THE MAGAZINE FOR THE DRAINAGE,WATER &WASTEWATER INDUSTRIES
CASE STUDIES
maintained throughout thewinter,making the biological process very efficient.
The second lagoon (also 42mx 24mwith rounded ends) has been converted for rawleachate balancing, allowing for controlled blending of incoming leachates. For both lagoons, full process controls have now been installed,with a newsodiumhydroxide storage and dosing systemfor pH control.
He added: “It is a complex application due to the oval shape of the (1400m3) lagoon.Weworked long and hardwith Landia to find the bestway to heat the biologicalmixed liquor and keep itwarmduring thewintermonths. Itwas imperative that the contents of the lagoon would be aerated andmixed properly”.
Comprising a Landia Chopper Pump and venturi nozzle, four Landia 18.5kWAirJetswere installed to provide thoroughmixing 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 suitable time for settling.
So, in the 42mx 24m(approx.) lagoon, a 3kWsubmersible propeller mixer fromLandiawas also installed. This smallmixing unit runs for just a short time - only starting upwhen the AirJets stop. Aimed against the flow, the propellermixer’s job is to act as a brake, slowing down the movement in the lagoon.
‘Consistent temperature’ Jonty Olufsen continued:
“With this combination fromLandia, the result is that excellent three- dimensionalmixing is in place. Fromthe previously unsatisfactory temperatures of just 5 degrees Cwith the oldmechanical floating aerators, a consistent temperature of around 20 degrees C is
FOLLOW US
Previously, the plantwas predominantly amanual operation,with very little process automation or data acquisition or recording, and no automated pH control option. Nowthough, as Principal Contractor, Phoenix Engineering’s full design and refurbishment has seen the installation of a complete newelectrical control and automation system with control building, remote IO and control panels. All newprocess instrumentationwas fitted,with thewhole plant nowlinked back remotely to Phoenix Engineering’s DLOG (digital logbook).
Seed sludge froma number of leachate treatment plants around the countrywas sourced by Yorwaste,with support fromPhoenix Engineering for biological commissioning towards the end of 2019. The two companies alsoworked together to source and deliver newduty/ standby pump skids - fabricated, built, and tested at Phoenix Engineering’sworkshop, then delivered and installed on site – aswas a newgantry arrangement for access to, and to support newcontrol panels, instruments, and aerators.
‘First-class refurbishment’
Speaking for Yorwaste, CallumDuff, Landfill Restoration and Aftercare Manager, said: “Aswell as ensuring thatwe recycle and recover as much as possible of thematerialwe collect,we also take our responsibility to the environment seriously, sowe carried out a lengthy search for the right people to partnerwith for the upgrade of our HarewoodWhin Leachate Treatment plant”.
He added: “Fromstart to finish, Phoenix Engineeringworkedwith us to deliver a first-class refurbishment.With the Landia aerators andmixer, they have shown their keenness and capability to ensure that the leachate is treatedwith optimumefficiency”.
July 2020 | drain TRADER 25
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