In this study, we examined the influence of the organic carbon-to-nitrogen ratio (chemical oxygen demand (COD/N)) and dissolved oxygen (DO) levels on the removal efficiency of pollutants and on the change in total microflora in the cyclic activated sludge system (CASS) in the Nyingchi prefecture in Tibet. The results demonstrated that the treatment performance was the best when the COD/N ratio was 7:1 or the DO levels were 2–2.5 mg/L in comparison with four different tested COD/N ratios (4:1, 5:1, 7:1, and 10:1) and DO concentrations (0.5–1, 1–2, 2–2.5, and 2.5–3.5 mg/L). The treatment performance can be explained by the relative operational taxonomic unit richness and evenness of the microbial communities in activated sludge. Evident microbial variance was observed, especially different COD/N ratios and DO concentrations, which were conducive to the disposal of urban sewage in plateaus. The results help to understand sewage treatment under different COD/N ratios or DO concentrations on plateaus. This work provides practical guidance for the operation of any wastewater treatment plant on a plateau.

This study evaluated the efficiency of wastewater treatment in constantly aerated CASS under different temperature levels, 4±1, 10±1, 15±1 and 20±1°C at Tibet Nyingtri. The change of microbial community structure of activated sludge reference to temperature levels was also analyzed. Results demonstrated that the treatment performance was the largest at the 20±1C by comparing the 4±1, 10±1, 15±1 and 20±1C four conditions. Bacteria belonging to the phylum proteobacteria, firmicutes, bacteroidetes, acidobacteria, nitrospira and chloroflexi have only been detected in this reactor. Ammonia and nitrate levels in all four reactors indicated efficient nitrification process. Results of this study offer new insights into understanding the performance of activated biomass vis-à-vis microbial community structures and degradative efficiency with reference to temperature levels on plateaus. This information would be useful in improving the efficiency of any wastewater treatment plant at high altitudes.

China's environmental pollution governance has entered the game stage centered on interests, and there are three main bodies in environmental pollution governance: the central government, local governments and firms. The research firstly reveals the relationships among the central government, local governments, and firms in the process of environmental governance, and then analyzes the game among the central government, local governments and firms using game theory in Economics. Finally, the research makes a conclusion and proposes some corresponding policy proposals so as to solve the problem of environmental pollution.

Gaining carbon neutrality by 2060 and achieving carbon peaking by 2030 will involve formidable challenges for China in the future. In order for the government to effectively implement carbon emission reduction policies, it will be critical to comprehend the spatial patterns of carbon stocks in terrestrial ecosystems (LULCs) in the context of the region’s future development. In this study, we proposed LULC models for the Lhasa River Basin in Tibet from 2020 to 2040 under three distinct development scenarios. With the exception of the 2040 BAU scenario, the study’s findings indicate that carbon stocks in the future in the Lhasa River Basin will increase significantly in comparison to 2020. Furthermore, the overall carbon stocks in the basin will decrease significantly in the aforementioned development scenarios of 2040 and 2030. We ought to closely monitor the alterations in carbon stock and landscape composition that arise in the Lhasa River Basin as a result of the expansion of croplands. In the Lhasa River Basin, the degrees of variation in the spatial patterns of carbon stock are the least pronounced under all three scenarios, with the ELP scenario being particularly noteworthy.