title: The effect of low-temperature transformation of mixtures of sewage sludge and plant materials on content, leachability and toxicity of heavy metals.
abstract: The aim of the study was to determine the influence of the process of low-temperature transformation and the addition of plant material to sewage sludge diversifying the content of mobile forms of heavy metals and their ecotoxicity. The experimental design included: sewage sludge+rape straw, sewage sludge+wheat straw, sewage sludge+sawdust, sewage sludge+bark and sewage sludge with no addition. The mixtures were subjected to thermal transformation in a chamber furnace, under conditions without air. The procedure consisted of two stages: the first stage (130°C for 40 min) focused on drying the material, whereas in the second stage (200°C for 30 min) proper thermal transformation of materials took place. Thermal transformation of the materials, caused an increase in total contents of heavy metals in comparison to the material before transformation. From among elements, the cadmium content changed the most in materials after thermal transformation. As a result of thermal transformation, the content of water soluble form of the heavy metals decreased significantly in all the prepared mixtures. Low toxicity of the extracts from materials for Vibrio fischeri and Lepidium sativum was found in the research, regardless of transformation process. L. sativum showed higher sensitivity to heavy metals occurring in the studied extracts from materials than V. fischeri, evidence of which are the positive significant correlations between the content of metals and the inhibition of root growth of L. sativum.
authors.affiliation: Department of Agricultural and Environmental Chemistry, University of Agriculture in Krakow, Al. Mickiewicza 21, 31-120 Krakow, Poland. Electronic address: k.gondek@ur.krakow.pl.
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Gondek
authors.affiliation: Department of Agricultural and Environmental Chemistry, University of Agriculture in Krakow, Al. Mickiewicza 21, 31-120 Krakow, Poland. Electronic address: Agnieszka.Baran@ur.krakow.pl.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Baran
authors.affiliation: Department of Agricultural and Environmental Chemistry, University of Agriculture in Krakow, Al. Mickiewicza 21, 31-120 Krakow, Poland. Electronic address: m.kopec@ur.krakow.pl.
authors.forename: Michał
authors.initials: M
authors.lastname: Kopeć
mesh_terms: D048908:Aliivibrio fischeri / Q000187:drug effects; D003890:Desiccation; D054750:Ecotoxicology; D004785:Environmental Pollutants / Q000032:analysis* / Q000633:toxicity; D031220:Lepidium sativum / Q000187:drug effects; D019216:Metals, Heavy / Q000032:analysis* / Q000633:toxicity; D018547:Plant Stems / Q000737:chemistry*; D012722:Sewage / Q000737:chemistry / Q000382:microbiology; D013696:Temperature; D014865:Waste Disposal, Fluid / Q000379:methods*
chemical_list: D004785:Environmental Pollutants; D019216:Metals, Heavy; D012722:Sewage
keywords: Biochar; Heavy metals; Mobility; Sewage sludge; Toxicity