Review Reports - Strain Screening and Conditions Optimization in Microalgae-Based Monosodium Glutamate Wastewater (MSGW) Treatment

Round 1

Reviewer 1 Report

please optimize a few things:

line 54: Chlorella or clorella?

line 56: which chlorella?

line 56: why TN and NH3+, not Nitrate and NH3+ is given?

line 102; For description of the apparatus: only light intensity is given, not the form of the vessel. the effectivity of the light depends on the penetration depth (or exact form), please add some geometric parameters

Fe3+: in which form is it used? as sulfate?, with or without complex buildner, gelates or any other stabilization? this is very important for the effectivity and stability in the oxidation form.

Fe3+: are the concentration calculated from the input or measured during the experiments?

Fig 1: diution -> dilution

Conclusion is too short, please write the optimal constellation (light, Fe, concentrations....)

Author Response

Reviewer1：

please optimize a few things:

1) line 54: Chlorella or clorella?

A:We are sorry that this is due to our carelessness in writing, and it has been corrected in the article at line 167 now.

2) line 56: which chlorella?

A: Thanks for your reminding, the cited document uses Chlorella vulgaris FACHB-8 to carry out experiments, which has been indicated in the article at line 170-171.

3) line 56: why TN and NH3+, not Nitrate and NH3+ is given?

A: In this cited literature, only TN, TP and NH₃⁺ were determined. Because total nitrogen (TN) is commonly used as an indicator of the release standard, rather than nitrate-nitrogen.

4) line 102; For description of the apparatus: only light intensity is given, not the form of the vessel. the effectivity of the light depends on the penetration depth (or exact form), please add some geometric parameters

A: According to your suggestion , We have made the following modifications to your suggestion. The light intensity of 90 μmol m^–2 s^–1 with a photoperiod cycle of 12:12h light/dark was provided by LED arrays with 6500 K LED cool daylight above the culture. The specific information about the light incubator has been added in the article at lines 204-206.

5) Fe3+: in which form is it used? as sulfate?, with or without complex buildner, gelates or any other stabilization? this is very important for the effectivity and stability in the oxidation form.

A : Thank you for your supplement. The Fe³⁺ used in this experiment was in the form of ferric chloride, and boric acid (H₃BO₃) was present in the trace metal solutions for the purpose of stabilization. In response to your suggestions, we have made the following modifications: add reagent description in lines 441-442.

6) Fe3+: are the concentration calculated from the input or measured during the experiments?

A : Thanks for your reminding. Fe³⁺ concentration was calculated from the input as indicated “initial Fe³⁺ concentrations”.

7) Fig 1: diution-> dilution

A : I am very sorry for the problems in the marking of the Figure 1. due to the trial and error of writing. Thank you for your correction.

8) Conclusion is too short, please write the optimal constellation (light, Fe, concentrations....)

A : Thank you for your suggestion. According to your suggestion, we add the optimization results of various factors in the conclusion section in lines 806-820.

Reviewer 2 Report

The manuscript has focused on the study of microalgae– 2 based monosodium glutamate wastewater (MSGW) treatment. The results were reasonable. I would like to recommend the publication of this study if the following improvements could be made.

1) The explanation in the literature review section needs to have more depth. Besides showing the research trend in the related field, you need to critically review the previous related studies and reveal the knowledge gaps and inconsistencies in the literature. Then, you need to relate it to the objectives of the study. The authors need to emphasise the research novelty and research significance of the study.

2) The original MSGW wastewater characteristics were as follows (mg L–1 ): pH, 4.01±0.01; COD, 347562.5±11226.83; TN, 46526.32 ± 4211.40; TP, 2756.15 94 ±163.77; NH4 +–N, 16281.75 ± 567.47, please Rewrite the sentence because the pH doesn’t have the unit of measure mg/L.

3) Please make a correlation between informations about growth medium from fig 2 – whith the information from section 2.2. For example MSGW of 1000–fold dilution is (1000MSGW) not just MSGW.

4) The information provided in the Table 1 – without the last row is presented also in the Figure 3. Please maintain a single representation.

5) Authors should conclude by stating the highlights of the study, benefits and the applicability of your findings/results for further work and recommendations.

Author Response

Reviewer2：

The manuscript has focused on the study of microalgae–based monosodium glutamate wastewater (MSGW) treatment. The results were reasonable. I would like to recommend the publication of this study if the following improvements could be made.

A : Thank you for your suggestion. Based on your suggestion, we have incorporated additional introductions regarding the current research bottleneck and further refined the research purpose of this study in line 188-195.

2) The original MSGW wastewater characteristics were as follows (mg L–1 ): pH, 4.01±0.01; COD, 347562.5±11226.83; TN, 46526.32 ± 4211.40; TP, 2756.15 94 ±163.77; NH4 +–N, 16281.75 ± 567.47, please Rewrite the sentence because the pH doesn’t have the unit of measure mg/L.

A : Thank you for your suggestion. The issue has been amended in lines 412-414 now.

3) Please make a correlation between informations about growth medium from fig 2 – with the information from section 2.2. For example MSGW of 1000–fold dilution is (1000MSGW) not just MSGW.

A : Thanks for your correction, the information in Figure 2 and 2.2 has been matched.

4) The information provided in the Table 1 – without the last row is presented also in the Figure 3. Please maintain a single representation.

A: Thank you for your suggestion. According to your suggestion, we have removed the nutrient removal rates and maintain the specific growth rates in Table.1.

5) Authors should conclude by stating the highlights of the study, benefits and the applicability of your findings/results for further work and recommendations.

A : Thank you for your suggestion. According to your suggestion, we have made corresponding supplementary modification in line 826-828 of the article.

Reviewer 3 Report

In this paper, The application of microalgae for monosodium glutamate wastewater (MSGW) treatment can result in simultaneous wastewater purification and biomass recovery. The algae species that can grow and survive in diluted MSGW were screened, and the wastewater composition and growth conditions were optimized to obtain high algal biomass and nutrient removal. Among the tested species, Chlorella sp. FACHB–30 exhibited the highest potential for MSGW treatment, achieving a maximum specific growth rate of 0.28 d⁻¹ and the highest COD removal rate of 61.50% after 20 d of cultivation with trace metals supplementation in the wastewater. This work can give some guidance for the microalgae–based MSGW treatment. However, before considering publication, there are some issues that need to be clarified. The detailed comments are as follows:

1. The graphical abstract needs to be added.

2. There are many water treatment technologies, such as adsorption, photocatalysis and microwave catalysis, should be introduced in the introduction. The advantages and disadvantages of these techniques should be introduced. The new reviews and references on adsorption, photocatalytic purification and microwave catalysis of wastewater should be introduced and cited. Microwave catalysis: Separation and Purification Technology, 307 (2023) 122716; Advanced oxidation: Surfaces and Interfaces, 36 (2023) 102564; Journal of Catalysis, 374, 2019, 118-126.

3. At the beginning of the abstract, a brief background of the MSGW should be provided.

4. MSGW is treated as a pollutant. Please describe the hazards of MSGW in more detail.

5. The cultivation diagram of microalgae strains should be provided。

6. The MSGW processing device diagram needs to be provided.

7. Some tense problems, grammatical problems and the beauty of pictures in the article need to be further improve.

Author Response

Reviewer3：

1. The graphical abstract needs to be added.

A: Thanks for suggestion. We have added the graphical abstract according to your suggestion.

A: According to your suggestion, water treatment technology and its advantages and disadvantages are added in the article, which is presented in the article in line 71-80. The references of microwave catalysis and advanced oxidation were also added in the reference list.

3. At the beginning of the abstract, a brief background of the MSGW should be provided.

A : Thanks to your suggestion, we now add a description of the background of MSG wastewater to lines 11-14 of the abstract.

4. MSGW is treated as a pollutant. Please describe the hazards of MSGW in more detail.

A : Thank you for your suggestion. According to your suggestion, we have described the monosodium glutamate wastewater pollution in lines 81-85 of the article.

5. The cultivation diagram of microalgae strains should be provided。

A: Thanks for suggestion. The cultivation diagram of microalgae strains has been added and descripted in the graphical abstract.

6. The MSGW processing device diagram needs to be provided.

A: Thanks for suggestion. In this study, we only carry out the batch culture in the flasks, and all the details have been descripted in the text and the graphical abstract.

7. Some tense problems, grammatical problems and the beauty of pictures in the article need to be further improve.

A : Thank you for your suggestion. We have revised tense problems, grammatical problems all through the manuscript and beautified the pictures in the article.

Round 2

Reviewer 3 Report

accepted