Biostabilization of Heavy Metals in the Leather Industry Treatment Sludge Compost by Vermicomposting
Project no. 870 · Status: Kapanmış · 2017
Summary
The aim of the project is to investigate the use of leather industry treatment sludge with high organic load and chromium content as a source of organic matter in agricultural soils by vermicomposting. Organic cow manure (CM) and sludge compost (SC) obtained from the treatment plant of a private leather processing factory were mixed in certain proportions, moistened and Eisenia foetida worms were added. Mixing ratios were realized as 100% CM (VK0), 70% CM + 30% SC (VK1), 50% CM + 50% SC (VK2) and 30% CM + 70% SC(VK3). The experiment was carried out at a constant temperature of 24 oC and in a dark environment according to a randomized plot design with three replicates. The experiment was completed after 4 months and vermicomposting samples were taken for chemical analysis. Applications had statistically significant effects on the pH, EC, total C, P, K, Mg, Fe, Zn, Cu and Mn contents of the vermicompost and the number of worms. Significant changes depending on time occurred in total C, N, P, Ca, Cu and Cr and total Cr amounts in worm biomass. The total amount of elements in vermicomposts were determined below the allowable limit values. While the highest total Cr amounts occurred in 30% CM + 70% SC application, the amount of this element decreased due to the decreasing doses of the sludge compost. Throughout the vermicomposting process, total Cr reduction rates were between 30% and 96%. While the highest total Cr amount in the worm biomass has been observed in the application of 30% CM + 70% SC, the amount of this element in the worm biomass has also decreased due to the decreasing doses of the sludge. These results show that Eisenia foetida can absorb the chromium in the vermicomposts. As a result of the project, it was determined that the total Cr amount of the sludge compost belonging to the treatment plant of the leather processing plant has decreased significantly with vermicomposting and has an organic waste content suitable for agricultural land in terms of other chemical properties. Keywords: Chemical properties, Eisenia foetida, leather sludge, total chromium, vermicomposting.