The biohydrogen production efficiency and performance of hydrogen-producing acetogen in a four-compartment anaerobic baffled reactor (ABR) were studied by gradually increasing the influent normal molasses wastewater (NMWW) proportion. When the influent NMWW proportion increased to 55%, ABR could develop microbial community with methanogenic function in 63 days and reach a stable operation. When the influent NMWW proportion increased to 80% and reached a stable state, ethanol fermentation was established from butyric acid fermentation in the first three compartments, whereas butyric acid fermentation in the fourth compartment was strengthened. The average biohydrogen production yield and biohydrogen production capacity by COD removal increased to as high as 12.85 L/day and 360.22 L/kg COD when the influent NMWW proportion increased from 55% to 80%, respectively. Although the biogas yield and the specific biogas production rate reached 61.54 L/day and 232 L/kg MLVSS·day, the biohydrogen production yield and specific biohydrogen production rate were only 12.85 L/day and 48 L/kg MLVSS·day, which results in hydrogen consumption by homoacetogenesis and methanogenesis.

In agroecosystems, different cropping patterns cause changes in soil physicochemical properties and thus in microbial communities, which in turn affect crop yields. In this study, the yields of soybean continuous cropping for 5 years (C5), 10 years (C10), and 20 years (C20) and of soybean-corn rotational cropping (R) treatments were determined, and samples of the tillage layer soil were collected. High-throughput sequencing technology was used to analyze the diversity and composition of the soil bacterial and fungal communities. The factors influencing microbial communities, along with the effects of these communities and those of soil chemical indexes on yield, were further evaluated. The results showed that the community richness index of bacteria was higher in C20 than in R and that of fungi was highest in C5. The differences in the bacterial and fungal communities diversity indexes were not significant among the different continuous cropping treatments, respectively. The soil microbial community composition of all continuous cropping treatments differed significantly from R. The dominant bacterial phylum was Actinobacteriota and the dominant fungal phylum was Ascomycota. The relative abundance of Fusarium did not differ significantly among the continuous cropping treatments, while that of the plant pathogen fungi Lectera sp., Plectosphaerella sp., and Volutella sp. increased with continuous cropping years. Soil pH, SOM, N, and TP had significant effects on both bacterial and fungal communities, and TK and C/N had highly significant effects on fungal communities. The yield of C5 was significantly lower than that of R, and the differences in yield between C10, C20, and R were not significant. TN, TP, and pH had significant effects on yield, and fungal community abundance had a greater negative effect on yield than bacterial community abundance.