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1)INTRODUCTION:

1.1)The aim of the summer practice:

The main aim of the summer practice is to observe how water is cleaned in wastewater and

water treatment plants, what kind of processes are done in these facilities and to learn an

environmental engineer’s duties and responsibilities in these plants. Moreover, the other aim

of the summer practice is to observe business relations between co-workers, to learn some

essential rules in work life and to understand the relationships between treatment plants and

other departments in factory.

1.2) Information about the institution:

Turkish Aerospace Industries (TUSAŞ or TAI) was established on May 15 th, 1984 by Turkish

and U.S. partners in Kazan/ Ankara. In 2005, Turkish shareholders purchased foreign shares

and TAI became one of the important companies in Turkey. TAI’s vision and mission are to

become a world brand aerospace company and to lead the development of Turkey’s aerospace

industry. TAI works the design, development, modernization, integration, and life cycle

support of integrated aerospace systems. TAI defined its business in six strategic groups

which are aero structures group, aircraft group, helicopter group, UAV group, space group,

special programs group, and logistics. TAI’s boundaries reach 5.000.000 m2 and it has about

5.000 employees (organization chart can be seen in app.1) hence, it is a very big company. It

produces very important and different kinds of aircrafts and satellites like ANKA, HURKUS,

GOKTURK, TURNA, SİMSEK, and ATAK. It produces them for government and some

significant foreign companies. (‘TAI Website’, 2013)

1.3) TAI and environment:

In 1988, TAI has completed all infrastructural investments about treating, destroying, and

storage some dangerous wastes which pollute the environment. TAI has built 3 facilities that

are potable water treatment facility, industrial waste pretreatment facility, and domestic

wastewater treatment facility for protecting the environment. Besides these treatment

facilities, air and soil pollutions are controlled by institution and some processes are happened

for reuse and recycle of wastes. TAI believes that if a company wants to succeed in today’s

world, it should target to provide healthy environment and people. TAI’s environmental

policy bases on some essential ideas such as minimization of wastes, sustainable

development, continuous improvement and protecting the natural resources and environment.

TAI’s environmental management system is suitable for international standards. Its

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environmental management system follows the rules of environmental legislation and work

safety which are determined by law. TAI’s environmental management system conforms to

ISO 14000 and BS 7750 standards. TAI’s environmental management system is commanded

by quality and guarantee departments of the company in a year for two times. It is also

controlled by government and partner companies like Cınar Engineering Consultancy Inc. Co.

in a month.

In TAI, first 2 days, trainees were informed about works of company, rules that we have to

obey and trainees were educated about some topics like occupational health and safety,

foreign object damage (FOD) ,and technical services and plants.(TAI plants site plan can be

seen in app.2). During the summer practice, first 3 weeks, all treatment plants were observed

and last week chemical processing department of company was observed. Plants capacities

are presented in Table 1.1.

Table 1.1: Treatment Plants’ Capacities

Treatment Plants Their Capacities

Domestic Wastewater Treatment Facility 2500 m3 / day

Industrial Waste Pretreatment Facility

Chemical waste storage tanks 420 m3

Acidic waste treatment system 28 m3 / hour

Caustic waste treatment system 7 m3 / hour

Back- up unit 28 m3 / hour

Solvent recovery units

Solvent recovery unit 1 190 L / hour

Solvent recovery unit 2 95 L / hour

Coolant recycle unit 2300 L / day

Potable Water Treatment Facility 360 m3 / hour

2) DOMESTIC WASTEWATER TREATMENT FACILITY

Domestic wastewater treatment facility was established to supply irrigation water

requirement. The sewer waters of TAI houses, TAI social facilities, and 4. Main Jet Military

Base and wastewaters coming from industrial waste pretreatment facility are treated in this

plant to obtain irrigation water. Wastewaters are treated to remove suspended solids,

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dissolved organic matters, colloidal particles, pathogens, inorganic matters, and nutrients by

using active sludge process and biological treatment.

Image 2.1: Domestic Wastewater Treatment Plant

250 L / person /day (total population is approximately 10000 person) wastewater comes the

facility and it passes through the different units of the facility. (Floor plan of the facility can

be seen in app.3)

2.1) The constituents of the domestic wastewater treatment facility:

2.1.1) Mechanical screens:

The wastewater getting from the factory and surrounding passes through mechanical screen.

There are two mechanical screens but one of them is used because the other one of them is

enough to remove solid matters. In this unit, big solid maters like stone, paper, hairs, rubbish,

and plastics in domestic wastewater are split and these matters are removed regularly from

this unit. And then, the wastewater which is eliminated from big solid matters is taken to the

grit chamber.

2.1.2) Grit chamber:

In this unit, the wastewater is waited to precipitate sand and other large inorganic matters by

helping of gravity. Then, the wastewater is taken to balancing pools and precipitated sand and

other matters are pumped to sludge drying beds.

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2.1.3) Balancing pools:

The wastewater is collected these pools because system can be affected some changes like

increasing or decreasing of flow rate of wastewater. In these pools, the wastewater is balanced

and it is taken to the oil separator by helping of pumps. In mechanical screens and grit

chamber units, pumps are not used for passing the wastewater.

2.1.4) Oil separator:

Oil in the wastewater accumulates on the surface of the water because of its density and the

oil is swept away the surface of the wastewater. Then, oil is taken to drying beds by using

valve. The wastewater runs down to the aeration basin.

2.1.5) Aeration basin:

This unit is very important because biological treatment happens in there. Bacteria have

important roles in this unit. The wastewater is treated with the help of bacteria. First of all, Al2

(SO4)3 and caustic lime are added to the wastewater coming from the oil separator to

precipitate PO4 and other ions getting from industrial waste pretreatment facility and to

balance the pH. This process should be done before the wastewater enter the pool because

bacteria can be affected from that kind of ions. In the pool (its capacity is 2000 m3), there are

bacteria and other microorganisms such as sarcodina, protozoa, ciliates and rotifer and they

also form the active sludge. Active sludge process aims to decompose the organics in the

wastewater by the microorganisms to inorganics and gases. In TAI, domestic wastewater

treatment plant was designed as to active sludge process. In the pool, aerobic microorganisms

separate organic wastes to inorganic compounds.

Organic waste + O2 + aerobic microorganisms → CO2 +H2O + inorganics + more microorg.

For aerobic treatment, O2 is very essential. In the bottom of the pool, there are many blowers

which give compressed air to the system. The concentration of dissolved O2 should be higher

than 0.5 mg/ L so that microorganisms can work efficiently. The concentration of dissolved

O2 should be controlled regularly because if the concentration of dissolved O2 is very low,

system will be anaerobic and microorganisms cannot work. In the above equation, organic

pollutants turn into new microorganisms and this reaction is called synthesis step. This step

enables to treat wastewater in high quantity and at the end of the reaction, settleable biological

floccules are created. These floccules flocculate with each other and new big floccules are

created (for this process, some surface interactions like absorption and adsorption occur) to

remove organics from the water. Then, these new microorganisms are occurred endogen

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respiration reactions to gain energy when the amount of organics decreases. The endogen

respiration reaction is:

Microorganisms + 5O2 → 5CO2 + NH3 + 2H2O2 + energy

At the end of this reaction, NH3 gets out and for the oxidation of ammonia nitrosomanas and

nitrobacter can carry out nitrification reactions if there is plenty of O2 in the system. The

concentration of the microorganisms should be desirable limit to happen synthesis and

respiration reactions. Active sludge is used to reach desirable limit. Active sludge is made of

new microorganisms coming from synthesis reactions that come together to form flocculation.

The wastewater runs out from aeration basin to the settlement tank after complementation of

biological treatment. In the settlement tank, floccules fall down to bottom of the tank. And,

floccules in the bottom of the tank are active sludge. If the concentration of microorganisms

in the aeration basin is undesirable limit, active sludge will be added to aeration basin

sufficiently from the settlement tank.

Influent Effluent

Return Activated Sludge

Waste Sludge

Figure 2.2: Flow Diagram of Activated Sludge

Temperature, pH, the concentration of dissolved oxygen, the amount of organics and presence

of toxic matters are so important points for biological treatment process to work with no

problems. (Curi & Baban, no date) Hence, after the biological treatment of wastewater, it

flows to settlement tank.

Settlement

Tank

Aeration

Basin

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Image 2.3: Aeration Basin

2.1.6) Settlement tank:

The water with settleable biologic floccules flows thru the settlement tank (its capacity is

1050 m3) and the water is waited in there for enough time to precipitate settleable biologic

floccules with the help of gravity. In the tank, there is a comb to sweep away precipitated

floccules or active sludge from the bottom of the tank. Excess quantity of active sludge is sent

to sludge drying beds and remaining quantity of active sludge is sent to aeration basin as

return active sludge by using pumps. The quantity of return active sludge can be determined

by observing the concentration of microorganisms and dissolved oxygen. Therefore, the water

runs down to chlorination channel.

Image 2.4: Settlement Tank

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2.1.7) Chlorination channel:

In this channel (its capacity is 110 m3/ hour), sodium hypochloride (NaOCl) is added to water

to disinfect it from microbes. In the channel, there is some stair like barriers so that NaOCl

and water can mix each other homogenously. Then, the water is sent to irrigation tank.

Image 2.5: Chlorination Channel

2.1.8) Irrigation tank:

The water coming from the chlorination channel is stored in the irrigation tank (its capacity is

1050 m3). The water is distributed from this tank to units of factory by using pumps.

2.1.9) Sludge drying beds:

Oil getting from oil separator and sludge getting from settlement tank are taken to drying

beds. This unit has 16 drying beds (each beds’ capacity is 50 m3/ day) and they have sand and

gravels so that sludge can be filtered. Filtered water is taken to aeration basin by pumping.

And, warming and air conditioning are essential points to dry the sludge. Dried sludge can be

used as a fertilizer.

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Image 2.6: Sludge Drying Beds

2.2) The analyses performed in the domestic wastewater treatment facility:

In the domestic wastewater treatment facility laboratory, analyses are performed in daily and

one or two analyses are performed in weekly. In daily analysis, samples are taken from

entrance water, aeration basin, recycle sludge, and exit water. (Analyses done in daily report

and essential parameters can be seen in app.4) Moreover, the water in the irrigation tank is

analyzed in daily. (Analysis report can be seen in app.5) And also, monthly analyses are done

by the partner companies. The results of the analyses are controlled by looking water

pollution control regulations tables prepared by ministry of environment. (These tables can be

seen in app.6, app.7, and app.8)

2.2.1) pH:

The samples taken from entrance water, aeration basin, exit water, and the irrigation tank are

analyzed by using pH meter.

2.2.2) Turbidity:

The turbidity of samples that are taken from irrigation tank and exit water is measured by

using turbidimeter in potable water treatment facility laboratory.

2.2.3) Conductivity:

The conductivity of the sample taken from irrigation tank is measured with the help of

conductivity probe.

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2.2.4) Dissolved oxygen:

The solubility of O2 in water is one of the very important parameters. In aeration basin,

minimum 0.5 mg / L O2 is required so that aerobic microorganisms can live and they can carry

out synthesis and endogen respiration reactions. When DO level is low, microbes cannot work

and wastewater cannot be treated efficiently. When Do level is so high, process becomes

costly, hence an optimum level of DO should be given in to system. Also, temperature should

be around 20oC because, DO concentration decreases with increasing temperature. The

temperature of entrance and exit water is measured. DO concentration of aeration basin and

exit water is measured by using probe.

2.2.5) Biochemical oxygen demand:

BOD is the amount of oxygen needed by microorganisms for the degradation of organic

substances. BOD test is done for 5 days at 20oC. BOD5 test is done for entrance and exit

water.

Table 2.7: BOD5 Determination

Sample volume - Factor Range of BOD5

428 ml - 1 0-40 mg /L

360 ml - 2 0-80 mg /L

244 ml - 5 0-200 mg /L

157 ml - 10 0-400 mg /L

94 ml - 20 0-800 mg /L

56 ml - 40 0-2000 mg /L

21.7 ml - 100 0-4000 mg /L

For BOD5 determination, 500 ml black bottle is used. For example, 94 ml entrance water is

taken into the bottle. In the inward of the bottle’s cap, KOH is present to catch CO 2 produced

by the microorganisms’ metabolic reactions. On the bottle’s cap, there is a digital device that

measures the quantity of consumed O2. And also, there is a magnetic mixer to provide

homogeneity. The bottle is incubated at 20oC for 5 days. At the end of 5 days, BOD5 is read

from digital device. The result is controlled from the table 2.7.

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2.2.6) Chemical oxygen demand:

In COD test, oxygen equivalent of an organic substance is measured by using the strong

oxidizing agent, K2Cr2O7. COD test is done in the potable water treatment facility laboratory

if it is needed. For the test, Dr. Lange ampoules are used.

2.2.7) Imhoff cone:

For this test, 100 ml sample taken from aeration basin is decanted into Imhoff cone. After

half an hour, the result is read as ml / L. This test aims to give information about the quantity

of settleable solids in settlement tank. If test is waited for long hours, DO concentration will

be less and denitrification process will begin. Moreover, some sludge will rise to surface of

the water and conditions will turn to anaerobic conditions.

2.2.8) Free chlorine and chloride:

Free chlorine in the exit water and irrigation tank is measured by using color spectrum. A few

drops orthotoludiene is added to sample and color is compared with color spectrum. This test

gives information about the chlorination process in the chlorination channel. For chloride test,

potassium chromate is added to the sample is taken from irrigation tank and it is titrated with

AgNO3. And, when color changes yellow to brown, the quantity of consumed AgNO3 gives

the amount of chloride in the sample.

2.2.9) MLSS and MLVSS:

MLSS (mixed liquid suspended solids) test is performed to know the amount of suspended

solids in sample. This test is done for sample taken from aeration basin; recycle sludge, exit

water, and irrigation tank. The filter paper is weighed and the value is recorded. Filter is

placed on vacuum flask and the sample is filtered. The filter with solids is incubated at 103oC

in oven for 1 hour and then filter is weighed. The result is in mg / L.

MLSS = [(filter paper + incubated solids) – (tare of filter paper)] / volume of sample*1000

MLVSS (mixed liquid volatile suspended solids) test is done for the sample taken from

aeration basin, and recycle sludge. The filter incubated at 103oC is ignited at 550oC for 1 hour

and filter is weighed. Inorganic matters remain on the filter so organics (microorganisms)

burn.

MLVSS = [(filter paper + incubated solids at 103oC) – (filter paper + ignited solids at 550oC)]

/ volume of sample*1000 in mg / L

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2.2.10) SVI and SDI:

SVI (sludge volume index) and SDI (sludge density index) are the parameters that give

information about sludge in aeration basin.

SVI = imhoff / MLSS in aeration basin *1000 in ml / mg

SDI = 100 / SVI in mg / ml

Percentage of recycle sludge = MLSS in aeration basin / [(MLSS in recycle sludge) – (MLSS

in aeration basin)] *1000 in %

2.2.11) Food to microorganisms:

F/M ratio is another parameter to work efficiently biological treatment process. F/M ratio

should be low value so low food to lots microorganisms.

F/M ratio = (BOD5 * flow rate of water) / (total volumes of settlement tank and aeration basin

* MLVSS in aeration basin) in kg BOD / kg MLVSS

2.2.12) Fecal coliform bacteria test:

The water in the irrigation tank is used to water the trees, grass and flower however; fecal

coliform test should be done for public health. The sample taken from irrigation tank is put on

a special filter and filter is put on nutrient agar in petri dish. It is incubated at 44 oC for 24

hours. At the end of 24 hours, the colonies are observed and the result is controlled with

respect to standards.

3) INDUSTRIAL WASTE PRETREATMENT FACILITY

Industrial waste pretreatment facility was established to dispose of acidic and basic wastes,

coolant, and all dangerous chemical wastes which go out during all production processes. In

the facility, treated wastes are stored in their class and then waste is sent to licensed

companies, water that gets out during treatment is sent to domestic wastewater treatment

facility. Also, solid wastes are collected in this facility and they are sent to licensed companies

to annihilate. In TAI, many harmful chemicals like chromic acid, nitric acid, caustic soda,

colors, coolant, maskant, phosphoric acid, hydrofluoric acid, and trichloroethylene are used to

product pieces of aircrafts.

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Image 3.1: Industrial Waste Pretreatment Facility

All wastes that are coming from other sections of factory are stored separately in five tanks

because chemicals are not mixed with each other and chemicals do not reach with each other.

Table 3.2: Chemical Waste Storing Tanks

Tank No Involved Waste Their Capacities

T-1 Concentrated acid waste 45 m3

T-2 Diluted acid waste 200 m3

T-3 Caustic waste 75 m3

T-4 Alkaline cleaner 25 m3

T-5 Caustic waste 60 m3

Image 3.3: Chemical Waste Storing Tanks

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In this facility, there is acid waste treatment system, caustic waste treatment system, back up

unit, coolant recovery unit, and solvent recovery unit. Other wastes which are not treated are

collected in general points of factory and they are transported to industrial waste pretreatment

facility and they are classified and sent to licensed companies to annihilate them. (Floor plan

of the facility can be seen in app.9)

3.1) Acid waste treatment system:

The main aim of this system is that Cr+6 are reduced to Cr+3, because the waste contains a

large amount of chromic acid. And also waste contains other acids such as phosphoric acid,

hydrofluoric acid, nitric acid, and hydrochloric acid. For these acids, neutralization process is

performed. This system can process 28 m3waste in an hour. All concentrated acids are stored

in T-1 tank. Concentrated acids are taken from T-1 tank to T-2 tank and they are diluted in

there. Diluted acids that reach some volume pump automatically to reactor 1(R-1). Sulfuric

acid (H2SO4) is added to R-1 reactor so that pH value of reactor can be around 1.8-2.5. In this

range, sodiummetabisulfide (Na2S2O5) can reduce Cr+6 to Cr+3. By the addition of

sodiummetabisulfide, reduction process is done.

Na2S2O5 + H2O → 2NaHSO3

NaHSO3 + H2O ↔ H2SO3 + NaOH

3NaHSO3 + 2H2CrO4 + 3H2SO4 → Cr2 (SO4)3 + 3NaHSO4 + 5H2O

After the reduction process, the acids are sent to reactor 2(R-2). Sodium hydroxide (NaOH) is

added to this reactor so that pH value of reactor can be around 6-8. This addition and pH

value result the neutralization of other acids and formation of Cr (III) hydroxide.

Cr(SO4)3 + 6 NaOH 2 Cr(OH)3 + 3 Na2SO4

After the neutralization process, the waste is taken to reactor 3(R-3). Anionic polymer is

added to this reactor so that settleable floccules can be formed. Anionic polymer is a

polyelectrolyte and it can bridge with metal hydroxides. By the addition of anionic polymer,

chromium and other heavy metals can flocculate and be formed settleable floccules. pH is

controlled by using pH meter and for this process pH value should be higher than 6. If pH

value decreases, NaOH will add to increase the pH value. Composed settleable floccules are

pumped to clarifier. Clarifier is like a cone. Floccules accumulate in the bottom of cone and

the water goes out to top of the cone. Overflowing water from top of the clarifier is sent to

domestic wastewater treatment facility. Before sending this water, it is analyzed with respect

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to chromium and heavy metals levels. If the levels of metals are above the standards, the

water is sent to T-1 tank and it is treated once more. Sludge in the bottom of the clarifier is

sent to filter press. In filter press, harmful metals and wastes are pressed and they become like

sludge cakes. These cakes with no water are collected and sent to licensed companies to

destroy.

In this treatment system, pH value is measured by pH meter. For reduction process, color

changes are observed. If the color changes yellow to green- blue, the waste can be sent to T-2.

For flocculation process, composed floccules are observed the surface of the reactor. Also,

three reactors have mixers to get homogenous mixture. Moreover, pumps are used to transport

waste. (The flow chart of acid waste treatment system can be seen in app.10)

Image 3.4: Acid Waste Treatment System

3.2) Caustic waste treatment system:

Caustic waste contains sodium hydroxide, potassium permanganate, sodium aluminate, and

sodium sulfide. If the waste contains chromium, waste is sent to acid waste treatment system.

Caustic waste contains a large amount of aluminum. Caustic waste treatment systems

processes are similar to acid waste treatment system processes. This system can process 7 m3

wastes in an hour. All caustic wastes are stored in T-3 and T-5 tanks. Caustic wastes are

pumped to reactor 4 (R-4) which has two parts. In the first part of the reactor, sulfuric acid

(H2SO4) is added to reactor so that pH value of reactor can be around 7-8. This addition

results the neutralization of wastes. Neutralization process causes the precipitation of

aluminum and other heavy metals.

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NaOH + H2SO4 → H2O + Na2SO4

2NaAlO2 + 4H2SO4 → Al2 (SO4)3 + Na2SO4 + 4H2O

NaAlO2 + 3NaOH + 2H2SO4 → 2Na2SO4 + Al (OH) 3 + 2H2O

Al2 (SO4)3 + 6NaOH → 2Al (OH) 3 + 3Na2SO4

NaHS + H2SO4 → NaHSO4 + H2S

After the precipitation process, waste is sent to second part of the reactor for flocculation

process. Anionic polymer is added to reactor to flocculate aluminum and other heavy metals.

And also, pH is fixed around 7-8 by adding sulfuric acid if it is needed. Then, waste with

floccules is pumped to clarifier. In clarifier, water and sludge are separated each other. Water

is sent to domestic wastewater treatment plant if levels of aluminum and other heavy metals

are low. Sludge is sent to filter press to become cake. These cakes are collected and sent to

licensed companies to destroy.

Reactor 4 contains a scrubber. At the end of the neutralization and precipitation process, H2S

that is very dangerous toxic gas emerges. This scrubber scrub H2S gas and gas is washed and

then it is given to the atmosphere. In the facility, there is an alarm system, if the level of H2S

is above of standards and breathing of H2S is hazardous for employees, system warns the

employees. (The flow chart of caustic waste treatment system can be seen in app.11)

3.3) Back-up unit:

When there is a problem with acid waste treatment system or caustic waste treatment system,

the backup unit is used to go on treatment processes. This unit maintains treatment processes’

continuity.

3.4) Coolant recovery unit:

The aim of this unit is to recover the borax oil which is used for blanking and cooling of parts

of airplanes. Polluted oil is stored in barrels and they are sent to industrial waste pretreatment

facility. Polluted oil is taken to coolant recovery unit which has two parts. In the first part of

unit, oil is filtered to remove swarf and big solid particles. Then, creamy region on the surface

of oil is separated from oil by using gravity. This unwanted oil is deposited in barrels and they

sent to licensed companies. The remaining part of oil is taken to second part of unit. In there,

oil is filtered again by using ultrafiltration to remove the water. And, pasteurization process is

done to kill bacteria in the oil. Hence, the oil is recovered but it cannot use in the blanking and

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cooling processes. Some ingredients are added to oil so that it can use in processes of factory.

For this reason, it is sent to licensed companies to recover the oil completely.

3.5) Solvent recovery unit:

Before the chemical processing of metal parts, metal parts are cleaned from oil by using

solvents such as trichloroethylene, trichloroethane. Polluted solvents are taken to vapor

degreaser and they sent to solvent recovery unit which has two parts. In this unit, solvent is

recovered by using distillation process. Recovered solvent is sent to process control laboratory

to analyze. It can be used again after quality control and addition of ingredients. The waste

remaining in the solvent recovery unit is collected and sent to licensed companies.

In this every parts of factory, there is collecting points of all kinds of wastes. These wastes are

sent to industrial waste pretreatment facility. In there, they are classified, treated, recovered,

storage for temporarily. However, annihilation process does not happen in there. Moreover,

the quantity of collecting wastes is recorded and the ministry of environment is informed

about these records. For air pollution, scrubber is used and in heat station and chemical

processing departments, some types of filters are used.

3.6) The analyses performed in the industrial waste pretreatment facility:

In the industrial waste pretreatment laboratory, the samples that are taken from heat station

are analyzed. Heat station generates water vapor. This vapor is used to fulfill heating need of

recreational facilities and is used in production departments of factory. The analyzed samples

gotten from condensate tanks, feed water tank, enter and exit of the water softener, expansion

tank feed pumps.

3.6.1) pH:

pH values of all samples measured by pH meter. pH value of water should be around 5-8. If

the pH value is higher, the formation of scab in the system equipment’s is observed. If the pH

value is lower, the formation of corrosion in the system equipment’s is observed.

3.6.2) Conductivity:

Conductivity determines the dissolved ions in water. If the water is pure, conductivity of this

water decreases. There is a ratio between conductivity of water and total dissolved solids.

Conductivity should be controlled because; dissolved solids can accumulate with the help of

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heat in the regions of system that water flows slowly. Conductivity is measured by using

probe.

3.6.3) Alkalinity:

There are two alkalinity; phenolphthalein and methyl orange. From these alkalinities,

concentrations of hydroxide carbonate and bicarbonate ions are found. If the concentration of

alkalinity in boiler feed water is too high, it can cause formation of carbon dioxide. And,

carbon dioxide causes formation of corrosion condensate return systems. Hence, the quality of

water vapor decreases. Moreover, alkalinity should be high so that it can prevent from acidic

corrosion and the formation of scab in the system equipment’s. (The experiment is expressed

in potable water treatment analysis.)

3.6.4) Total hardness:

Dissolved magnesium and calcium ions in water determine the hardness of water. Total

hardness contains temporarily hardness and permanent hardness. Calcium carbonate and

magnesium carbonate cause temporarily hardness. Calcium sulfate, magnesium sulfate,

calcium chloride, magnesium chloride, calcium nitrate, and magnesium nitrate cause

permanent hardness. Hardness is important for the system equipment’s. (The experiment is

expressed in potable water treatment analysis.)

3.6.5) Iron:

If there is iron in water, it looks colored and it causes the formation of residue in steam boiler.

4. POTABLE WATER TREATMENT FACILITY

Potable water treatment facility was established to get from raw water to potable water for

human consumption. It treats on average 2500 m3 / day. Treated water is distributed to TAI’s

houses, facilities, and 4. Main Jet Military Base (in total approximately 10000 people). Raw

water is coming from Çamlıdere dam or Kurtboğazı dam to this facility. In this facility,

chemical and physical treatment processes are performed. In this facility, for good water

quality, a lot of analyses are done and regulations and standards are followed strictly. (The

flow chart of the plant can be seen in app.12)

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4.1) The constituents of the potable water treatment facility:

The raw water (heavy metals cannot be found in this water.) coming from dams passes

through pressure-reducing valve. In the pressure reducing valve, the pressure of raw water is

reduced from around 6 bar to 0.3 bar. At the same time, raw water comes to the system with

360 m3 flow rate. First of all, the pH value of raw water is controlled. If the pH value is larger

than 9, sulfuric acid (H2SO4) will added to water to get pH value around 7, because, chlorine

and cationic polymer work very well at pH 7-8. In the pipe, chlorine as a gas is added to raw

water to disinfect. Chlorine destroys pathogenic microorganisms in water. Also, the bad taste

and odor of water is removed. Moreover, chlorine provides the removal of iron and

manganese from water.

2 Fe2+ + Cl2 + 6H2O → 2 Fe (OH) 3 ↓ + 2 Cl- + 6 H+

Mn2+ + Cl2 + 2 H2O → MnO2 ↓ + 2 Cl- + 4 H+

2 Fe2+ + MnO2 + 5 H2O → 2 Fe (OH) 3 ↓ + Mn2O3 ↓ + 4 H+

Mn2+ + MnO2 + H2O → Mn2O3 ↓ + 2 H+

Chlorine is a powerful disinfectant if it is used at suitable temperature and pH.

Cl2 (gas) + H2O → HCl + HOCl

HOCl ↔ H+ + OCl-

HOCl separates inadequately at pH levels below 7, hence predominately HOCl can be found

comparatively at lower pH. OCl- can be found relatively above pH 9.5. HOCl is a powerful

disinfectant than OCl- and this expresses the importance of pH. pH of entered water is

measured automatically.

Then, cationic polymer is added to raw water. The main aim of cationic polymer is the

formation of settleable floccules. Cationic polymer has a long chain and large mass. Cationic

polymer exchanges their ions with colloidal particles ions which have negative charges. By

adding chlorine and cationic polymer, coagulation and flocculation processes happen. After

this processes, water is taken to the clarifier.

4.1.1) Clarifier:

Clarifier is pool that has 450 m3 capacities. In the clarifier, lime (Ca (OH) 2) is added to water

for continuity coagulation and flocculation processes. By adding lime, calcium and

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magnesium ions that cause hardness in water are precipitated. Hence, the hardness of water

decreases.

Ca(HCO3)2 + Ca(OH)2 → 2 CaCO3 ↓ + 2 H2O

Mg (HCO3)2 + Ca (OH) 2 → CaCO3 ↓ + MgCO3 + 2 H2O

MgCO3 + Ca (OH) 2 → CaCO3 ↓ + Mg (OH) 2 ↓

For above reactions, pH is an important parameter. At pH value 10-15, the precipitation of

CaCO3 is observed. For further reactions, a high pH value is needed. The pH of our water does

not enough to happen above reactions. The aim of adding lime in this facility is that the

formation of floccules is happened faster. Moreover, lime killed the microorganisms and lime

also removes iron ions.

In the clarifier, there is a comb like in the settleable tank in domestic wastewater treatment

plant. This comb sweeps away precipitated floccules by gravity to bottom of the pool. The

bottom of cone is like cone and precipitated floccules are accumulated in there. Then, sludge

is sent to concentrator. The water is taken to sand filters.

Image 4.1: Clarifier

4.1.2) Sand Filters:

The aim of the sand filters is to keep suspended colloidal particles that cannot be removed in

clarifier and to eliminate the turbidity of water. Sand layers consist of layers. The bottom

layer is nozzle, the middle layer is pebbles, and the upper layer is sand. The sand filters are

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open and the process can be observed. The water coming from clarifier is run to sand filters.

All suspended and colloidal solids in water are accumulated in the voids of layers of sand

filters. Then, the filtered water is taken to water storage tanks. The accumulated particles in

voids of sand are sent to concentrator by doing backwashing. The sand filters should be

backwashed periodically to filter the water efficiently. In backwashing process, the air is blow

from nozzles and the accumulated particles in voids of sand are mixed up in water. Then, the

water is sent to the concentrator and the sand filters become clean. In backwashing process,

blowing air and other things are controlled by mechanically such as pumps and valves. These

are not automatic, they are controlled manually.

4.1.3) Concentrator:

Concentrator is a pool shaped like the clarifier.The backwashed water coming from sand

filters is collected in there. The suspended solids are precipitated by gravity in there. And

then, the water is taken to sand filter again to filter. Also, the sludge coming from the clarifier

is accumulated in there. The collected sludge in the bottom of the pool is removed

periodically. Vacuum filter unit is not used to filter the sludge because of economic reasons.

4.1.4) Water storage tanks:

This facility has two water storage tanks and their capacities are 5000 m3. The water taking

from sand filters, first of all, is chlorinated for disinfection. And, sulfuric acid is added for

adjusting pH if it is needed. Then, the water is collected in water storage tanks. The water

storage tanks are also cleaned periodically.

4.1.5) Air pressure tanks:

Four air pressure tanks are used to distribute the water to TAI’s houses, facilities, and 4. Main

Jet Military Base. Each tank has 80 m3 capacities.

4.2) The analyses performed in the potable water treatment facility:

In the potable water treatment facility laboratory, a lot of experiments are done. The samples

are taken entrance and exit of the unit and some general points in the unit during the

treatment. The some samples that come from industrial waste pretreatment facility and

domestic wastewater facility are also analyzed in there. In the laboratory, physical, chemical,

and biological analyses are done. The analyses results are recorded and the analyses report is

kept.

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4.2.1) pH:

In this facility, pH value of exit water is adjusted to 6.5-8.5 as much as possible. For

coagulation processes, pH value is important and it is measured every point of system by

using pH meter. pH value is important also for hardness of water.

4.2.2) Alkalinity:

Alkalinity is a measure of the volume of water to counteract strong acid. Alkalinity in water

occurs from the existence of hydroxides (OH-), carbonates (CO32-), and bicarbonates (HCO3

-).

pH is an important parameter to determine the alkalinity. If the pH value of water is above

8.3, there will be carbonate or phenolphthalein alkalinity. If the pH value of water is between

8.3 and 4.5, there will be bicarbonate or methyl orange alkalinity. Carbonate and bicarbonate

ions help the precipitation of toxic metals like arsenic.

The samples are gotten from the entrance, clarifier, sand filters, and water storage tank. A few

drops of methyl orange (indicator) are added to 100 ml of sample because the pH value of

sample is below 8.3. The color of sample is yellow-orange. Then, the sample is titrated with

H2SO4 until the color changes to reddish-orange. The spent volume of H2SO4 shows the

methyl orange alkalinity. If the pH value of sample is above 8.3, phenolphthalein will be

added. And, the sample is titrated with H2SO4 until the color changes from pink to colorless.

The spent volume of H2SO4 shows the phenolphthalein alkalinity. In this facility, pH value of

water is below 8.3 and methyl orange alkalinity is found. (Eaton & Franson , 2005)

4.2.3) Hardness:

Hardness is caused by divalent metallic cations like Ca2+, Mg2+, and Fe2+. Mainly calcium

and magnesium ions cause hardness in water. Hard waters are not dangerous for people

health, it can be consumed. However, hard waters increase the soap consumption. Hard waters

cause scaling in hot water pipes, boilers in the system. The samples are gotten from the

entrance, clarifier, sand filters, and water storage tank. The Erichrome Black T (indicator) and

NH4Cl – NH3 buffer solution are added to 100 ml sample. . Then, the sample is titrated with

EDTA until the color changes from purple to deep purple. The spent volume of EDTA shows

the hardness of the sample.

4.2.4) Turbidity:

Turbidity of water shows how much suspended solids exist in water. Turbidity of water

should be removed because suspended particles can be microorganisms and they threat the

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people health. Also, they can plug the filters in the system. Turbidity is measured by using

turbidimeter.

4.2.5) Chlorine:

In this facility, chlorine is used for disinfection the water. The concentration of chlorine in

the system is controlled with the help of electronic device. The concentration of free residual

chlorine in water storage tank is measured. A few drops orthotoludiene is put in 100 ml

sample and the sample gives yellow color. There are prepared samples that have different

concentrations (from 0.1mg / L to 1 mg / L). The sample is compared with the others and the

concentration of sample is determined. The free residual chlorine concentration should be

around 0.3-0.5 ppm.

4.2.6) Jar test:

This test is performed to observe the efficiency of coagulation process and formation of

floccules. The concentrations of coagulants, polymer, lime, and chlorine are determined by

looking the result of this test.

4.2.7) Bacteria test:

The bacteria test is performed twice a month. The samples that are taken from every points of

the system are incubated at 44oC for 1 day.

4.2.8) Other tests:

In this facility; iron analysis, phosphate analysis, sulfate analysis, ammonium analysis, nitrite

and nitrate analysis, spent O2 for organics analysis, the analyses of other ions such as CN, Pb,

Mn, Cu, F2, Ni, Cd, Cr+6 are performed. For these analyses, Dr. Lange prepared ampoules are

used. The values of these ampoules are read in an electronic device.

In this facility, a lot of experiments are done to follow the regulations and standards. Drinking

water standards and tables are followed regularly.

5. CHEMICAL PROCESSING DEPARTMENT:

In this department, different types of chemical processes are performed on parts of aircrafts.

This department produces a large amount of industrial waste. These wastes are sent to

industrial waste pretreatment facility. If in the chemical processing department, work load

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increases, in the industrial waste pretreatment facility, work load will increase as well. In this

department, chromic acid anodizing, boric-sulfuric acid anodizing, chemical conversion

coating (chem-film), chemical milling of aluminum alloys, wet blast, brush cadmium / nickel/

tin plating, passivation, phosphoric acid anodizing for metal bonding, and heat treatment

processes are happened. Also, the parts of aircrafts are colored in there.

6. DISCUSSION:

Practicing in TAI was the right decision, because, I could observe three facility. First, I saw

domestic wastewater treatment facility. In this facility, every unit works very good. I could

observe every unit in aplenty of time. I could understand my theoretical knowledge very well

by observing the units. Especially, the aeration basin and the behaviors of microorganisms

were very helpful to me. I guess one missing thing in domestic wastewater treatment facility

is the lack of technology. However, this situation can be understood because facilities were

established in 1988. Second, I saw industrial waste pretreatment facility. This facility is a

hardworking facility. There is so much work load on it due to chemical processing

department. I observe every unit in the facility and I could understand chemical reactions that

happen in there. I guess, in this facility, the number of employees is not enough because every

person had very much work. Also, the treatments and reactions were observed by looking

color changes. There are not technological equipment’s to observe the reactions. Moreover,

the number of performed experiments was not enough. For air pollution, more precautions

should be taken. The facility should work more than 8 hours to do the treatment efficiently.

Third, I saw potable water treatment facility. In this facility, I saw a lot of experiments and

their devices. I could observe every unit in there very well. This facility is a little bit

technologic compared to others. In general, the facilities serve their purposes. I could

compare three facilities between each other. Moreover, I observed work life. I observed the

relationships between the employees between each other and chief. I learned to company

rules. I obeyed these rules during my summer practice. I learned an environmental engineer’s

responsibilities and duties. As a result, this summer practice was an informative experience

for me.

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7. REFERENCES:

1. TAI website. (2013). Retrieved from https://www.tai.com.tr/tr

2. Curi, K., & Baban, A. (no date). Biyolojik arıtmanın esasları ve işletme özellikleri

3. Eaton, A., & Franson, A. (2005). Standard methods for the examination of water &

wastewater. New York: American Public Health Association

8. APPENDICES: