Evaluating Earthworms’ Potential for Remediating Soils Contaminated with Olive Mill Waste Sediments

Round 1

Reviewer 1 Report

The reviewed manuscript concerns vermiremediation of oil mill waste contaminated soil. The processing of this waste is extremely important especially in the Mediterranean region countries. The manuscript is well written and requires only minor changes before publication.

Details:

In section 2.2, please add the characteristics of the soil used during the experiment,

Please explain in section 3.3 why the content of T.O.C, Total N, Na (Fig.6) increases after 30 days of remediation. This is an interesting phenomena because these ingredients were not introduced during the experiment but their value increases significantly.

Author Response

We would like to thank you for sparing the time to make useful comments. All suggestions and corrections have been taken into account, and the manuscript has been changed accordingly.

Major changes were:

• English style was corrected.
• Plot labels in Figure 5 were corrected, but its meaning does not change.
• New references were added because some parts of the manuscript were improved according to reviewers’ comments (sections 2.1, 2.2, and 3.2).

R1: In section 2.2, please add the characteristics of the soil used during the experiment,

Authors (Au): This information has been included (lines 79-82).

R1: Please explain in section 3.3 why the content of T.O.C, Total N, Na (Fig.6) increases after 30 days of remediation. This is an interesting phenomena because these ingredients were not introduced during the experiment but their value increases significantly.

Au: That is a good observation. The increase of these soil variables could be due to the fact that earthworms were fed during the 30-d incubation period (indicated in line 115). However, other factors such as inhibition of microbial mineralization of organic matter should not be excluded, but our data do not provide any clear evidence about this hypothesis. We have added some comments about this possibility avoiding excessive speculation (lines 354-361).

Author Response File: Author Response.docx

Reviewer 2 Report

The disposal of the solid and/or liquid wastes originating from the olive oil industry represents a big environmental problem in the Mediterranian countries. The waste is rich of  organic matter and nutrients, and theoretically could be used as valuable organic fertilizer. Because of the phytotoxicity of this material, the potential land use of these wastes is impossible without any remediation measure. Earthworms belong to the organisms suitable for bioremediation of the soils contaminated by organic pollutants, but, compared to soil microorganisms, these organisms are usually less tolerant to the elevated contaminant levels. Thus, the investigations concerning the ecotoxicity assessment and response of the earthworms on the various contaminants are reasonable. The manuscript contains a lot of results, well presented and discussed, and deserves publication. However, some modifications are necessary before potential acceptance of the text:

1. Please, check carefully the text, some typos occurr within the text body
2. Line 19: „increase of the efficiency“ compared to what?
3. Line 20: please, use „amended“ better than „contaminated“ soil (within whole text)
4. Lines 81-83: the sentence is unclear
5. Line 81: better „individuals“ than „specimens“
6. Lines 171-172: Fritsch Analysette 3 Spartan is not he agate mill, but vibration sieve shaker
7. Line 218: biochar do not belong to the soil contaminants, but to the soil additives
8. Figure 4: why are the bars for 10 and 20% different from 40%?
9. Line 335: maybe Fig. 5?
10. Line 353: please, try to estimate the remediation efficiency and duration of the remediation measure by using earthworms

Author Response

We would like to thank you for sparing the time to make useful comments. All suggestions and corrections have been taken into account, and the manuscript has been changed accordingly.

Major changes were:

• English style was corrected.
• Plot labels in Figure 5 were corrected, but its meaning does not change.
• New references were added because some parts of the manuscript were improved according to reviewers’ comments (sections 2.1, 2.2, and 3.2).

However, some modifications are necessary before potential acceptance of the text:

• Please, check carefully the text, some typos occurr within the text body

Authors (Au): done.

• Line 19: „increase of the efficiency“ compared to what?

Au: Because, we did not make an efficiency analysis of both methods (regular bioremediation using native microorganisms versus vermiremediation), we have changed this sentence.

• Line 20: please, use „amended“ better than „contaminated“ soil (within whole text)

Au: Changed as suggested, unless we refer to soils unintentionally contaminated with a high OMW concentrations.

• Lines 81-83: the sentence is unclear

Au: Corrected.

• Line 81: better „individuals“ than „specimens“

Au: Corrected.

• Lines 171-172: Fritsch Analysette 3 Spartan is not he agate mill, but vibration sieve shaker.

Au: Corrected.

• Line 218: biochar do not belong to the soil contaminants, but to the soil additives

Au: Totally agree. Corrected.

• Figure 4: why are the bars for 10 and 20% different from 40%?

Au: That was a problem of MSWord-to-PDF conversion. We have changed the colour of all figures to avoid this problem.

• Line 335: maybe Fig. 5?

Author Response File: Author Response.docx