Effect of Adding Drinking Water Treatment Sludge on Excess Activated Sludge Digestion Process
, Maulana Yusup Rosadi 4, Faisal Arsyad 3, Yanqiu Lu 1 and Huifang Wu 1,*Round 1
Reviewer 1 Report
The reuse of water treatment sludge as a coagulant for post - treatment
of activated sludge digestion process may be interesting proposition from the perspective of sustainable development.
Some general remarks:
- The title accurately describe the study.
- Abstract corresponds to the scope of paper.
- The layout is clear and content is logically divided.
- Methodics is exactly described and confirm the high level.
- Results are presented in one table and in nine figures.
- Most of thr references are up - to - date and relevant.
Detail remarks:
1.The results may be more describe respect other studies.
2. Conclusions should reinforce the main issues in this paper (see line 100, 101, 102).
Author Response
Dear Editors and Reviewers:
Thank you for your letter and the reviewers’ comments.
These comments are valuable and helpful for our research. We have made the revisions and we look forward to meeting the approval. Revised parts are marked in yellow in the paper.
Point 1: The results may be more describe respect other studies.
Response 1: More previous studies were cited to describe the results (see line 198,206,229,337-339).
Point 2: Conclusions should reinforce the main issues in this paper (see line 100, 101, 102).
Response 2: The conclusions were modified to reinforce the summary of the main issues in the paper (see line 345-346, 354-358).
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Hello dear authors.
The paper is nice but needs a little change in:
line 48: In sentence: However, . . . there is twice mentioned aerobic instead anaerobic and aerobic.
Line 89 and 90: the sentence: It was also observed that natural organic matter
90 leakage from the alum sludge, does not make sence.
Otherwise I did not found any problem.
Author Response
Dear Editors and Reviewers:
Thank you for your letter and the reviewers’ comments.
These comments are valuable and helpful for our research. We have made the revisions and we look forward to meeting the approval. Revised parts are marked in yellow in the paper.
Point 1: line 48: In sentence: However, . . . there is twice mentioned aerobic instead anaerobic and aerobic.
Response 1: The sentence was revised to “However, various problems still remain in aerobic and anaerobic digestion process.” (see line 48).
Point 2: Line 89 and 90: the sentence: It was also observed that natural organic matter leakage from the alum sludge, does not make sence.
Response 2: The sentence was rewritten as “In addition, some researchers have observed the leakage of natural organic matter in alum sludge reuse” (see line 91-92).
Author Response File: Author Response.pdf
Reviewer 3 Report
This manuscript deals with using drinking water treatment sludge in activated sludge digestion process. Study provides important results and can be published after minor revision.
Abstract:
- add information about the coagulant used in the drinking water treatment.
Introduction
- Lines 68-77: One option for the DWTS treatment is to dissolve and use dissolved Al/Fe in synthesis of new products, e.g. adsorbents, which could be mentioned here. For consideration: Chemical Engineering Journal, Volume 361, Pages 680-689, https://doi.org/10.1016/j.cej.2018.12.122
- Line 95: bath >> batch?
Materials and methods
- line 106: write polyaluminium (not separately)
- line 140: write ”Mineralogy of the DWTS…” instead of ”The morphological structure of the DWTS…”
- line 174: add space between value and unit (1mL)
-line 180: add the g value of centrifugation.
Results and discussion
- It is suggested to measure composition for the DWTS using XRF, to be sure what are the main inorganics in the sample. XRD shows that there is some amorphous material.
- Fig. 3 and 5 captions: write more details.
Author Response
Dear Editors and Reviewers:
Thank you for your letter and the reviewers’ comments.
These comments are valuable and helpful for our research. We have made the revisions and we look forward to meeting the approval. Revised parts are marked in yellow in the paper.
Point 1: Abstract: - add information about the coagulant used in the drinking water treatment.
Response 1: The coagulant which used in the drinking water treatment was noted in the abstract. The sentence is “Drinking water treatment sludge (DWTS) is a waste by-product from water treatment plant where aluminum and iron salts are the most commonly used coagulants.” (see line 19 and 20).
Point 2: Introduction: - Lines 68-77: One option for the DWTS treatment is to dissolve and use dissolved Al/Fe in synthesis of new products, e.g. adsorbents, which could be mentioned here. For consideration: Chemical Engineering Journal, Volume 361, Pages 680-689, https://doi.org/10.1016/j.cej.2018.12.122
Response 2: The study which was conducted by Zhang et al. was cited in introduction (see line 74-76).
Point 3: Introduction: - Line 95: bath >> batch?
Response 3: The word “batch” was revised (see line 97).
Point 4: Materials and methods: - line 106: write polyaluminium (not separately)
Response 4: The word “polyaluminium” was revised (see line 108).
Point 5: Materials and methods: - line 140: write ”Mineralogy of the DWTS…” instead of ”The morphological structure of the DWTS…”
Response 5: The sentence was rewritten as “Mineralogy of the DWTS was determined by X-ray diffractometer” (see line 142-143).
Point 6: Materials and methods: - line 174: add space between value and unit (1mL)
Response 6: Space was added between value and unit (see line 176).
Point 7: Materials and methods: -line 180: add the g value of centrifugation.
Response 7: The g value of centrifugation was added as “(centrifugation force: 2147 g)” (see line 182,184).
Point 8: Results and discussion: - It is suggested to measure composition for the DWTS using XRF, to be sure what are the main inorganics in the sample. XRD shows that there is some amorphous material.
Response 8: Since this experiment was carried out a few months ago, we are sorry for that we didn’t save the DWTS sample, so we cannot conduct the measurement of XRF. Certainly, the major chemical compounds of the DWTS sample can be determined by XRF. Although the characteristics of DWTS are related to the quality of raw water and types of coagulants, SiO2 is the main component of the DWTS (Chiang et al., 2009; Ahmad et al., 2016a). The purpose of XRD analysis in this study is to identify the morphological structure of DWTS and illustrate that the removal of dissolved pollutants may be adsorbed by amorphous aluminum hydroxide precipitate. In some previous studies, it is reasonable to believe that the DWTS is amorphous from XRD analysis (Yang et al., 2006; Yang et al., 2008; Ahmad et al., 2016b). References as following: Chiang, K.-Y.; Chou, P.-H.; Hua, C.-R.; Chien, K.-L.; Cheeseman, C. Lightweight bricks manufactured from water treatment sludge and rice husks. Journal of Hazardous Materials, 2009, 171, 76-82. https://doi.org/10.1016/j.jhazmat.2009.05.144.; Ahmad, T.; Ahmad, K.; Alam, M. Characterization of Water Treatment Plant’s Sludge and its Safe Disposal Options. Procedia Environmental Sciences, 2016a, 35, 950-955. https://doi.org/10.1016/j.proenv.2016.07.088.; Yang, Y.; Zhao, Y.Q.; Babatunde, A.O.; Wang, L.; Ren, Y.X.; Han, Y. Characteristics and mechanisms of phosphate adsorption on dewatered alum sludge. Separation and Purification Technology, 2006, 51,193–200. https://doi.org/10.1016/j.seppur.2006.01.013.; Yang, Y.; Zhao, Y.Q.; Kearney, P. Influence of ageing on the structure and phosphate adsorption capacity of dewatered alum sludge. Chemical Engineering Journal, 2008, 145, 276-284. https://doi.org/10.1016/j.cej.2008.04.026; Ahmad, T.; Ahmad, K.; Alam, M. Sustainable management of water treatment sludge through 3‘R’ concept. Journal of Cleaner Production, 2016b, 124, 1-13. http://dx.doi.org/10.1016/j.jclepro.2016.02.073
Point 9: Results and discussion: - Fig. 3 and 5 captions: write more details.
Response 9: More details were added in Fig. 3 and 5 captions (see line 262-263, 278-280).
Author Response File: Author Response.pdf
