Tank-in-tank challenge completed as FLI CAP technology delivers advanced aeration system for leading food producer

Fifteen years after completing its first wastewater treatment project for one of the UK’s most recognisable names in freshly prepared food, FLI CAP Technology has successfully delivered a bespoke, state-of-the-art installation for the same valued customer.

To support increased production demands—including the addition of a fourth manufacturing line to boost output by 35%—FLI CAP Technology was tasked with designing and installing a new CIRIA C736-compliant above-ground treatment tank. This required the creation of a secondary containment system, or "tank within a tank," presenting significant access and maintenance challenges.

“The most effective way to aerate the new tank was with submersible mixers,” explained Chris Woods, Divisional Director at FLI CAP Technology. “But we wanted to eliminate the safety risks associated with working at height during maintenance.”

To overcome this, the team specified Landia’s AirJet system, chosen for its proven performance, efficiency, and durability. The 11kW AirJet—featuring Landia’s robust chopper pump—was installed at ground level, ensuring easy access and significantly improving safety. Working closely with Landia, FLI CAP developed an elevated aspiration setup that allowed the Venturi nozzles to deliver optimal mixing for the glass-lined steel tank (6m diameter, 9.4m height), enclosed within a bunded outer tank (7.9m diameter, 7.9m height).

The Landia AirJet is a compact, easily retrofitted aeration system that mixes and aerates wastewater or sludge without the need to empty the tank. It is particularly effective in eliminating odours and can also provide peak-load aeration or assist in cleaning and flushing processes.

“With our customer’s rapid growth, we needed an innovative, low-risk solution that aligned with CIRIA containment standards while simplifying maintenance,” said Woods. “The ground-mounted system not only meets compliance goals but also reduces health and safety risks, downtime, and operational costs.”

The full turnkey effluent treatment solution from FLI CAP Technology included much more than the aeration system. It also featured a solid screen, chemical dosing, and a new Dissolved Air Flotation (DAF) unit, integrated into a fully automated treatment process.

An extensive survey of the existing plant revealed that a complete upgrade was essential to meet future compliance and capacity needs. However, with no extra space on site, FLI CAP developed a phased installation strategy to ensure uninterrupted operation during the 18-month project. This included full design, supply, mechanical and electrical installation, and commissioning.

Project Phases:
•    Phase One: Demolition of the old chemical store, installation of a new final effluent sewer, a new ETP building, and new DAF equipment.
•    Phase Two: Removal of the old ETP and DAF system, followed by civil works to install new plinths for the screen and balance tank in the reclaimed space.
•    Phase Three: Decommissioning of the original balance tank and gantry, removal of old pumps, and installation of new raw effluent suction pumps.

The upgraded effluent treatment system is fully automated and managed via a new PLC control system with colour touchscreen interface. Treated effluent is safely discharged through a monitored sewer connection.

“This has been our seventh—and arguably most complex—project for this key customer,” added Woods. “Their growth has been phenomenal, but we’ve continued to meet their evolving needs with innovative, compliant, and cost-effective wastewater solutions.

“With increasing demand for CIRIA-compliant containment, we’re proud to partner with Landia, whose reliable, ground-mounted pumps and mixers integrate seamlessly with our custom-designed systems. Their support and equipment quality give us—and our customers—complete peace of mind.”