Water Supply Engineering: Water Treatment Technologies

Front

What is the Carmen-Kozeny equation used for?

Back

It is used to calculate the theoretical clean water head loss in a uniform mixed bed filter.

Front

What factors affect head loss in a filter according to the CK equation?

Back

1. High filtration rate (V_s) results in a large head loss. 2. High filter porosity (e) leads to a small head loss. 3. Deeper filter bed (L) gives a higher head loss. 4. Larger-size medium (d_p) reduces head loss.

Front

What is the Rose equation used for?

Back

It is similar to the CK equation and can be used directly for hydraulic calculations in rapid sand filters.

Front

What happens to the porosity (e) of a filter in the CK and Rose equations?

Back

The porosity is constant in the CK and Rose equations but is a function of the degree of clogging.

Front

What is the relationship between head loss and suspended solids removed in a clogged filter?

Back

The head loss through the filter is related to the amount of suspended solids removed.

Front

What turbidity levels indicate that a filter must be backwashed?

Back

When the head loss or effluent turbidity reaches a predetermined value, typically exceeding 0.1 - 0.2 NTU for filtered water.

Front

What are the key components of a sand filter?

Back

1. Filter box 2. Filter media (e.g., silica sand, anthracite coal) 3. Underdrain system.

Front

What is the effect of medium size on filter performance?

Back

Small-size medium increases filtration efficiency but results in high resistance, leading to lower flow rates and frequent backwash. Large-size medium reduces filtration resistance but sacrifices efficiency.

Front

What is the rule regarding medium density in filter design?

Back

Low-density medium should be placed on top of high-density medium.

Front

What is the purpose of the underdrain system in a filter?

Back

To collect the filtered water and distribute the backwash water.