In the current study, a comparison between the diferent Mn3O4/ZnO, CuO/ZnO and Fe2O3/ZnO nanocomposites with respect to their structural, morphological, optical and photocatalytic properties is presented. The nanostructure nature of the investigated composites was confrmed by the XRD and SEM analysis. The nanocrystalline ZnO, M3O4, CuO and Fe2O3 phases were observed with diferent crystalline structure, including hexagonal, tetragonal, monoclinic and rhombohedral, respectively. The morphology of ZnO based nanocomposites was found to be dependent on the type of the metal oxide added to ZnO nanostructure. In addition, the studied nanocomposites showed diferent optical properties. The highest and lowest band gap of 3.14 and 2.00 eV were obtained for ZnO nanoparticles and Fe2O3/ZnO nanocomposite. Concerning the photocatalytic properties, the ZnO nanoparticles, Mn3O4/ZnO, CuO/ZnO and Fe2O3/ZnO nanocomposites showed an efciency of 49.63, 29.8, 11.61 and 95.34%, respectively, for the photodegradation of methylene blue. The Fe2O3/ZnO nanocomposites exhibited the highest activity for water purifcation compared to the other nanocomposites

This study investigated the bioelectrical performance of a single-chamber microbial fuel cell (SCMFC) fueled with acetate as the electron donor and inoculated with municipal solid waste rejected fractions (MSWRFs) as a microbial inoculum. The molecular characterization of the bacterial community structures of the anodic biofilm was conducted based on 16s RNA gene sequencing. The results indicated that the highest open-circuit voltage (OCV) was 797 mV and the system had a maximum power density of 134.5 mW/m2 at a stable current density of 328 mA/m2 . The microbial fuel cell’s (MFC) columbic efficiency (CE) was 55% at a maximum substrate degradation rate of about 86.6% based on COD removal efficiency. The molecular analysis of the anodic bacterial isolates indicated that the phylogenetic bacterial mixture was dominated by seven strains with similarity percentage above 99% for each strain: Enterococcus faecalis, Clostridium butyricum, Bacillus sp., Bacillus subterranous, Enterobacter celoaca, Klebsiella pneumonia, and Escherichia coli. These results suggested that MSWRFs bacterial consortia have a moderate symbiotic structure as indicated by electrons release in parallel with substrate decomposition.

This study aimed to evaluate the capacity of different inoculum sources and their bacterial diversity to generate hydrogen (H₂). The highest Simpson (0.7901) and Shannon (1.581) diversity indexes for H₂-producing bacterial isolates were estimated for sewage inocula. The maximum cumulative H₂ production (H_max) was 639.6 ± 5.49 mL/L recorded for the sewage inoculum (SS30) after 72 h. The highest H₂-producing isolates were recovered from SS30 and identified as Clostridium saccharobutylicum MH206 and Lactobacillus brevis MH223. The H_max of C. saccharobutylicum, L. brevis, and synergistic coculture was 415.00 ± 24.68, 491.67 ± 15.90, and 617.67 ± 3.93 mL/L, respectively. The optimization process showed that the H_max (1571.66 ± 33.71 mL/L) with a production rate of 58.02 mL/L/h and lag phase of 19.33 h was achieved by the synergistic coculture grown on 3% molasses at 40 °C, pH 7, and an inoculum size of 25% (v/v). This study revealed the economic feasibility of the synergistic effects of coculture on waste management and biohydrogen production technology.