Start-up and Initial Operation of Singapore's 800,000 m³/day Changi Water Reclamation Plant

The new Changi Water Reclamation Plant (CWRP) in Singapore is designed for ultimate expansion to 2,400,000 m³/day. Construction of the initial 800,000 m³/day phase began in 2001 and will be completed in mid 2008. Designed as a compact, underground facility, the plant incorporates stacked rectangular primary and secondary clarifiers along with the anoxic step feed process. Solids processing consists of centrifuge thickening, anaerobic digestion, centrifuge dewatering, and thermal drying. A 227,000 m³/day “NEWater® Factory”, or Reclaimed Water Production Plant, will be constructed under a Design Build Own and Operate (DBOO) concession on top of the liquid process modules to produce high grade water for indirect potable and non-potable uses. Phased start-up of the facility began in February, 2007 and has continued through 2008. Initial performance has generally met expectations, resulting in excellent performance when the plant is not hydraulically overloaded, partial nitrification and denitrification as intended with the anoxic step feed process used which provided stable treatment and avoided significant pH depression, and SVI values which averaged 105 mL/g and were consistently below 150 mL/g.