title: Fate of heavy metals and major nutrients in a sludge-soil-plant-leachate system during the sludge phyto-treatment process.
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 phytotreatment of sludge can be coupled with sludge leachate recycling for crop production and re-collection of the sludge residue for landfilling.
authors.affiliation: Key Laboratory of Soil Environment and Waste Reuse in Agriculture of Guangdong High Education Institutes, South China Agricultural University, Guangzhou, China.
authors.forename: Tianfen
authors.initials: T
authors.lastname: Xu
authors.affiliation: South China Institute of Environmental Science, Ministry of Environmental Protection Guangzhou, China.
authors.forename: Jinrong
authors.initials: J
authors.lastname: Qiu
authors.affiliation: Key Laboratory of Soil Environment and Waste Reuse in Agriculture of Guangdong High Education Institutes, South China Agricultural University, Guangzhou, China.
authors.forename: Qi-Tang
authors.initials: QT
authors.lastname: Wu
authors.affiliation: Key Laboratory of Soil Environment and Waste Reuse in Agriculture of Guangdong High Education Institutes, South China Agricultural University, Guangzhou, China.
authors.forename: Xiaofang
authors.initials: X
authors.lastname: Guo
authors.affiliation: Key Laboratory of Soil Environment and Waste Reuse in Agriculture of Guangdong High Education Institutes, South China Agricultural University, Guangzhou, China.
authors.forename: Zebin
authors.initials: Z
authors.lastname: Wei
authors.affiliation: Key Laboratory of Soil Environment and Waste Reuse in Agriculture of Guangdong High Education Institutes, South China Agricultural University, Guangzhou, China.
authors.forename: Fangwen
authors.initials: F
authors.lastname: Xie
authors.affiliation: Department of Biology, Hong Kong Baptist University, Hong Kong, China.
authors.forename: Jonathan W C
authors.initials: JW
authors.lastname: Wong
mesh_terms: D031055:Alocasia / Q000737:chemistry / Q000378:metabolism; D001673:Biodegradation, Environmental; D018533:Biomass; D019216:Metals, Heavy / Q000032:analysis* / Q000378:metabolism; D010944:Plants / Q000737:chemistry* / Q000378:metabolism*; D031963:Sedum / Q000737:chemistry / Q000378:metabolism; D012722:Sewage; D012987:Soil / Q000737:chemistry; D012989:Soil Pollutants / Q000032:analysis* / Q000378:metabolism; D003313:Zea mays / Q000737:chemistry / Q000378:metabolism
chemical_list: D019216:Metals, Heavy; D012722:Sewage; D012987:Soil; D012989:Soil Pollutants