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Stone media TF design Example 1
Calculate the BOD loading, hydraulic loading, BOD removal efficiency, and effluent BOD concentration of a single-stage trickling filter based on the following data: Design assumptions: Influent flow =1530 m3/d Recirculation ratio = 0.5 Primary effluent BOD = 130 mg/L Diameter of filter = 18 m Depth of media = 2.1 m Water temperature =18oC

Stone media TF design Solution) (1) BOD loading rate (kg/m3/d)
BOD load = BOD Conc. x Influent flow = 130 mg/L x m3/d =198.9 kg/d Volume of filter = surface area of filter x depth = π (18 m x 18m)/4 X 2.1 m = 533 m3 BOD loading rate = BOD load / volume of filter =0.37 kg/m3/d

Stone media TF design Solution) (2) Hydraulic loading rate (m3/m2/d)
Total flow to the media = influent + recirculation flow = 1530 m3/d + (1530 m3/d x 0.5) Surface area of filter = π (18 m x 18m)/4 = 254 m3 Hydraulic loading rate = Total flow to the media / area of filter = 9.04 m3/m2/d

Stone media TF design Solution) (3) Effluent BOD (mg/L)
BOD removal efficiency for first-stage filter at 20oC, %

Stone media TF design Example 2
A municipal wastewater having a BOD of 200 mg/L is to be treated by a two-stage trickling filter. The desired effluent quality is 25 mg/L of BOD. If both of the filter depths are to be 1.83 m and the recirculation ratio is 2:1, find the required filter diameters. Assume the following design assumptions apply. Design assumptions: Influent flow =7570 m3/d Recirculation ratio = 2 Depth of media = 1.83 m Water temperature =20oC BOD removal in primary sedimentation = 35% E1=E2 =0.65

Stone media TF design Example 2 BOD=200mg/L BOD=25mg/L
Primary Clarifier Secondary Clarifier TF1 TF2

Stone media TF design Solution) (1) Compute the recirculation factor
= (1+2)/ (1+0.2)2 = 2.08

Stone media TF design Solution)
(2) Compute the BOD load for the first filter BOD load = BOD Conc. x Influent flow = 200mg/L*(1-0.35) x m3/d =1234kg/d (3) Compute the volume for the first stage V= 388 m3

Stone media TF design Solution)
(4) Compute the diameter of the first filter A= V/depth = 388 m3/1.83m = 212 m2 Diameter = 16.4 m (5) Compute the BOD load for the second filter BOD load to the second filter = (1-E1) x BOD load to the first filter = ( ) x 1234 kg BOD/d = 437 kg BOD/d

Stone media TF design Solution)
(6) Compute the volume for the first stage V= 1096 m3 (7) Compute the diameter of the first filter A= V/depth = 1096 m3/1.83m 599 m2 Diameter = 27.6 m

Stone media TF design Solution)
(8) Compute the BOD loading to each filter (9) Compute the hydraulic loading to each filter

Plastic media

Plastic media Schulze formula
The liquid contact time (t) of applied wastewater Where: t = liquid contact time, min D= depth of media (m) q = hydraulic loading, (m3/m2/h) C, n = constants related to specific surface & configuration of media

Plastic media hydraulic loading (q) Where: Q= influent flow rate L/min
A=filter cross section area m2

Plastic media TF design
Schulze formula Where: Se= BOD concentration of settled filter effluent, mg/L So= influent BOD concentration to the filter, mg/L k=wastewater treatability and packing coefficient, (L/s)0.5/m2 D=packing depth, m q= hydraulic application rate of primary effluent, excluding recirculation, L/m2*s n=constant characteristic of packing used (assumed to be 0.5).

Plastic media TF design
Example 3 Given the following design flow rates and primary effluent wastewater characteristics, determine the following design parameters for a trickling filter design assuming 2 reactors at 6.1 m depth, cross-flow plastic packing with a specific surface area of 90 m2/m3, a packing coefficient n value of 0.5, & a 2-arm distributor system. The required minimum wetting rate=0.5L/m2*s. Assume a secondary clarifier depth of 4.2m and k value of 0.23. Design conditions Item unit Primary effluent Target effluent Flow m3/d 15,140 BOD mg/L 125 20 TSS 65 Temp oC 14

Plastic media TF design
Example 3 Calculate the followings Diameter of TF, m Volume of packing require, m3

Plastic media TF design
Solution (1) Diameter of tower trickling filter, m Correct k for temperature effect

Plastic media TF design
Solution (1) Diameter of tower trickling filter, m Determine the hydraulic loading rate Determine the tower area Determine the tower diameter

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