Bullocks Flat STP Process Support

  • ASpect’s Client: Perisher Blue Pty Ltd
  • Head Client: Perisher Blue Pty Ltd
  • Plant Configuration: SBR
  • Plant Size: 1000 EP
  • Project Value: $21k (ASpect Fee $21k)
  • Project Duration: September 2018 to Ongoing

Bullocks Flat STP Process Support (SBR), for Perisher Blue (NSW).

Bullocks flat is possibly the most difficult plant in Australia to operate.  It is located at the Skitube, just outside the Kosciusko National Park.  It is operated by Perisher Blue Pty Ltd (PBPL).  In winter, it is snow covered with temperatures dropping well below freezing in winter.  Because it services the ski tube train station, the population is transient and highly variable.  In summer, it services the workforce of less than ten people.  On a winter weekend there can be up to 5000 people transiting through the train station to the Perisher Blue ski resort.  The sewage is therefore predominately urine, high in nitrogen and low in carbon.  The lack of permanent load, the low temperatures, poor sewage characteristics and sudden increases in load make it extremely difficult to maintain a stable performance.  This had led to a range of operational problems for over a decade, including problematic activated sludge organisms (zooglia) and frequent excursions above EPA licence limits.  PBPL had engaged consultants to review the plant in the past, but none had been able to resolve these issues.  At the suggestion of the NSW EPA, PBPL engaged ASpect to have a fresh look at the operation of the plant.  ASpect suggested heating, which PBPL immediately undertook with the use of a simple on-demand hot water service.  ASpect provided advice on the timing and ramp up urea dosing projection (urea dosing provides the nitrogen load necessary in autumn to establish the required nitrifier population for ammonia removal in winter).  ASpect developed a spreadsheet tool, based on nitrifier kinetics but customised to the plant, with simple inputs of temperature, wasting time and aeration time.  This not only optimised the ramp up dose but also allowed the operators to judge whether operating conditions were sustainable.  ASpect provided advice on modification to controls, plus ongoing troubleshooting and advice on set point adjustments.  ASpect suggested a reduction in carbon (sucrose) dosing to prevent proliferation of problem organisms.  The result was that the plant was able, for the first time, to sustain operation throughout the 2019 ski season without licence excursions.