ZVI (Fe0) Desalination: Stability of Product Water

David Antia

doi:10.3390/resources5010015

Abstract

A batch-operated ZVI (zero valent iron) desalination reactor will be able to partially desalinate water. This water can be stored in an impoundment, reservoir or tank, prior to use for irrigation. Commercial development of this technology requires assurance that the partially-desalinated product water will not resalinate, while it is in storage. This study has used direct ion analyses to confirm that the product water from a gas-pressured ZVI desalination reactor maintains a stable salinity in storage over a period of 1–2.5 years. Two-point-three-litre samples of the feed water (2–10.68 g (Na+ + Cl−)·L−1) and product water (0.1–5.02 g (Na+ + Cl−)·L−1) from 21 trials were placed in storage at ambient (non-isothermal) temperatures (which fluctuated between −10 and 25 °C), for a period of 1–2.5 years. The ion concentrations (Na+ and Cl−) of the stored feed water and product water were then reanalysed. The ion analyses of the stored water samples demonstrated: (i) that the product water salinity (Na+ and Cl−) remains unchanged in storage; and (ii) the Na:Cl molar ratios can be lower in the product water than the feed water. The significance of the results is discussed in terms of the various potential desalination routes. These trial data are supplemented with the results from 122 trials to demonstrate that: (i) reactivity does not decline with successive batches; (ii) the process is catalytic; and (iii) the process involves a number of steps.

Highlights

Desalination associated with zero valent iron (ZVI, Fe0 ) has been demonstrated in more than 160 batch trials and by monitoring the salinity of water flowing through granular Fe0 permeable reactive barriers (PRB) [6,7,8,9,10]
These trials have demonstrated that ZVI desalination has potential applications for groundwater management, road runoff water management, agricultural water management, municipal and domestic water, emergency and disaster water requirements, feed and waste water treatment associated with conventional desalination plants, waste water associated with the extractive industries and environmental damage mitigation [1,2,3,4,5,6,7,8,9,10]
This study has used direct ion analyses (Figure 3, Tables A1–A11) to confirm that the product water from a gas-pressured ZVI desalination reactor maintains a stable salinity in storage over a period of 1–2.5 years

Summary

Introduction

Desalination associated with zero valent iron (ZVI, Fe0 ) has been demonstrated in more than 160 batch trials (utilizing 0.2–240 L/batch [1,2,3,4,5]) and by monitoring the salinity of water flowing through granular Fe0 permeable reactive barriers (PRB) [6,7,8,9,10]. The increase in crop value is unlikely to economically sustain the delivery cost of desalinated, or partially desalinated, water of more than $0.1–$0.5/m3 [2]

Methods

Results

Discussion

Conclusion