Removal of microcystin-LR from drinking water using a bamboo-based charcoal adsorbent modified with chitosan

A new kind of low-cost syntactic adsorbent from bamboo charcoal and chitosan was developed for the removal of microcystin-LR from drinking water. Removal effciency was higher for the syntactic adsorbent when the amount of bamboo charcoal was increased. The optimum dose ratio of bamboo charcoal to chitosan was 6：4, and the optimum amount was 15 mg/L; equilibrium time was 6 hr. The adsorption isotherm was non-linear and could be simulated by the Freundlich model （R2 = 0.9337）. Adsorption efficiency was strongly afflected by pH and natural organic matter （NOM）. Removal efficiency was 16% higher at pH 3 than at pH 9. Efficiency rate was reduced by 15% with 25 mg/L NOM （UV254 = 0.089 cm-1） in drinking water. This study demonstrated that the bamboo charcoal modified with chitosan can effectively remove microcystin-LR from drinking water.

Metagenomic insights into the effects of submerged plants on functional potential of microbial communities in wetland sediments

Submerged plants in wetlands play important roles as ecosystem engineers to improve self-purification and promote elemental cycling.However,their effects on the functional capacity of microbial communities in wetland sediments remain poorly understood.Here,we provide detailed metagenomic insights into the biogeochemical potential of microbial communities in wetland sediments with and without submerged plants(i.e.,Vallisneria natans).A large number of functional genes involved in carbon(C),nitrogen(N)and sulfur(S)cycling were detected in the wetland sediments.However,most functional genes showed higher abundance in sediments with submerged plants than in those without plants.Based on the comparison of annotated functional genes in the N and S cycling databases(i.e.,NCycDB and SCycDB),we found that genes involved in nitrogen fixation(e.g.,nifD/H/K/W),assimilatory nitrate reduction(e.g.,nasA and nirA),denitrification(e.g.,nirK/S and nosZ),assimilatory sulfate reduction(e.g.,cysD/H/J/N/Q and sir),and sulfur oxidation(e.g.,glpE,soeA,sqr and sseA)were significantly higher(correctedp<0.05)in vegetated vs.unvegetated sediments.This could be mainly driven by environmental factors including total phosphorus,total nitrogen,and C:N ratio.The binning of metagenomes further revealed that some archaeal taxa could have the potential of methane metabolism including hydrogenotrophic,acetoclastic,and methylotrophic methanogenesis,which are crucial to the wetland methane budget and carbon cycling.This study opens a new avenue for linking submerged plants with microbial functions,and has further implications for understanding global carbon,nitrogen and sulfur cycling in wetland ecosystems.