# Experimental Study on the Desalination of Waste Leachate Using the Combined Freezing Method
## 4 Conclusions  
This study focuses on evaluating and analyzing the effectiveness of three different methods of ice crystal desalination. Based on the above research, conclusions are summarized as follows:  
The optimum experimental conditions for determining the freezing time and freezing temperature by the single-factor method are 18 h and \(-\)15 \({}^{\circ}\)C, respectively.  
When the FGM is used to treat waste leachate wastewater, the rate of desalination increases as the rate of ice formation decreases. At higher ambient temperatures, the FGM has a better desalination effect, but it is not conducive to the removal of organic pollutants. When the ice production rate is 40%, the salt rejection reaches 84.28% at an average temperature of 5 \({}^{\circ}\)C in the winter. The salt rejection is even higher at an average temperature of 28 \({}^{\circ}\)C in the summer, reaching 87.71%.  
The FCM is a common desalination method, and its desalination effect is influenced by the centrifugal time and rotation speed. Research has found a significant correlation between the centrifuge time, centrifuge speed, and salt rejection (\(p<0.05\)). Increasing the centrifugal time and speed helps to improve the salt rejection, and increasing the centrifugal speed within the range of 1000-2000 rpm can accelerate the discharge of concentrated brine more effectively.  
The most promising FBM is the FCBM, which has higher desalination stability compared to the FGBM. As the blowing time increases, the salt rejection continues to increase, with a salt rejection of 93.86% at 5 min of blowing. Compared to the FGM and FCM, it accelerates the desalination process and improves salt rejection.  
Overall, our research results indicate that the combined freezing method for desalination is feasible and can be reasonably selected based on the water quality and effluent standards of different wastewaters. Especially when using the FCBM for wastewater treatment, shortening the desalination process and improving the desalination efficiency are undoubtedly promising. It is worth noting that the freezing method produces a large amount of concentrate in the process of waste leachate treatment, which may lead to a waste of resources and environmental pollution problems. Therefore, subsequent research will focus on improving the process parameters and recycling concentrate resources and, at the same time, pay attention to the removal of different salt ions in wastewater to gain a deeper understanding of the differences in the removal of salt ions by freezing methods.  
X.W.: Conceptualization, Data curation, Formal analysis, and Writing--original draft. C.Z.: Funding acquisition, Data curation, Supervision, and Writing--review and editing. B.G.: Methodology and Data curation. B.Z.: Funding acquisition and Data curation. X.L.: Investigation. Y.G.: Investigation. Y.D.: Data curation. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the National Natural Science Foundation of China (41877041), Qilu University of Technology (Shandong Academy of Sciences) Science Education Industry Integration Innovation Pilot Project (2020 KJC-ZD13), the Natural Science Foundation of Shandong Province (ZR2022 MC204), and study on the Application of Highly Substituted Cationic Starch in Textile Industry (2021 CXY-09).  
Not applicable.  
**Data Availability Statement:** Data is contained within the article.  
**Conflicts of Interest:** The authors declare no conflict of interest.