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The application of anaerobic digestors to decentralized wastewater treatment systems (DWTS) has gained momentum worldwide due to their ease of operation, high efficiency, and ability to recycle wastewater. However, the microbial mechanisms responsible for the high efficiency and ability of DWTS to recycle wastewater are still unclear. In this study, the microbial community structure and function of two different anaerobic bioreactors (a primary sludge digestor, PSD, and anaerobic membrane bioreactor, AnMBR) of a DWTS located in Germany was investigated using 16S rRNA gene amplicon and metagenomic sequencing, respectively. The results showed that the microbial community structure was remarkably different in PSD and AnMBR. Methanobacteriaceae and Syntrophaceae were identified as the families that significantly differed in abundance between these two bioreactors. We also used genome-centered metagenomics to predict the microbial interactions and methane-generating pathway, which yielded 21 near-complete assembled genomes (MAGs) (average completeness of 93.0% and contamination of 2.9%). These MAGs together represented the majority of the microbial community. MAGs affiliated with methanogenic archaea, including Methanobacterium sp., Methanomicrobiales archaea, Methanomassiliicoccales archaea, and Methanosaeta concilii, were recruited, along with other syntrophic bacterial MAGs associated with anaerobic digestion. Key genes encoding enzymes involved in specific carbohydrate-active and methanogenic pathways in MAGs were identified to illustrate the microbial functions and interactions that occur during anaerobic digestion in the wastewater treatment. From the MAG information, it was predicted that bacteria affiliated with Bacteroidetes, Prolixibacteraceae, and Synergistaceae were the key bacteria involved in anaerobic digestion. In the methane production step, Methanobacterium sp. performed hydrogenotrophic methanogenesis, which reduced carbon dioxide to methane with hydrogen as the primary electron donor. Taken together, our findings provide a clear understanding of the methane-generating pathways and highlight the syntrophic interactions that occur during anaerobic digestion in DWTS.

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The performance of a fluidized bed reactor using immobilized Phanerochaete chrysosporium to remove 2,4-dichlorophenol (2,4-DCP) from aqueous solution was investigated. The contribution of lignin peroxidase (LiP) and manganese peroxidase (MnP) secreted by Phanerochaete chrysosporium to the 2,4-DCP degradation was examined. Results showed that Lip and Mnp were not essential to 2,4-DCP degradation while their presence enhanced the degradation process and reaction rate. In sequential batch experiment, the bioactivity of immobilized cells was recovered and improved during the culture and the maximum degradation rate constant of 13.95 mg (Ld)⁻¹ could be reached. In continuous bioreactor test, the kinetic behavior of the Phanerochaete chrysosporium immobilized on loofa sponge was found to follow the Monod equation. The maximum reaction rate was 7.002 mg (Lh)⁻¹, and the saturation constant was 26.045 mg L⁻¹.

2015): Research on a new electrochemical method combined with chemical coagulation in removal of lead, zinc, and copper from wastewater, Desalination and Water Treatment,Research on a new electrochemical method with iron electrodes and aluminum electrodes for removal of lead, zinc, and copper from wastewater was studied. Several parameters such as initial pH, hydraulic retention time, mass of Fe/C, applied voltage, and particle diameter of Fe/C were studied to achieve a high removal capacity. The results indicated that the new electrochemical method using aluminum electrodes or iron electrodes for removal efficiency of lead, zinc, and copper are very high. But the lifetime of aluminum electrodes is smaller than 2.44 times the lifetime of iron electrodes. The optimal condition of the new electrochemical method was achieved in two iron electrodes, an initial pH of 4-6, a hydraulic retention time of 75 min, a mass of Fe/C of 125 g, an applied voltage of 10 V, and a particle diameter of Fe/C of 20-27 mesh. At this optimal condition and the initial concentration of ions of 50 mg/L, the residual concentration of lead, zinc, and copper are 0.548, 0.886, and 0.588 mg/L, respectively. The treated wastewater continues the use of chemical coagulation method to adjust the solution pH value of 9. After all treatment processes have been completed, the effluent wastewater is very clear and its quality exceeds the direct discharge standard.