Reference no: EM132354298
Advanced Water & Wastewater Treatment Assignment - Wastewater Treatment Process Design
Table 1 shows a typical wastewater flow rate generated on a normal day from a newly developed community. Characteristics of wastewater are detailed in Table 2. Additionally, wastewater contains particles such as plastic bottles, toilet paper, silt, and sand. Average water temperature throughout the year is 22oC.
Table 1: Details of the wastewater flow rate on a normal day
|
Time
|
Flow (m3/s)
|
Time
|
Flow (m3/s)
|
|
0:00
|
0.0875
|
12:00
|
0.135
|
|
1:00
|
0.07
|
13:00
|
0.129
|
|
2:00
|
0.0525
|
14:00
|
0.123
|
|
3:00
|
0.0414
|
15:00
|
0.111
|
|
4:00
|
0.0334
|
16:00
|
0.103
|
|
5:00
|
0.0318
|
17:00
|
0.104
|
|
6:00
|
0.0382
|
18:00
|
0.105
|
|
7:00
|
0.0653
|
19:00
|
0.116
|
|
8:00
|
0.113
|
20:00
|
0.127
|
|
9:00
|
0.131
|
21:00
|
0.128
|
|
10:00
|
0.135
|
22:00
|
0.121
|
|
11:00
|
0.137
|
23:00
|
0.11
|
Table 2: Wastewater characteristics
|
Parameters
|
Concentration (mg/L)
|
|
Alkalinity as CaCO3
|
100
|
|
pH
|
7.3
|
|
Suspended Solid (SS)
|
250
|
|
Total dissolved solids (TDS)
|
510
|
|
Chloride
|
50
|
|
BOD5
|
210
|
|
COD
|
425
|
|
Total organic carbon
|
160
|
|
Ammonia-N
|
40
|
|
Total Kjeldahl nitrogen (TKN) as N
|
45
|
|
PO4-P
|
9.5
|
|
Total PO4-P
|
12
|
Table 3: Details of unit processes, design parameters and design guidelines
|
Unit process
|
Design parameters
|
Design guidelines
|
|
Screening
|
Cross-sectional area, height, number of screening
|
Flow rate = peak flow (Table 1), coarse bar screen 1.0 to1.5 cm width, 4.0 to 5.0 cm clear spacing, <60o to the horizontal, channel with 0.75 to 0.80m
|
|
Grit chamber
|
Volume, dimension (length, width & depth)
|
Flow rate= peak flow (Table 1), horizontal flow rate = 0.25 m/s, water retention time = 1-2 min
|
|
Equalization basin
|
Volume
|
Provide 25% excess capacity for the equipment, use Table 1.
|
|
Primary sedimentation tank
|
Volume, dimension (diameter, depth), number of tanks
|
Flow rate= average flow rate (Table 1), overflow rate = 30 to 50 m3/m2.d, hydraulic retention time = 1.5 to 2.5 h. Circular sedimentation tank, Diameter = 3 to 50 m and water depth = 3 to 5 m.
|
|
Aeration tank
|
Volume, quantity of sludge produced in a day, amount of air to be supplied in a day, check the F/M
|
90% BOD5 is soluble BOD given in Table 2, effluent standards = 25 mg/L BOD5 & 30 mg/L SS. BOD5 of the SS is 65 % of SS. Ks = 25 to 100 mg/L BOD5, µm = 1to 8 d-1, kd = 0.01to 0.30 d-1, Y =0.4 to 0.8 mg VSS/mg BOD5 removed, MLVSS = 1500 to 2200 mg/L
|
|
Secondary Sedimentation Tank
|
Volume, dimension (diameter, depth), number of tanks
|
MLSS = 2550 to 2950 mg/L, Diameter = 3 to 50 m and water depth = 3 to 5 m. 40 to 50% of wastewater will be recirculated to the aeration tank. Follow attached the materials
|
Q1. Design unit processes (screening, grit chamber, equalization basin, primary sedimentation tank, aeration tank & secondary sedimentation tank) using the water flow rates (Table 1), water characteristics (Table 2), design parameters and guidelines (Table 3). The flow rate given in Table 1 will be different for the individual. Multiply the flow rate given in Table 1 by (1+XY*0.01). XY is the last two digits of your id number. If need more data and information, please follow the reference books and lecture materials.
Q2. If the new unit process is designed to remove 25 mg-N/L NH3, calculate the amount of air (kg/day) to be supplied to convert ammonia to nitrate. Calculate the quantity of sludge (kg/day) produced due to NH3-N oxidation. Yield is 0.3.
Q3. PO4-P removal of the designed wastewater treatment process is only 30%. However, PO4-P discharge limit into the receiving water body is < 0.5 mg/L. You are asked to design a chemical treatment process to bring PO4-P < 0.5 mg/L. In such condition, how much alum (based on theoretical calculation) will require in a day and how much chemical sludge will be produced?
Q4A. Write the characteristics of the sludge produced from the primary treatment process. What are the treatment processes would you apply to manage the sludge (from the primary treatment process). Answer this question by students whose id end at 0-5.
Q4B. Write the characteristics of the sludge produced from the secondary treatment process. What are the treatments processes would you apply to manage the sludge (from the secondary treatment process). Answer this question by students whose id end at 6-9.
Q5A. If you are asked to upgrade the given wastewater treatment plant (details in Tables 1-3) to produce the water which can be reused (such as for gardening, for car washing, etc) what are the additional treatment units required? Draw the flow diagram of the additional treatment process and mention the objectives of each treatment unit process. Not necessary to calculate the size of the treatment process. Answer this question by students whose id end at 0-5.
Q5B. A small town located in the rural area produces a similar quantity and quality of the wastewater given in Tables 1 and 2. The produced wastewater should be treated and disposed of in a nearby river. You are hired to design the pond system to treat the wastewater. Draw the flow diagram of the pond system and write the objectives of each pond. Not necessary to calculate the size of the treatment process. Answer this question by students whose id end at 6-9.