Document Type

Journal Article

Department/Unit

Department of Biology

Title

Fate of heavy metals and major nutrients in a sludge-soil-plant-leachate system during the sludge phyto-treatment process

Language

English

Abstract

Land application of sewage sludge usually leads to increased levels of heavy metals in soil, plants and groundwater. Pre-treatment using plants has been proposed to reduce the contents of heavy metals and water in sludge prior to land application. This study quantified the transfer of Zn, Cd, Pb and major nutrients in a sludge-soil-plant-leachate system during the treatment of sewage sludge. To accomplish this, a two year pot experiment was carried out to collect leachate, mono- and co-cropping of Sedum alfredii and feed crops was conducted in sludge with an under-layer soil support. Sludge phyto-treatment increased Zn and Cd concentrations in the under-layer soil, but not Pb. Specifically, 70%, 70% and 80% of the original Zn, Cd and Pb, respectively, remained in the sludge, while about 40%, 70% and 60% of the original N, P and K remained. Only 3% to 5% of Cd and Zn and < 1% of Pb were transferred into the under-layer soils or leachates, while more than 12% of the N and P were transferred. Co-planting S. alfredii and feed crops led to a significant reduction of heavy metals in leachates when compared with sludge without planting. Overall, sludge leachate is more appropriate than whole sludge for recycling in agriculture since it reduces the chance of heavy metal contamination in the agro-ecosystem; therefore, co-cropping phyto-treatment of sludge can be coupled with sludge leachate recycling for crop production and re-collection of the sludge residue for landfilling. © 2013 Taylor & Francis.

Keywords

heavy metals, major nutrients, sewage sludge, sludge-soil-plant-leachate system

Publication Date

2013

Source Publication Title

Environmental Technology

Volume

34

Issue

15

Start Page

2221

End Page

2229

Publisher

Taylor & Francis

DOI

10.1080/09593330.2012.744472

ISSN (print)

09593330

ISSN (electronic)

1479487X

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