engleski

Influence of digested wastewater sludge on early growth of the perennial ryegrass (Lolium perenne L.)

Effects of residual wastewater sludge, amended with zeolites, on the early growth of perennial ryegrass (Lolium perenne L.) were investigated. For that purpose growth parameters, photosynthetic pigments content, substrate characteristics, levels of macro- and micronutrients, as well as toxic elements in plant tissue, plant inorganic matter and substrates, sewage sludge and soil, were determined. Among the growth indicators, only protein content and inorganic matter in plant tissue was found to be influenced by the type and composition of the substrate. Sewage sludge was found to contain elevated levels of Mo, Ni, Pb, Sb, Se, Sr and Zn, while Cu and Sn were found in one order of magnitude higher levels compared to the control sample. Application of sewage sludge, however, modified only the content of Cu and Zn in the plant tissue, inducing accumulation of these elements by a factor of 2. Despite the fact that all other measured elements (Al, As, Ba, Ca, Cd, Co, Cr, Cs, Fe, K, Li, Mg, Mn, Na, Ti, U and V) were found in plant tissue at similar levels regardless of the substrate metal loading accumulation indices point to overall lower bioavailability of elements from digested sludge in comparison with control substrate. Moreover, metal concentrations in all analyzed plant samples were below legally established limits.

wastewater sludge; perennial ryegrass; growth parameters; toxic elements; bioavailability ;

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