Abstract
The objective of this project is to design a new desalination system with energy efficiency approaching the theoretical thermodynamic limit—even at high recovery ratio. The system uses reverse osmosis (RO) and a batch principle of operation to overcome the problem of concentration factor which prevents continuous-flow RO systems from ever reaching this limit and thus achieving the minimum possible specific energy consumption, SEC. Batch operation comprises a cycle in three phases: pressurisation, purge, and refill. Energy recovery is inherent to the design. Unlike in closed-circuit desalination (CCD), no feedwater is added to the pressure circuit during the pressurisation phase. The batch configuration is compared to standard configurations such as continuous single-stage RO (with energy recovery) and CCD. Theoretical analysis has shown that the new system is able to use 33% less energy than CCD at a recovery ratio of 80%. A prototype has been constructed using readily available parts and tested with feedwater salinities and recovery ratios ranging from 2,000 to 5,000 ppm and 17.2–70.6%, respectively. Results compare very well against the standard configurations. For example, with feedwater containing 5,000 ppm NaCl and recovery ratio of 69%, a hydraulic SEC of 0.31 kWh/m3 was obtained—better than the minimum theoretically possible with a single-stage continuous flow system with energy recovery device.
Original language | English |
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Pages (from-to) | 23206-23216 |
Number of pages | 11 |
Journal | Desalination and Water Treatment |
Volume | 57 |
Issue number | 48-49 |
Early online date | 9 May 2016 |
DOIs | |
Publication status | Published - 2016 |
Event | European Desalination Society conference EuroMed 2015: Desalination for Clean Water and Energy - Palermo, Italy Duration: 10 May 2015 → 14 May 2015 |
Keywords
- batch desalination
- brackish water
- high efficiency
- high recovery
- RO
- solar
- sustainable development