Issue 6, 2011

Constructed wetlands using aluminium-based drinking water treatment sludge as P-removing substrate: should aluminium release be a concern?

Abstract

This study investigated an important issue of aluminium (Al) release from a novel reuse of Al-based water treatment sludge (Al-WTS) in constructed wetland system (CWs) as alternative substrate for wastewater treatment. Al-WTS is an inevitable by-product of drinking water treatment plants that use Al-salt as coagulant for raw water purification. It has recently been demonstrated that Al-WTS can be reused as a low-cost phosphorus (P) adsorbent and biofilm carrier in CWs for wastewater treatment. However, to facilitate the large scale application of Al-WTS in CWs as wetland substrate, concerns about Al leaching during its reuse in CWs must be addressed as Al is a dominant constituent in Al-WTS. In this study, a desk review of literature on Al release during Al-WTS reuse was conducted. Furthermore, a 42-week Al monitoring was carried out on a pilot field-scale CWs employing Al-WTS as main substrate. Results show that 22 out of the 35 studies reviewed, reported Al release with levels of soluble Al reported ranging from 0.01 to about 20 mg Lāˆ’1. Monitoring of Al in the pilot field-scale CWs shows that there was Al leaching. However, except for the first three weeks of operation, effluents concentrations of both total- and soluble-Al were all below the general regulatory guideline limit of 0.2 mg Lāˆ’1. Overall, the study addresses a vital concern regarding the successful application of Al-WTS in CWs and shows that Al release during such novel reuse is quite low and should not preclude its use.

Graphical abstract: Constructed wetlands using aluminium-based drinking water treatment sludge as P-removing substrate: should aluminium release be a concern?

Article information

Article type
Paper
Submitted
01 Jan 2011
Accepted
12 Apr 2011
First published
05 May 2011

J. Environ. Monit., 2011,13, 1775-1783

Constructed wetlands using aluminium-based drinking water treatment sludge as P-removing substrate: should aluminium release be a concern?

A. O. Babatunde, J. L. G. Kumar and Y. Zhao, J. Environ. Monit., 2011, 13, 1775 DOI: 10.1039/C1EM00001B

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