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In this study, an enhanced coagulation-flocculant process incorporating magnetic powder was used to further treat the secondary effluent of domestic wastewater from a municipal wastewater treatment plant. The purpose of this work was to improve the discharged water quality to the surface water class IV standard of China. A novel approach using a combination of the response surface methodology and an artificial neural network (RSM-ANN) was used to optimize and predict the total phosphorus (TP) pollutant removal and turbidity. This work was first evaluated by RSM using the concentrations of coagulant, magnetic powder, and flocculant as the controllable operating variables to determine the optimal TP removal and turbidity. Next, an ANN model with a back-propagation algorithm was constructed from the RSM data along with the non-controllable variables, raw TP concentration, and raw water turbidity. Under the optimized experimental conditions (28.42 mg/L coagulant, 623 mg/L magnetic powder, and 0.18 mg/L flocculant), the TP and turbidity removal reached 88.79 ± 5.45% and 63.48 ± 9.60%, respectively, compared with 83.28% and 59.80%, predicted by the single RSM model, and 87.71 ± 5.74% and 64.62 ± 10.75%, predicted by the RSM-ANN model. The treated water were 0.17 ± 6.69% mg/L of TP and 2.46 ± 5.09% NTU of turbidity, respectively, which completely met the surface water class IV standard (TP < 0.3 mg/L; turbidity < 3 NTU). Therefore, this work demonstrated that the discharged water quality was completely improved using the magnetic coagulation process. In addition, the combined RSM-ANN approach could have potential application in municipal wastewater treatment plants. [ABSTRACT FROM AUTHOR]

Owing to the limited natural distributions and special medicine-industrial values of Viola philippica , it's urgently needed to explore its population-level differences for promoting the resource utilization efficiencies of this plant. The hypothesis of this study was that different populations of V. philippica plants would have broad-scale differences and interactions of leaf-accumulated metabolites and leaf-colonized bacteria. Hence, two populations (vi-p and vi-j) of this plant were typically collected in China for analyzing multiomics. At first, vi-p and vi-j leaf metabolomes (LMs) were presented with 1,003 metabolites; in contrast of vi-p-LMs, 445 differently accumulated metabolites (DAMs) were identified in vi-j-LMs, with the only up-regulated lipids, vitamin and ketone compounds, the only down-regulated aldehyde compounds, the most up-regulated flavonoids, and the most down-regulated phenylpropanoid compounds. In comparative of vi-p leaf transcriptomes (LTs), 4,645 differently expressed genes (DEGs) were identified in vi-j-LTs, which were typically involved in a series of extracellular defenses and secondary metabolic pathways; the DEGs were frequently co-enriched with DAMs in three biosynthesis pathways of phenylpropanoid, flavonoid, and α-linolenic acid. Furthermore, these DAMs were also found to have the significant correlations with some different types or/and abundances of leaf-assembled bacteria (DTAB) between vi-p and vi-j leaf-assembled bacterial communities (LABCs). Taken together, this study reveals the broad-scale patterns of regulating vi-p and vi-j leaf DAMs with DEGs and DTAB, suggesting that it's essential of keeping plant-population and -habitat diversities for harvesting population-level DAMs in V. philippica. • The plant-level functional metabolites were integrally uncovered in V. philippica. • Two plant populations were identified with differently accumulated metabolites (DAMs). • The typical DAMs were co-enriched with differently expressed genes (DEGs). • These DAMs were also correlated with different types or/and abundances bacteria (DTAB). [ABSTRACT FROM AUTHOR]