At a recent Leachate Treatment Plant Refurbishment efficient aerators were needed to both fully mix and aerate the whole lagoon. In fact, consistently good mixing and oxygen transfer are always at the core of any successful aeration lagoon design. That’s where aerator and pump specialist Landia’s equipment has been used, and we are pleased to reproduce their Press Release below.
Read on to find out how the selection of Landia AirJet Aerators has achieved a successful Leachate Treatment Plant upgrade at Yorwaste’s Harewood Whin Landfill.
Press Release 25 May 2020:
Phoenix and Landia Fix the Mix at Leachate Lagoon
Landia aerators are playing an important role in the success of Yorwaste’s Harewood Whin Leachate Treatment Plant, which has been extensively upgraded by Phoenix Engineering.
Biological Treatment Efficiency was Inadequate During Winter Months
Managing over half a million tonnes of waste per year in Yorkshire, Yorwaste brought in Phoenix Engineering to carry out detailed process studies, and then to design and construct a major refurbishment of the treatment plant, originally built in 1990. This included the enhancement of a challenging oval-shaped lagoon, which during the winter months was not achieving sufficient biological treatment efficiency.
Higher-Strength Leachates Needed to be Treated
Jonty Olufsen, Managing Director of Phoenix Engineering, explained:
“We designed a new lagoon arrangement to focus on treating higher strength leachates within the landfill, which were a problem for the previous treatment plant system. During the winter, the existing mechanical floating aerators meant the lagoon could only operate at around 5 degrees C, when to achieve the most effective biological treatment, it should have been more like 20 degrees C”.
“It is a complex application due to the oval shape of the (1400m3) lagoon. We worked long and hard with Landia to find the best way to heat the biological mixed liquor and keep it warm during the winter months. It was imperative that the contents of the lagoon would be aerated and mixed properly”.
Landia 18.5kW AirJets Installed
Comprising a Landia Chopper Pump and venturi nozzle, four Landia 18.5kW AirJets were installed to provide thorough mixing and aeration. With its effective knife system, the Landia Chopper Pump ensures that the aerator does not get clogged due to contaminants in the leachate.
During the settlement period of the leachate treatment plant, any movement in the lagoon had to be stopped as quickly as possible before the start of the next cycle to ensure a suitable time for settling.
So, in the 42m x 24m (approx.) lagoon, a 3kW submersible propeller mixer from Landia was also installed. This small mixing unit runs for just a short time – only starting up when the AirJets stop. Aimed against the flow, the propeller mixer’s job is to act as a brake, slowing down the movement in the lagoon.
‘Consistent Temperature’ Needed for the Biological Process
Jonty Olufsen continued:
“With this combination from Landia, the result is that excellent three-dimensional mixing is in place. From the previously unsatisfactory temperatures of just 5 degrees C with the old mechanical floating aerators a consistent temperature of around 20 degrees C is maintained throughout the winter, making the biological process very efficient.
The second lagoon (also 42m x 24m with rounded ends) has been converted for raw leachate balancing, allowing for controlled blending of incoming leachates. For both lagoons, full process controls have now been installed, with a new sodium hydroxide storage and dosing system for pH control.
Leachate Treatment Plant Refurbishment Includes New Process Automation
Previously, the plant was predominantly a manual operation, with very little process automation or data acquisition or recording, and no automated pH control option. Now though, as Principal Contractor, Phoenix Engineering’s full design and refurbishment, has seen the installation of a completely new electrical control and automation system with control building, remote IO, and control panels. All new process instrumentation was fitted, with the whole plant now linked back remotely to Phoenix Engineering’s DLOG (digital logbook).
Biological Commissioning Was Carried Out by Phoenix Engineering
Seed sludge from a number of leachate treatment plants around the country was sourced by Yorwaste, with support from Phoenix Engineering for biological commissioning provided toward the end of 2019. The two companies also worked together to source and deliver new duty/standby pump skids. These were fabricated, built, and tested at Phoenix Engineering’s workshop, then delivered and installed on-site.
The Leachate Treatment Plant Refurbishment included a new gantry arrangement for access to, and to support new control panels, instruments, and aerators.
‘First-class Leachate Treatment Plant Refurbishment’
Speaking for Yorwaste, Callum Duff, Landfill Restoration, and Aftercare Manager said:
“As well as ensuring that we recycle and recover as much as possible of the material we collect, we also take our responsibility to the environment seriously, so we carried out a lengthy search for the right people to partner with for the upgrade of our Harewood Whin Leachate Treatment plant”.
“From start to finish, Phoenix Engineering worked with us to deliver a first-class refurbishment. With the Landia aerators and mixer, they have shown their keenness and capability to ensure that the leachate is treated with optimum efficiency”.