Depth filtration is a key unit operation in water treatment. It enables this process to be demonstrated.
Raw water contaminated with solids is pumped from above into a filter. The solids are captured and retained as the raw water flows through the filter bed. The water itself passes through the filter bed and emerges at the bottom end of the filter. The treated water (filtrate) flows into a tank. Over time, more and more solids are deposited in the filter bed which increases its flow resistance. This process is detectable by the increasing pressure loss between the filter inlet and outlet. The flow through the filter decreases. Backwashing with treated water cleans the filter bed and reduces the pressure loss again.
Learning Objectives/Experiments
- Pressure conditions in a filter
- Factors influencing the pressure loss (Darcy’s law)
- Flow rate
- Height of the filter bed
- Permeability of the filter bed
- Determine the pressure in the filter bed (Micheau diagram)
- Backwash of filters
- Observe the fluidisation process
- Determine the expansion of the filter bed
- Determine the required flow velocity (fluidisation velocity)
Specification
- Depth filtration and backwash
- Separate supply unit with tank and pump for raw water
- Pump for backwashing the filter
- 10 tube manometers to measure the pressures
- Plotting of Micheau diagrams
- Electromagnetic flow rate sensor
- 4 ball valves with motor
- Measurement of flow rate, differential pressure, system pressure and temperature
- Control of flow velocity
Technical data
- Filter
- inside diameter: 106mm
- total height: 1125mm
- max. filter bed height: approx. 700mm
- Raw water pump
- max. flow rate: 150L/min
- max. head: 9m
- Backwash pump
- max. flow rate: 40L/min
- max. head: 10m
- Tanks for raw water and treated water
- capacity: each 180L
Measuring ranges
- flow rate: 0…1300L/h
- pressure: 1x 0…0,6bar, 10x 0…1260mmWC
- differential pressure: -1…1bar
- temperature: 0…100°C
- filter bed height: 0…720mm
- 230V, 50Hz, 1 phase
- 230V, 60Hz, 1 phase, 230V, 60Hz, 3 phases
