FEATURE MIXING, WEIGHING & CONVEYING MIXER ACHIEVES ENERGY NEUTRAL GOAL
Landia’s GasMix system has been installed on Downers Grove’s primary digester, reducing the particle size in the sludge, optimising active digestion and therefore improving biogas yields
A
t the Downers Grove Wastewater Treatment Centre in Illinois, the
Landia GasMix digester mixing system has increased biogas production by approximately 20 percent. The enhanced mixing of the digester by
the externally-mounted Landia system has also increased the destruction of volatile solids from approximately 55 to 65 per cent VS destruction. Two years on since it became the
became the first municipality in North America to introduce Landia’s GasMix technology, Downers Grove no longer has to flare off any gas, achieving optimum mixing and the lowest possible parasitic load from a system that runs for just 12 minutes per hour. Downers Grove’s general manager,
Nicholas Menninga, said: “For our primary digester, we’d had issues for years with a
compressor, which wouldn’t really move the gas as we wanted it to. After looking at several options as a replacement, the Landia GasMix was the most cost- effective option, and was a straightforward retrofit.” Installed on Downers Grove’s 460,000
gallon primary digester, the Landia GasMix incorporates an external 49 hp Landia chopper pump which draws sludge from the digester, reducing particle size before pumping through an aspirating venturi nozzle. The resulting vacuum sucks biogas down
from the headspace of the digester as gas is injected into the liquid, mixing the sludge vertically and preventing a layer of scum or crust forming on the surface. A high-pressure mixing nozzle then
injects liquid into the lower half of the digester, creating a horizontal, rotational
In addition to Downers Grove (above), the Landia GasMix system has been installed in numerous municipal and industrial digesters all over the world, including biogas plants using food waste and/or agricultural slurries and other high- solids feedstocks
The GasMix has no moving parts, so is easy to maintain
A STACK OF PRODUCTION AND HEALTH BENEFITS
“To help two Morrisons packing plants overcome production bottlenecks, Brillopak has installed four Crate DeStakers at the start of four robotic pick and place case packing cells. However, the real benefit is the difference the machines have made to workforce health and safety and job satisfaction,” reports Rushden’s site manager Andy Day. Upstream, Brillopak Crate DeStakers have put a stop to operatives repeatedly overstretching to lift, separate
and place clean retail baskets in a constant stream onto conveyors for filling. Both Rushden and Gadbrook fresh produce depots supplying Morrisons’ customers nationwide recently
invested in four UniPacker Robotic Pick and Place Cells for packing vertical form fill and seal potato bags into standard sized 600mmx400mm crates. Having automated their packing lines, both sites needed assurance that the supply of crates to the robotic cells would be fast enough to not cause a backlog or result in labour being relocated to such a strenuous and repetitive task. According to the Health & Safety Executive, the moving of awkward heavy loads is one of the key causes of
manual handling musculoskeletal injuries and work-related upper limb disorders (WRULDs). The Brillopak crate separation and palletising systems are designed to address these issues by removing one of the most labour intensive tasks in case packing. Prior to the automated lines going in, operatives at Morrisons loaded crates manually onto the conveyor.
With more than 720 pallets passing through each facility daily, unloading the two-metre high stacks, separating, filling and then palletising the crates was physically demanding work. Now, all movement of the empty and filled crates is done using robotics. Automating every part of the
process has resulted in 90% of the physical labour being taken off the line at Rushden. Empty crates are automatically fed onto each packing line via a low belt conveyor, presenting stacks in a line
to the Crate DeStaker. The Destaker lifts up a whole stack while simultaneously pulling down the bottom crates. This motion ejects two crates at a time in a consistent line out onto the main conveyor track to the robotic potato case loading station. Each Brillopak Crate DeStaker unit can separate up to 480 crates every half an hour. Operatives then
manoeuvre another pallet of washed and empty crate stacks into position on the infeed conveyor, so the process can continue. “The benefit to health and safety and workforce wellbeing is evident,” reports Rushden machine operative
Dave. “The machine just does it for you. As people are rotated around different packing and warehouse tasks, the team seems a lot more cohesive.” Site manager Andy Day agrees. “It’s a much calmer processing environment. Because the process is so
streamlined, it feels less chaotic. Empty and filled crates are stacked in an orderly way, with clearly defined work and storage areas. Staff rotate around different jobs. This has increased team morale. Plus, they are not being constantly exposed to repetitive tasks, which is much better for occupational health.” Brillopak
www.brillopak.co.uk
mixing pattern that prevents heavier solids from settling, thus mixing the whole tank and not just parts of it. The solids content and characteristics of the sludge is set up so that it determines the operation time of each valve for optimum mixing performance and energy efficiency. Menninga added: “With the Landia
GasMix there are no moving parts inside the digester, so it is very easy to maintain. By continuously reducing the particle size, the low-viscosity sludge helps reduce surface scum. This not only makes the whole system run more efficiently, but significantly increases the volume of active digestion and therefore the gas yields. “From sizing up the equipment for our
primary digester to installation and optimisation, we’ve also had very good support from Landia throughout,” he said. The energy-efficient mixing solution,
together with on-site generation of electricity from a Nissen CHP unit (and other energy-efficiency improvements) has enabled Downers Grove Wastewater Treatment Centre to become 100 percent net energy neutral. The anaerobic digesters at the Centre
process a mixture of primary sludge, waste activated sludge and FOG co- digestion.
Landia
www.landia.co.uk
34 FEBRUARY 2020 | PROCESS & CONTROL
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