Wastewater Collection And Treatment in

Upcoming IIT Palakkad Permanent Campus

CE3025 - Environmental Engineering

Department Of Civil Engineering

Indian Institute of Technology, Palakkad

Submitted By- Submitted To-

Ishan Agrawal (101501015) Dr. Sunitha K Nayar

Ashutosh Maurya (101501009)

Swati (101501026)

Divyansh Dubey (101501012)

Akshansh Gupta (101501003)

The project aims at designing wastewater collection system for the campus and setup a

treatment plant. Specifications of the entire management system such as pipe diameters, capacity

of the treatment plant, etc. are calculated based on population estimates for the next 30 years.

Factors including topography of the campus, isolation of the location and ease of discharge are

considered to decide the site for the treatment plant as well as the course of the sewer conduits.

Various components of the treatment plant are designed based on flow characteristics, type of

contaminants, acceptable effluent standards and typical dimensions.

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 ACKNOWLEDGEMENT

The successful completion of this project brings immense joy and satisfaction for the entire team

involved. We extend our gratitude to Dr Sunitha K Nayar for giving us the opportunity to work

upon this problem statement. Inputs from her lectures for this course as well as her guidance all

through our period of work were invaluable.

Mr Vineesh Kumaran from the engineering works department was appreciably cooperative in

providing us with the required maps and drawings for the project.

This report is a result of the combined efforts and dedication of all the members of the group and

a significant credit goes to our team work as well.

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 TABLE OF CONTENT

1. Treatment Plant Site Identification ………………………………………………6

2. Population and Influent Amount Estimation …………………………………….7

3. Design of Sewer Conduits ……………………………………………………....10

4. Wastewater Treatment Process ……………………………………………….....13

4.1 Primary Treatment ………………………………………………………….13

4.2 Secondary Treatment ..……………………………………………………...14

4.3 Sludge Thickening …………………………………………………………..15

4.4 Sludge Digestion …..………………………………………………………..15

4.5 Disinfection ……..………………………………………………………......15

5. Treatment Plant Design ……………………………………………………….....16

5.1 Design of Receiving Chamber ………………………………………………16

5.2 Design of Grit Chamber ……………………………………………………..16

5.3 Design of Bar Screen ………………………………………………………...18

5.4 Design of Primary Sedimentation Tank ……………………………………..19

5.5 Design of Trickling Filter …………………………………………………...20

5.6 Design of Secondary Clarifier ……………………………………………....21

​ 5.7 Design of Disinfection Tank ………………………………………………...22

6. Treatment plant design parameters.………………………………………………23

7. Contribution of team members ………………………………………………….27

8. References ……………………………………………………………………….28

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 LIST OF TABLES

1. Population Estimation …………………………………………………………..7

2. Influent Amount Estimation ……………………………………………………..8

3. Pipe diameter ……………………………………………………………………13

4. Treatment plant design parameters ……………………………………………...23

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 LIST OF FIGURES

1. Location of Treatment Pant ………………………………………………………6

2. Course of Sewer Conduit ………………………………………………………..10

3. Screen …………………………………………………………………………....18

4. Suspended solids and BOD removal as a function of overflow rate ……………19

5. Flow chart of treatment plant …………………………………………………....25

6. Plan of treatment plant …………………………………………………………...26

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 1. Treatment Plant Site identification

Fig. 1 Location of Treatment Pant

The red rectangle in the drawing represents the location of the treatment plant. The elevation of

the area, obtained by using the contour map of the permanent campus site lies around 103

metres. Attempts have been made to keep the plant at the lowest possible altitude to avoid

pumping mechanisms for the wastewater to reach the treatment facility. A secluded location has

been chosen to cause minimum hindrance to general campus life and ease of transportation from

far away places.

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 2. Population and Influent Amount Estimation

All estimates have been made for a period of 30 years.

Categories Population

UG Program 6000*

Masters Program 1800*

Doctoral Program 1200*

Total number of students 9000

Faculty 600​#

Faculty with family 2400​#

Staff 600​^

Staff with family 1800​^

Total Population 13,200

Table 1 Population Estimation

* UG Students per department per year - ​100

Total number of departments -​ 15

For 4 years of UG Program, Total number of UG Students = ​15*4*100

= 6000

Students in masters program per department -​ ​120

Total contribution to population = ​120*15

= 1800

Students in doctoral program per department -​ 80

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Total contribution to population = ​80*15

= 1200

# Assumed faculty - student ratio - ​1:15

Number of faculty members = ​9000/15

= 600

Assumed family size - 4

Total contribution to population = ​600*4

= 2400

^ Assumed number of staff members -​ 600

Assumed family size - 3

Total contribution to population = ​600*3

= 1800

Category Amount of Influent (MLD)

Hostel Complex 1.0*

Residential Complex 0.80​#

Academic Complex 0.450​^

Total Influent Amount 2.250”

Table 2 Influent Amount Estimation

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For influent amount estimation, it is assumed that 80% of the consumed water goes out as

wastewater.

* Assumed daily consumption per student - ​135 lit/head/day

Total wastewater output = ​0.8*135*9000

= ​972000 L/day

=0.972MLD

≃ 1.0M LD

# Assumed daily consumption by faculty, staff and respective family members -​ 225 lit/head/day

Total wastewater output = 0.8*225*4200

=​ 756000​ L/day

=​0.756MLD

≃ 0.80M LD

^ Assumed daily consumption - ​50 lit/head/day

Total wastewater output = ​0.8*50*(9000+600+600)

= ​408000L/day

=​0.408MLD

≃ 0.450M LD

“ Total discharge from campus = ​1.0+0.80+0.450

= ​2.25MLD

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 3. Design of Sewer Conduits

The bold lines in the picture represent the plan for the pipelines carrying wastewater from across

the campus to the treatment plant (T).

Fig. 2 Course of Sewer Conduit

Half of the total discharge from the academic complex (225 kL/day) is collected at node 1 and

carried to T. Node 2 receives wastewater from the other half of the academic area (225 kL/day)

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and 2/3rd of the influent released by the hostel complex (670 kL/day) which is transported here

from node 3.

Node 7 is used to locally collect inflow from 1/3rd of the future residential complex (270

kL/day) which then goes to node 6 and meets the other 1/3rd of the residential inflow (270

kL/day). Finally all the wastewater from node 6 goes to node 5 and receives the remaining ⅓ of

the residential wastewater on the way. Henceforth, the entire wastewater from the residential

complex reaches node 5 and then to node 4 where it meets the remaining 1/3rd of the wastewater

volume from the hostel complex coming from node 8 (330kL/day). Finally, from node 4, it

reaches the treatment facility, T.

CALCULATION OF PIPE DIAMETER USED BETWEEN NODE 1 & TREATMENT PLANT

We assume half flow condition in the pipes. The material selected is PVC ( Manning’s

coefficient, n - ​0.01) for it is extremely chemical-resistant, able to withstand acids, salts and

bases because of which it is often used in sewage piping. It is even resistant to some solvents,

such as fuel and paint thinners.

Let the diameter of the pipe be D.

Total Discharge, Q - 225 kL/day

- ​ 0.002604 ​m3​​ /s

Elevation of node 1 (upstream end)- ​109.4 ​m

Elevation of Treatment plant (downstream end)-​ 103 ​m

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Distance between node 1 and treatment plant - 600 m

109.4−103
Slope, S​0​ = 600

= ​0.010667

πD2
So, Sectional area of flow, A = 8
πD
Wetted Perimeter, P = 2
A
Hydraulic radius, R = P

D
= 4

1 πD8/3 S 1/2
Using Manning’s equation, ​Q = n ( 8*4 2/3
0
)

3/8
8*42/3 Qn
On rearranging, ​D = ( )
πS 1/2
0

On substituting Q = ​0.002604 ​m3​​ /s, n = 0.01 and S​0​ = ​0.010667

D = 0.09 m

=​ 3.54​ in

Based on available pipe diameters,​ D = ​4​ in

Similar calculation were performed for the all paths and results are tabulated below .

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 Table 3 Pipe diameter

4. Wastewater Treatment Process

Water collected in wastewater sewers contains wide variety of contaminants have to be removed

before disposal into the river. In our case, major part of wastewater is black water and grey

water and these contains contaminants like suspended solids, biodegradable organics, pathogens

and nutrients. So following processes are required for treatment of wastewater before disposal.

4.1 Primary Treatment

Wastewater contains a wide variety of solids of various shapes, size and densities. Effective

removal of these solids may require a combination of unit operations such as screening and

settling.

A. Screening

This stage of the plant will have screening devices to remove coarse solids which consist

of sticks, rags, boards and other large objects from wastewater.

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 B. Grit Chamber

Wastewater contains a wide assortment of inorganic solids which are abrasive in nature

and will cause wear of pumps and sludge handling equipment. Additionally these

materials are non-biodegradable therefore desirable to separate them from the organic

suspended solids

C. Primary sedimentation tank

It is a unit operation designed to concentrate and remove suspended organic solids from

the wastewater. It will be equipped with mechanical scrappers to settle sludge and drive it

towards a hopper from where it will be pumped to the treatment facility. Grease or oil

will be skimmed off as they gradually rise to the surface of the water.

4.2 Secondary Treatment

Considering the low population and scarcity of level terrain in the permanent campus, we

propose to setup a trickling filter for secondary treatment of wastewater. It will be used to

degrade the biological content of the sewage derived from human and food waste, soaps and

detergents. Low operational costs and power requirements are other reasons for this choice over

suspended culture system.

The biomass generated by trickling filter represents a substantial organic load and must be

removed to meet acceptable effluent standard by secondary clarifier. Design of secondary

clarifier for attached cultural system (trickling filter) is same as primary clarifier.

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4.3 Sludge Thickening

The sludge produced and collected during the primary and secondary treatment processes will be

concentrated and thickened to enable further processing. It will be put into a gravity thickening

tank for settling and dewatering. The remaining water will be sent for further treatment and the

sludge will be sent for digestion.

4.4 Sludge Digestion

The sludge settling out after the primary and secondary treatment stages will be directed to

digesters where it undergoes anaerobic digestion. The methane gas and other nutrient rich bio

solids formed in this process can be recycled and used for supplying power to the treatment

plant.

4.5 Disinfection

After the primary and secondary treatment procedures, there are still some diseases causing

organisms in the remaining treated wastewater. To eliminate them, the wastewater will be

subjected to disinfection for a period of 15 minutes in tanks that contain a mixture of chlorine

and sodium hypochlorite. The effluent will be later released into the environment through the

local waterways.

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5. Treatment Plant Design

5.1 Design of Receiving Chamber

Assumed detention time, t - ​60 sec

Average flow =​ 2250 KL/D

Maximum Flow, q = ​2250 * 2.5

= ​5625 m3​ ​/day

= ​3.9 m3​

Provide the dimensions as Length = ​3 m

Width = ​1.5 m

Depth = ​1 m

Corrected volume = ​4.5 m3​

5.2 Design of Grit Chamber

Average Flow-​ 2.25 MLD

Maximum Flow = ​2.5*​ Average flow

=​ 2.25*2.5

= 5.625 MLD

= 0.065 m3​ ​/s

Assuming settling velocity = ​0.02 m/s

Velocity of Flow =​ 0.3 m/s

Assuming the depth of the tank, D = ​1.5*W​ , where, W-Width of the tank

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 Q
Area of cross section of the tank = V

0.065
W*D = 0.3

1.5 W​2​ = ​0.216

W =​ 0.38 m

D = ​1.5*​W

= ​0.57 m

0.57
Detention time, t = 0.02

= 28.5 sec

Length, L = Vt

= 0.3*28.5

= 8.55 m

Provide length, L = ​8.6 m

Provide a free board of ​0.3 m​ and Grit accumulation zone of ​0.25 m

Then, D = 0.57 + Free Board + Grit Accumulation Zone

= ​0.57 + 0.3 + 0.25

​= 1.12 m

Provide D = ​1.2 m

Length, ​L = ​8.6 m

Width, ​W =​ 0.4 m

Depth, ​D = ​1.2 m

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5.3 Design of Bar Screen

Number of bars in the screen is taken as ‘​n​’

Assumed bar diameter, d = ​10 mm

Clear Spacing, s = ​10 mm

Width, w = d(n+1) + s*n

​400​ = 10(n+1) + 10*n

n = ​19.5

Provide​ n = ​20 bars

​Fig. 3 Screen

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5.4 Design of Primary Sedimentation Tank

We assume a 60% removal of suspended solids at average flow.

Fig. 4 Suspended solids and BOD removal as a function of overflow rate

For 60% suspended solids removal, the overflow rate is ​35​ m/d.

2.25*1000m3 /d
Required Surface Area = = ​65​ m​2
35 m3 /m2 .d

Using Circular Tank, the diameter is

d=
√ 4*A
π =
√ 4*65
3.14 =​ ​9.09​ m

Taking the diameter of 9m and assuming a sidewall depth of 3m,

Volume of tank, V = 3*65

= ​195 m2​
195 m3
​Detention time at average flow, t = 2250 m3 /d

= ​2.08 hours

5625 m3 /d
At peak flow conditions, the overflow rate - 65 m2

= ​86.5 m/day

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Permissible range of overflow rate - 80 to 100 m/day

Hence, OK.

Typical speed of sludge scraper =​ ​0.03 rev/min

Bottom Slope =​ 80 mm/m

5.5 Design of Trickling Filter

We propose to install a high rate filter with hydraulic loading ‘​Q​’ and diameter ‘​d​’

Assuming ​ Influent
​ substrate concentration, S​0​ = ​200 mg/l

and Effluent substrate concentration, S​e​ = ​25 mg/l

Treatment constant, k =​ 0.055 min-1​

Coefficient relating to the medium characteristics, n = ​0.5

Circulation ratio, R = 2

S 0 +RS e
BOD in the mixture of raw and recycled mixture applied to the medium, S​a​ = 1+R

200 + 2*25
=​ 1+2

= ​83.33 mg/L

−kD
Se e Qn
Sa
= −kD
(1+R)− Re Qn
−0.055*1.5
eQ0.5
25
83.33
= −0.055*1.5
(1+R)− Re Q0.5

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 Q = ​0.029​ m​3​/m​2​.min

Total flow from campus, q = ​2250 m3​ ​/day

= 1.5625 m3​ ​/min

= 1.5625
0.029

= ​53.88 m2​

√
4A
Diameter of the filter, d = π

= ​8.28 m

Provide d = ​8.5m

Efficiency of trickling filter​ ​= ( 200−25

​= ​87.5%

5.6 Design of Secondary Clarifier

Design parameters are same as the primary sedimentation tank.

Diameter = ​9 m

Depth = ​3 m

Bottom Slope = ​80 mm/m

Detention time = ​2.08 hr

Speed of Sludge Scraper =​ 0.03 rev/sec

5.7 Design of Disinfection Tank

Design average flow for tank = ​2250 m3​ ​/day

Chlorine dosage = ​5 mg/L

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Contact time = ​15 min

Residual chlorine =​ 0.2 mg/L

2250 15
Volume of tank = 24 *
*60

=​ 23.4 m3​

Provide the dimensions as , Length = ​4 m

Width = ​3 m

Depth = ​2 m

Corrected volume = ​24 m3​

Amount of chlorine required per day =​ 2250*1000*5

= 11250000 mg/day

= ​11.25 kg/day

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6. Treatment plant design parameters

S.No. Design Specifications

1. Receiving Chamber

Length 3m

Width 1.5 m

Depth 1m

Detention Time 60 sec

2. Screen

No. of bars 20

Diameter of bars 10 mm

Clear Spacing 10 mm

3. Grit Chamber

Length 8.6 m

Width 0.4 m

Depth 1.2 m

4. Primary Sedimentation Tank

Diameter 9m

Depth 3m

Detention Time 2.08 hrs

Bottom Slope 80 mm/m

Speed of Sludge Scraper 0.03 rev/min

5. Trickling Filter

Diameter 8.5 m

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 Depth 1.5 m

Medium Plastic media

Type High rate filter

Influent BOD 200 mg/L

Effluent BOD 25 mg/L

Recycling Ratio 2

6. Secondary Clarifier

Diameter 9m

Depth 3m

Detention Time 2.08 hrs

Bottom Slope 80 mm/m

Speed of Sludge Scraper 0.03 rev/min

7. Disinfection Tank

Length 4m

Width 3m

Depth 2m

Amount of Chlorine 11.25 kg/day

Table 4 Treatment plant design parameters

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Fig 5 Flow chart of treatment plant

25
Fig 6 Plan of Treatment Plant

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7. CONTRIBUTION OF TEAM MEMBERS

Ishan Agrawal - Calculation of population and influent amount, design parameters

Ashutosh Maurya - Deciding the location of the treatment plant and calculation of pipe diameters

Swati - Calculation of influent amount and Making project report

Divyansh Dubey - Treatment process selection and calculation of design parameters

Akshansh Gupta - Population estimation and Making project report

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8. REFERENCES

● Environmental Engineering by Howard S. Peavy and Donald R. Rowe

● https://en.wikipedia.org/wiki/Sewage_treatment

● https://en.wikipedia.org/wiki/Wastewater_treatment

● https://www.conserve-energy-future.com/process-of-wastewater-treatment.php

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