Biofilm microbial community structure in an urban lake utilizing reclaimed water

Analyses of biofilm community structure may potentially be employed for aquatic ecosystem health assessment, however, to date, biofilm diversity within urban lakes using reclaimed water has not been examined. Accordingly, the microbial community diversity and structure of biofilms from the surface of multiple matrices with varying roughness (0.1, 1.0 and 10.0 μm) were characterized using a suite of molecular techniques including scanning electron microscopy, genetic fingerprinting and phospholipid-derived fatty acid analyses. Samples were largely comprised of inorganic particles, algae and numerous bacterial species; 12 phospholipid-derived fatty acid (PLFA) types were identified, significantly less than typically associated with sewage. Both growth matrix surface roughness and biofilm growth phase were shown to concur with significantly different microbial quantity and community structures. Gram-negative bacteria bacillus i15:03OH and 18:0 were the dominant bacterial genera, collectively comprising ≈75 % of identified PLFA species content. Calculated species diversity (H) and species dominance (D) exhibited identical correlational patterns with measured water quality parameters; significant positive correlations were exhibited with respect to Mg2, while significant negative correlations were found for NO3, TP, BOD, COD, SP, PO4, SO4 and pH. Results indicate that analyses of biofilm formation and structure could be effectively used to undertake integrated assessments of the ecological health of lake systems using reclaimed water. Further work is required to elucidate the optimum conditions for sample collection and analytical interpretation

Effect of Different Phosphates on Pyrolysis Temperature-Dependent Carbon Sequestration and Phosphorus Release Performance in Biochar

Carbon sequestration is the primary function of biochar. Hence, it is necessary to design biochar with high carbon (C) retention and low C loss. In this study, three P compounds, including KH2PO4, Ca(H2PO4)2, and NH4H2PO4, were premixed with corn stalk (1:4, w/w), aiming to produce biochars (CSB+K, CSB+Ca, and CSB+N) with high C sequestration and slow release of P at three temperatures (300, 500, and 700 °C). The addition of all P sources obviously increased C retention, with the order of NH4H2PO4 (65.6–83.5%) > Ca(H2PO4)2 (60.4–78.2%) > KH2PO4 (50.1–76.1%), compared with the pristine biochar (47.8–73.6%). The addition of Ca(H2PO4)2 and KH2PO4 led to an increase in aromaticity and graphitization, as evidenced by H/C, FTIR, Raman and XPS analysis, whereas an opposite result occurred on CSB+N. Furthermore, all three phosphates reduced C loss of biochars with H2O2 oxidation, and CSB+Ca showed the best effect. Ca(H2PO4)2 and KH2PO4 pretreated biochars had higher resistance to K2Cr2O7 oxidation and thermal treatment. In contrast, the C loss of NH4H2PO4-added biochar at 500 and 700 °C with K2Cr2O7 oxidation was increased by 54% and 36%, respectively. During the pyrolysis process, Ca(H2PO4)2 was transformed into insoluble Ca2P2O7, leading to the lowest P release rate of CSB+Ca. This study indicates that co-pyrolysis of corn stalk and Ca(H2PO4)2 is optimal for increasing C retention, enhancing C stability and improving slow-release performance of P regardless of pyrolysis temperature

Biofilm microbial community structure in an urban lake utilizing reclaimed water

Analyses of biofilm community structure may potentially be employed for aquatic ecosystem health assessment, however, to date, biofilm diversity within urban lakes using reclaimed water has not been examined. Accordingly, the microbial community diversity and structure of biofilms from the surface of multiple matrices with varying roughness (0.1, 1.0 and 10.0 μm) were characterized using a suite of molecular techniques including scanning electron microscopy, genetic fingerprinting and phospholipid-derived fatty acid analyses. Samples were largely comprised of inorganic particles, algae and numerous bacterial species; 12 phospholipid-derived fatty acid (PLFA) types were identified, significantly less than typically associated with sewage. Both growth matrix surface roughness and biofilm growth phase were shown to concur with significantly different microbial quantity and community structures. Gram-negative bacteria bacillus i15:03OH and 18:0 were the dominant bacterial genera, collectively comprising ≈75 % of identified PLFA species content. Calculated species diversity (H) and species dominance (D) exhibited identical correlational patterns with measured water quality parameters; significant positive correlations were exhibited with respect to Mg2, while significant negative correlations were found for NO3, TP, BOD, COD, SP, PO4, SO4 and pH. Results indicate that analyses of biofilm formation and structure could be effectively used to undertake integrated assessments of the ecological health of lake systems using reclaimed water. Further work is required to elucidate the optimum conditions for sample collection and analytical interpretation