Imhoff Tank Design

2. Sludge storage at 5 ft3 per capita = 5 x 150 = 750 ft3.

3. Sludge drying beds at 1.25 ft2 per capita = 150 x 1.25 = 188ft2.

4. Trickling filter loading at 4000lb of BOD/acre-ft = 0.25lb/yd3. Loading based on 0.17 lb of BOD/capita with 35 percent removal in primary settling = 150 x 0.17 x 0.65 = 16.6 lb/day.

400 16.6 3

H 43,560 x

Hence, the required filter diameter,

Imhoff Tank
FIGURE 3.14 Section through Imhoff tank, with design details.

The volumetric loading 15,000

7T X 20 X 20 = __X— = 2 080,000 gpd / acre on a 4 43,500

6-ft deep filter.

15,000 3

5. Final settling provides 2-hour detention. ——— x 2 = 1250 gal =167 ft

With a surface

2 180 x tank depth settling rate = 500 gpd / ft2 =-—; tank depth = 5.6 ft.

2-hour detention

6. If the BOD in the raw sewage is 200mg/l, and the Imhoff tank removes 35 percent, the applied BOD = 0.65 x 200 = 130mg/l. According to the National Research Council Sanitary Engineering Committee formulas,* a filter loaded at 400 lb of BOD per acre-ft will produce an average settled effluent containing 14 percent of that applied, or 0.14 x 130 = 18mg/l.

High-Rate Trickling Filter Plant with Imhoff Tank

1. Flowing through channel same as with standard rate filter = 209 ft3.

2. Sludge storage at 8ft3/capita = 8 x 150 = 1,200ft3.

3. Sludge drying beds at 1.50ft2/capita = 150 x 1.50 = 225 ft2.

4. Trickling filter loading at 3000lb of BOD/acre ft = 1.86lb/yd3. Loading based on 0.17 lb of BOD per capita with 35 percent removal in primary settling = 150 x 0.17 x 0.65 = 16.6 lb/day. The BOD in the raw sewage

Renewable Energy Eco Friendly

Renewable Energy Eco Friendly

Renewable energy is energy that is generated from sunlight, rain, tides, geothermal heat and wind. These sources are naturally and constantly replenished, which is why they are deemed as renewable.

Get My Free Ebook


Post a comment