Conference Papers | 2009 Conference Papers

DENITRIFICATION PROBLEMS AFTER UPGRADE OF THE OLD BAR STP

Lindsay Walsh, Process Operator, MidCoast Water.

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The Old Bar Sewerage Treatment Plant was commissioned in 1985 and upgraded 2004. 

The original plant had two 2000 EP intermittent aeration Pasveer channels with a catch pond of 2ML. Effluent held in two ex-filtration ponds and passed through dunes into the ocean. There were also two sludge lagoons of 700kL and two sludge holding beds.

With the expected increase in population over the next 20 years, MidCoast Water decided the plant was in need of an upgrade to cope with this increase.

The upgraded plant has a design capacity of around double the original plant to 7,800 EP with scope for a further stage 3 upgrade to 18,000 EP.

Following commissioning we were unable to achieve satisfactory denitrification in the bioreactor resulting in high nitrate levels in the effluent and loss of alkalinity.