Enhanced denitrification of secondary effluent using composite solid carbon source based on agricultural wastes and synthetic polymers

Solid-phase denitrification is a promising approach to enhance nitrate removal. In this work, polybutylene succinate (PBS) and peanut shell (PS) (with crosslinked polyvinyl alcohol–sodium alginate (PVA-SA) as carrier) were used to prepare a composite solid carbon source (3P) to denitrify the secondary effluent. The results showed that for carbon release performance, 3P had not only a large release of organics, like PS, but also the excellent sustainability of PBS. Among the short chain fatty acids released by PBS, PS, PVA-SA and 3P, the percentages of acetic acid were 59.42%, 72.54%, 72.29% and 92.11%, respectively. When 3P was used as external carbon source, denitrification performance could be enhanced with effluent dissolved organic carbon lower than 20 mg/L. The prepared 3P could improve denitrification, from both microbial and kinetic aspects. The relative abundance of Gammaproteobacteria increased from 39.32% to 43.58%, and the half saturation constant of the fitting Monod equation was 21.28 mg/L. The prepared 3P is an ideal carbon source for secondary effluent denitrification. Using multiple crosslinking methods to produce carrier is an effective way to show the properties of each material.

Forming an Optically Transparent Graphene Film via the Transformation of C60 Molecules

This study aims to optimize the production conditions for forming graphene directly on a quartz substrate, using a carbon 60 (C60) thin film as a solid carbon source. In this experiment, we focused on the relationships between the thickness of the C60 film and the nickel (Ni) catalyst film and the heat treatment conditions. As the thicknesses of the C60 and Ni catalyst films increased, high-crystallinity multi-layered graphene was formed, however the optical transparency of the graphene film decreased. Scanning Electron Microscopy (SEM) observations and Raman scattering spectroscopy showed that after changing the atmosphere of the heat-treatment from an argon (Ar) gas to an Ar+ hydrogen (H2) gas, the optical transparency of the graphene film was remarkably improved, due to the migration and vaporization of the Ni film, and due to etching of the multi-layered graphene.