Consider a domestic sewage treatment plant in a tropical region at sea level (average temperature 28°C) treating 4500 m3/day of influent, with the following composition:
1400 mg COD/L; 600 mg BOD/L; 750 mg SS/L; 60 mg NH4-N/L, 20 mg PO4-P/L
The water is treated in a conventional trickling filter. The objective is to have both organic BOD removed and full nitrification.
The trickling filter operates at an hydraulic load of 0.05 m3/m2h. Calculate the smallest possible height (in meter) of the trickling filter. (Use the smallest possible diameter that you calculated in question 2b.) Assume a maximum BOD-load for full nitrification.
What is the smallest possible height (m) for the trickling filter?
Hey u got the answers of other questions i need 2 marks to get 60% so please help
Kamran, did u get the answer for question 2? I am so confused, please help!
KAMRAN
Please can you help for some questiom , the course will end after 5 hours and I can not finish the materials
To calculate the smallest possible height of the trickling filter, we need to determine the organic BOD load and the maximum BOD load for full nitrification.
Step 1: Calculate the organic BOD load:
Organic BOD Load (g/d) = Influent Flow Rate (m³/day) × Influent BOD concentration (mg/L) × 0.001 (to convert mg to g)
Organic BOD Load = 4500 m³/day × 600 mg/L × 0.001 = 2700 g/d
Step 2: Calculate the maximum BOD load for full nitrification:
Maximum BOD Load for Full Nitrification (g/d) = NH4-N Load (g/d) × 3.5 (ratio of BOD production to NH4-N oxidation)
NH4-N Load (g/d) = Influent Flow Rate (m³/day) × NH4-N concentration (mg/L) × 0.001 (to convert mg to g)
NH4-N Load = 4500 m³/day × 60 mg/L × 0.001 = 270 g/d
Maximum BOD Load for Full Nitrification = 270 g/d × 3.5 = 945 g/d
Step 3: Calculate the required volume of the trickling filter:
Trickling Filter Volume (m³) = Organic BOD Load (g/d) / Maximum BOD Load for Full Nitrification (g/d)
Trickling Filter Volume = 2700 g/d / 945 g/d ≈ 2.857 m³
Step 4: Calculate the surface area of the trickling filter:
Trickling Filter Surface Area (m²) = Trickling Filter Volume (m³) / Height (m)
We need to solve this equation to find the smallest possible height of the trickling filter, so we rearrange the equation:
Height (m) = Trickling Filter Volume (m³) / Trickling Filter Surface Area (m²)
Given the hydraulic load of 0.05 m³/m²h, we can calculate the surface area as follows:
Trickling Filter Surface Area (m²) = Influent Flow Rate (m³/day) / Hydraulic Load (m³/m²h) / 24 (to convert from h to day)
Trickling Filter Surface Area = 4500 m³/day / 0.05 m³/m²h / 24 = 375 m²
Finally, let's substitute the values into the equation:
Height (m) = 2.857 m³ / 375 m² ≈ 0.0076 m
Therefore, the smallest possible height of the trickling filter is approximately 0.0076 meters.