Abstract
The option of building smaller, decentralized plants is more feasible now that HP pumps and energy recovery devices (ERD) are available for use in small-scale seawater desalination plants with efficiencies comparable to those typically associated with larger plants. A demonstration SWRO system producing 125 cubic meters of product water per day was designed and commissioned utilizing the Danfoss iSave 21 energy recovery device. The desalination subsystem utilizes an inter-staged membrane configuration, low flux, and low recovery design to reduce specific energy consumption, fouling potential, and membrane cleaning requirements. Test results show that a specific energy consumption lower than 2 kWh/m3 is easily achievable utilizing standard components, and that the improved second-generation iSave 21 unit has significantly lower lubrication flows than the previous model.