Landia dives deep for Scottish Water
8 Feb 2021
Scottish Water consumers expect a lot from their utility companyand Landia has been in at the deep end when it comes to supplying the goods...
Scottish Water’s activities play a huge role in the country’s supply, with nearly a quarter of a million households and an estimated 150,000 businesses depending upon it daily for drinking water alone.
On top of that, the utility firm also has responsibility for removing nearly 850 million litres of waste water from properties every 24 hours.
Regulatory demands and rising consumer and industry pressures have put the onus on the company to invest in cutting edge improvements.
Last year, Scottish Water opened a £21 million wastewater treatments works (WWTW) near the Aberdeenshire town of Inverurie.
Delivered by ESD (the joint venture involving Galliford Try, MWH Treatment and Black & Veatch), this involved award-winning new technology capable of breaking sludge into granules.
One year on and following an intricate diving operation, ESD has completed the successful upgrade of its mixing operation at Scottish Water’s Wastewater Treatment Plant (WWTP) in St Andrews, Fife.
Since 2002 this had been served by three very low rpm Landia mixers. To ensure there was no interruption to the crucial aeration process in the oxidation ditches, a team of three divers and a dive manager carried out the inspection and work in six metres deep zero-visibility wastewater.
The WWTP is situated close to where the game of golf was allegedly played for the first time in the 15th century and just a few miles from the oldest golf course in the world.
With UV filters for its final effluent, it is in an extremely sensitive area that welcomes visitors from all over world. At just 34 rpm, the 4 kW Landia mixers very gently mix sludge so as not to cause any process-damaging floc shear.
St Andrews WWTP site manager, Alan Mearns commented: “Working purely by touch in such a challenging environment wasn’t easy at all for the divers, but over the three-day installation that included new guide rails, they did a great job in ensuring that we could still maintain sufficient flow for our process.”
In addition to the three adjustable- pitch submersible Landia units in the main oxidation ditch, there is also one of the company’s mixers in the sludge holding tank for SAS (Surplus Activated Sludge) and one in the anoxic inlet tank.
Apart from a 10-minute stop every four hours, the three Landia mixers in the oxidation ditch run 24/7, sustaining a required gentle flow of just 0.3 metres per second. Landia’s in-house team will also service the mixers every six months. “The Landia mixers have always worked well,” says site manager Mearns.
“This is the type of reliable equipment we want as ESD delivers improvements to Scotland’s water and wastewater infrastructure.”
