The plant requires augmentation to the liquid stream, and the aerobic digestion to be converted to anaerobic digestion, so that it can serve future population growth.
A study also determined that the liquid stream at Quakers Hill needed to be replaced and the best option was to direct the waste sludge to a combined solids handling facility at St Marys WRP. 10ML/day screened and de-gritted sewage will be transferred from Quakers Hill to St Marys, combined with screened primary and waste activated sludge. Combining the solids produced at Quakers Hill with the solids produced at St Marys provides the scale needed for beneficial recovery of the energy. Energy recovery is enhanced using the Thermal Hydrolysis process.
The new anaerobic digestion and energy recovery facility is large enough to treat sludge production from both the St Marys WRP and Quakers Hill WRP, and has the flexibility to implement co-digestion. Additionally, a new 12-kilometre 250mm sludge transfer pipeline from the Quakers Hill WRP to the St Marys WRP will be built.
The ADAPT JV is also delivering a large treatment upgrade at St Marys to provide an additional 48ML/day of capacity to the existing plant. This capacity boost will be through an extension (stage 4 bioreactor) to the existing 5 stage Bardenpho process, which will allow biological nutrient removal of phosphorous and nitrogen. This will add capacity to provide treatment facilities to another 280,000 Equivalent Population.