21 April 1995

Smaller bubble is better for slurry

MINI-BUBBLES are more effective at aerating slurry than big bubbles, says Lanmark Water.

The London-based firms Pore-Tec bubbler system produces bubbles that are claimed to be ten times smaller than those from conventional fine bubble aerators, and up to 30 times smaller than coarse bubble models.

"Greater oxygen transfer efficiency is the key to the system," says the firms Guy Youngman.

"This comes from ultra-fine bubbles ability to stay in the slurry longer, and their greater surface area. The mixing effect is also better because bigger bubbles create a violent but concentrated reaction, whereas finer bubbles disperse over a wider area and lift."

Sold into the agricultural sector by Bristol-based Livestock Systems, the Landmark system comprises a Roots blower unit which pushes air through a manifold and along a series of rubber pipes; manifold and pipes are fixed to the slurry tower floor.

The rubber compound used to make the pipes, allows the ultra-fine holes to open when under pressure and close when the blower switches off. This reduces the risk of blockage.

"We know the system works from our experience in other industries," Mr Youngman says.

"Now, the plan is to take the units up to farm size. All this entails is increasing the number of distribution pipes and fitting bigger blower units."