BayCEER Workshop 2016

The use of schwertmannite material to remove selenate and selenite from contaminated water

P 3.5 in Water and the environment: From biosphere to geosphere

Introduction

 Selenium (Se), an essential micronutrient to humans and animals, is among the list of oxyanions that leads to contamination of natural waters and aquatic environments. Thus, to meet the EU drinking water standard (10 µg/L), selenium removal from aquatic ecosystems is often required. Mainly, the inorganic species selenite and selenate require specific attention because of their high solubility in water. Various treatment technologies have been investigated to remove selenium from water; however, they have been limited either by generating large amounts of waste or by high cost maintenance operations. At present, adsorbent techniques are the most advantageous due to their simple design and cost-effectiveness. Schwertmannite (SHM) an iron oxyhydroxide (Fe₈O₈(OH)₆SO₄) has been recently applied with success to remove chromate and arsenate. Therefore, SHM is a good candidate to remove selenium oxyanions. The objective of our work is to develop an ecological filter based on SHM adsorbents to reduce both selenite and selenate from contaminated water.

Material and Methods

 The methodology focuses on two steps: first, understanding the relationship between Se oxyanion adsorption, pH and the surface of SHM adsorbents and second, reducing the competitiveness of sulphate towards selenate in raw water. Furthermore, the methodology adopts an interdisciplinary approach combining hydrochemistry and technical development. The regeneration of SHM adsorbents and the exploration of potential use of waste material into industries will be also taken into consideration.

Results

The expected results aim to optimise the performance of SHM adsorbents and predict their long term loading capacity.

Conclusions

A suitable design and optimal operation for Se water clean-up technology based on SHM adsorbents will be developed.

 

Keywords: - Selenium oxyanions - Selenite - Selenate - Schwertmannite - Water pollution