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Operations & Management
Case Study: Successful Hibernation & Re-Start of an Anaerobic Digestor

Quote

“ During the Covid shutdown Alpheus were able to draw up full plans for both partial & full-scale hibernation of the reactor. This work now forms part of our site crisis plan. We re-started successfully & achieved full environmental consent within our allocated timeframe. ”

Ed Thom Glenmorangie Distillery Manage

The Background

Design

The Background

Alpheus began providing Operations & Management (O&M) services at the Glenmorangie distillery Wastewater Treatment & Anaerobic Digestion (AD) Plant in Tain, Scotland, in January 2020.

The AD Plant had been following a planned feeding schedule to systematically maintain the anaerobic digestor throughout the distillery’s planned shutdown. However, when the country was forced into lockdown in March 2020 due to COVID19, Glenmorangie took the decision to delay distillery start-up for an undetermined amount of time.

If the original feed plan had been followed, stored feed supplies would have been depleted by the end of the planned two-week shutdown. This presented Alpheus & our client with a huge challenge for maintaining biomass activity throughout this unknown period – one which also presented potentially significant costs & environmental impact.

The Service

Hardhat

The Service

We initially worked with our client to understand & advise on all possible existing options & the implications of each. We believed there could be an alternative – one that would offer greater cost & environmental savings for our client.

An Innovation Group was established to devise a bespoke plan to hibernate the digestor in which it, & all equipment, would be shut down. This had never been done before at Glenmorangie, so the plan carried a certain level of risk but we - & our client – were confident that our specialist capabilities, expertise & experience would enable us to deliver it.

The Implementation

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The Implementation

Key Hibernation Challenges:
To ensure the biomass remained viable & ready to start-up at any time, our technical team closely monitored biomass activity throughout the hibernation period. The reactor & gas holder were replicated within the site laboratory through daily experiments, & all parameters & readings were closely monitored.

Key ‘Re-Start’ Challenges:
After 5 weeks, Glenmorangie gave notice of their intention to re-start the distilling process.

We produced a detailed plan to re-start the digestor within 21 days & process the required volume. We closely monitored the digestor to manage the biomass during the stabilisation period so no consent issues were caused. Biomass had to be allowed to re-grow gradually, (having reduced to approx. 25% of its normal treatment capacity in the hibernation period).

Digestor temperature was gradually brought back up to operating temperature & a stepped feeding regime implemented. VFA/Alkalinity results (aka FOS/TAC) were closely monitored daily, to ensure maximum performance & start-up rates were achieved. We worked closely with the distillery during start-up stage, so we knew how much effluent they would be sending us & when.

The Outcomes

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The Outcomes

✓ Significant environmental & cost savings through not running the plant unnecessarily, including:
• 100% saving on waste disposal & feedstock transportation, (also reducing carbon emissions)
• 99% saving on chemical usage
• 84% reduction in valuable gas flaring
• 62.5% electric reduction
✓ 100% compliance throughout hibernation.
✓ No disruption to the distillery’s production process.
✓ A very satisfied client!


Author Marcus Green