At present, research on the influence of human activities (especially urbanization) on the microbial diversity, structural composition, and spatial distribution of rivers is limited. In this paper, to explore the prokaryotic community structure and the relationship between the community and environmental factors in the Jialing River Basin of Chongqing, so as to provide a basis for monitoring microorganisms in the watershed. The V3–V4 region of the 16 S rRNA gene was analyzed by high-throughput sequencing and the microbial community of the waters of the Jialing River was analyzed for the diversity and composition of the prokaryotic community as well as the species difference of four samples and correlations with environmental factors. The main results of this study were as follows: (1) The diversity index showed that there were significant differences in the biodiversity among the four regions. At the genus level, Limnohabitans, unclassified_f_Comamonadaceae, and Hgcl_clade were the main dominant flora with a high abundance and evenness. (2) A Kruskal–Wallis H test was used to analyze the differences of species composition among the communities and the following conclusions were drawn: each group contained a relatively high abundance of Limnohabitans; the Shapingba District had a higher abundance of Limnohabitans, the Hechuan District had a wide range of unclassified_f_Comamonadaceae, and the Beibei District had a higher Hgcl_clade. (3) Through the determination of the physical and chemical indicators of the water—namely, total nitrogen, total phosphorus, chemical oxygen demand, chlorophyll A, and an analysis by an RDA diagram, the results demonstrated that the distribution of microbial colonies was significantly affected by the environmental factors of the water. Chemical oxygen demand and ammonia nitrogen had a significant influence on the distribution of the colonies. Different biological colonies were also affected by different environmental factors.

Hydrogen and methane, as chemical raw materials with broad application prospects in the future market, can be produced by the two-phase anaerobic co-digestion of rice straw and sludge. The study was carried out using a medium-temperature batch experiment with rice straw, a rural crop residue from Sichuan, and residual sludge from a sewage treatment station. The effect of the mixing ratio of rice straw and rural sludge on hydrogen and methane production from anaerobic digestion was investigated with a view to alleviating the energy crisis and efficient resource utilization. The experimental results showed that hydrogen production was most favorable when rice straw/sludge = 5:1, with a cumulative hydrogen yield as high as 38.59 ± 1.12 mL/g VSadded, while methane production was most favorable when 3:1, with a cumulative methane yield as high as 578.21 ± 29.19 mL/g VSadded. By calculating the energy yield, it was determined that 3:1 is more favorable for the two-phase anaerobic digestion capacity of rice straw and sludge, which is as high as 20.88 ± 1.07 kJ/g VSadded, and its conversion of hydrogen and methane is 0.75% and 78.19%, respectively. The hydrogen production pathway was dominated by the butyric acid type, whose hydrogen production phase pH (5.84 ± 0.13) was slightly higher than the optimal pH for hydrogen-producing bacteria, while the methanogenic phase could meet the optimal pH for methanogenic bacteria (6.93 ± 0.17).

Harmful cyanobacterial blooms pose a major threat. Among them, Microcystis aeruginosa has raised serious concerns for human health due to its frequent occurrence. In this study, an ecological floating-bed system consisting of activated carbon fibers, aquatic plants (Ipomoea aquatica Forsskal), animals (Daphnia), and a solar-powered ultrasonic device was designed. The algae-killing efficiency, removal mechanism, and toxicological effects of the floating-bed system on Microcystis aeruginosa were determined under different conditions. The results showed that the average activity of algal cell dehydrogenase (DHA) was reduced by 64.09%, the average malondialdehyde (MDA) content was reduced to 0.125 μmol/L, and the average removal rate of soluble protein was 57.22% under optimal conditions (pH = 7, temperature = 25 °C, dissolved oxygen concentration = 5 mg/L, and hydraulic retention time = 36 h). Scanning electron microscopy (SEM) analysis showed that the structure within the cells of Microcystis aeruginosa was severely damaged after treatment with the solar-powered ultrasonic carbon fiber eco-floating-bed system. Fourier transform infrared (FTIR) spectroscopy analysis showed that the pyrrole ring of chlorophyll-a was degraded. In addition, a tadpole-based micronucleus test and a comet assay were conducted to assess cell viability and DNA damage in water samples treated with the floating-bed system, and the results confirmed that chromosome damage and genotoxicity were significantly reduced. These findings suggest that the floating-bed system is effective in destroying algal cells, leading to massive algal cell death and reducing the risk of secondary contamination. This study provides a new perspective for further research on ecological floating-bed technology, demonstrating its potential practical application in the prevention and control of cyanobacterial blooms.