Keywords: Performance, Screening, Aeration Tank, biological


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International Journal of Scientific & Engineering Research, Volume 6, Issue 7, July-2015 ISSN 2229-5518

1672

Design & Performance Evaluation of Wastewater Treatment Plant-D at Tirumala

G.Chandrakant,P.Jaswanth,S.Teja reddy,G.Kiranmai
Abstract:- The increasing of population in pilgrimage area Tirumala near Tirupati in Chittoor District of Andhra Pradesh, observed as a result of the development of the modern societies is accompanied by concerns in the water sector, as a result of the increasing requirements for water supply and wastewater treatment. This situation justifies the evaluation of the system performance that covers protection of water resources &management.Poorly treated wastewater with high levels of pollutants caused by poor design, operation or maintenance of treatment systems creates major environmental problems, when such wastewater is discharged to surface water or on land. Considering the above stated implications an attempt has been to evaluate the performance of wastewater treatment plant (WWTP) near balaji nagar area at Tirumala (PlantD) capacity of 3 MLD, were collected from each units (Screening & Grit chamber, Aeration tanks, Secondary Clarifier, Storage Tank) at a peak hour. Parameters analyzed for evaluation of performance of WWTP are Total Solids, Oil &Grease, Chlorides, Sulfates, Nitrates, Nitrites, COD, and [email protected] 20° C. Tests were performed to find the fate of pollutants in WWTP. The present study shows that COD removal efficiency of WWTP was found to be 69.39% and BOD5 removal efficiency of WWTP was found to be 62.78%. The production of sludge in the treatment plant is used as a fertilizer. The treated effluent water goes to the territory treatment plant i.e., plant –D.
Keywords: Performance, Screening, Aeration Tank, biological oxygen demand, chemical oxygen demand

are 10MLD.they were design four wastewater

treatment plants in different areas i.e.,

1. INTRODUCTION
1.1 LOCATION OF STUDY he increasing of population in pilgrimage area Tirumala near
TTirupati in Chittoor District of
Andhra Pradesh, observed as a result of the
IJSER development of the modern societies is



Sri Varimetlu (Block-A) capacity of 2MLD,



Opposite to Annaprasdham (Block-B)

capacity of 3MLD,



GangammaGudi Area (Block-C) capacity

of 5 (2+3)MLD,



Balaji Nagar Area (Block-D) capacity of

3MLD.

From the above wastewater treatment plants. We

accompanied by concerns in the water sector, as a have taken Block-D for the performance evaluation.

result of the increasing requirements for water supply and wastewater treatment. This situation justifies the evaluation of the system performance that covers protection of water resources & management.
The temple (13°40′59.7″N 79°20′49.9″E) is

1.2 THE AREAS COVERED UNDER THIS

BLOCK-D PLANT ARE



Pilgrim Amenity Complex I,II.III,



CRO Complex



JEO’S Office

visited by about 50,000 to 100,000 pilgrims daily (30 •

Choultries I II,&III

to 40 million people annually on average), while on •

Panchjanyam Rest House

special occasions and festivals, like the annual •

Koushbham Rest House

Brahmotsavam, the number of pilgrims shoots up •

Police Quarters

to 500,000, making it the most-visited holy place in •

RTC Garage Area Near Balaji Nagar Area

the world. The Tirumala Hill is 853m above sea •

Donor Guest House Near Balaji Nagar

level and is about 10.33 square miles (27 km2) in Area

area. Total average wastewater produce in tirumala



Part Of Employees Quartets

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1.3 FLOW DIAGRAM OF WASTEWATER TREATMENT PLANT -D In this WWTP only Primary, Secondary Treatment units are present form the fig-1, effluents came from this plant goes for further treatment to Block-C.

RAW WATER

IJSER SCREENING
CHAMBER

AERATION TANKS

CLARIFIER

STABILIZATION TANK

BLOCK C

SLUDGE DRYING
BEDS

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Figure 1: Wastewater Treatment Plant Flow Diagram (BLOCK-D) Capacity of 3MLD.

IJSER

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residue is used for landfills or as a soil conditioner. The

1.4. EXPERIMENTAL PROCESSES IN SEWAGE TREATMENT

principal function of primary treatment is to act as a precursor to secondary treatment.

The degree of treatment can be determined by 2.3 SECONDARY WASTEWATER TREATMENT

comparing the influent wastewater characteristics to the

Secondary treatment involves further treatment of

required effluent wastewater characteristics after reviewing the effluent, coming from the primary sedimentation tank and

the treatment objectives and applicable regulations. is directed principally towards the removal of biodegradable

Although these operations and processes occur in a variety organics and suspended solids through biological

of combinations in treatment systems, it has been found decomposition of organic matter, either under aerobic or

advantageous to study their scientific basis separately anaerobic conditions. In these biological units, bacteria will

because the principals involved do not change3.

decompose the fine organic matter, to produce a clearer effluent.

The treatment reactors, in which the organic matter is

decomposed (oxidized) by aerobic bacteria are known as Aerobic

2. CLASSIFICATION OF

biological units; and may consist of:

SEWAGE/WASTEWATER TREATMENT METHODS

• Filters (intermittent sand filters as well as trickling filters), • Aeration tanks, with the feed of recycled activated

2.1 PRELIMINARY WASTEWATER TREATMENT

sludge (i.e. the sludge, which is settled in secondary sedimentation tank, receiving effluents from the

aeration tank), and

Preliminary wastewater treatment is the removal of

• Oxidation ponds and aerated lagoons.

IJSER such wastewater constituents that may cause maintenance
or operational problems in the treatment operations, processes, and ancillary systems. It consists solely of separating the floating materials (like dead animals, tree branches, papers, pieces of rags, wood etc.) and the heavy settle able inorganic solids. It also helps in removing the oils and greases, etc. from the sewage. This treatment reduces the BOD of the wastewater, by about 15 to 30%. Examples

Since all these aerobic units, generally make use of primary settled sewage; they are easily classified as secondary units. The treatment reactors, in which the organic matter is destroyed and stabilized by anaerobic bacteria, are known as anaerobic biological units and may consist of:
• Anaerobic lagoons, Septic tanks, Inhofe tanks, etc.

of preliminary operations are:

Out of these units, only anaerobic lagoons make use of

• Screening and combination for the removal of debris and rags. • Grit removal for the elimination of coarse suspended matter that may cause wear or clogging of equipment and • Floatation / skimming for the removal of oil and grease.

primary settled sewage, and hence, only they can be classified under secondary biological units. Septic tanks and Inhofe tanks, which use raw sewage, are not classified as secondary units. The effluent from the secondary biological treatment will usually contain a little BOD (5 to 10% of the original), and may even contain several mg/L of DO. The organic solids/ sludge

separated out in the primary as well as in the secondary

2.2 PRIMARY WASTEWATER TREATMENT

settling tanks are disposed off by stabilizing under anaerobic conditions in a Sludge digestion tank.

In primary treatment, a portion of the suspended solids and organic matter is removed from the wastewater. This removal is usually accomplished by physical operations such as sedimentation in Settling Basins. The liquid effluent from primary treatment, often contains a large amount of suspended organic materials, and has a high BOD (about 60% of original). Sometimes, the preliminary as well as primary treatments are classified together, under primary treatment. The organic solids, which are separated out in the sedimentation tanks (in primary treatment), are often stabilized by anaerobic decomposition in a digestion tank or are incinerated. The

2.4. TERTIARY/ ADVANCED WASTEWATER TREATMENT AND WASTEWATER RECLAMATION
Advanced wastewater treatment, also called tertiary treatment is defined as the level of treatment required beyond conventional secondary treatment to remove constituents of concern including nutrients, toxic compounds, and increased amounts of organic material and suspended solids and particularly to kill the pathogenic bacteria. In addition to the nutrient removal processes, unit operations or processes frequently employed in advanced

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ISSN 2229-5518

wastewater treatment are chemical coagulation, by irrigation and intermittent filtration. Also, as populations

flocculation, and sedimentation followed by filtration and grew, the quantity of wastewater generated rose rapidly and

chlorination. Less used processes include ion exchange and the deteriorating quality of this huge amount of wastewater

reverse osmosis for specific ion removal or for the reduction exceeded the self-purification capacity of the streams and river

in dissolved solids. Tertiary treatment is generally not bodies. Therefore, other methods of treatment were developed

carried out for disposal of sewage in water, but it is carried to accelerate the forces of nature under controlled conditions

out, while using the river stream for collecting water for re- in treatment facilities of comparatively smaller size. In general

use or for water supplies for purposes like industrial from about 1900 to the early 1970s, treatment objectives were

cooling and groundwater recharge

concerned with:-

3. METHODOLOGY
3.1 PERFORMANCE ANALYSIS OF THE WWTPS
The methodology developed to study the performance of the WWTP is divided into the following steps:

(i) The removal of suspended and floatable material from wastewater, (ii) The treatment of biodegradable organics (BOD removal) and (iii) The elimination of disease-causing pathogenic microorganisms.
3.2 SCREENING

• Identification and characterization of flows associated to the operation of WWTP, namely:
• Pollutants – Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total

Screening is the first unit operation used at wastewater treatment plants (WWTPs). Screening removes objects such as rags, paper, plastics, and metals to prevent damage and clogging of downstream equipment, piping, and appurtenances. Some modern wastewater treatment

Suspended Solids (TSS), Oil & Grease, Chlorides, plants use both coarse screens and fine screens.

IJSER Sulfates, Nitrates, Nitrites, Phosphorus;
Determination of the specific consumption indicator and specific production for each identified parameter, by dividing the annual flow of a given parameter by the affluent flow rate, thus facilitating the comparison between

3.2.1 DESIGN CRITERIA
Screening devices are classified based on the size of the material they remove (the screenings). The “size” of screening material refers to its diameter. Table 2 lists the

treatment plants of different sizes.

correlation between screening sizes and screening device classification. In addition to screening size, other design

The determination of the pollutant loads present in the wastewater entering and leaving the WWTP was carried

considerations include the depth, width, and approach velocity of the channel.

out monthly, considering the monthly average flow rate

and the monthly average concentration of each pollutant,

being the annual value given by the sum of all monthly

values.

Methods of wastewater treatment were first developed in response to the adverse conditions caused by the discharge of wastewater to the environment and the concern for public health. Further, as cities became larger; limited land was available for wastewater treatment and disposal, principally

TABLE 1: SCREENING DEVICES CLASSIFICATION

Screening Device

Size Classification/Size Range of Screen Opening

Bar Screen Manually Cleaned Mechanically Cleaned

Coarse/25-50 mm Coarse/15-75 mm

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Fine Bar or Perforated Coarse Screen (Mechanically Cleaned)

Fine Bar

Fine Coarse/3-12.5 mm

Perforated Plate

Fine Coarse/3-9.5 mm

Rotary Drum

Fine Coarse/3-12.5 mm

Fine Screen (Mechanically Cleaned) Fixed Parabolic Rotary Drum Rotary Disk

Fine/0.25-3.2 mm Fine/0.25-3.2 mm Very Fine (Micro)/0.15-0.38 mm

3.2.2 DESIGN OF BAR SCREENING:

(Cross-sectional area is increased by 50% to compensate for the obstruction posed by the bars of

the grill)

Capacity of the plant –D,

Q =3MLD

=3*106*10-3m3/day

Adjust for the flow area blocked by the bars

=3000m3/day

= 0.1157*1.5= 0.18m2

=3000/24*60*60

Depth of screening, d = 1m

= 0.0347m3/sec

Width of screening b= 0.18m

Design flow velocity V=0.3m/sec

Gap between two bars of the screen

= 10mm

Cross-sectional area of screen channel, A= Q/V

IJSER =0.1157m2

Width of a bar = 5mm

So, Number of Bar screens= 12

3.3. AERATION TANK The aeration tanks, which are used to hold

sludge settling and recycle and wasting.

excess

sludge

the wastewater while oxygen is mixed into it, are

The length of the tank depends upon the

made of reinforced concrete and are left open to the type of activated sludge plant. Except in the case of

atmosphere at the top. An oxygen source supplies extended aeration plants and completely mixed

the oxygen and an agitator which mixes the water plants, the aeration tanks are designed as long

so that oxygen gets dispersed evenly throughout narrow channels. The width and depth of the

the entire volume of water.

aeration tank depends on the type of aeration

equipment employed. The depth controls the

3.3.1. DESIGN CONSIDERATION

aeration efficiency and usually ranges from 3 to 4.5 m. The width controls the mixing and is usually

kept between 5 to 10 m. Width depth ratio should

The items for consideration in the design be adjusted to be between 1.2 to 2.2. The length

of activated sludge plant are aeration tank capacity should not be less than 30 or not ordinarily longer

and dimensions, aeration facilities, secondary than

100

m

3.3.2 DESIGN OF AREATION TANK:

= 0.000250kg/lit

Capacity of the plant –D, Q = 3MLD

BOD load/da =3000*0.000250*103

= 3000m3/day

= 750kg/day

Empirical value, for typical Indian domestic sewage. BOD may range from 200-250mg/L. we have taken the highest value in the range: so that the STP can deal with lighter loads also
BOD in sewage =250mg/lit (Inlet)

F/M

= 0.12

The above value is taken from the available range of 0.10-0.12.the higher limit represents the worst case scenario (more food in the sewage for the bacteria existing in the aeration tank)

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1678

M (Biomass) = 750/0.12 = 6250 kg
We will choose to introduce a 20% safety margin
=6250*1.2 = 7500kg Design MLSS (Level) = 3500mg/lit
= 3.5kg/m3 Aeration tank volume, V= 7500/3.5
=2142.85m3 Average Retention time, = 2142.85*24/3000

= 17.14Hrs

Provide 3 Aeration tanks,

So, each tank volume = 2142.85/3

= 714.28m3

Depth of each tank,

D= 4.5m

Area of each tank, A= 158.72m2

We provide,

Breadth of each tank, B = 10m

Length of each tank, L = 16m

Size of each tank, L*B*D= 16m*10m*4.5m

tank)

3.4 CLARIFIER

from the actual water. The water is dumped into the middle of the tank and flows out in the radial

The next step is transferring the fluid into the primary clarifying or settling tank. As the

direction. A mechanical scraper runs on the bottom to remove all of the debris that settles, while a strip

IJSER debris containing, and now aerated, fluid flows
into the clarifying or sedimentation tanks, it is slowed down considerably to allow the remaining debris mixed in with the wastewater to separate
3.4.1. DESIGN OF CLARIFIER:

of jagged metal around the top to catch all of the floating debris (Metcalf & Eddy, Wastewater Engineering, 1972).
Assuming 24 hours of pumping in small plants. The 4 hours of down time of a worst-case

scenario. in practice, pumping will be done for

Capacity of the plant –D,Q = 3000m3/day

more than 24 hours.

= 125m3/hr

Maximum hourly throughput = 3000/24

Design overflow rate

=25m3/m2/day

Cross sectional area of tank

= 125/1.041

= 1.041m3/m2/hrs.

= 120.076m2

Dimensions For circular tank Diameter= 12.36m

= 3.622kg/m2/hrs.

Depth of Tank,d= 3m

Weir length in clarifier= π* Dia

Solids load =Hourly throughput*MLSS

= 3.14* 12.36

= 125*3.5

= 38.81m

=437.5kg/hrs.

Weir loading rate = (sewage flow rate)/ (length of weir)

Solids loading rate

= (solids load)/ (area of

=3000/38.81

=437.5/120.076

= 77.3m3/m/day

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International Journal of Scientific & Engineering Research, Volume 6, Issue 7, July-2015 ISSN 2229-5518
Volume of tank =Area * Depth

1679
=2.88 Hrs.

=120.76*3 =360.228 m3

Compared to ideal range of 2.5-3 hours, the above results are shown within the limits

Hydraulic Detention time = (Tank volume) (throughput Rate) *24hr.

3.5. WHY SHOULD SEWAGE/WASTEWATER IS TREATED BEFORE DISPOSAL:

(ii) Untreated wastewater (sewage) containing a large amount of organic matter, if discharged into a river/stream, will

Sewage/Wastewater treatment involves breakdown of complex organic compounds in the wastewater into simpler compounds that are stable and nuisance-free, either physico-chemically and or by using micro-organisms (biological treatment). The

consume the dissolved oxygen for satisfying the biochemical oxygen demand (BOD) of wastewater and thus, deplete the dissolved oxygen of the stream; thereby, causing fish kills and other undesirable effects.

adverse environmental impact of allowing untreated wastewater to be discharged in groundwater or surface water bodies and/or land is as follows -

(iii) Wastewater may also contain nutrients, which can stimulate the growth of aquatic plants and algal blooms; thus, leading to

(i) The decomposition of the organic

eutrophication of the lakes and streams.

materials contained in wastewater can lead to the production of large quantities of malodorous gases.

(iv) Untreated wastewater usually contains numerous pathogenic, or disease causing microorganisms and toxic compounds, that

IJSER dwell in the human intestinal tract or may
be present in certain industrial waste. These may contaminate the land or the water body, where such sewage is disposed. For the above-mentioned reasons, the treatment and disposal of wastewater, is not only

and processes occur in a variety of combinations in treatment systems, it has been found advantageous to study their scientific basis separately because the principals involved do not change3.

desirable but also necessary

4. ANALYSIS

3.6 EXPERIMENTAL PROCESSES IN SEWAGE TREATMENT
The degree of treatment can be determined by comparing the influent wastewater characteristics to the required effluent wastewater characteristics after reviewing the treatment objectives and applicable regulations. Although these operations

We did grab sampling for each and every unit influent & effluents in peak hours in quality & quantity. Parameters analyzed for evaluation of performance of WWTP are Total Solids, Oil & Grease, Chlorides, Sulfates, Nitrates, Nitrites, COD, BOD5 @ 20°.
The analysis report as given below Table-2

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TABLE 2: UNIT WISE REMOVAL EFFICIENCY OF WASTEWATER TREATMENT PLANT

NSLo. PARAMETERS

UNITS

SCREENING CHAMBER

WASTEWATER TREATMENT UNITS

AERATION TANK

SECONDARY CLARIFIER

STABILIZATION TANK

Influent

7.17

7.14

7.13

7.12

1

pH

Effluent

7.14

7.13

7.12

7.12

Removal efficiency

%

0.42

0.14

0.14

0.00

Influent

mg/L

200.00

400.00

210.00

0.00

IJSER 2

TDS

Effluent

mg/L

200.00

210.00

0.00

0.00

Removal efficiency

%

0.00

47.50

100.00

0.00

Influent

mg/L

2100

2200

1200

600

3

TSS

Effluent

mg/L

1800

1200

600

600

Removal efficiency

%

14.29

45.45

50

0

Influent

mg/L

5.12

3.64

2.56

1.72

4

OIL & GREASE

Effluent

mg/L

3.64

2.56

1.72

1.72

Removal efficiency

%

28.91

29.67

32.81

0.00

Influent

mg/L

Effluent

mg/L

5

BOD 5 @ 200C

Removal efficiency

%

157.50 127.50
19.05

127.50 95.00
25.49

95.00 65.00
31.58

65.00 58.62
9.82

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1681

Influent

mg/L

6

COD

Effluent

mg/L

Removal efficiency

%

202.66 160.00 21.05

160.00 102.00 36.25

101.33 62.00 38.81

Influent

mg/L

7

CHLORIDES

Effluent

mg/L

Removal efficiency

%

99.99 99.99 0.00

99.99 100.00 -0.01

109.99 89.99 18.18

Influent

mg/L

15.60

15.60

4.00

IJSER 8 PHOSPHOROUS

Effluent

Removal efficiency

Influent

9

SULFATES

Effluent

Removal efficiency

10

NITRITES

Influent Effluent

mg/L %
mg/L mg/L
%
mg/L mg/L

15.60 0.00
70.00 66.00 5.71
3.00 2.66

4.00 74.36
66.00 68.00 -3.03
2.66 4.20

3.52 12.00
69.00 36.00 47.83
4.20 0.22

Removal efficiency

%

11.33

-57.89

94.76

Influent

mg/L

11

NITRATES

Effluent

mg/L

Removal efficiency

%

1.24 1.32 -6.45

1.32 1.60 -21.21

1.60 0.00 100.00

62.00 61.85 0.24
89.99
89.99 0.00
3.52 3.52 0.00
36.00 36.00 0.00
0.22 0.22 0.00 0.00 0.00 0.00

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Keywords: Performance, Screening, Aeration Tank, biological