PUMPS, VALVES & ACTUATORS
OVERCOMING OFFENSIVE ODOURS
A new aeration system, which incorporates a Landia chopper pump and AirJet, has rescued a paper mill in
El Salvador that was on the brink of $M fines for causing major odour issues
C
hanges to environmental regulations had put the paper mill into a crisis situation, despite the fact that they had already installed four 30HP surface aerators in their aeration tank in an attempt to quell the increasingly bad odour problems. With the authorities set to take serious punitive measures, the paper mill called in wastewater treatment business, Black Waters to see if they could bring about a solution. “This was a major challenge,” said Roberto Escalante, Principal of Black Waters. “Nobody in our industry particularly relishes working with a slanted floor (!) rectangular tank (1,000m3
), but
I can tell you that the twisted face of the paper mill’s CEO was in far more pain than mine!
“It was primitive; in a bad way, resulting in the possibility of substantial fines that caught the paper mill completely off guard,” he added.
“The odours were awful, so we went straight into action with a sludge sampler to see what
R
was going on, in order to establish a proper profile.”
Across the 23m length tank, which has a shallow end at 1.87m and a deep end of 4m, Escalante found that only five of the one- meter sections were free from sediment. The rest ranged from 0.8” to as much as 18” of sediment, varying from light brown towards the shallow end to thick dark gray at the deep end.
“At the deep end it was septic, because the surface aerators couldn’t mix the tank comprehensively. The slanted tank had become a biological reactor, but with the buildup of sediment, there just wasn’t enough oxygen to allow the bugs to do their job properly. They couldn’t ‘breathe’ and so would die. It was nasty.”
He continued: “All well and good having VALVES PLAY A ROLE IN REFINERY’S NEAR ZERO INITIATIVE
otork has supplied over 200 actuators to ONE-Dyas for the N05-A upstream gas processing platform, located in the Dutch North Sea. The Skilmatic SI intelligent self- contained electro-hydraulic actuators, IQT3 Pro intelligent part-turn electric actuators and CVA continuous unrestricted modulating actuators, will support the electrification and automation of the platform.
HSM Offshore was contracted to build N05-A – which will turn upstream wet natural gas into dry natural gas for pipeline export – by Dutch exploration and production company ONE-Dyas. The platform, which began production in the winter of 2024/2025, is expected to reach ‘near zero’ operational emissions (Scope 1 and 2) and will be the North Sea’s first fully electrified gas production platform. Electrification is central to the near-zero strategy, with power primarily supplied by a nearby German offshore wind farm, Riffgat. Reduced maintenance visits and limited unplanned helicopter flights also form part of the near-zero initiative. The platform will be fully automated and normally unmanned, with all plant equipment controlled autonomously. Reliability is also key to reducing unplanned visits to the platform.
Electric actuators only consume power when in operation, unlike pneumatic actuators and controls, which need a constant supply of either gas or locally produced compressed air. Rotork performed a factory fit of the Skilmatic SIs with free issued valves for the N05-A project, which were fitted and calibrated at Rotork’s Rotterdam Service Centre then shipped to the HSM Offshore yard.
rotork.com/en 22 JUNE 2025 | PROCESS & CONTROL
some mixing, but this dire situation very much needed some oxygen. The wastewater from the paper, which in this case was from a process manufacturing tissue paper, is surprisingly abrasive. Surface aerators can make it appear as if there is lots happening, but underneath the surface it can be a totally different story. In a fairly short space of time, foul odours will soon tell you that something is seriously wrong!”
With a potential $M lawsuit for violations on the horizon, Black Waters urgently sought a rapid but long-lasting solution, consulting with contacts in the US and beyond to see what might be available.
The recommended solution certainly wasn’t the cheapest, but it came in the form of a simple design, combining a proven chopper pump with a venturi nozzle; the Landia AirJet. Simultaneously mixing and aerating, this system effectively keeps wastewater fresh; economically delivering dissolved oxygen to provide complete aeration.
The next challenge for Black Waters was how to incorporate what would be six of the new Landia AirJets onto both sides of the tank. “Landia helped us calculate the best positioning,” said Escalante, “and I was really pleased that their vastly experienced Aftermarket Manager, Ken Jacobs came over from the US to help ensure that the installation went smoothly. The Landia AirJets had to be installed with middle guideline poles that had to be embedded in specially built concrete blocks. This allowed the aerators to be then slid to the bottom of the basin. The Landia Chopper Pumps that are part of the AirJet system do a great job, and are proving very reliable. Everything is fine now. Thank goodness those horrible odours are no more!”
Landia
www.landiaworld.com
Roberto Escalante, Principal of Black Waters
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