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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.

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Presentation on theme: "Stone media TF design Example 1 –Calculate the BOD loading, hydraulic loading, BOD removal efficiency, and effluent BOD concentration of a single-stage."— Presentation transcript:

1 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 m 3 /d Recirculation ratio = 0.5 Primary effluent BOD = 130 mg/L Diameter of filter = 18 m Depth of media = 2.1 m Water temperature =18 o C

2 Stone media TF design Solution) (1) BOD loading rate (kg/m 3 /d) –BOD load = BOD Conc. x Influent flow = 130 mg/L x 1530 m 3 /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 m 3 –BOD loading rate = BOD load / volume of filter =0.37 kg/m 3 /d

3 Stone media TF design Solution) (2) Hydraulic loading rate (m 3 /m 2 /d) –Total flow to the media = influent + recirculation flow = 1530 m 3 /d + (1530 m 3 /d x 0.5) –Surface area of filter = π (18 m x 18m)/4 = 254 m 3 –Hydraulic loading rate = Total flow to the media / area of filter = 9.04 m 3 /m 2 /d

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

5 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 m 3 /d Recirculation ratio = 2 Depth of media = 1.83 m Water temperature =20 o C BOD removal in primary sedimentation = 35% E 1 =E 2 =0.65

6 Stone media TF design Example 2 Primary Clarifier Secondary Clarifier TF 2 TF 1 BOD=200mg/LBOD=25mg/L

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

8 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 7570 m 3 /d =1234kg/d (3) Compute the volume for the first stage – V= 388 m3

9 Stone media TF design Solution) (4) Compute the diameter of the first filter A= V/depth = 388 m 3 /1.83m = 212 m 2 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

10 Stone media TF design Solution) (6) Compute the volume for the first stage –V= 1096 m 3 (7) Compute the diameter of the first filter A= V/depth = 1096 m 3 /1.83m 599 m 2 Diameter = 27.6 m

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

12 Plastic media

13 Schulze formula The liquid contact time (t) of applied wastewater Where: t = liquid contact time, min D= depth of media (m) q = hydraulic loading, (m 3 /m 2 /h) C, n = constants related to specific surface & configuration of media

14 Plastic media hydraulic loading (q) Where: Q= influent flow rate L/min A=filter cross section area m 2

15 Plastic media TF design Schulze formula Where: S e = BOD concentration of settled filter effluent, mg/L S o = influent BOD concentration to the filter, mg/L k=wastewater treatability and packing coefficient, (L/s) 0.5 /m 2 D=packing depth, m q= hydraulic application rate of primary effluent, excluding recirculation, L/m 2 *s n=constant characteristic of packing used (assumed to be 0.5).

16 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 m 2 /m 3, a packing coefficient n value of 0.5, & a 2-arm distributor system. The required minimum wetting rate=0.5L/m 2 *s. Assume a secondary clarifier depth of 4.2m and k value of –Design conditions ItemunitPrimary effluentTarget effluent Flowm 3 /d15,140 BODmg/L12520 TSSmg/L6520 Temp oCoC14

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

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

19 Plastic media TF design Solution –(1) Diameter of tower trickling filter, m b.Determine the hydraulic loading rate c.Determine the tower area d.Determine the tower diameter

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