This week at Davis: 21 June 2019

Romance of the wastewater treatment plant

Through the eyes of an Antarctic Electronics Engineer

As we settle in to the true winter period of our year at Davis, we immerse ourselves in the grand occasion of a Midwinter in Antarctica… a time of fun, festivity and community with what has become a close-knit and happy group. The freezing cold midwinter swim and a spectacular dinner shared in the best company, all making for memories that will last a lifetime.

Meanwhile, behind all the romance lies important maintenance work that continues to be carried out by the trades team. Recently plumber Dan and dieso Luke tackled a major maintenance item in the Wastewater Treatment Plant… sounds appetising, yes?

The decanter centrifuge is basically a long rotating spiral shaft. It takes sludge from an anoxic aeration tank, combines it with long-chain polymer material and process water from a dosing tank, and spins the resulting mixture at 3500 RPM to separate solids from liquids for further processing.

The centrifuge has been in operation at Davis for a few years, and was due for internal inspection and replacement of the bearings, comprising two main bearings — one needle and one ball race, and two carrier roller bearings.

The tear-down and clean-up took about 8 hours. Old bearings were removed and everything thoroughly inspected before beginning the rebuild process. New bearing inners were heated gently prior to fitting. Luke used our 'free' refrigerator — the outside temperatures of around −20°C, to shrink the bearing outers into their housings.

Only a final application of a special grease for this plant remains to be done. All up, the job took the best part of three days and should see the decanter running smoothly for a good while. Throughout the job, Dan has recorded every step in photographs. These and his detailed observations will serve as a useful reference for future tradies when this maintenance task becomes due again.

Elsewhere at Davis, outdoor activity continues despite our diminishing daylight. This week Simon, Dan and I installed two stress sensors in the sea ice just off station. These instruments continuously record minute stress dynamics in the local sea ice. The data is used by researchers studying Sea Ice Processes and Change within AAD, UTAS, IMAS, CSIRO and BoM.

We are now also into the routine of weekly sea ice monitoring, drilling at seven fixed locations adjacent to the station. A task shared throughout the station team, with this week’s sea-ice monitoring data proudly presented by Choots and Brownie. The data they collect also contributes to research.

Finally, last weekend brought our most significant weather events of the season so far. One delivered our lowest temperatures with air to −32.5°C (windchill −42.5°C), only to be followed by a sharp rise in temperature and blizzard conditions. Lasting about a day and a half with peak wind gusts up to 75 knots (150km/h), large drifts of snow and ice have been deposited around station. The team have been hard at work clearing doorways, opening roads, checking blizz lines and attending to the many and varied details required to maintain safe and efficient operations on station.

Mike (Electronics Engineer)

Davis diesel fitter working on waste water decanter
Luke lifting the centrifuge assembly clear of the decanter.
(Photo: Dan G)
Davis diesel fitter working on waste water decanter
Centrifuge assembly cleaned and ready to dismantle
(Photo: Dan G)
Davis diesel fitter working on waste water decanter
Centrifuge parts ready for reassembly
(Photo: Dan G)
Davis diesel fitter working on waste water decanter
Luke fits an outer seal
(Photo: Dan G)
Davis waste water decanter
Centrifuge assembly re-installed and running smoothly
(Photo: Dan G)
Sea ice stress sensors in action
Mike running system checks on the ice stress sensors
(Photo: Simon G)
Sea ice stress sensors in action
Davis Station sea ice stress sensor operating well after a recent blizzard
(Photo: Mike H)
Snow drifts at Davis Station
Blizzard changing the station landscape with snow drifts around SMQ building.
(Photo: Mike H)
Snow drifts at Davis Station
Big snow drifts requiring big machinery to open the roads around station.
(Photo: Mike H)