Comparison of sewage sludge toxicity to plants and invertebrates in three different soils

Understanding the effect of soil type on the overall toxicity of sewage sludge is one of the most important issues concerning environmental risks associated with the sewage sludge land application. The aim of the study was to determine the influence of different soils (sandy, loamy and OECD soil) on sewage sludges toxicity in relation to plants (Lepidium sativum, Sorghum saccharatum, Sinapis alba) and an invertebrate species (Heterocypris incongruens). The most evident negative influence of sewage sludges on root growth was observed in the case of OECD soil. The EC50 values determined on the basis of the root growth inhibition of all tested plants were in the range 0.1–6.4%, 0.03–9.4% and 6.6–22.1% (% of sewage sludge kg−1 soil) for OECD, sandy and loamy soil, respectively. Soil type also affects the sewage sludge toxicity in relation to H. incongruens. The LC50 (mortality) values ranged from 0.26% to 11.5% depending on the sludge tested. For EC50 (growth inhibition) values ranged from 10.7% to 36.2%.

Research highlights
► Toxicity of sewage sludge in three different soils (loamy, sand and OECD) were tested.
► Sewage sludge toxicity was directly linked to type of soil.
► OECD soil had the higher negative influence on most of tested plants.