Enhanced anaerobic digestion performance and sludge filterability by membrane microaeration for anaerobic membrane bioreactor application.

Slow dissolution/hydrolysis of insoluble/macromolecular organics and poor sludge filterability restrict the application potential of anaerobic membrane bioreactor (AnMBR). Bubble-free membrane microaeration was firstly proposed to overcome these obstacles in this study. The batch anaerobic digestion tests feeding insoluble starch and soluble peptone with and without microaeration showed that microaeration led to a 65.7-144.8% increase in methane production and increased critical flux of microfiltration membrane via driving the formation of large sludge flocs and the resultant improvement of sludge settleability. The metagenomic and bioinformatic analyses showed that microaeration significantly enriched the functional genes and bacteria for polysaccharide and protein hydrolysis, microaeration showed little negative effects on the functional genes involved in anaerobic metabolisms, and substrate transfer from starch to peptone significantly affected the functional genes and microbial community. This study demonstrates the dual synergism of microaeration to enhance the dissolution/hydrolysis/acidification of insoluble/macromolecular organics and sludge filterability for AnMBR application.

[Identification and PAC Adsorption of Foulants Responsible for Irreversible Fouling During Ultrafiltration of Dongjiang River Water].

Foulants responsible for hydraulic irreversible fouling in Dongjiang River water were identified by ultrafiltration process and their removal by powdered activated carbon (PAC) adsorption treatment was investigated using fluorescent excitation emission matrix and parallel factor analysis (EEM-PARAFAC). A correlation analysis was then carried out for samples between the maximum fluorescence intensities (Fmax) of three PARAFAC components after PAC adsorption and the surface properties of corresponding PAC samples. The results showed that two humic-like (C1 and C3) and one tryptophan-like fluorescent components were obtained through PARAFAC analysis, in which tryptophan-like component C2 was found to be the main substance in hydraulic irreversible foulants extracted from fouled membrane. Furthermore, the results of correlation analysis suggested that microspore area of PAC correlated with PAC adsorption of tryptophan-like fluorescent components, which played an important role in irreversible fouling. Both BET and mesopore+macropore area of PAC correlated with its adsorption of humic-like fluorescent components. The result provided support for selecting PAC in PAC-ultrafiltration hybrid process, which would be more effective for fouling control.