The Oily sludge with high water content (OS) was dewatered, modified and converted into solid fuel by a novel chemical conditioner (OSO-101). The effect of OSO-101 dosage on the dewaterability of OS was studied, showing that OSO-101 dosage of 15% (wt.) could achieve the best dewaterability efficiency of OS (98.18%). Meanwhile, compared with some conventional conditioners, OSO-101 developed by our team was more effective in improving OS dewaterability efficiency. And OSO-101 may have free radical reaction, polar reaction and redox reaction with petroleum hydrocarbons in OS, thereby polymerizing and forming condensed solid structures. The calorific value change of OS after conditioning, heavy metal content and dioxins content of fly ash leached from incinerated product were measured for resource analysis and environmental assessment. Results showed that the resultant OS fuel blocks had extremely low content of heavy metals, dioxins and other toxic and hazardous substances leached from fly ash, thereby no secondary treatment and fully meeting environmental protection emission standards. Additionally, OSO-101 had certain economic rationality, and could effectively recover the calorific value contained in OS. This research is expected to provide new insights for efficient dewaterability and modification of OS, as well as subsequent resource utilization and harmless treatment, bringing potential environmental and economic benefits.
Research Article
Novel Conditioner For Efficient Dewaterability And Modification of Oily Sludge With High Water Content
https://doi.org/10.21203/rs.3.rs-774729/v1
This work is licensed under a CC BY 4.0 License
Journal Publication
published 28 Nov, 2021
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Oily sludge
Conditioner
Dewatering
Harmless treatment
Resource recovery
(1) OS was dewatered, conditioned and converted into solid fuel by OSO-101.
(2) The dewaterability efficiency of OS was 98.18% with the addition of 15 wt.% OSO-101.
(3) OSO-101 can increase calorific value of OS and improve feasibility for fuel utilization.
With the rapid development of global economy and the deterioration of crude oil, the amount of oily sludge with high water content (OS) is ascending year by year, and processing difficulty also increases (Ren et al., 2020). OS is composed of water, organic matter and solid residue, which forms a multiphase mixed system. Due to the difference of production area and refining method of crude oil, the water content, oil content and solid content of OS are generally 80 ~ 99%, 0.5 ~ 50% and 0.2 ~ 40%, respectively (Ningbo et al., 2021). The water in OS does not exist alone, and most of that is combined with other ingredients (e.g., petroleum substances) to form a fairly stable emulsified structure such as oil-in-water and water-in-oil. Organics in OS includes crude oil, asphalt, alkanes and some benzene series. Thus, OS has the characteristics of serious emulsification, high viscosity and difficulty in sedimentation and dewaterability (Zhang and Liu, 2013). Additionally, OS also contains toxic, harmful and refractory organics such as benzene, phenols and anthracene, as well as heavy metal salts (copper, chromium, mercury, etc). It will endanger ecological environment and human health if directly stacked or improperly handled (AL-Doury, 2019). According to the "Solid Waste Environmental Pollution Prevention Law" and the "Hazardous Waste List", OS needs to be harmlessly treated and used as resource.
At present, the main treatment methods of OS include conditioning-mechanical separation (Hou et al., 2013), solvent extraction (Mohit et al., 2020), freezing/thawing (Ju et al., 2012), pyrolysis (Liu et al., 2021), incineration (Dal Mas et al., 2021), solidification method (Hu et al., 2020), etc. Among them, incineration method is to treat OS with the characteristics of low oil content, a certain calorific value (Tunçal and Uslu, 2014). The technical advantages of incineration are rapid operation, thorough treatment, high sterilization rate and great reduction effect. After treatment, the reduction rate of OS can reach ~ 95%. In this case, the organics in OS will be completely oxidized and then completely decomposed, discharged in the form of fly ash, flue gas, slag, etc, which solves the foul smell of OS (Xiehong et al., 2017). However, there exists problems such as secondary pollution, high cost and energy consumption. In particular, the leaching amount of heavy metals and the produced dioxins are relatively high after incineration (Hu et al., 2013). Hence, it is urgent to transform OS into solid fuel by conditioning. Briefly, OS is firstly dehydrated and modified, and then converted into solid fuel. In this way, the harmless treatment of OS can be reached, and the residual value of OS can be recycled to realize resource utilization to the greatest extent.
Based on this, we developed a novel OS conditioner (OSO-101). On one hand, the reduction, harmlessness and stabilization of OS processing were realized. On the other hand, the resource utilization of OS was completed. Free radical reaction, polar reaction and redox reaction with were possibly involved between OSO-101 and petroleum hydrocarbons, thereby OS could be polymerized and converted into condensed solid structures. Moreover, the mixed solid was stable, irreversible and would not cause secondary sludge (Qinghua et al., 2021). Simultaneously, OSO-101 made long-chain non-flammable components (e.g., asphaltenes and gums) polymerize, and the water adsorbed in OS was converted into free water and released (Zhang et al., 2014). Under normal temperature and pressure, OS was finally transformed into solid fuel after curing in natural conditions for 3–5 days or reacting by mechanical drying for 1 h, which had great incineration performance. The whole treatment process would not produce wastewater and exhaust gas, and is safe, harmless and simple to operate. Automatic production could be realized in this treatment process, in which small space occupation, short investment cycle and quick effect could also be reached.
Herein, X-Ray fluorescence (XRF) and other methods were utilized to analyze the physicochemical properties of OS, and the effect of OSO-101 dosage on the dewaterability of OS were studied. Then, the effects of conditioning and incinerating on the solid-phase morphology, element composition and surface functional groups of OS were analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and some other characterization methods. Finally, the calorific value change of OS after conditioning, heavy metal content and dioxins content of fly ash leached from incinerated product were measured for resource analysis and environmental assessment.
2.1 Materials
OS used in this work was taken from Shanghai Huarun Dadong Hazardous Waste Disposal Center (Shanghai, China), and the conditioner OSO-101 was produced by Zhongze Green Link Energy Environmental Technology Co., Ltd (our group). OSO-101 mainly contains calcium oxide (CaO), calcium sulfate (CaSO4), calcium carbonate (CaCO3), etc, in which the auxiliary materials were agricultural organic waste or industrial solid waste. For comparison, alum, lime, gypsum and fly ash, which were all purchased from Sinopharm Chemical Reagent Co., Ltd (Shanghai, China), were also used in this work. In the experiment, deionized (DI) water was used for solution preparation. All chemicals were purchased in analytical grade or higher purity and can be used directly without further purification.
2.2 Characterization of oily sludge
The oil content of OS samples was evaluated by Soxhlet extraction method. According to crude oil water content determination method (GB/T 8929 − 2006), the water content of OS was determined. Then, the solid content was the total amount minus water content and oil content. The elemental composition of OS was determined by XRF (Model Var10EL-III, Elementar, Germany). Fourier transform infrared spectroscopy (FT-IR, Nicolet 6700, Thermo Fisher Scientific, USA) was used to analyze the surface functional groups of OS. SEM (S-3400 II, Hitachi, Japan) was used to scan OS after spraying gold, and the scanning voltage was 2.0 kV and the magnifications were 5000, 10000, 20000 and 30000 times. The composition and crystal phase of OS were analyzed by XRD (X’TRA, ARL, Switzerland) (40 kV and 40 mA). X-ray photoelectron spectroscopy (XPS, PHI 5000 VersaProbe, Japan) was performed to investigate surface chemistry of OS after dewatering (OSAD) and after incineration (OSAI).
2.3 Conditioning process
The effect of OSO-101 dosage on the dewaterability of OS was studied to explore the optimum dosage of conditioner. A certain amount of OS was weighed and placed in ceramic dishes, in which 5%, 10%, 15% and 20% (wt.) OSO-101 were added respectively and stirred evenly. OSAD was obtained, weighed at intervals after drying at 20°C, and compared with dewaterability of alum, lime, gypsum and fly ash. Then, OSAD was incinerated at 900°C to obtain OSAI. The dewatering rate (Dw) and capillary suction time (CST) were used to measure dewaterability of OS. Dw was calculated by Eq. (1) (Dandan et al., 2020). CST was determined by using a TRITON Type 304M CST-meter.
(1)Where, ms (g) is the mass of water in OS (g), mc (g) is the reduced water mass of OS after adding OSO-101.
2.4 Analytical methods
In order to explore the resource utilization potential of OS after conditioning, industrial analysis and calorific value measurement were carried out on OSAD. The calorific value of OSAD refers to "Coal Calorific Value Measurement Method" (GB/T 2013 − 2008), and the industrial analysis of OSAD refers to "Coal Industrial Analysis Method" (GB/T 2012 − 2008). The fly ash after incineration was leached in accordance with standard method "Solid waste leaching toxicity leaching method, sulfuric acid and nitric acid method" (HJ/T 299–2007). The inductively coupled plasma optical emission spectrometer (ICP-MS, PerkinElmer, Optima 8000, USA) was used to quantitatively detect heavy metal content and chloride ion concentration of fly ash leached from OSAI. Gas chromatographic-mass spectrometry (GC-MS) (7890AGC/597D, Agilent Technologies Co., Ltd, USA) was used to analyze the content of dioxins.
3.1 Characterization of OS
As presented in Fig. 1(a), it is experimentally found that the water content, oil content, and solid content of OS are 79.30%, 11.31%, and 9.39%, respectively, in which the water content in OS is relatively high. The main constituent elements in OS are C and O (Fig. 1(b)). In addition, OS also contains heteroatoms such as Ca, Si, Al and S (to be discussed in Sect. 3.4). The generation of S element may be attributed to the concentrated sulfuric acid added in process of demulsification and degreasing (Jin et al., 2021). Al element may originate from the corrosion and leaching of the Al coating on the bottom of oily tank. The industrial analysis results of OS are shown in Table S1, and the moisture (Mad), ash (Aad), volatile content (Vad), and fixed carbon (FCad) of OS are 79.30%, 8.74%, 10.39% and 1.57%, respectively. It can be seen from Table S1 that OS has the characteristics of high Mad, low Aad, low Vad and low FCad. High water content made OS disposal extremely energy-consuming by incineration and released excess offgas simultaneously. Therefore, efficient dehydration of OS is imperative for resource utilization.
3.2 Effect of OSO-101 dosage on dewatering rate
After adding varying dosage of OSO-101, the results of Dw are shown in Fig. 1(c). Dw of OS could reach 79.52% after the addition of 5% OSO-101, and its effect on dewaterability of OS was obvious. When the dosage of OSO-101 reached 15%, Dw could further increased to 98.18%, showing that the rise of OSO-101 dosage could significantly improve oil-water separation efficiency of OS. However, Dw of OS was reduced to 95.99% while OSO-101 dosage reached 20%. This may be because excessive OSO-101 reacted with organic matters in OS through free radical reaction, polar reaction and redox reaction, which made particle sizes of OS smaller and affected its dewaterability (Guo et al., 2016). The drying images and incineration images of OS after adding different OSO-101 dosage also proved above conclusions (Fig. 2). The appearance of OSAD gradually changed from black to light yellow, and the appearance of OSAI also gradually changed from dark red to light yellow, which demonstrated efficient dewaterability and modification of OSO-101 on OS. In summary, it can be preliminarily determined that 15% OSO-101 could achieve the best dewaterability efficiency for OS studied in this experiment.
3.3 Effect of different conditioners on CST
Some conventional modifiers such as alum, lime, gypsum and fly ash were used in the comparative study of OS dewaterability and conditioning (Fig. 3). After conditioning OS with alum, lime, gypsum and fly ash, CST decreased from 2000 s to 758 s, 1232 s, 1362 s and 1426 s, respectively, while CST dropped from 2000 s to 342 s with the addition of OSO-101. High CST reveals that OS is difficult to dehydrate. The significant reduction on CST indicated that OSO-101 had the advantage of high-efficiency dehydration for OS, which could greatly reduce volume of OS and reduce cost of subsequent incineration treatment. Furthermore, the change trend of CST was basically similar for different conditioners (Fig. 3). As the dosage of conditioners increasing, CST firstly dropped to the lowest value, and then showed an upward trend. As reported in the literatures,although both alum and lime are the most commonly used conditioners in OS treatment, alum has better dewaterability efficiency and chemical conditioning properties for OS. It is well known that lime will increase solid content and pH value of final products (Buyukkamaci and Kucukselek, 2007). Gypsum (CaSO4·2H2O) is another material used for conditioning OS, which is usually precipitated from water with high salinity. The addition of gypsum obviously enhanced release of water and established a more rigid lattice structure. Fly ash is the residual waste in incineration process. Although it can also be used as conditioner for zero-cost materials, the use of fly ash will possesses serious risks of toxic heavy metals release (Chen et al., 2018). In view of these discussions above, OSO-101 developed by our team was more effective in improving OS dewaterability.
3.4 Effect of solid phase morphology and composition on dewatering process
SEM images and drying images of OSAD at optimal OSO-101 dosage are shown in Fig. 4 and Fig. 5, respectively. The microscopic morphology of OSAD under different magnifications were observed. OSAD was mainly composed of spherical particles and there were some rod-shaped particles attached to the surface (Fig. 4). This may be ascribed to successful conditioning and modification of OS by OSO-101, which significantly promoted efficient dewaterability. It was found that Dw increased from 0 to 98.18% during the 72 h conditioning and drying experiment (Fig. 1(a)). OSAD gradually changed from black viscous solids to yellow-brown solid powder (Fig. 5). As demonstrated in Fig. 6(a) from XRD results, OSAD contained CaSO4 (JCPDS File No. 01-0385), CaCO3 (JCPDS File No. 24–0027), and SiO2 (JCPDS File No. 30-1127) and other substances. There may be some minor minerals, such as MgCO3 (JCPDS File No. 08-0479), BaMg(CO3)2 (JCPDS File No. 12–0530), CaAl2SiO8 (JCPDS File No. 41-1486) and so on. OSAD was incinerated to form OASI, and characteristic diffraction peaks of CaSO4 and CaCO3 disappeared due to high temperature decomposition. Additionally, the intensity of characteristic diffraction peaks of CaO at 32°, 38° and 39° (JCPDS File No. 74-1226) increased and the peak shape became sharper, indicating that crystallinity was enhanced (K and A, 2008).
FT-IR spectra of OSAD and OSAI were compared in Fig. 6(b). It can be found from that the vibration peak of OSAD at 3420 cm− 1 represented the vibration of O-H. This finding was due to the carboxyl and hydroxyl structures in OSAD (Girault et al., 2015). A vibration peak of C = O appeared at 1660 cm− 1, illustrating that there may be carboxyl groups in OSAD. The characteristic peak at 1461 cm− 1 corresponded to the asymmetric stretching vibration of C-H in -CH2 and -CH3. There was a characteristic peak at 1116 cm− 1, resulting from the existence of C-O bond. It can be inferred that OSAD should be dominated via alcohols, phenols and oxygen-containing heterocyclic compounds (Guo et al., 2011). However, compared with FT-IR spectra of OSAI, there was no vibration peak at 1660 cm− 1 and 1461 cm− 1, indicating that there was no carboxyl group in OSAI. OSAI had a characteristic peak of C-O bond at 1157 cm− 1, demonstrating that there may be ester compounds in OSAI. It was speculated that main chemical functional group should be C = C and C = O in OSAI. Therefore, OSAI mainly contained ketones, esters and unsaturated hydrocarbons. As a result that chemical conversion reactions occurred in the petroleum compounds during incineration process, mainly from alcohols and phenolic compounds to ketones. C-C bond and C-O bond may react to form ketones and olefins through dehydrogenation condensation reaction (Zhao et al., 2018).
The specific existence forms of C, O and S elements in OS and OSAD are determined by XPS. Figure 7(b1) and Fig. 7(c1) are XPS peak fitting diagrams of C ls, demonstrating that there were three main forms of C elements in OS and OSAD, namely sp2-C, C-O and C = O (Mu et al., 2021). The specific parameters of each C element form are shown in Table S2. The sp2-C had a maximum of 72.36%, followed by C-O (26.41%), and C = O bond had a minimum of 1.23% in OS (Table S2), while sp2-C had a maximum of 70.65%, followed by C-O (27.54%), and C = O bond had a minimum of 1.82% in OSAD. Thus, C in OS and OSAD mainly existed in the form of sp2-C, which may come from the polycyclic aromatic hydrocarbon coke on OS and OSAD (Long et al., 2013). It is worth mentioning that after OS was conditioned via OSO-101, the content of sp2-C decreased from 72.36–70.65%, which meant that OSO-101 may have free radical reaction, polar reaction and redox reaction with petroleum hydrocarbons in OS, thereby polymerizing and forming condensed solid structures (Kuang et al., 2011). Figure 7(b2) and Fig. 7(c2) are the O 1s high-resolution analytical spectra of OS and OSAD. There were two main forms of O elements in OS and OSAD. Most of O elements in OS and OSAD existed in the form of quinone groups. Notably, after being conditioned by OSO-101, the content dropped from 68.68–57.63% (Table S3). Similarly, the content of phenolic-OH and etheric C-O-C rose from 31.32% to 42.37, which confirmed that OSO-101 may have an oxidation-reduction reaction with OS. Figure 8(b3) and Fig. 8(c3) are the XPS spectra of S 2p. There were six main forms of S element in OS and OSAD, which were sulfate sulfur, sulfonic sulfur (sulfone), sulfide (sulfoxide), aromatic sulfur (thiophene), aliphatic sulfur and mercaptan (Zhen et al., 2019). In OS, aliphatic sulfur existed at most 27.03% and sulfate sulfur existed at least 3.14% (Table S4). In contrast, aliphatic sulfur was at most 23.61% and sulfide (sulfoxide) was at least 9.70% in OSAD. Therefore, S in OS and OSAD was commonly present in the form of aliphatic sulfur and the total content of organic sulfur was relatively higher. Additionally, XPS is used to determine element content on the surface of OS and OSAD (15% OSO-101), indicating that the content of C, O, Cl decreased slightly after conditioning and the content of N and S elements rose (Table S5). XPS characterization proved successful chemical conditioning of OSO-101 on OS.
3.5. Resource recovery analysis
3.5.1 Analysis calorific value change
Generally, calorific value of materials is the basic condition for fuel utilization. To realize fuel treatment of OS after dehydration and conditioning, its calorific value needs to be analyzed. After adding different OSO-101 dosages, the changes of OSAD calorific value are shown in Fig. 8. Calorific value of OSAD without OSO-101 was basically the same as that after adding fly ash, which were 10285.13 kJ/kg and 10354.56 kJ/kg, respectively. When the dosage of OSO-101 increased from 5–15%, calorific value of OSAD increased from 12842.14 kJ/kg to 14564.45 kJ/kg, increased by 11.82%. As OSO-101 dosage increasing, calorific value of OSAD slightly dropped to 14337.15 kJ/kg. It shows that OSO-101 can not only strengthen efficient dewaterability of OS, but also increase calorific value of OS and improve feasibility of fuel utilization. Actually, the treatment process of OS was a natural curing and drying process, and its purpose was to further reduce the water content and increase calorific value through evaporation. Basically, the heat released by incineration cannot be increased by simple natural curing and drying. But the latent heat loss of vaporization was reduced due to reduction of water in OS, thereby improving incineration efficiency of OS (Zubaidy and Abouelnasr, 2010). As a result, it is economically reasonable to use OSO-101 to strengthen efficient dewaterability and modification of OS, and it can effectively recover the calorific value contained in OS (Leena and Kurian, 2021).
3.5.2 Analysis of fly ash leaching
Dioxins are composed of two groups of 210 chlorinated aromatic compounds, which are carcinogenic and teratogenic to humans. The formation of Dioxins was due to that the organics containing chlorine decomposed or burned (Zhang et al., 2017). Thus, chlorine is a necessary factor for the generation of dioxins, and chloride ions in OS should be reduced during OS incineration process. Heavy metal content and dioxins content of fly ash leached from incinerated product were measured (Table 1 and Table 2). The results suggested that the fly ash leached from OSAD had extremely low content of toxic heavy metals. Among them, the concentrations of beryllium (Be), total chromium (Cr) and Cr6+ were all below detection limit. Moreover, the dioxin content in fly ash produced after OSAD incineration was reduced from 3.61 µgTEQ/kg to 0.051 µgTEQ/kg. The chloride ion concentration dropped from 170.80 ppm to 35.18 ppm, that is a decrease of 79.4%. So OSAD can be fabricated to an OS fuel block with better overall performance. Additionally, the content of heavy metals and dioxin produced in fly ash after incineration can be further reduced without affecting fuel performance. The content of dioxins in fly ash after incineration was in full compliance with the "Air Pollutant Emission Standards" (GB3095-2012). OSO-101 conditioner can completely realize the harmlessness and cleaning of OS, and has high environmental benefits (K and A, 2007).
|
Heavy metal |
OSAI(15%)/(mg/L) |
GB16889-2008 |
|---|---|---|
|
Barium (Ba) |
1.49 |
25 |
|
Beryllium (Be) |
ND* |
0.02 |
|
Total chromium (Cr) |
ND |
4.5 |
|
Copper (Cu) |
3.89 |
40 |
|
Nickel (Ni) |
0.03 |
0.5 |
|
Zinc (Zn) |
35.2 |
100 |
|
Arsenic (As) |
1.6×10− 2 |
0.3 |
|
Selenium (Se) |
2.1×10− 3 |
0.1 |
|
Mercury (Hg) |
1.5×10− 3 |
0.05 |
|
Antimony (Sb) |
2.48 |
- |
|
Manganese (Mn) |
1.64 |
- |
|
Cr6+ |
ND |
1.5 |
| * ND means that the detection result was less than detection limit. | ||
|
Oily sludge samples |
Clˉ/(ppm) |
Dioxins/(ugTEQ/kg) |
GB16889-2008/(ugTEQ/kg) |
|---|---|---|---|
|
OS |
170.80 |
3.61 |
≤ 3 |
|
OSAI(15%) |
35.18 |
0.051 |
3.6. Environmental assessment
OS is a precious secondary resource, and random discharge without treatment will not only cause huge damage to the environment, but also a huge waste of resources. With the increasingly rigid environmental regulations, harmless, clean and resource-based OS treatment method will become an inevitable trend. Based on this, OSO-101 conditioner can dehydrate and convert OS into solid fuel, which has the following excellent environmental and economic benefits: (1) simple equipment, convenient operation, low energy consumption, no secondary sludge treatment; (2) The solid fuel after polymerization has good thermal stability and better incineration performance (14564.45 kJ/kg). Thus, OSO-101 conditioner can completely realize harmless, clean and resource treatment of OS. And OS fuel blocks had extremely low content of heavy metals, dioxins and other toxic and hazardous substances leached from fly ash, and could fully meet environmental protection emission standards.
After analyzing the physical and chemical properties of OS through X-Ray fluorescence (XRF) and other methods, it was found that the water content in OS was relatively high (79.30%). The main constituent elements in OS were C and O. The effects of different dosages of OSO-101 on the dewaterability of OS were experimentally studied. The results suggested that the dosage of OSO-101 to achieve the best dewaterability for OS studied in this experiment was 15% (wt.%) and Dw can reached as high as 98.18%. Meanwhile, some conventional conditioning agents such as alum, lime, gypsum and fly ash were used in comparative studies of OS conditioning, indicating that OSO-101 developed by our team was more effective in improving OS dewaterability. OSO-101 may have free radical reaction, polar reaction and redox reaction with petroleum hydrocarbons in OS, thereby polymerizing and forming condensed solid structures through SEM, XRD, FT-IR and XPS characterization. Resource recovery analysis showed that oily sludge fuel blocks made of OS after OSO-101 conditioning had extremely low content of heavy metals, dioxins and other toxic and hazardous substances leached from fly ash, not requiring secondary treatment and fully meeting environmental protection emission standards. What’s more, adding OSO-101 as a conditioner to OS can not only strengthen efficient dewaterability of OS, but also can increase calorific value of OS and improve feasibility for fuel utilization, realizing environmental protection and energy saving of oily sludge disposal with prevalent application prospects.
Ethics approval (All studies above did not involve human patients or had any human intervention, so Ethical Approval may be not required.)
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Authors Contributions
Conceptualization: Biming Liu, Yue Teng; Methodology: Yue Teng, Wenbin Song; Formal analysis and investigation: Wenbin Song; Writing - original draft preparation: Yue Teng; Writing - review and editing: Biming Liu, Yue Teng; Funding acquisition: Biming Liu; Resources: Biming Liu; Supervision: Haixia Wu.
Funding
This research was supported by Science Fund Program for Young Scholars of the National Natural Science Foundation of China (51707093).
Competing Interests
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Availability of data and materials
Data available within the article or its supplementary materials. The authors confirm that the data supporting the findings of this study are available within the article and/or its supplementary materials.
Author Statement
Manuscript title (Novel Conditioner for Efficient Dewaterability and Modification of Oily Sludge with High Water Content):
I have made substantial contributions to the conception or design of the work; or the acquisition, analysis, or interpretation of data for the work; And I have drafted the work or revised it critically for important intellectual content; And I have approved the final version to be published; And I agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.
All persons who have made substantial contributions to the work reported in the manuscript, including those who provided editing and writing assistance but who are not authors, are named in the Acknowledgments section of the manuscript and have given their written permission to be named.
Printed name: Yue Teng
Date signed/appended: 2021.08.04
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