Doosan picks up prize for zero liquid system
Doosan Hydro Technology was among the winners of the 2015 David W York Water Reuse Project of Year Award for its part in the city of Palm Coast's zero liquid discharge (ZLD) plant at Citation Boulevard, Florida.The Florida Water Environment Association (FWEA) awarded the prize to Doosan, the city's utility department, and the project design engineer, McKim and Creed.
The ZLD recovers and treats close to 100% of the concentrate produced at the water plant saving up to 6Ml of water each day. Previously, the water had to be discharged to a surface water body.
The ZLD system started up earlier this year at Citation Boulevard. The primary components of the ZLD process are automated lime soda softening and ultra-filtration systems (UF). The softened water is conveyed to a UF system to remove additional solids. The ZLD-treated water is then disinfected before being blended with the existing water treatment plant permeate and raw water bypass.
Sludge removed from the ZLD process is transferred to a solids handling system, where it is thickened prior to dewatering. Various process streams, including the water removed from the sludge through thickening and dewatering, are recycled back into the ZLD treatment process, increasing the recovery of the system to nearly 100%. The city contracts with a haulier to reuse the dewatered lime solids in the production of concrete aggregate and paver base.
The ZLD system was fully integrated into the existing plant so that the existing water treatment plant reverse osmosis system and the ZLD process operate as one treatment plant.