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1.0 Abstract
Water and wastewater treatment can be divided into three types of treatment
which are physical treatment, chemical treatment as well as biological treatment.
According to the United Nations, physical water treatment can divided into screening,
sedimentation, flotation, granular medium filtration. While for chemical water treatment
it is divided into chemical precipitation, adsorption, disinfection, chlorination, ion
exchange and other chemical applications. The biological treatments are by treating with
activated sludge process, aerated lagoon, trickling filters and biological nutrient removal.
Besides that, the methods such as coagulation-flocculation, electrochemical oxidation and
membrane filtration also can be used in order to treat the unwanted contaminants in
water. In this experiment, the waste water in run unto batch treatment tank as well as
aeration tank and its pH, total dissolved solid (TDS), and conductivity were recorded. In
the batch treatment tank the pH of the waste water were neutralized by using the
coagulant (acid) and caustic soda (basic). On the other hand, in the aeration tank, the
aerator was turned on to add oxygen to water to convert undesirable substances to a more
manageable form (oxidation) as well as to eliminated undesirable gases dissolved in the
water (degasification). Based on the result, it can be seen that the parameters we
measured are compliant with Standard A set by the Department of Environment Malaysia
(DOE).
A distributed control system (DCS) refers to a control system, in which the
controllerelements are not central in location but are distributed throughout the system
with each component sub-system controlled by one or more controllers. The entire
system of controllers is connected by networks for communication and monitoring. Inthis experiment, VMware player is used to simulate the DCS to study single loop PID
level control. In order to achieve that objective, five trial sets of PID tuning parameters is
input to the system and load disturbance is applied to that respective tuning. The process
response of that respective tuning is observed and commented. Based on the result, the
third trial set of PID tuning parameters give the best result where the process value
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remain at the steady state and equally adapt when load disturbance is applied to the
system. For the first and the fifth trial set of PID tuning parameters, the result is equally
the same where the process value did not achieved the steady state even after the load
disturbance is applied. For the second trial, the time interval taken for the process value
to reach steady state is fairly slow and lastly for the fourth trial, the time interval taken for
the process value to reach steady state is very slow. When the load disturbance is applied
to the both trials, the process value reach the steady state is slow pace. In conclusion, the
best PID tuning parameters which are (gain, reset and rate) to control the level in DCS is
5, 30 seconds and 0 second respectively.
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2.0 Introduction
Wastewater is created when water spent or used with dissolved or suspended
solids is discharged from communities, homes, industrial, homes, commercial
establishments, and farms. The water and wastewater need to be treated in order to
remove as much of the suspended solids, organic matter, nutrients, disease-causing
organisms as possible before the remaining water which is also called as effluent is
discharged back to the environment.
According to Sincero et all in their writing, wastewater is divided into two
categories which are sanitary and non-sanitary wastewater or called also as sanitary
sewage. The sanitary wastewaters are wastewaters that have been contaminated with
human wastes. Meanwhile, non-sanitary wastewater is usually waste products from the
industries. The industrial wastewaters are the wastewaters which produced in the process
of manufacturing. In addition to that, the other group is sewage which is the wastewaters
released by the residences, business and also industries in a community. Untreated
wastewater will contains high level of organic material, microorganisms, toxic
compounds as well as numerous pathogens and give the adverse effects to the
environment, humans or animals depending on the types and concentration of waste.
Water and wastewater treatment can be divided into three types of treatment which are
physical treatment, chemical treatment as well as biological treatment. According to
United Nations, the physical water treatment can divided into screening, sedimentation,
flotation, granular medium filtration. While for chemical water treatment it is divided into
chemical precipitation, adsorption, disinfection, dechlorination, ion exchange and other
chemical applications. The biological treatments are treating with activated sludge
process, aerated lagoon, trickling filters and biological nutrient removal. Besides that, the
methods such as coagulation-flocculation, electrochemical oxidation and membrane
filtration also can be used in order to treat the unwanted contaminants in water.Department of Environment Malaysia (DOE) has outlined the discharge limits of
the wastes as indicated below:
Parameters Units Standards
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A B
1. Temperature 0C < 40.00 < 40.00
2. pH pH 6.0 9.0 5.5 9.0
3. BOD5 at 200C mg/L < 20.00 < 50.00
4. COD mg/L < 50.00 < 100.00
5. Suspended Solids mg/L < 50.00 < 1006. Mercury mg/L < 0.005 < 0.05
7. Cadmium mg/L < 0.01 < 0.02
8. Chromium, hexavalent mg/L < 0.05 < 0.05
9. Arsenic mg/L < 0.05 < 0.10
10. Cyanide mg/L < 0.05 < 0.10
11. Lead mg/L < 0.10 < 0.50
12. Chromium, trivalent mg/L < 0.20 < 1.00
13. Copper mg/L < 0.20 < 1.00
14. Manganese mg/L < 0.20 < 1.00
15. Nickel mg/L < 0.20 < 1.00
16. Tin mg/L < 0.20 < 1.0017. Zinc mg/L < 2.00 < 2.00
18. Boron mg/L < 1.00 < 4.00
19. Iron mg/L < 1.00 < 5.00
20. Phenol mg/L < 0.001 < 1.00
21. Chlorine, Free mg/L < 1.00 < 2.00
22. Sulphide mg/L < 0.50 < 0.50
23. Oil & Grease mg/L Not Detectable 10.00
Table 1: Discharge Limit by DOE
In the water river, sewage as well as wastewater, there are several major
parameters that can be identified which are then divided into four parameters. For
instance, physical parameters such color, odor, temperature and turbidity, chemical
parameters that includes biological oxygen demand (BOD), chemical oxygen demand
(COD), total organic carbon (TOC) as well as total oxygen demand (TOD). In addition to
that, pH, acidity and alkalinity are falls into inorganic chemical parameters. Lastly are
bacteriological parameters such viruses, pathogens and others (United Nation, 2003).
In order to produce clear water, the wastewater needs to undergo treatment
process. The treatment process consists of preliminary treatment, primary treatment,
secondary treatment an advanced treatment (Prabu et all, 2011, Mancl). The primary,
secondary and tertiary treatments are the treatments that are carried out before the final
disposal.
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The preliminary treatment is a first step or called also as a screening process
where this process consists of physical unit operations. This treatment is done in order to
protect the pumping and other equipments in the treatment plant. This process is
conducted to screen out, grind out as well as separate and remove the debris. In addition
to that, the preliminary treatment also remove the sticks, rags, large food particles, sand,
rubbish, toys or other large materials, reduces or eliminates the non-favorable wastewater
characteristics such odors, organic loading. Besides that, there are other process belong
the preliminary treatment such equalization, flow equalization and neutralization (Prabu
et all, 2011).
After the screening step, the treatment is proceed with the primary treatment
which are involves the treatment and partial removal of suspended solids, organic matter
and greases from wastewater. This stage is acts as a precursor for the secondary
treatment. The aim of this process is to produce a liquid effluent for downstream
biological treatment and separate the solids as sludge. In this process, the wastewater is
left in a tank for several hours to allow the heavy particles to settle down at the bottom,
meanwhile the greases is float to the top. In order to enhance this primary treatment, the
pre-aeration or mechanical flocculation with chemical additions can be used in this
process.
After that, the clarified wastewater will flow on to the next stage which called as
secondary treatment or biological treatment. This treatment is to remove the soluble and
colloidal organics and suspended solids that escape the primary treatment. Besides that, it
is also to reduce the BOD and COD of wastewater. According to Mancl, in this process,
the bacteria or sewage organisms are cultivated and added in this wastewater, they absorb
the organic matter as their food supply. In order to achieve the secondary treatment, there
are three approaches are used such fixed film, suspended film and also lagoon systems.
Besides knowing as biological treatment, the treatment under trickling filtration, activated
sludge process, oxidation ditch and oxidation ponds are the some procedures belonging to
secondary treatment (Prabu et all, 2011).
Then, the wastewater treatment proceeds to the next treatment which is tertiary or
final treatment. This tertiary treatment is done for purification of wastewater and it
focuses on the removal of significant amounts of nitrogen, phosphorus, heavy metals,
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biodegradable organics, disease-causing organisms such bacteria and viruses. The treated
wastewater can be disinfected by adding chlorine or otherwise by using ultraviolet light
(Marcl). But, as a precaution step, the chlorine cannot be added in high quantities because
high levels of chlorine may be harmful to aquatic life and others. Besides that, the
treatment systems also often add a chlorine-neutralizing chemical to treat the wastewater
before it is discharged.
In conjunction with the water treatment, Marcl has stated that there are also
advanced treatment such coagulation process. The coagulation is needed in some
treatment in order to remove nutrients from the wastewater. Besides that, according to
Subramanian, there are several other methods to remove suspended solids (micro
staining, coagulation, filtration and flocculation), removal of dissolved solids (ion
exchange, reverse osmosis, electrodiallysis), removal of dissolved organic compounds
(adsorption, sludge treatment and disposal and disinfection). There is also other method
such membrane bioreactor (MBR) (Radjenovi et all, 2008)
Figure 1 below exhibit the typical process flow of wastewater treatment
. Figure 1: Typical Wastewater Treatment
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3.0 LITERATURE REVIEW
3.1 Wastewater
Wastewater is any water that has been adversely affected in quality by
anthropogenic influence. It comprises liquid waste discharged by domestic residences,
commercial properties, industry, and/or agriculture and can encompass a wide range of
potential contaminants and concentrations. In the most common usage, it refers to the
municipal wastewater that contains a broad spectrum of contaminants resulting from the
mixing of wastewaters from different sources. The objective doing waste water treatment
is to make sure that all human and industrial waste can be disposed without cause a
danger human health and damage natural environment. To remove solids, organic matter
and nutrients from wastewater, combination of physical, chemical and biological
treatment is need. In order to describe different step in wastewater treatment the term that
be used is preliminary, primary secondary, and tertiary or advanced wastewater
treatment. A generalized wastewater treatment is shown in Figure 2.
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Figure 2 Process in wastewater process
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3.2 Biological treatment
Biological treatment methods is the most effective and eco-friendly than any other
available treatment process cause them to dominate the secondary wastewater treatment
sector. The demand for biological wastewater treatment equipment is on growth path
which is catalysed by the need to meet obligatory wastewater treatment standards,
imposed by environmental legislation to municipalities and industries in the vast part of
developed countries.
The main advantages of biological wastewater treatment are as follows:
Low capital and operating costs compared to alternatives such as chemical-oxidation
processes
True destruction of organics, versus mere phase separation, such as with air stripping
or carbon adsorption
Oxidation of a wide variety of organic compounds
Removal of reduced inorganic compounds, such as sulphides and ammonia, and total
nitrogen removal possible through de-nitrification
Operational flexibility to handle a wide range of flows and wastewater characteristics
Reduction of aquatic toxicity
The purpose of biological treatment of wastewater is to reduce BOD content in the
water by using the bacteria which feed on the organic materials in the wastewater. The
principle in the biological process is the bacteria will eat all the organic material present
in the wastewater and using their metabolism it will change organic material into cellular
mass. This cellular is no longer in the solution but will be precipitated at the bottom of
settling tank. The water exiting the tank is much clearer before it entered the tank. Supply
of oxygen also needed in this process because cells or bacteria not only need organic
material as food but also oxygen to breathe just like human. Without the oxygen the
biological degradation of the waste is slowed down thereby requiring a longer residency
time of water in the system.
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4.0 OBJECTIVE
The main aim of this experiment is to treat the municipal or industrial wastewater influent
by using chemical and biological treatment. This treatment is used in order to produce
clean water before it is discharge because wastewater has a lot of contaminants that will
cause the adverse effects to environment. The chemical treatment process is done by
adding the chemical compound such coagulant, caustic soda and flocculants. Meanwhile,
the biological treatment is the treatment by using bacteria which the bacteria will absorb
the organic matter as the food supply.
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5.0 METHODOLOGY
5.1 Treatment of Water and Wastewater Using Chemical & Biological Process
At the plant, the bulky box tank is filled with raw water samples. Valves (V1, V2
& V4) were opened while valves V3 & VA were closed to fill wastewater at batch
treatment tank. The portable transfer pump, P1 was started to fill the tank at 250 L
marked on the tank. The pump was stopped and the mechanical agitator, M1 was started.
The speed of the agitator was controlled using the interval located inside the Aquatrend
Panel. The pH of the wastewater solution was checked by using conductivity meter. If the
solution in basic condition, the coagulant is added until achieved 8.5 meanwhile if the
solution in acid condition, the is added caustic soda until pH achieved 7. The value of the
waste water pH, total dissolved solid and the conductivity in the batch treatment tank
were recorded according to Table 4.1. The valves (VB & VC) were opened while valve
VA was closed. Batch treatment transfer pump, TP1 was started. The transfer pump will
stop automatically when the water level in batch treatment tank is low, which is detected
by a level sensor. Valve VE was opened on the Aeration Tank to blow the wastewater byusing compressed air. The value of the waste water pH, total dissolved solid and the
conductivity in the aeration tank were recorded according to Table 4.2. Overall, this
process can be described in Figure 3.1.
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Figure 3.1: Single capacity tank pressure PID control
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6.0 Result and Discussion
6.1 Results:
Parameter Value
pH 85
TDS 850 mg\L
Conductivity 1363 S\cm
Table 1: Batch Treatment Tank (BTT)
Parameter Value
pH 10.61
TDS 1324 mg\L
Conductivity 834 S\cm
Table 2: Aeration Tank (AT)
6.2 Discussion:
Sewage is the wastewater released by residences, businesses and industries in a
community. It is 99.94 percent water, with only 0.06 percent of the wastewater
containing dissolved and suspended solid material. The cloudiness of sewage is caused
by suspended particles.
In our experiment, we conducted treatment for the water using chemical and biological
processes. In this process, we controlled the pH of the waste water till it reached a pHbetween 7 and 8 which is the suitable range for drinking. We kept treating the waste
water till it matched the standards for the drinking water which is set up by the
Department of Environment Malaysia (DOE).
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This treatment is in two steps. First at the Batch Treatment Tank (BTT), chemicals
compounds such as caustic soda, coagulant and flocculants are used to treat the water,
where they separate suspended solids and greases from wastewater and also reduce
and/or increase the pH level. Waste-water is held in a quiet tank for several minutes. The
solids drawn off the bottom and skimmed off the top receive further treatment as sludge.
The clarified wastewater flows on to the next stage of wastewater treatment. Clarifiers
and septic tanks are usually used to provide in this step. Before transfer the water to the
next tank, we measured the parameters of the waste water. As we see from Table 1, the
pH value of the waste water matches the standard which has been set up by DOE in
standard A.
Then, we transferred the waste water to the Aeration Tank (AT). We couldnt get the
final result of this treatment due do the time constraint of our experiment. But referring to
our literature review, this step of treatment is a biological treatment process to remove
dissolved organic matter from wastewater. Sewage microorganisms are cultivated and
added to the wastewater. The microorganisms absorb organic matter from sewage as their
food supply. Three approaches are used to accomplish secondary treatment; fixed film,
suspended film and lagoon systems.
According to the theory, after finishing the above steps, we come to the final step. Final
treatment focuses on removal of disease-causing organisms from wastewater. Treated
wastewater can be disinfected by adding chlorine or by using ultraviolet light. High levels
of chlorine may be harmful to aquatic life in receiving streams. Treatment systems often
add a chlorine-neutralizing chemical to the treated wastewater before stream discharge.
There was no data available from the PC as the sensors in the automated system were not
functioning. Hence no BOD or COD values were taken. The other parameters were
measured by using other available instruments.
As we observed our data, table 1 and 2, we can see that our experiment ran correctly
because it matches with the standard set of data given by the DOE.
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Questions:
1. What is the purpose of adding caustic soda into the Batch Treatment Tank in the
Chemical & Biological Treatment Unit?
Caustic soda is sodium hydroxide and is used to lower the alkalinity of the
waste water. The common factors for selecting caustic soda are its stronger
basicity and easier storage and handling.
2. What is the name of processes occurred in the Batch Treatment Tank after adding
caustic soda, alum & polymer?
The process is flocculation
3. What is the purpose of aeration inside the Aeration Tank?
In industrial water conditioning, one of the major objectives of aeration is to
remove carbon dioxide. Aeration is also used to oxidize soluble iron and
manganese (found in many well waters) to insoluble precipitates. Aeration is
often used to reduce the carbon dioxide liberated by a treatment process. For
example, acid may be fed to the effluent of sodium zeolite softeners for boiler
alkalinity control. Carbon dioxide is produced as a result of the acid
treatment, and aeration is employed to rid the water of this corrosive gas.
Similarly, when the effluents of hydrogen and sodium zeolite units are
blended, the carbon dioxide formed is removed by aeration. Others purposes
are for the removal of volatile organic substances, hydrogen sulfide,
ammonia, and volatile organic compounds.
4. Why level sensors are used on the system?
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Level sensors detect the level of substances that flow, including liquids,
slurries, granular materials, and powders.Water treatment applications
place high demands on pressure and level measuring instruments.
5. What is the function of diammonium phosphate in Chemical & Biological
Treatment Unit?
Diammonium phosphate is a water-soluble salt. It enhances the growth of
the bacteria which is used in the water treatment.
6. Compare your results with EQA Standard?
The pH values obtained in our experiment comply with EQA Standard A.
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7.0 Conclusion and Recommendation
7.1 Conclusion
In this experiment, the objective was to treat the waste water using chemical & biological
process. Due to the time constraint, we could only treat the water using the chemical
process. In this part of experiment, we achieved our objectives and could manage to reach
the Standard A as given by the DOE.
In the other hand, we couldnt treat the waste water using a biological process due to
equipment problems and a lack of time. But we could get the clear idea of that process
form the articles which we referred to for this experiment.
From this experiment, we learned that waste water must be treated before being released
back to the environment for industrial or residential usage to remove the suspended solids
and other microorganisms which may have harmful effects to consumers. The kind of
treatment utilized in this experiment is suitable to treat the waste water as the chemical
and biological process helps to remove the suspended solids and microorganisms in the
water.
7.2 Recommendation
The first recommendation is for a longer time period to conduct the experiment as the
bacterias used need a few days to reach optimum growth levels.
The second is to ensure that all the equipments and tanks in the water treatment plant are
maintained well in order to ensure that accurate readings can be taken during the
experiment.
The equipments used in measuring the parameters must also be properly calibrated to
ensure that accurate results are obtained.
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8.0 References
1. Sincero, A. P., & Sincero, G. A. (2003). Physical-chemical treatment of water and
wastewater. IWA Publishing.
2. United Nation Economics and Social Commission for Western Asia (2003).
Waste-water treatment technologies : A general review. Available online at
3. http://www.igemportal.org/Resim/Wastewater%20Treatment%20Technologies
%20A%20general%20review.pdf
4. Prabu, S. L., Suriyaprakash, T. N. K., & Kumar, J. A. (2011). Wastewater
treatment technologies: A review.Pharma Times, 43(5), 1-5
5. Mancl, K. Wastewater treatment principles and regulations. Available online at
http://ohioline.osu.edu/aex-fact/0768.html
6. Subramanian, M. S. Advanced Waste Water Treatment. Module 1.5.
environmental Chemistry and Analysis. Available online at
7. http://nptel.iitm.ac.in/courses/IITMADRAS/Enivironmental_Chemistry_Analysis/
Pdfs/1_5.pdf
8. http://engineering.dartmouth.edu/~cushman/courses/engs37/biotreatmenttypes.pdf
9. http://water.me.vccs.edu/courses/ENV149/methods.htm
10.http://www.fao.org/docrep/t0551e/t0551e05.htm#3.2.1%20preliminary
%20treatment
11.Radjenovi, J., Matoi, M., Mihatovi, I., Petrovi, M., & Barcel, D. (2008).
Membrane reactor (MBR) as an advanced wastewater treatment technology. Hdb
Env Chem, 5(S/2), 37-101.
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http://www.igemportal.org/Resim/Wastewater%20Treatment%20Technologies%20A%20general%20review.pdfhttp://www.igemportal.org/Resim/Wastewater%20Treatment%20Technologies%20A%20general%20review.pdfhttp://ohioline.osu.edu/aex-fact/0768.htmlhttp://nptel.iitm.ac.in/courses/IITMADRAS/Enivironmental_Chemistry_Analysis/Pdfs/1_5.pdfhttp://nptel.iitm.ac.in/courses/IITMADRAS/Enivironmental_Chemistry_Analysis/Pdfs/1_5.pdfhttp://engineering.dartmouth.edu/~cushman/courses/engs37/biotreatmenttypes.pdfhttp://water.me.vccs.edu/courses/ENV149/methods.htmhttp://www.fao.org/docrep/t0551e/t0551e05.htm#3.2.1%20preliminary%20treatmenthttp://www.fao.org/docrep/t0551e/t0551e05.htm#3.2.1%20preliminary%20treatmenthttp://www.fao.org/docrep/t0551e/t0551e05.htm#3.2.1%20preliminary%20treatmenthttp://www.igemportal.org/Resim/Wastewater%20Treatment%20Technologies%20A%20general%20review.pdfhttp://www.igemportal.org/Resim/Wastewater%20Treatment%20Technologies%20A%20general%20review.pdfhttp://ohioline.osu.edu/aex-fact/0768.htmlhttp://nptel.iitm.ac.in/courses/IITMADRAS/Enivironmental_Chemistry_Analysis/Pdfs/1_5.pdfhttp://nptel.iitm.ac.in/courses/IITMADRAS/Enivironmental_Chemistry_Analysis/Pdfs/1_5.pdfhttp://engineering.dartmouth.edu/~cushman/courses/engs37/biotreatmenttypes.pdfhttp://water.me.vccs.edu/courses/ENV149/methods.htmhttp://www.fao.org/docrep/t0551e/t0551e05.htm#3.2.1%20preliminary%20treatmenthttp://www.fao.org/docrep/t0551e/t0551e05.htm#3.2.1%20preliminary%20treatment