Study the effect of by-products from olive oil extraction on the earthworm activity
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Date
2022
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Abbes Laghrour University- Khenchela
Abstract
The current study aims to investigate the effects of olive mill wastewater (OMWW) and olive
mill pomace (OMP) and their combination on the growth, reproduction, survival of the two
earthworm species Aporrectodea trapezoides, and Eisenia fetida. Furthermore, their effects on
the soil physicochemical characteristics such as (pH, Electrical conductivity (EC), Organic
matter (OM), Organic carbon (OC), Total nitrogen (TN), Assimilable phosphorus (P),
Phenolic compounds (PP), in addition, FTIR spectroscopy is used to determine the soil
polyphenols. Moreover, the current study aims to determine the accumulation of heavy metals
from OMWW and OMP in the soil and the bioaccumulation in the two different earthworm
species using five increasing doses of OMWW and OMP ranging as follows: 12.5%, 25%,
50%, 75%, and 100% w/w. Findings revealed that olive mill wastes have significant effects
on the earthworm endpoints (survival, growth, and reproduction), and showed growth
enhancement at lower concentrations of OMP, while mortality of earthworms and
reproduction inhibition are found at high doses of OMP and the combination, Eisenia fetida
were found more sensitive to exposing to olive mill wastes than Aporrectodea trapezoides. As
well as OMWW and OMP have also significant effects on soil physicochemical properties,
decrease in soil pH, increase in soil EC, soil OM content, as well as soil OC content. FTIR
analysis was showed raise in soil polyphenols content under treatment with OMWW and
OMP, meanwhile, soil TN and soil P were not shown a significant change under the
treatments applied especially under lower doses. Besides, OMWW and OMP were found
contain significant amounts of heavy metals, as a consequence causing a remarkable
accumulation of metals in the soil such as (Cadmium (Cd), Chromium (Cu), Copper (Cr),
Zinc (Zn), and Iron (Fe), which cause crucial environmental hazards. In addition to the soil
accumulation of metals, olive mill wastes were found to cause serious bioaccumulation of
heavy metals in earthworm tissue. Results revealed that Aporrectodea trapezoides has the
ability to accumulate heavy metals in their tissue more than Eisenia fetida.