Two Egg-Shaped Digesters, Australia

Egg-shaped digesters (ESDs) offer many operational advantages in waste water treatment plants. A pair of ESDs were completed in 1996 as part of a sewerage treatment plant upgrade at Woodman Point in Perth, Australia. Each digester holds 8,000 m³. The tender for Stage 1 of the plant upgrade also included an equipment room, a mechanical contract for all the necessary process work, an access tower with connecting overhead bridges and a wet gas storage tank for methane. The tender called for design-and-construct submissions and either steel or concrete could be used for the construction of the digesters. A design team combining overseas and local companies was chosen whose tender bid specified prestressed concrete.