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Against the backdrop of the great challenge of climate change and growing global environmental concerns, this study deals a systematic literature review of research related to Environmental Kuznets Curve (EKC) from 1991 to 2023, details the background, definition, significance, critiques, theoretical foundations and model specifications of EKC, and summarizes the data, variables, econometric methods and findings used in over 100 EKC studies. This study focuses on EKC studies that examine the relationship between energy consumption, economic growth and environmental degradation, with most of the studies reviewed using global pollutants (carbon emissions) to measure the level of environmental degradation. This study found that EKC still has great research potential, and with the development of energy diversification, energy consumption in EKC studies have been further subdivided into renewable or non-renewable energy consumption; innovative EKC studies in the last few years have favoured the use of novel environmental and economic indicators and econometric method, and have validated the existence of EKC at the sectoral level rather than the national level. Finally, the present study summarizes the development and innovations of EKC and provides suggestions for future research aimed at advancing the development of EKC and environmental management. • The study provides a systematic literature review of Environmental Kuznets Curve. • The study critically reviews the critical issues that have emerged in recent years. • The study summarizes innovations in environmental and economic indicators. • This study innovatively analyses from the perspective of energy diversification. • The study suggests specific future research from novel direction. [ABSTRACT FROM AUTHOR]

The phosphorus content in eel aquaculture wastewater exceeds the discharge standard, and the amount of wastewater discharged is substantial. Therefore, there is an urgent need to explore an economical and efficient method of treating aquaculture wastewater. This study explored the use of Desmodesmus sp. PW1, a type of microalgae, to treat eel aquaculture wastewater. By optimizing the conditions, Desmodesmus sp. PW1 achieved a total phosphorus (TP) removal efficiency of 92.3%, as well as total nitrogen (TN) and ammonia nitrogen (NH 4 +-N) removal efficiency of 99%, using a photoperiod of 24:0, a temperature of 25 °C, and an inoculation amount of 15%. Furthermore, Desmodesmus sp. PW1 demonstrated a high self-flocculating efficiency (>90%) within 100 min of settling, which facilitated biomass recovery. Subsequently, a semi-continuous treatment process mode was established with a sewage renewal rate of 90%. The results showed that after four rounds of sewage renewal operations, the microalgae biomass in the sewage treatment system could be maintained between 160.0 and 220.0 mg/L, and the average removal rate of TP was 0.13 mg/(L * h). The lipid content of algae cells collected in the semi-continuous treatment system for eel aquaculture wastewater was as high as 36.5%, and the biodiesel properties met the biodiesel standards authorized by Europe and the United States. Overall, this study provides an economical and effective strategy for converting wastewater into high-value microalgae products. [Display omitted] • Desmodesmus sp. PW1 demonstrated high removal efficiencies of 92.3% for TP and 99% for TN in treating eel aquaculture wastewater • Desmodesmus sp. PW1 demonstrated a self-flocculating efficiency of over 90% within a settling time of 100 min. • A semi-continuous model with a renewal rate of 90% for treating eel aquaculture wastewater was constructed. • Desmodesmus sp. PW1 contained 36.5% lipid that can be utilized for preparing biodiesel. [ABSTRACT FROM AUTHOR]