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In this work, fouling mechanisms of mixed foulants, that is, bovine serum albumin (BSA) and humic acid (HA), on nanofiltration (NF) under different factors, including pH, ionic strength, and Ca2+, were investigated by using atomic force microscopy (AFM). Considering that fouling behavior mainly appeared at the polyamide (PA) separation layer of NF membrane, AFM probes modified with PA which was the dominating material of effective separation layer, and coating [BSA-HA]nwere prepared. Fouling mechanisms of mixed foulants on the NF membrane were studied through measurements of the interfacial forces of [BSA-HA]n–PA membrane and [BSA-HA]n–[BSA-HA]n. Fouling experiments with [BSA-HA] nwere carried out using PA membrane, and the results indicated severe flux reduction occurring at low pH, thereby decreasing the ionic strength or adding Ca2+. The fouling behavior of NF membrane was determined by the interfacial forces (F/R) of [BSA-HA]n–PA and [BSA-HA] n–[BSA-HA]n, thus both forces were measured. Results showed that the forces of [BSA-HA] n–PA membrane were stronger than those of [BSA-HA]n–[BSA-HA]n. Moreover, both forces were enhanced with low pH, ionic strength and added Ca2+. Results verified that the F/R of [BSA-HA]n–PA membrane determined the cake formation occurrence time, and F/R of [BSA-HA]n–[BSA-HA]nmaintained a linear correlation with fouling degree.

Coking wastewater is one of the most toxic industrial effluents since it contains high concentration of toxic organic compounds. Biological treatments are widely applied in coking wastewater treatment, pollutants can be degraded completely due to the synergistic effect of the community composition. In this study, the community structure and degradation of organic compounds of a full-scale coking wastewater treatment plant with anaerobic, anoxic, and oxic process (A1/A2/O) were studied. GC-MS results showed that phenols, indole, quinoline and pyridine, accounting for 61.70, 13.63, 7.71 and, 2.30%, respectively, were the main organic pollutants in the raw coking wastewater. Those pollutants were degraded gradually during the A1/A2/O bioprocess, respectively. High throughput pyrosequencing was applied to investigate the bacterial community, the sequences could be affiliated to 21 phylogenetic groups, including Proteobacteria, Chloroflexi, Bacteroidetes, Planctomycetes, Synergistetes, Chlorobi, Acidobacteria, Nitrospira, Firmicutes, and Actinobacteria. Diversity and richness indexes, venn analysis and principal component analysis indicated that the diversity and abundance of species in three samples were different. The abundance of the phylum Proteobacteriaaccounted for 84.64% (A1), 62.73% (A2), and 83.24% (O) of the total reads, respectively. The corresponding most dominant orders in three samples were Pseudomonadales(A1), Syntrophobacterales(A2), and Burkholderiales(O), respectively. While genus Pseudomonas, Desulfoglaeba, and Diaphorobacterwas the dominant bacterium in three samples, respectively.