CHAPTER 1
INTRODUCTION
1.1 Water
Water is a common chemical substance that is
essential for the survival of all known forms of life. In typical usage, water refers only to its liquid form or state,
but the substance also has a solid state, ice, and a gaseous state, water
vapor or steam. About 1.460 platinum (Pt.)
(1021kilograms) of water covers 71% of the Earth's surface, mostly in oceans and other large water bodies,
with 1.6% of water below ground in aquifers and
0.001% in the air as vapor, clouds (formed
of solid and liquid water particles suspended in air), and precipitation.[1] Saltwater oceans hold 97%
of surface water, glaciers and polar ice
caps 2.4%, and other land surface water such as rivers, lakes and ponds 0.6%. Some of the Earth's water is contained within water
towers, biological bodies, manufactured products, and
food stores. Other water is trapped in ice caps, glaciers, aquifers, or in
lakes, sometimes providing fresh water for life on land. At ambient
temperature, it is a nearly colorless (with a hint of blue), tasteless, and odorless liquid.
Many substances dissolve in water and it is commonly referred to as the
universal solvent. Because of this, water
in nature and in use is rarely pure.
1.2 Industrial Uses of
Water
Industries that produce
metals, wood, paper, chemicals, gasoline, oils, and most other products all use
water in some part of their production process. Industry depends on water, much
like agriculture and domestic households depend on water. Total industrial
water use in the world is about 22%, with high-income countries using 59%, and
low-income countries using a minuscule 8%. Industry is reliant on water
for all levels of production. It can be used as a raw material, solvent,
coolant, transport agent, and energy source.
1.3 Waste Water
Wastewater can be
described as a mixture of undesirable substances, or “pollutants,” in water.
Industrial wastewater is the aqueous discard that results from the use of
water in an industrial manufacturing process or the cleaning activities that
take place along with that process.
1.4 Problems Caused By Waste Water
Virtually all types of water pollution are
harmful to the health of humans and animals. Different forms of pollutants
affect the health of animals in different ways:
- Heavy metals from industrial processes can accumulate in nearby lakes and rivers. These are toxic to marine life such as fish and shellfish, and subsequently to the humans who eat them. Heavy metals can slow development; result in birth defects and some are carcinogenic.
- Industrial waste often contains many toxic compounds that damage the health of aquatic animals and those who eat them. Some of the toxins in industrial waste may only have a mild effect whereas other can be fatal. They can cause immune suppression, reproductive failure or acute poisoning.
- Microbial pollutants from sewage often result in infectious diseases that infect aquatic life and terrestrial life through drinking water. Microbial water pollution is a major problem in the developing world, with diseases such as cholera and typhoid fever being the primary cause of infant mortality.
- Organic matter and nutrients causes an increase in aerobic algae and depletes oxygen from the water column. This causes the suffocation of fish and other aquatic organisms.
- Sulfate particles from acid rain can cause harm the health of marine life in the rivers and lakes it contaminates, and can result in mortality.
- Suspended particles in freshwater reduces the quality of drinking water for humans and the aquatic environment for marine life. Suspended particles can often reduce the amount of sunlight penetrating the water, disrupting the growth of photosynthetic plants and micro-organisms.
Water is a great playground for us all. The scenic and
recreational values of our waters are reasons many people choose to live where
they do. Visitors are drawn to water activities such as swimming, fishing,
boating and picnicking.
1.7 OBJECTIVES AND METHODOLOGY
The objective of the
project was to analyze industrial waste water and then suggest a treatment
system. For this purpose different local industries were visited and
samples were collected from each industry. The marble industry was given as our
main concern because in NWFP they are present in huge amount and they pollute water
and our environment up to large extent. The samples were then tested for
different parameters.
CHAPTER 2
MARBLE INDUSTRY
2.1 Introduction
The term marble (from the marmoaos stone or boulder) is restricted
granular limestone and dolomite that have been recrystallized under the
influence of heat, pressure, and rarely aqueous solution. Commercially it
includes all decorative calcium rich rocks capable of taking polish and
suitable for decorative and structural purposes is termed marble.
Extensive deposits of marble are found at several places in the
N.W.F.P. it takes good polish and has attractive appearance, therefore the there
exists a lot of marble factories in the this area. These factories have small
scale setups.
The marble factories have small scale setups. They are present in
huge no. in NWFP and collectively these small units discharge a huge quantity
of waste water in the nearby water resources.
2.2 Use of Water
The marble units consume huge quantity of water. That is why tube
wells are present. The flow rate of water found in pioneer marble factory was
0.65 lit /sec. The water is used for the following purposes in marble
factories.
- Washing of marble rocks
- During cutting process
- Cooling of cutting blades
- During sizing process
- For polishing of raw marble
2.3 Manufacturing Process
2.3.1 Raw Material Transportation
Raw materials is used in rock form and transported by trucks into
industry and then internal transport and adjustment is carried out through
cranes, chain pulley or by hands. During transportation and unloading
steps dust generated.
2.3.2 Cutting
In cutting section of marble factory, the marble rocks converted
into small plain blocks through cutting machines on which different types of
cutting blades are present.
2.3.3 Sizing
In sizing section the large marble plains are cut according to the
demand size. Water is used from the top to cool the cutters which is
contaminated with the dust particles and thus become polluted. This waste water
is discharged into environment.
2.3.4 Polishing
Polishing is done for the brightness of tiles face. In polishing
soap and water are used. This waste water is discharged into environment.
Finishing and smoothing of tiles is done and edges are balanced.
2.4 Waste Water
The water which is used
by marble industries during different manufacturing steps as illustrated in
process flow diagram is discharged as waste water. This waste water pollutes
our environment in different forms. The contamination and parameters of waste water
of marble industry is shown in table 2.1.
Table 2.1
characteristics of waste water of marble industry
Parameters Pioneer
marble Pakistan marble
PH 7.01
8.09
Conductivity
ms/cm) 0.477
0.39
Hardness (mg/lit) 1120
1060
Alkalinity (mg/lit) 530
612
Salinity 0.01%
0.012%
TSS (mg/lit) 200
250
TDS (mg/lit) 4210
3960
Turbidity
(ntu) 126
93
Potassium (mg/lit) 2.0
2.06
Chloride (mg/lit) 1340
1300
DO (mg/lit) 0.03
0.033
Sulphide (mg/lit)
185
230
COD (mg/lit) 240
260
BOD (mg/lit) 70
66
WASTE WATER ANALYSIS
PH
The term pH
refers to the concentration of hydrogen ions in an aqueous solution, where
“Aqueous
solution” means either pure water or water with small (in terms of molar
amounts) quantities of substances dissolved in it. Strong solutions of
chemicals such as one molar sulfuric acid or a saturated solution of sodium
chloride do not qualify as aqueous solutions. In those solutions the normal pH
range of 0 to 14, which equals the negative logarithm of the hydrogen ion
concentration in moles per liter, has no meaning. Because the pH of an aqueous
solution is numerically equal to the negative log of the hydrogen ion
concentration (in moles per liter) and can be readily calculated using the
following equation, it is therefore indicative of the acidic or basic condition
of a wastewater (pH values between 0 and 7.0 indicate acidic conditions, and pH
values between 7.0 and 14 indicate alkaline conditions). However, pH is not
equivalent to acidity or alkalinity. A wastewater may have a pH of 2.0 but have
lower acidity than another wastewater having a pH of 4.0. Likewise, a
wastewater having a pH of 9.0 may, or may not, have more alkalinity than a
wastewater having
a pH of 10.6.
PH values were determined in laboratories in quickest
possible time. First PH meter was calibrated with buffer 4 and 7.Then PH Values
of samples were measured.
Determination of Conductivity:
Conductivity is the measurement of
water capacity for conveying electrical current and is directly related to the
concentration of ionized substances in water. It estimates the total soluble salts.
Conductivity has relationship with total dissolved solids. It is useful to
repeat the specific conductance does measure the dissolved or total solids. But
indicate with a simple test the ability of water examined to carry an electric current.
The conductivity is useful because it can be readily and precisely determined.
The conductivity was determined in the laboratory with Horiba water quality
meter Minami-Ku Kyoto, Japan. The instrument was calibrated with KCL and
distilled water. Then conductivity of the samples was measured in micro-Siemens
per centimeter.
Dissolved Oxygen:
1 ml Manganese
Sulphate solution, Alkali Iodide Azide, concentrated H2SO4 and starch indicator was added
to 250 ml of sample. Then titrated against 0.025 N Na2S2O3 solution.
Calculation:
DO mg/L=A*N88000/ml of sample
A=ml of Na2S2O3
N=Normality of Na2S2O3
Total solids:
Total solids in water may be
either suspended or dissolved but each one pollutes water.
The residue that is left after
evaporating a sample of water at 103oC is referred to as the total solids value
of that sample. It is generally regarded as everything that was in the sample
that was not water; however, any of the substances originally present, organic
or inorganic that volatilized at 103oC or less will not be in the residue.
Dry and clean evaporating dishes were taken and put in oven at a
temperature
Of 103 C for one hour. The dishes
were cooled in desiccator for about 45 minutes and then weighed. After weighing
known volume of each sample was taken in dishes and put in drying oven at a
temperature of 103-105 C for an hour. Then dishes wee cooled at room
temperature and reweigh.
Total solid mg/L=A-B*1000/ml
of sample
A=weight of china dish dried
residues
B=weight of empty dishes
Total Dissolved Solids
100 ml of filtrated sample was dried
in a crucible. The change in weight corresponded to the weight of dissolved
solid.
Calculation:
Dissolved solid mg/L=A-B
*1000/ml of sample
A=weight of dissolved solids
+dish
B=weight of empty dishes
Suspended solids:
Solids that will not pass through a 0.45 micron filter are
referred to as total suspended solids
(TSS). Because the standard method for measuring TSS
involves shaking the sample thoroughly before filtering, the TSS actually
includes all undissolved solids as opposed to simply the dissolved solids that
will not settle.
Suspended solids
(mg/L) =Total solids – dissolved solids
Biological Oxygen Demand (BOD):
The standard 5-day BOD test is the most commonly used method
to estimate the total
quantity of biodegradable organic material in wastewater.
The results of the 5-day BOD test (abbreviated BOD5) are considered to be
estimates of the amount of oxygen that would be
consumed by microorganisms in the process of using the
organic materials contained in a
wastewater for food for growth and
energy. Some of the organic material will thus be
For determination of BOD,we have to find out
1. Initial
2. Final DO after 5 days
incubation at
The BOD is computed from the
difference
Between initial DO and final DO by
using the formula:
BOD5= (DOi –
Dof)/Po
Where Po is the
dilution factor.
Alkalinity
Alkalinity is defined as the
quantity of ions in water that will react to neutralize hydrogen ions.
Alkalinity is thus a measure of the ability of water to neutralize acid.
Alkalinity the sum total of components in water that tends to elevate the PH of
water above the value of about 4.5.Alkalinity was determined by "Titration
method
50 ml of sample was taken in
a titration flask. Then titrated against 0.02 N
Sulfuric acid with few drops of
indicator to methyl orange endpoint.
Alkalinity as CACO3 mg/L= (A*N*50,000)/ml of sample
A=ml of H2SO4
N=normality of H2SO4
Chlorides:
Chlorides is one of the major in
organic anions in water. In potable water the salty taste is produced due to
the chlorides. The Cl concentration is mostly higher in waste water. They
remain soluble in water, unaffected by the biological process, therefore,
reducible by dilution. Their concentration at higher levels that adjacent of
pollution 9usually chloride concentration under 10 mg/L is expected).
100 ml of sample was taken in a conical flask.21 ml of H202 was added
and stir for a minute. Then 1 ml K2CrO4 indicator was added and titrated with
standard AgNO3 titrant to a pinkish yellow end point.
Calculation:
Chloride mg/L= [(A – B)*N*356450]/ml
of sample
A=ml of titrant for sample
B=ml of titrant for blank
N=normality of AgNO3
Hardness:
50 ml of sample was taken and a
buffer solution was added to it.2-3 drops of Arechrome black tea were added as
an indicator and titrated against EDTA.End point was wine red to blue.
Calculation:
Hardness mg/L=vol.of EDTA*Normality
of EDTA *35000/ml of sample
Sulphide:
5 ml of Iodine was taken in a
titration flask and 2 ml of 6 NH4CL was added to it
Then 100 ml of sample was added.
If the color of Iodine changes to colorless, then add more 7 ml of starch
indicator and titrated against Na2S2O3 solution until blue
Color disappear.
Calculation:
Sulphide mg/L=(A*B) –
(C*D)*16000/ml of sample
A=ml of Iodine solution
B=Normality of Iodine
solution
C= ml of Na2S2O3
D=Normality of Na2S2O3
solution
TURBIDITY
Turbidity refers to the
light-scattering properties of a sample. Turbidity can be described as
“haziness” or “milkyness” and is caused by fine particles scattering light at
more or less 90 degrees to the direction from which the light enters the
sample. Turbidity is not to be confused with color, nor color with turbidity.
Turbidity is normally measured using an electronic device in which a beam of
ordinary white light is directed through a certain path length of the sample.
Photometers placed at right angles to the direction of travel of the light beam
detect the amount of light diverted, which is directly proportional to the
turbidity, expressed in Nephelo-metric Turbidity Units
(NTUs).
Turbidity of the sample was
determined by using the Hriba water quality meter Minami-Ku Kyoto, Japan. The
instrument was calibrated according to instructions manual. Then the turbidity
of the sample was measured in NTU (neophelometery turbidity unit).
Chemical Oxygen Demand
Chemical oxygen demand (COD) is a second method of estimating how much
oxygen would
be depleted from a body of receiving
water as a result of bacterial action. Whereas the BOD
test is performed by using a
population of bacteria and other microorganisms to attempt to
duplicate what would happen in a
natural stream over a period of 5 days, the COD test
uses a strong chemical oxidizing
agent, potassium dichromate or potassium permanganate,
to chemically oxidize the organic
material in the sample of wastewater under conditions of heat and strong acid.
The COD test has the advantage of not being subject to interference
from toxic materials as well as
requiring only 2 or 3 hours for test completion, as opposed to 5 days for the
BOD test. It has the disadvantage of being completely artificial, but is
nevertheless
considered to yield a result that
may be the oxygen-demanding properties of a wastewater. used as the basis on
which to calculate a reasonably accurate.
Parameters Marble industry Ghee industry Match
industry
Ph 7.01 9.9 10
Conductivity (ms/cm) 0.477 0.904 0.32
Hardness (mg/lit) 1120 73.5 227
Alkalinity (mg/lit) 530 120 575
Salinity 0.01%
Tss (mg/lit) 200 1300 1400
Tds (mg/lit) 4210 500 4500
Turbidity
Potassium (mg/lit) 2.0
Chloride (mg/lit) 1340 127.6 503
Do (mg/lit) 0.03 3.0 4.2
Sulphide (mg/lit) 185
COD (mg/lit) 240 130 3200 Bod (mg/lit) 70
TSS = total suspended
solids
TDS = total dissolved
solids
DO = dissolved oxygen
COD = chemical oxygen
demand
BOD = biochemical
oxygen demand
NOVEL NANO-CATALYSTS
FOR WASTEWATER TREATMENT
Received: 06/11/07
Accepted: 14/12/07
H. HILDEBRAND
K. MACKENZIE
F-D. KOPINKE
Halogenated organic compounds (HOCs) are
among the most widely distributed water pollutants in industrialized countries.
These organic molecules play an important role as solvents and additives in
different industries. HOCs are mostly hazardous and toxic compounds may cause
serious health problems such as cancer or mutagenic damage. Therefore, a
complete destruction of these compounds is required. Ordinary wastewater
treatment works cannot handle the problem. Thus, high priced and
energy-intensive methods still have to be employed to solve this problem.
Current detoxification techniques such as adsorption on activated carbon or
oxidation of the wastewater components do not lead to an environmentally
friendly and economically priced solution.
The present paper aims at a treatment
technique designed for special industrial wastewaters contaminated with only
traces of halogenated organic compounds (HOCs) – concentrations. A novel
promising trend in environmental research is the application of nano-reagents
(such as zero-valent iron) and nano-catalysts. As known from nano-sized metal
particles, nano-catalysts have the advantage of very high reaction rates due to
high specific surface areas and low mass-transfer restrictions. These
nano-catalysts have been successfully tested in different reactor systems at
the laboratory scale. Using Pd on nano-scale supports leads to enormous
activity of the catalyst which is several orders of magnitude higher than
reached in conventional fixed-bed reactors. The ferromagnetism of the carriers
enables a separation of the catalysts from the treated water by means of
magneto-separation. This gives the chance to reuse the catalyst several times.
The preferred reductant for the HDH
reaction is molecular hydrogen. For highly contaminated waters, alternative
hydrogen donors such as formic acid have been successfully tested.
Our research follows the idea to
detoxify the water by a selective destruction of the HOCs using the
method of HDH on palladium-containing nano-catalysts. Detoxification means that
persistent HOCs are converted into organic compounds which can easily be
removed by biodegradation in a wastewater treatment plant. Reductive
hydrodehalogenation reactions are very efficient and selective.
RX
+ H2 pd catalyst HX + RH
For this reaction H2 or a hydrogen source as
reducing agents are required. The
Products are predominantly non-toxic
organic molecules and small amounts of HX. Palladium containing catalysts in
the form of catalyst pellets are commonly used in fixed bed reactors in
technical processes such as hydrogenation. Specific catalytic activity APd is
used as measure of the Pd efficiency. It is already known that the smaller the
catalysts size, the higher the catalytic activity. This leads to the approach
to utilize smaller catalyst particles such as fine grained powders or even
nano-particles. A novel promising trend in environmental research is the
application of nano-reagents (such as zero-valent iron and nano-catalysts. For
special applications in wastewater treatment we were able to generate extremely
active palladium catalysts on the basis of ferromagnetic carrier colloids. The
magnetic nano-sized carriers (such as zero-valent iron or magnetite) were
spiked with traces of Pd (0.1 wt.-%). The magnetic properties of the carriers
ensure a separation of the catalyst from the treated water by means of
magneto-separation. This gives the chance to reuse the catalyst several times.
The efficiency of separation can even be enhanced by placing thin steel wires
in the magnetic field .This technology ensures a high rate of the
nano-catalysts recovery.
Formic acid can also be used and found to be suitable as H-donor. A desirable technological goal is an
inexpensive reactor configuration where the catalytic system should be easy to
handle. We regard agitated batch reactors as an attractive solution for
steadily or discontinuously occurring small volumes of contaminated water. The
water to be treated is mixed with the nano-catalyst and an H-donor. During
reaction the mixture is stirred continuously. After the complete
dehalogenation, the catalyst is extracted from the detoxified water leaving the
reactor by means of magneto-separation. The catalyst may then be reused in the
next reaction cycle or collected for regeneration. The catalytic material was
tested in various technological options incl. batch and continuous flow
reactors depending on kind and amount of wastewater. The catalytic activity of
the described particles for probe HOCs such as chloro-benzene or TCE is
extremely high (up to 8000 L·gPd -1·min-1).
The
DE halogenation activities of the nano-catalyst were studied in batch and
column experiments using various probe HOCs such as chlorobenzene, chloroform
and trichloroethylene. For tests with low HOC concentrations (1-20 ppm), clear
screw-cap bottles (250 ml) equipped with valves were used. The tests with
formic acid as H-donor were carried out comparable to the described batch
experiments. With this catalytic system, various tests have been carried out.
First, the Pd content was determined. The result showed that all the introduced
Pd precipitated on the magnetite surface (cPd = 0.1 wt-%). There was no loss of
palladium observed. The Pad/magnetite catalyst was then tested in batch
experiments under various conditions. The results show, that very high
catalytic activities (up to 8000 l·gpd -1·min-1) could be found for different
test substances such as chlorobenzene (MCB). The extraction of the magnetite
particles from the reaction suspension by means of magneto separation was
carried out as described above with a high efficiency. In a test with the
continuous flow-through reactor, 97.6 % of the introduced amount of the
Pd/magnetite nano-catalyst was recovered in the magneto-separation vessel. The
remaining 2.4 % divide into the dissolved fraction and a remaining thin film of
particles precipitated on the reactor walls. The results shown prove that a
continuous flow-through reactor is a suitable reactor type for treatment of
continuously occurring HOC-contaminated wastewater. The extremely high catalyst
activities, the stability of the Pd/magnetite system in a near-neutral reaction
medium and the good recovery rates of the catalyst by magneto-separation are
very promising preconditions for a successful application of the novel catalyst
system for wastewater treatment process.
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