Resources
VENTURI AERATORS
Description
Venturi aerators are used to dissolve oxygen efficiently into wastewater to encourage aerobic microorganisms to oxidise organic pollutants and reduce the BOD value.
A venturi aerator is a submerged jet aeration device in which the liquid being aerated is pumped through a nozzle inserted into a larger diameter tube, creating a low pressure region around the nozzle. This region is connected by a pipe to atmosphere, and a flow of air is entrained. The jet of well-mixed liquid and air emerges from the venturi barrel as a plume which causes a secondary entrainment in the surrounding liquid, mixing and aerating it.
In deep tanks the air tube may be connected to a low pressure air blower. Venturi aerators can be formatted with single or multiple barrels and can be used to supply air, oxygen or mixtures of the two.
Application
Venturi aerators are used to dissolve oxygen efficiently into wastewater to encourage aerobic microorganisms to oxidise organic pollutants and reduce the BOD value.
A venturi aerator is a submerged jet aeration device in which the liquid being aerated is pumped through a nozzle inserted into a larger diameter tube, creating a low pressure region around the nozzle. This region is connected by a pipe to atmosphere, and a flow of air is entrained. The jet of well-mixed liquid and air emerges from the venturi barrel as a plume which causes a secondary entrainment in the surrounding liquid, mixing and aerating it.
In deep tanks the air tube may be connected to a low pressure air blower. Venturi aerators can be formatted with single or multiple barrels and can be used to supply air, oxygen or mixtures of the two.
Sizing
Venturi aerators are available in sizes ranging from 2 kW to 15 kW. The power efficiency is about 13-16 kg O2/kWh for self-entraining aerators and about 20-25 kg O2/kWh with air blowers. A typical installation treating wastewater in a 250 m3 tank would require about 15 kW of electrical capacity, consumed by the aerator pump and blower. A versatile installation with 4 twin barrel venturi aerators and three blowers serving a 1750 m3 tank has an average power input of 75 kW and oxidises 2750 kg COD/day with a retention time of 17 days.