Proceedings

Ringsend WwTW is the largest wastewater treatment plant in Ireland, producing approximately 101 tonnes of sludge each day. Drum thickeners and centrifuges are used to dewater sludge on site before CAMBI Hydrolysis, thermal drying and post digestion, with polymer conditioning required for each dewatering unit operation. In 2012 annual polymer usage stood at 370 tonnes per annum with large variations evident in dose for individual dewatering unit operations. This paper outlines how a Six Sigma/Lean approach identified and measured significant levels of wastage and variation in polymer dose throughout the plant, the steps taken to reduce waste and variation and the control measures which were used to maintain the improvement. Overall polymer consumption has been reduced by 19% at Ringsend WwTW with reductions as high as 33% for some centrifuges.

Keywords: Biosolids, Hydrolysis, Energy Reduction, Polymer, Sludge Treatment