Flotation processes are used to separate solids from a liquid (e.g. water). The flotation process most commonly used in water treatment is dissolved air flotation.
The suspension to be treated (raw water) is placed in a tank. Flocculation chemicals can be added to the raw water in order to improve the flotation of the contaminants. Powdered activated carbon is suitable as a contaminant. A pump transports the raw water, which enters the flotation column via a vertical pipe. The height of the supply line can be adjusted.
A water circuit with pump is connected to the flotation column. At the highest point of the circulation there is negative pressure. The required air for the flotation is sucked in by opening a valve located at this point. The air dissolves in the water under pressure. Part of the water flows back to the pump via a bypass. The other part of the water enters a pressure vessel filled with Pall rings. The pressure vessel ensures a sufficiently long dwell time to dissolve the air and to separate undissolved air.
Learning Objectives/Experiments
- How dissolved air flotation works
- Dissolving gases in liquids
Features
- Mechanical water treatment
- Transparent tank for observing the processes
Specification
- Flotation column made of plexiglass
- Raw water tank with stirring machine
- Peristaltic pump for pumping raw water
- Pulsation dampener to create a smooth raw water flow
- Continuously adjustable speeds of peristaltic pump and stirring machine
- Height-adjustable inlet for raw water into the flotation column
- Pressure and flow rate of the circulation adjustable
- Water circuit with pump and bypass
- No compressed air required
- Transparent pressure vessel with Pall rings
- Measurement of flow rate, pressure and temperature
Technical data
- Flotation column
- inner diameter: 115mm
- height: 900mm
- volume: approx. 10L
Tanks
- raw water: 8L
- treated water: 15L
- pressure vessel: 1,5L
- Raw water pump (peristaltic pump)
- max. flow rate: 24L/h
- max. speed: 200min-1
- Circulation pump (centrifugal pump)
- max. flow rate: 660L/h
- max. head: 65m
- Stirring machine: max. 330min-1
Measuring ranges
- flow rate: 5…60L/h
- pressure: 0…10bar
- temperature: 0…60°C
- 230V, 50Hz, 1 phase
- 230V, 60Hz, 1 phase
- 120V, 60Hz, 1 phase
