Application of Decentralized Wastewater Treatment Technology in Rural Domestic Wastewater Treatment
Round 1
Reviewer 1 Report
Comments and Suggestions for Authors1. The article has serious problems and needs a lot of revision.
(1) The systematic introduction of DWTS in different countries should be reduced, the length from 76 lines to 197 lines is too long, and this is not the key point. Different regions are suitable for different technologies due to their different environments and pollutants, so more technology-related content should be explained.
(2) In the background introduction, the author mentions that the existing crude domestic sewage discharge and simple sewage pipe network collection methods in rural areas not only cannot guarantee high sewage collection efficiency, but also cannot realize the separation of rain and pollution. However, in the subsequent content, there is no mention of the collection of existing rural crude domestic sewage, but all talks about the treatment of the problem, but the treatment has mature technology, collection is really a difficult problem, the article should add this literature as support.
(3) The comparison of various technologies is not intuitive enough, and comparative analysis should be carried out in the form of tables, rather than large paragraphs of text description. In addition, we can not only start from the perspective of performance and advantages and disadvantages, cost is also a very important reference index, low cost is very important for rural areas.
(4) After reading this article, I feel useless. It only introduces various DWTS technologies in general, but the most important outlook is not presented. Which direction should be developed in this field in the future, and the most important problems to be solved are not presented.
Author Response
General Comment: The article has serious problems and needs a lot of revision. The specific comments are:
Response: Thanks for your comments. Major revisions were made in this revised manuscript according to your comments (please see the following responses).
Comment 1: The systematic introduction of DWTS in different countries should be reduced, the length from 76 lines to 197 lines is too long, and this is not the key point. Different regions are suitable for different technologies due to their different environments and pollutants, so more technology-related content should be explained.
Response 1: Thanks for your comments. Section 2 was rewritten and revised as you suggested.
Comment 2: In the background introduction, the author mentions that the existing crude domestic sewage discharge and simple sewage pipe network collection methods in rural areas not only cannot guarantee high sewage collection efficiency, but also cannot realize the separation of rain and pollution. However, in the subsequent content, there is no mention of the collection of existing rural crude domestic sewage, but all talks about the treatment of the problem, but the treatment has mature technology, collection is really a difficult problem, the article should add this literature as support.
Response 2: Thank you for your comments. The introduction was rewritten and the difficulties in the collection of rural sewages were added as you suggested.
Comment 3: The comparison of various technologies is not intuitive enough, and comparative analysis should be carried out in the form of tables, rather than large paragraphs of text description. In addition, we can not only start from the perspective of performance and advantages and disadvantages, cost is also a very important reference index, low cost is very important for rural areas.
Response 3: Thank you for your comments. According to your suggestions, the comparison of various technologies was added and exhibited in Table 1, Table 2, and Table 4.
Comment 4: After reading this article, I feel useless. It only introduces various DWTS technologies in general, but the most important outlook is not presented. Which direction should be developed in this field in the future, and the most important problems to be solved are not presented.
Response 4: Thank you for your comments. The conclusions and outlook were rewritten and revised as you suggested.
Reviewer 2 Report
Comments and Suggestions for Authors1. The main objectives of the submitted study is to compare currently implemented decentralized wastewater technologies for rural domestic wastewater treatment. This objective, however, has not been fulfilled as expected for the following reasons:
- In principal there is no difference between treatment technologies used for centralized and decentralized systems. The key difference between the two approaches is that centralized treatment requires extensive network of pipes and pumps for the collection or distribution of wastewater. Decentralized treatment uses right-sized plants that serve remote communities or that are dispersed throughout a broader community, with each serving a smaller population near the point of use. More elaboration on this point is required.
2. Section 2 and section 3 has to be merged in one section. Both discusses the same issue (wastewater treatment technology as related to countries.
3. Some sentences are too long (e.g. line 39to 47).
4. Some typing mistakes which has to be corrected (e.g. line 45).
5. Figure 1 is not readable.
6.The abbreviations are confusing. The same abbreviation is used for different a words (e.g. A is used for Aerobic, Anaerobic &Anoxic)
Comments on the Quality of English Language
Minor typing correction is required
Author Response
General Comment: The main objectives of the submitted study is to compare currently implemented decentralized wastewater technologies for rural domestic wastewater treatment. This objective, however, has not been fulfilled as expected for the following reasons:
Response: Thanks for your comments. Major revisions were made in this revised manuscript according to your comments (please see the following responses).
Comment 1: In principal there is no difference between treatment technologies used for centralized and decentralized systems. The key difference between the two approaches is that centralized treatment requires extensive network of pipes and pumps for the collection or distribution of wastewater. Decentralized treatment uses right-sized plants that serve remote communities or that are dispersed throughout a broader community, with each serving a smaller population near the point of use. More elaboration on this point is required.
Response 1: Thanks for your comments. The key difference between the two approaches was added in the introduction section as you suggested.
Comment 2: Section 2 and section 3 has to be merged in one section. Both discusses the same issue (wastewater treatment technology as related to countries.
Response 2: Thanks for your comments. Section 2 was rewritten and shorten in the revised manuscript.
Comment 3: Some sentences are too long (e.g. line 39 to 47).
Response 3: Thanks for your comments, the sentences in the manuscript were simplified as you suggested.
Comment 4: Some typing mistakes which has to be corrected (e.g. line 45).
Response 4: Thank you for your comments. The whole manuscript was carefully checked to correct the typing mistakes as you suggested.
Comment 5: Figure 1 is not readable.
Response 5: Thanks for your comments. The description about this figure in the text was revised as you suggested.
Comment 6: The abbreviations are confusing. The same abbreviation is used for different a words (e.g. A is used for Aerobic, Anaerobic &Anoxic)
Response 6: Thanks for your comments. The A/O process is the abbreviation of Anoxic/Oxic, which is a combination of an anoxic pool and an aerobic pool. A/A/O process is the abbreviation for Anaerobic-Anoxic-Oxic, which adds one step anaerobic treatment compared with the A/O process. A/O/A process is the abbreviation of anaerobic/anoxic/oxygenated, which is a kind of to nitrification denitrification process of again. The abbreviations in the manuscript were carefully checked and corrected, and the full names of the abbreviations were added when they were presented for the first time.
Reviewer 3 Report
Comments and Suggestions for Authors
Application of Decentralized Wastewater Treatment Technology in Rural Domestic Wastewater Treatment
The study's authors aim to compare the treatment processes currently in use by examining their performance, advantages, and disadvantages. The findings will contribute to developing new ideas for rural wastewater treatment technologies. Demonstrated that the various treatment technologies can be classified into conventional methods, such as activated sludge, biofilm, and biogas digesters, as well as natural biological methods, like artificial wetlands and soil percolation systems. Additionally, combined treatment technologies are also discussed.
Authors need to revise the manuscript addressing all the comments
Comments
(1) The management of domestic wastewater (DWW) in rural areas has always been challenging due to characteristics such as the wide distribution and dispersion of rural households--- Provide specific information on the distribution of rural households.
(2) What is the present status of cities in heavily populated countries? What technology did they use to handle a significant influx of water? Is the technology they have employed sufficient to handle such a large volume of water?
(3) The global urban population facing water scarcity is projected to increase from 933 million in 2016 to 2.4 billion in 2050, with India projected to be the worst affected country, 80% of the world's wastewater flows back into the environment without being treated or reused, and the development of wastewater treatment infrastructure has not kept pace with the growth in demand--- What measures may be recommended for densely populated countries like India to address the problem of water shortage and promote water reuse? Are there any feasible and tangible solutions?
(4) 46% of the global population (3.6 billion people) lacks toilets to safely dispose of human excreta, and nearly 892 million people do not have access to adequate sanitation facilities, and they continue to defecate in the open--- What is the worldwide proportion of wastewater production from rural and urban areas? Which group, urban or rural individuals, has more responsibility for freshwater consumption? Who are the main contributors to water pollution? Both urban and rural populations lack access to sufficient sanitary facilities. If rural communities lack access to fresh water, it is unjust to hold them accountable for environmental and water shortage problems.
(5) The effluent from the four ponds of each household can also be used for irrigation of family gardens or flower seedlings, realizing the resourceful utilization of water resources and nitrogen and phosphorus pollutants and significantly improving the rural environment--- nitrogen and phosphorus pollutants and used to significantly improving the rural environment
(6) The results showed that N2O removal was best in I-A/O and NOx removal was most significant in C-A/O--- what is the percentage of N2O removal observed here.
(7) Current studies have found that BAF can also remove wastewater containing antibiotics, with the main mechanisms being biodegradation and adsorption--- What is the efficacy of the Biofilter in eliminating antibiotics from wastewater?
(8) CWs work on the principle of sedimentation, filtration, precipitation, volatilization, adsorption and plant uptake of a variety of microorganisms distributed in the soil and on the plant surface--- By what process do plants absorb a diverse range of microorganisms found in the soil and on the surface of plants?
Author Response
General Comment: The study's authors aim to compare the treatment processes currently in use by examining their performance, advantages, and disadvantages. The findings will contribute to developing new ideas for rural wastewater treatment technologies. Demonstrated that the various treatment technologies can be classified into conventional methods, such as activated sludge, biofilm, and biogas digesters, as well as natural biological methods, like artificial wetlands and soil percolation systems. Additionally, combined treatment technologies are also discussed.
Authors need to revise the manuscript addressing all the comments.
Response: Thanks for your comments. Major revisions were made in this revised manuscript according to your comments (please see the following responses).
Comment 1: The management of domestic wastewater (DWW) in rural areas has always been challenging due to characteristics such as the wide distribution and dispersion of rural households--- Provide specific information on the distribution of rural households.
Response 1: Thanks for your comments. The specific information on the distribution of rural households was added in the introduction section as you suggested.
Comment 2: What is the present status of cities in heavily populated countries? What technology did they use to handle a significant influx of water? Is the technology they have employed sufficient to handle such a large volume of water?
Response 2: Thanks for your comments. The relevant discussion and collusions were added in sections 2 and 6 as you suggested.
Comment 3: The global urban population facing water scarcity is projected to increase from 933 million in 2016 to 2.4 billion in 2050, with India projected to be the worst affected country, 80% of the world's wastewater flows back into the environment without being treated or reused, and the development of wastewater treatment infrastructure has not kept pace with the growth in demand--- What measures may be recommended for densely populated countries like India to address the problem of water shortage and promote water reuse? Are there any feasible and tangible solutions?
Response 3: Thanks for your comments. The measures recommended for densely populated countries to address the problem of water shortage and promote water reuse, as well as the feasible and tangible solutions were added in the conclusions and outlook as you suggested.
Comment 4: 46% of the global population (3.6 billion people) lacks toilets to safely dispose of human excreta, and nearly 892 million people do not have access to adequate sanitation facilities, and they continue to defecate in the open--- What is the worldwide proportion of wastewater production from rural and urban areas? Which group, urban or rural individuals, has more responsibility for freshwater consumption? Who are the main contributors to water pollution? Both urban and rural populations lack access to sufficient sanitary facilities. If rural communities lack access to fresh water, it is unjust to hold them accountable for environmental and water shortage problems.
Response 4: Thanks for your comments. According to the literature search, due to the differences between rural and urban population distribution, living habits, economic level and so on. Rural sewage is relatively dispersed, low concentration, large changes, and most of them do not contain heavy metals and toxic and harmful substances, but contain a certain amount of nitrogen and phosphorus, water quality fluctuations, strong biodegradability, and urban sewage composition is different. The decentralized sewage treatment technology described in this paper mainly deals with rural domestic sewage, which was the main aim of this manuscript.
Comment 5: The effluent from the four ponds of each household can also be used for irrigation of family gardens or flower seedlings, realizing the resourceful utilization of water resources and nitrogen and phosphorus pollutants and significantly improving the rural environment--- nitrogen and phosphorus pollutants and used to significantly improving the rural environment.
Response 5: Thanks for your comments. The original text was checked and revised as you suggested.
Comment 6: The results showed that N2O removal was best in I-A/O and NOx removal was most significant in C-A/O--- what is the percentage of N2O removal observed here.
Response 6: Thanks for your comments. The ratio of N2O removal in I-A/O were added in section 3.1.2 as you suggested.
Comment 7: Current studies have found that BAF can also remove wastewater containing antibiotics, with the main mechanisms being biodegradation and adsorption--- What is the efficacy of the Biofilter in eliminating antibiotics from wastewater?
Response 7: Thanks for your comments. The effectiveness of biofilters in eliminating antibiotics from wastewater were added in section 3.2.2 as you suggested.
Comment 8: CWs work on the principle of sedimentation, filtration, precipitation, volatilization, adsorption and plant uptake of a variety of microorganisms distributed in the soil and on the plant surface--- By what process do plants absorb a diverse range of microorganisms found in the soil and on the surface of plants?
Response 8: Thanks for your comments. Additional discussions were added in the section 4.1 as you suggested.
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsAll issues have been modified and can be accepted.
Reviewer 3 Report
Comments and Suggestions for AuthorsThe article may be considered for publication.
