Biostabilization of Tannery Sludge Compost by Vermicomposting
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Date
2022
Journal Title
Journal ISSN
Volume Title
Publisher
Ankara Üniversitesi
Abstract
The aim of this study is to investigate the stabilization of tannery sludge
compost mixed with cattle manure at the different ratios by employing an
epigeic earthworm Eisenia foetida and bioaccumulation of Cr in tannery
sludge by earthworms. Organic cattle manure (M) and sludge compost (S)
were mixed in certain proportions, moistened and Eisenia foetida worms
were added. Mixing ratios were as follows: 100% M (M100S0), 70% M +
30% S (M70S30), 50% M + 50% S (M50S50) and 30% M + 70% S (M30S70).
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 ended after 120 days and the following
parameters were evaluated in vermicomposts: pH, electrical conductivity
(EC), total nitrogen (TN), total organic carbon (TOC), C:N ratio, and total
macro and micro elements. In addition, it was determined total Cr, Cr (VI)
in vermicomposts and total Cr in E. foetida body. The results for TOC,
C:N ratio and total Cr showed decreases in their values at the end of the
vermicomposting process, whereas values for pH, EC, TON, Ca, and Mg
increase, indicating that the vermicomposting reached the maturity level.
All values of Cr (VI) of vermicomposts were below the detectable level.
During the vermicomposting process, the reduction rates of the total Cr
amounts were 96% (M70S30), 96% (M50S50) and 30% (M30S70),
respectively. While the highest total Cr amount in the earthworm body
was determined in M30S70 treatment, the amount of this element in the
earthworm body decreased due to the decreasing doses of tannery sludge
compost. These results show that E. foetida can bioacumulate the
chromium in tannery sludge compost. As a result, it was determined that
vermicomposting can be an alternate technology for the recycling and
environmentally safe disposal/management of tannery sludge compost
using an epigeic earthworm E. foetida.
Description
Keywords
Chemical properties, Eisenia foetida