Demonstration of an energy recovery device well suited for modular community-based seawater desalination systems : result of Danfoss iSAVE 21 testing

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.