with open porosity
dominating (closed porosity < 6.5%). The character of porosity and the
shape of the pores corresponds to the starch granules used, but the pore size
is determined by a complex interplay between starch swelling (during the
body-forming step) and pore shrinkage (during sintering of the ceramic).
Typically, for low starch contents (e.g. nominal starch contents of around
10%, v/v) starch swelling is a significant effect, and the pores after
sintering are larger than the size of the starch granules. For higher starch
contents swelling is constrained (by limited space and/ or water
availability), and the matrix shrinkage during sintering overcompensates
the swelling effect, so that the final pores in the ceramic can be
significantly smaller than the original starch granule size. In this paper it is
shown how porosity is related to pore size. In particular, it is demonstrated
that the porosity indirectly determined from image analysis (via the median
pore size) is closely related to the porosity directly measured via the
Archimedes method. On the other hand, mercury porosimetry measures the
distribution of pore throat sizes. With increasing starch content in the
suspension, the pore throat size in the as-fired ceramic materials increases,
resulting in a more open microstructure.
Eva Gregorova et al 2009 explains that potato starch is a common auxiliary
material in ceramic technology. Beside its traditional function as a pore-

14
forming agent, which is pyrolyzed and burned out during the heat-up stage
of the ceramic firing process, it has become an important body-forming
agent for ceramics during the last decade. In particular, the so-called starch
consolidation casting process is based on the ability of starch to swell in
aqueous media at a moderately elevated temperature (below 100°C) and
thus on the ability of starch granules to absorb free water from a particulate
suspension, which leads to the transformation of the more or less viscous
ceramic suspension to a viscoelastic (and finally elastic) solid after heating.
In this contribution we give a brief review of the uses of potato starch in
ceramic technology, especially as a pore- and body-forming agent in
traditional slip casting and starch consolidation casting. The discussion
includes the most important aspects of using potato starch in ceramic
technology, ranging from size and shape characterization, suspension
rheology, swelling kinetics and burnout behavior to the characterization of
the resulting ceramic microstructures and the properties of the final
ceramic materials.
Lei Yuan et al 2011 explains that Porous reaction-bonded silicon nitride
(RBSN) ceramics were fabricated by using potassium chloride (KCl) and
urea (CO(NH2)2) as pore-forming agent, respectively. Green bodies with
30% in mass KCl were subjected to presinter in Ar atmosphere at 1200℃
and then reaction-sintered. The properties of porous silicon nitride
ceramics adding different pore-forming agent were explored. And the
influence of presintering on apparent porosity, bulk density and bending
strength of porous ceramics were investigated. The results indicated that
the porosity of Si3N4 ceramics showed a nearly linear increase as the
content of KCl increasing, but urea was not. And after presintering, the
porosity had small decrease, but bending strength increased obviously.
Low bulk density with about 58.6% porosity Si3N4 ceramic was prepared
by adding 50 wt% KCl, and the main phase composition of porous ceramic

15
was α-Si3N4. Lots of needle-liked α-Si3N4, especially in the pores, could be
observed.
Fang Zang et al 2011 explains that the porous ceramics having cordierite
crystalline phases were made from kaolin, talc and α-alumina at 1200 °C
for 1 h. Coal powders and starch were used as pore-forming materials,
respectively. Physical and chemical properties and microstructure of two
samples were studied. The study results indicate that the pores of starch
samples are homogeneous. Compared to coal powders samples, the
porosity of starch samples is higher, but the bending strength is lower than
that of coal powders samples.
Jean Jacques et al 2011 explains that the simple and effective way of
making sure that water is of good quality is by making use of a household
water filter. It is, however, of critical importance that such a low cost water
filter is capable of removing suspended solids, pathogenic bacteria and
other toxins from the drinking water. A low cost, micro-porous ceramic
water filter with micron-sized pores was developed using the slip casting
process. Naturally occurring water from two streams and a lake containing
different species of bacteria was used in testing the ceramic filter’s
effectiveness in eliminating bacteria. The filter proved to be effective in
providing protection from bacteria and suspended solids found in natural
water. This filtration process is suggested as a possible solution for the
problem faced by more than 250 million people in Africa without provision
of clean drinking water.
N.R.A Manap et al 2013 explains that Pore forming agent is a pyrolysable
material, which burns out during firing. Preparation of porous ceramics
with controlled microstructure can be made using different pore forming

16
agents such as wheat particles, starch, PMMA, poppy seed and saw dust.
Porous silica, a ceramic, was successfully synthesised using rice husk ash
as the silica precursor via sol–gel process and employing yeast as the pore
forming agent. Yeast, a biological agent was added in increasing amounts
to a sol–gel silica system at solution level along with additives such as
glucose and water that allow the biological agent to multiply and grow and
in the process form porous ceramic structure. The porous ceramic was
dried in an oven at 110°C overnight. The resultant ceramic was
characterized in terms of product density, particle size, surface area and
pore volume using gas pycnometer and BET sorptometer respectively. The
specific surface areas ranged from 163·4 to 200·7 m2
g–1
while for the pore
volume the range was from 0·3410 to 0·4879 cm3
g–1
.
Shanti Lamichanne et al 2013 aims to compare the performance of three
different types of ceramic filter candles (Madhyapur Clay Candle, Puro and
Surya) in treating drinking water. Filter candles performance with and
without colloidal silver (CS) coating was determined based on flow rate,
E. coli and total coliform removal efficiency. Significant impact of CS
coating in removing and/ or inactivating E. coli and total coliforms were
observed for all filter candles and Puro filter candle was found to be the
most efficient one. Using MCC filter candle (which was built using locally
available materials) can achieve the highest filtration rate but E.Coli and
total coliforms removal efficiency could not meet the standard set by
World Health Organization (WHO) guideline. Further silver leaching test
demonstrated that silver concentration in the filtered water through the CS
coated filter was under the WHO guideline. There is a minimal difference
in the flow rate before and after CS coating in the candles demonstrating
the CS coating has not affected in the filtration rate. This study concludes

17
that locally available filter candles (Puro or Surya) in Nepal after CS
coating can be safely used in treating drinking water at household level.
Gupta et al 2013 explains the performance of two ceramic filter candles
and one silver-impregnated ceramic filter candle with a layer of activated
carbon, randomly selected from those available in the Indian commercial
market, were evaluated employing the Escherichia coli and poliovirus
challenge tests and a long-duration filtration test mimicking the home
treatment of water. None of the candles appeared reliable as
microbiological water purifiers. The study indicated that
specifications/standards should require filter candles to retain suspended
particles down to a size of 1 mu m to ensure at least a bacteriologically safe
filtrate. Additional disinfection or boiling must be practiced during
suspected outbreaks of waterborne viral diseases. Ball-clay mineral was
preferred because it exhibits high plasticity to hold the filter particles
together and it has a greater dry mechanical strength when fired .The
hardwood sawdust was preferred to softwood sawdust because it does
not cause bloating and results in a more uniform pore formation with
fewer defects in the filter.
Bolaji et al 2013 explains that a ceramic filter for point of use water
purification was designed fabricated and tested to evaluate its performance
in filtering water to the World Health Organization (WHO) standards. The
results of pH of water samples obtained after filtration ranged from 7.68 to
8.11. The range of values obtained after filtration for turbidity, hardness,
conductivity, Total dissolved solid (TDS) and Total suspended solid (TSS)
from water samples were 0.07 to 0.55 NTU, 6.0 to 34 mg/L, (1.5 to 3)
*103
S/m, 4 to 25mg/L and 0.04 to 0.11 mg/L respectively, while the filter
average removal efficiencies of these parameters were 93.1, 85.1, 91.6,

18
92.3, 91.4% respectively. Comparison of the result with the WHO
standards for drinking water showed that the ceramic water filter can
provide potable drinking water of required standards. The ceramic filters
was made from local materials, which included sawdust and clay. Silver
solution was applied to the surfaces of the constructed filter element.
Ceramic water filter combines the filtration capability of ceramic material
with the anti bacteriological qualities of colloidal silver. Ceramic water
filters rely on porous ceramic (fired clay) to filter microbes or other
contaminants from drinking water. The units feature a pore size that should
be small enough to remove virtually all bacteria and protozoa, and they
work by gravity filtration.
Ebele et al 2014 explains that Ceramic water filtration is the process that
makes use of a porous ceramic (fired clay) medium to filter microbes or
other contaminants from water. Ceramic water filtration has been greatly
improved upon such that it takes care of most microbial contamination in
water. However, the ceramic filter is not known to treat chemical
contaminants in water. This paper focuses was on developing a ceramic
filter that could treat certain chemical contamination in water at the
household level. Porous ceramic bodies were formulated and constituted
from various materials such as kaolin, laterite, bonechar and charcoal.
Bone char was added as a defluoridation agent while the charcoal doubled
as the pore-creating combustible material and as an Activated Carbon
media in the ceramic body for the adsorption of metals from water. The
formulated ceramic bodies were shaped into filters (pot) using the slip
casting technique and fired bisque (850 ̊C - 900 ̊C). The developed filter
samples were subjected to physical properties tests, while analysis on the
microbial and physio-chemical parameters of the filter-treated water
samples were compared vis-à-vis the raw water samples. The results

19
indicate that the developed filters were effective in the treatment of
chemical contaminants detected in the raw water samples; with significant
reductions in fluoride, lead, and sulphate levels amongst others. The
resulting filter samples also showed viability in physical handling strength
and flow rate; while the availability of the raw materials and the processing
technique used, makes a good economic case for the production of the
developed filters.
Sandeep Parma et al 2014 highlights the preparation of ceramic
membranes from a low-cost naturally occurring clay material viz. red mud.
Additives like sodium carbonate, sodium metasilicate and boric acid was
added in standard stoichiometric ratio with the processed clay material,
imparting characteristic properties. Paste casting method was followed for
fabricating circular disc shaped membranes with 50 mm × 5 mm
dimensions. Sintering effects were studied by exposing the membranes at
temperatures ranging between 500o
C to 800o
C in a programmable muffle
furnace. The membranes fabricated were characterized using standard
characterization techniques like Scanning Electron Microscopy (SEM) and
Powder X-ray Diffraction Analysis (PXRD). Finally, water permeation
studies were carried out in a standard membrane module within the
microfiltration regime i.e. < 5 kg cm-2, obtaining a standard permeation
flux and the data was used in calculating the porosity of the ceramic
membrane. These membranes were found well suited for oily waste water
studies. A maximum rejection of 53% was achieved with membrane
sintered at 8000
C.
Faustine Abigira et al 2014 explains the results of an experimental study
on the effects of double filtration on the rate of water percolation and E.
coli removal efficiency of ceramic water filters made from mixtures of
different ratios of clay powder, fine sawdust and powder of grog. The

20
results show that double filtration produces superior quality of filtered
water compared to single filtration although the rate of water percolation
is higher for single filtration.
Fakhrul Islam et al 2014 explains that the porous ceramic having effective
pore size less than 1 µm was fabricated by slip casting technique which
provides a low-cost and single-stage filtration process. This single-stage
filtration process removed suspended solids and pathogenic organism. In
this study, diatomaceous earth was used as pore-forming agent in clay
based ceramic body. Varied amount of diatomaceous earth was used with
fixed proportion of china clay, ball clay and limestone. X-ray fluorescence
spectroscopy (XRF) was used to determine the composition of raw
materials and final sintered filter body. In terms of porosity and flow rate,
25% diatomaceous earth shows better filtration property. It was found that
total porosity increased with decreasing milling time. As the firing
temperature increased, porosity decreased rapidly after 1100 °C. However,
the change of porosity in firing range of 1000 °C–1100 °C was found very
small. Mercury intrusion porosimetry was used to measure the pore size
and its distribution. An effective intra-particle pores in a range of 0.2-0.5
μm was identified. Inter- and intra-particle pores were observed using
scanning electron microscope (SEM). Microbial removal efficiency of
99.99% was measured, while water flow rate was found in a range of 200-
700 ml/hour.
Mohamad et al 2015 explains that porous cordierite is an advanced
ceramic, which is popular for its interesting properties such as excellent
thermal stability, high refractoriness and low dielectric constant. In this
study, samples have been prepared by the mixture of aluminium nitrate
nonahydrate, magnesium nitrate hexahydrate, tetraethylorthosilicate

21
(TEOS), ethanol and nitric acid through sol-gel route. Corn and potato
starch were used as pore forming agent. The amount of pore forming agent
added was varied according to their weight percent (5wt%, 10wt%, 15wt%
and 20wt%). The solution was then dried in oven at 90°C before sintered
at 1350°C. Particle size analyzer was used to characterize the properties of
pore forming agents. Scanning electron microscopy (SEM) and X-ray
diffraction (XRD) analysis were done on the produced samples. XRD
results proved that all the samples produced were pure a-cordierite without
the presence of other impurity or pore forming agent. From SEM results,
samples using potato starch as the pore forming agent have pore size larger
than corn starch due to the larger particle size of potato starch. Majority of
the samples show interconnectivity among pores. The pore shape produced
by potato starch is in prolate shape whereas for corn starch is in polyhedral
shape

22
CHAPTER 3
EXPERIMENTAL WORK
3.1 RAW MATERIALS
The raw materials used in the preparation of ceramic candle are
 Ball Clay
 China Clay
 Quartz
 Feldspar
 Sodium Carbonate
 Sodium Silicate.
The pore forming agents used are
 Bleached Wheat Flour
 Rice flour
 Coffee powder
 Sago
 Poppy Seed
 Calcium Carbonate
3.2 MINEROLOGY
3.2.1 Ball Clay
Ball clay is kaolinite sedimentary clay that commonly consists of
20-80% kaolinite, 10-25% mica, 6-65% quartz. Localized seams in the
same deposit have variations in composition, including the quantity of the
major minerals, accessory minerals and carbonaceous materials such

23
as lignite. They are fine-grained and plastic in nature, and, unlike
most earthenware clays, produce a fine quality white-
coloured pottery body when fired, which is the key to their popularity with
potters. Ball clays are relatively scarce deposits due to the combination of
geological factors needed for their formation and preservation. They are
commonly used in the construction of many ceramic articles, where their
primary role, apart from their white colour, is to either to impart plasticity
or to aid rheological stability during the shaping processes. It also has high
bonding qualities and tensile strength. It is therefore used in blend with non
– plastic to semi – plastics clays for obtaining requisite plasticity. It is
added in various proportions for the preparation of body composition of
various sanitary wares, bathtub tiles, porcelain, etc.
3.2.2 China Clay
China Clay, also called kaolin, falls under kaolinite group of clay
minerals. It results from the alterations of feldspars, granite, gneiss and
pegmatite rocks by hydrothermal action of aqueous solution. China Clay
usually carries some impurities in a small quantity such as silica, iron,
magnesium, titanium, calcium, potassium, sodium oxides, mica,
tourmaline, etc., which may be inherent in the parent rocks. The quality of
china clay depends much upon the impurities present. The chemical
composition of china clay is similar to that of ball clay, except that the ball
clay contains a large proportion of silica. China clay is mainly used in
ceramics, textiles, paper, paints, cosmetic, pharmaceuticals and in white
cement manufacturing.

24
3.2.3 Quartz
Quartz is a chemical compound consisting of one part silicon and
two parts oxygen. It is silicon dioxide (SiO2). It is the most abundant
mineral found at Earth's surface and its unique properties make it one of
the most useful natural substances. Quartz is the most abundant and widely
distributed mineral found at Earth's surface. It is present and plentiful in all
parts of the world. It forms at all temperatures. It is abundant in igneous,
metamorphic and sedimentary rocks. It is highly resistant to both
mechanical and chemical weathering. This durability makes it the
dominant mineral of mountaintops and the primary constituent of beach,
river and desert sand. Quartz is ubiquitous, plentiful and durable. Minable
deposits are found throughout the world. Quartz is one of the most useful
natural materials. Its usefulness can be linked to its physical and chemical
properties. It has a hardness of seven on Moh’s Scale which makes it very
durable. It is chemically inert in contact with most substances. It has
electrical properties and heat resistance that make it valuable in electronic
products. Its luster, color and diaphaneity make it useful as a gemstone and
also in the making of glass. It is used in glass making, as an abrasive,
sanitary ware, tableware, etc.
3.2.4 Feldspar
Feldspar is a very common igneous rock - more than half of the
earth’s crust is made of feldspar. When molecules of aluminum, silica and
oxygen get together with potassium, they combine to make the rock
feldspar. Feldspar often combines with quartz to make a much harder
igneous rock called granite. Feldspar and pyroxene combine to form
Basalt. When feldspar is in contact with wind or water, the wind and water

25
gradually grind the feldspar down into tiny grains that become one kind of
clay called kaolin. Feldspar is a common raw material used in glassmaking,
ceramics, and to some extent as a filler and extender in paint, plastics, and
rubber. In glassmaking, alumina from feldspar improves product hardness,
durability, and resistance to chemical corrosion. In ceramics, the alkalis in
feldspar (calcium oxide, potassium oxide, and sodium oxide) act as a flux,
lowering the melting temperature of a mixture. Fluxes melt at an early
stage in the firing process, forming a glassy matrix that bonds the other
components of the system together.
3.2.5 Sodium Carbonate and Sodium Silicate
The soda ash that the ceramic industry knows is a refined fine
granular white material. It is very pure (99%). Grades (light, natural and
dense) differ in particle size and therefore bulk density but they have the
same chemistry. The common ceramic use of soda ash is as a soluble
defloculant in ceramic slips and glazes. It works well in combination with
sodium silicate to produce body slips that do not gel too quickly and whose
rheology can be adjusted for changes in the hardness of the water. Higher
soda ash proportions (vs sodium silicate) will produce a slip that gives a
softer cast (stays wet longer). The total soda ash and sodium silicate
amount should be tuned to create a slip that will eventually gel if left to
stand. This thixotropic behavior will prevent it from settling. Sodium
carbonate is also the preferred defloculant for thinning glaze slurries.

26
3.3 BATCH COMPOSITION
Table 3.1 Batch 1 Composition Table 3.2 Batch 2 Composition
RAW MATERIAL WT %
China clay 25
Ball clay 25
Quartz 25
Feldspar 25
Sodium silicate 0.4
Sodium carbonate 0.2
Water 40
RAW MATERIAL WT %
China clay 25
Ball clay 25
Quartz 25
Feldspar 25
Sodium silicate 0.4
Water 40
Wheat flour 3
RAW MATERIAL WT %
China clay 20
Ball clay 20
Quartz 30
Feldspar 30
Sodium silicate 0.4
Water 40
Calcium carbonate 5
RAW MATERIAL WT %
China clay 25
Ball clay 25
Quartz 25
Feldspar 25
Sodium silicate 0.4
Water 40
Wheat flour 5

27
RAW MATERIAL WT %
China clay 25
Ball clay 25
Quartz 25
Feldspar 25
Sodium silicate 0.4
Water 40
Rice flour 5
RAW MATERIAL WT %
China clay 25
Ball clay 25
Quartz 25
Feldspar 25
Sodium silicate 0.4
Water 40
Sago 5
RAW MATERIAL WT %
China clay 25
Ball clay 25
Quartz 25
Feldspar 25
Sodium silicate 0.4
Water 40
Coffee powder 5
RAW MATERIAL WT %
China clay 25
Ball clay 25
Quartz 25
Feldspar 25
Sodium silicate 0.4
Water 40
Coffee powder 5

28
3.4 BODY PREPARATION
The raw materials and the pore forming agents were separately
weighed according to their respective composition and mix well with water
to impart green strength in the samples as the preparation is by wet method.
The mixture is then mixed using planetary mill for 4 hours to provide a
homogenous mix. The mixture is the obtained in a slurry form. The slurry
is shaped into body using plaster of paris of the required shape by slip
casting technique. The obtained sample is then dried at 60°C for 4-6 hours.
The sample is then fired at 1060°C for 48 hours with a soaking time of 2
hours and heating rate of 20°C/min. The fired samples were cooled at room
temperature and the samples were tested for various properties and their
microstructures were analyzed.

29
The flow chart for the production of ceramic candles is shown below :
Fig 3.1 Flow sheet for body preparation
Batch composition
Mixing
Planetary Mill
(4 hrs)
Slip casting
Drying
(60°C for 4-6 hrs)
Surface Finishing
Firing
(1060°C for 48 hrs)
Product tested for
properties and
characterization
Cooling

30
3.4.1 Mixing
The raw materials were mixed using planetary mixer. Initially the
raw materials were taken in the bowl and defloculants (Sodium Carbonate
and Sodium Silicate) and water were added subsequently to carry out the
wet mixing for 3 minutes. After mixing the batch became like in the form
of slurry. It is ensured that the homogeneous mixing was achieved.
3.4.2 Slip Preparation
After mixing, the slurry was milled in a planetary mill. The milling
was carried out for 4 hrs at constant speed. This ball milling reduces the
particle size of the batch raw materials, improves the homogenous mixing
and also improves the flow ability of the slip.
Fig 3.2 Slip preparation using Planetary Mill
3.4.3 Slip Casting
Initially the density, viscosity and flow ability of the slip was
checked to get better cast piece and also to avoid the casting defects. Before
the slip was poured into the plaster mould, the mould was cleaned using
brush and compressed air, then talc was applied (on the surface of the slip
- mould interface) to facilitate the smooth releasing of the casted piece form

31
the mould. Then, the slip was poured into the plaster mould and left for
casting. The slip was poured continuously into the mould to avoid the void
formation in the cast piece. Excess slip was drained out after the required
thickness formation. After casting, the finishing operation was carried to
remove the excess material and also to smoothen the surface of the casted
pieces.
Fig 3.3 Slip Casting
3.4.4 Drying
The casted products were initially left for floor drying for 24 hrs and
then oven dried at 60°C for 4-6 hrs. Usually the actual drying schedule of
the ceramic candle filters will depend on the thickness of the product.

32
Fig 3.4 Drying at 60°C in oven Fig 3.5 Dried Sample
3.4.5 Firing
The dried samples were fired in a furnace. The samples were fired
at 1060°C with a soaking time of 2 hrs. Firing was carried out for 48hrs.
The industrial heating cycle was followed for the firing. After firing, the
unloaded samples were cooled by natural cooling carried out at room
temperature.
Fig 3.6 Firing at 1060°C in furnace Fig 3.7 Fired Sample

33
3.5 TESTING
3.5.1. Linear Shrinkage
Linear Shrinkage refers to the changes in linear dimensions that has
occurred in test specimens after they have been subjected to firing. The
linear shrinkage, LS (%), of fired samples has been determined by means
of the following equation:
%𝐿𝑆 =
𝐿 𝑓 − 𝐿 𝑔
𝐿 𝑔
Being Lg and Lf the length (mm) of the green and fired specimens
respectively. The linear shrinkage values were calculated as wet to dry
shrinkage and dry to fired shrinkage to examine the drying and firing
shrinkage separately.
3.5.2. Bulk Density and Apparent Porosity
The bulk density of a porous material is defined as the ratio of mass
of material to its bulk volume. Whereas the apparent porosity is the ratio
of open pores to the bulk volume of the material. The latter value is
expressed in percentage.
The density, porosity and water absorption of the samples were
found by using Liquid Displacement technique based on Archimedes
principle. The dry weight (D) of the samples was measured. The samples
were then boiled in a beaker containing water for two hour in which
samples were in suspended position. The samples were boiled in water for
2 hours. After boiling the soaked samples were taken out and wiped with a
cotton cloth and the soaked weight (S) was measured. Then the samples
were suspended in a beaker containing water and suspended weight (W)

34
was measured. The density, porosity and water absorption were calculated
using the following formula respectively.
𝑩𝒖𝒍𝒌 𝑫𝒆𝒏𝒔𝒊𝒕𝒚 =
𝑫
𝑾 − 𝑺
𝑨𝒑𝒑𝒂𝒓𝒆𝒏𝒕 𝑷𝒐𝒓𝒐𝒔𝒊𝒕𝒚 =
𝑾 − 𝑫
𝑾 − 𝑺
𝑾𝒂𝒕𝒆𝒓 𝑨𝒃𝒔𝒐𝒓𝒑𝒕𝒊𝒐𝒏 =
𝑾 − 𝑫
𝑫
Where,
D - Dry weight of the sample in g
W - Soaked weight of the sample in g
S - Suspended weight of the sample in g
The porosity and water absorption values are either represented as
such or in terms of percentage.
Bulk density and apparent porosity are generally used for quality
control checks. They have an effect on other properties such as thermal
conductivity and thermal shock resistance of a material. Lower porosity of
a material can often have a greater resistance to chemical attack than the
higher porosity materials.
3.6 CHARACTERISATION
3.6.1. Total Dissolved Solids (TDS)
Total dissolved solids (TDS) is a measure of the combined content of
all inorganic and organic substances contained in a liquid in molecular,
ionized or micro-granular (colloidal sol) suspended form. It is the sum of
the cations (positively charged) and anions (negatively charged) ions in the

35
water. Therefore, the total dissolved solids test provides a qualitative
measure of the amount of dissolved ions in water. The total dissolved solids
test is used as an indicator test to determine the general quality of the water
in ppm as shown in Fig 3.8
Fig 3.8 TDS value for various types of water
TDS in water can be reduced by:
*Carbon Filtration
*Reverse Osmosis
*Distillation
*Deionization.
Why TDS?
The EPA Secondary Regulations advise a maximum contamination level
(MCL) of 500mg/liter (500 parts per million (ppm)) for TDS. Numerous
water supplies exceed this level. When TDS levels exceed 1000mg/L it is
generally considered unfit for human consumption. Most often, high levels
of TDS are caused by the presence of potassium, chlorides and sodium.
These ions have little or no short-term effects, but toxic ions (lead arsenic,
cadmium, nitrate and others) may also be dissolved in the water.

36
3.6.2. Scanning Electron Microscope (SEM)
The scanning electron microscope (SEM) uses a focused electron
beam of high-energy to produce a number of signals on the solid
specimens’ surface and generates an image using these signals. The signals
that are obtained from the electrons generate information about the sample
including the morphology (texture), chemical composition, orientation of
materials and crystalline structure making up the sample. The image
produced may be like a television picture that can be examined or
photographed. Accelerated electrons in a SEM carry appreciable amounts
of kinetic energy, and this energy is scattered into a number of signals
produced by electron-sample interactions. This occurs when the incident
electrons reduce their velocity in the solid sample. These signals constitute
secondary electrons (generating SEM images), backscattered electrons,
diffracted backscattered electrons, photons (characteristic X-rays used for
elemental analysis and continuum X-rays), visible light (cathode
luminescence), and heat. The SEM is used to generate high-resolution
images of shapes of objects and also allows spatial variation visualization
of chemical compositions. Nonconductive specimens tend to charge when
scanned by the electron beam, and especially in secondary electron
imaging mode, this causes scanning faults and other image artifacts. They
are therefore usually coated with an ultrathin coating of electrically
conducting material, deposited on the sample either by low- vacuum
sputter coating or by high-vacuum evaporation. Conductive materials in
current use for specimen coating include gold.

37
CHAPTER 4
RESULTS AND DISCUSSION
4.1 PHYSICAL PROPERTIES OF SAMPLE TRIALS
In order to study the influence of Pore forming agents in ceramic
filter candle, a range of batch composition were formulated with varying
pore forming agent and tri-axial composition.
Table 4.1 Initial & Final Thickness, Dry weight, Soaked Weight,
Suspended Weight of Sample Trials
BATCH
NO
INITIAL
THICKNESS
(mm)
FINAL
THICKNESS
(mm)
DRY
WEIGHT
(g)
SOAKED
WEIGHT
(g)
SUSPENDED
WEIGHT
(g)
1 4.6 4.2 44.58 53.03 23.36
2 4 3.6 38.41 46.54 20.65
3 4 3.55 43.39 53.01 23.27
4 4 3.5 40.98 49.74 20.85
5 3 2.6 19.33 25.22 11.34
6 3 2.5 23.32 29.83 13.20
7 4 3.2 26.88 35.03 14.48
8 3.5 3.2 36.46 47.70 19.60

38
4.2 TOTAL SHRINKAGE
Sample shrinks during firing depending upon the water
content present in it. Total Shrinkage of samples are summarized below
Table 4.2 Total Shrinkage of Sample
Fig 4.1 Total Shrinkage variation Graph of Samples
SAMPLE NO
TOTAL
SHRINKAGE
(%)
1 8.70
2 10.00
3 11.25
4 12.50
5 13.34
6 16.67
7 20
8 8.57

39
4.3 BULK DENSITY
Depending on the nature of pore forming agent, porosity will
occur in sample which is inversely proportional to the density of the
sample (i.e.) increase in porosity will decrease bulk density and vice
versa. The bulk density of the sample are tabulated below.
Table 4.3 Bulk Density of Samples
Fig 4.2 Bulk Density Variation Graph of Sample
SAMPLE NO
BULK DENSITY
(%)
1 1.503
2 1.483
3 1.460
4 1.418
5 1.393
6 1.402
7 1.308
8 1.290

40
4.4 WATER ABSORPTION
The amount of open pores present in the sample
determines the water absorption. The water absorption value of samples
are tabulated below.
Table 4.4 Water Absorption of Samples
Fig 4.3 Water Absorption Variation Graph of Samples
SAMPLE NO
WATER
ABSORPTION
(%)
1 18.95
2 21.17
3 22.17
4 21.38
5 30.47
6 27.92
7 30.32
8 30.83

41
4.5 APPARENT POROSITY
The apparent porosity of the sample depend upon the
nature of the pore forming agent present in it. The sample with poppy seed
showed high percentage of porosity (40 %). The apparent porosity value
of the sample are mentioned below
Table 4.5 Apparent Porosity of Samples
Fig4.4Apparent porosity Variation Graph of Samples
SAMPLE NO
APPARENT
POROSITY
(%)
1 28.48
2 31.40
3 32.30
4 30.32
5 39.94
6 39.14
7 39.65
8 40

42
4.6 TOTAL DISSOLVED SOLIDS
Ground water from Anna University was taken
for TDS test. The TDS of ground water along with the TDS of fitered
ground water using sample 8 was tested and compared.
TDS of Ground water – 365 mg/l
TDS of filtered Ground water using sample 8 – 186 mg/l
Percentage of Purification – 49.04
Fig 4.5 TDS value graph of unfiltered and filtered water

43
SCANNING ELECTRON MICROSCOPE
The SEM Images Of Sample 4 And Sample 8 are shown
below
Fig 4.6 Sample 4 SEM Micrograph Fig 4.7 Sample 8 SEM Micrograph

44
CHAPTER 5
CONCLUSION
The aim of this project work is to investigate the effect of porosity
of Ceramic Candle Filters by the addition of pore forming agents to its
triaxial body composition. The aim is a multifold one and includes (i)
increasing the porosity of the sample thereby more pathogens and
suspended particles can be removed (ii) to alter the raw material
composition by adding pore forming agents thereby reducing the cost of
production (iii) to explore the role of pore forming agents in the
manufacture of Ceramic Candle Filters and (iv) study the properties of the
Ceramic Candle Filters.
Various batch formulations were prepared with different pore
forming agents and their properties were evaluated.
• The sample in which poppy seed was added showed maximum
percentage of porosity. This sample composition was selected as the
best composition and the physical properties like density, porosity,
water absorption, shrinkage and TDS along with SEM micrograph
showed better properties than the remaining samples.
• The TDS of ground water filtered using sample in which poppy seed was
added showed better results than the TDS of ground water.
• Incorporation of pore forming agents into tri axial clay composition
resulted in Ceramic Candle Filters with Better properties, Reduction
in sintering temperature, Utilization of waste materials, and Cost &
Energy efficient production.

45
REFERENCES
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microstructure of porous alumina”, Journal of the European
Ceramic Society 27, 2007
2. Bonekamp BC, Schoute MJ, Goris MJAA, “Pore properties of
ceramic porous media prepared by slip casting of starch filled D-
alumina suspensions”, Euro-Ceramics, Volume 1 (Processing of
Ceramics), 1998
3. Chaudhuri .M, S.R. Verma, A. Gupta, “Performance evaluation
of Ceramic Filter Candles”, Environ. Eng.120, 1994.
4. Faustine Abiriga, Sam Obwoya Kinyera, “Water Purification by
Double Filtration Using Ceramic Filters”, Environment and Natural
Resources Research; Vol. 4, No. 2, 2014
5. Franz, A., “A Performance Study of Ceramic Candle Filters in
Kenya Including Tests for Coliphage Removal”, Cambridge:
Massachusetts Institute of Technology (MIT), 2005
6. Gregorová E, Živcová Z, Pabst W, “Porosity and pore space
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7. Gregorová E, Pabst W, "Porous ceramics prepared using poppy
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9. Gregorová E, Živcová Z, Pabst W, Kunertová A, “Starch-
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Baden, Germany, 2007

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10. Gregorová E, Pabst W, Bohaþenko I, “Characterization of
different starch types for their application in ceramic technology”,
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11. Gregorová E, Živcová Z, Pabst W, Sedlá ová I, “Characterization
of porous ceramics by image analysis and mercury porosimetry”,
Ceramika – Ceramics 97, 2006
12. Mohamad Hasmaliza, Yumin L, Norfadhilah I, “Porous
Cordierite Synthesised Using Corn Starch”, Advanced Materials
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13. Robert, W. D., “Development of a ceramic water filter for Nepal.
Dissertation for Master in Civil and Environmental Engineering”,
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Characterization of Microfiltration Ceramic Membrane for Oily
Waste Water Treatment”, International Journal of Research in
Engineering and Technology, 2014

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