It demonstrates the clarification of raw water containing solids using the dissolved air flotation process.
First, a suspension (raw water) is prepared in a tank. From here the raw water flows into a flocculation tank divided into three chambers. By adding a coagulant in the first chamber the repulsive forces between the solid particles are cancelled out. The solid particles combine into flocs. To create larger flocs a flocculant is added in the second chamber. The coagulant causes a drop of the pH value. By adding caustic soda the pH value of the water can be increased again. In the following third chamber of the flocculation tank low flow velocities are present to prevent any turbulence. Turbulence would impede the formation of flocs.
Learning Objectives/Experiments
- Functional principle of dissolved air flotation
- Creation of a stable operating state
- Effects of various parameters
- Coagulant concentration
- Flocculant concentration
- Determination of the hydraulic loading rate (rising velocity)
Specification
- Removal of solids from raw water using dissolved air flotation
- Conditioning of the raw water by flocculation
- 3 Metering pumps for chemicals
- Flocculation tank with 3 chambers and 4 stirring machines
- Flotation tank with electrically driven scraper
- Pressure tank and 2 circulation pumps
- Relief valve
- Separate supply unit with tank and pump for raw water
- Electromagnetic flow rate sensor
- Measurement of flow rate, pressure and pH value
- Control of the pH value
Technical data
- Tanks
- flotation tank: 150L
- flocculation tank: 45L
- raw water: 300L
- treated water: 80L
- sludge (float): 15L
- Raw water pump
- max. flow rate: 135L/min
- max. head: 7,0m
- Circulation pumps
- max. flow rate: each 18L/min
- max. head: each 50m
- Metering pumps
- max. flow rate: each 2,1L/h
- Stirring machines
- max speed: each 600min-1
- Measuring ranges
- flow rate: 0…550L/h (raw water)
- flow rate: 30…320L/h (recycle water)
- flow rate: 20…360L/h (air)
- pH value: 1…14
- pressure: 0…6bar (recycle water)
- 230V, 50Hz, 1 phase
- 230V, 60Hz, 1 phase; 120V, 60Hz, 1 phase
