Search

This paper focuses on the flocculability of simulated wastewater containing heavy metal ions (Fe3+, Cd2+) or phosphorus by zeolite, microbial flocculants (MBF) produced by Aspergillus niger and the composite flocculant composed of zeolite and MBF. The main results are presented as follows: zeolite was a good flocculant when the contamination of the three simulated wastewaters was low, but the treated water is of turbidness and the particles in it are hard to precipitate. The MBF have a good flocculability toward Fe3+ wastewater, as well as particulate matter. Significant changes in flocculability occurred after adding the composite flocculant in different simulated wastewaters, the best or least effect respective for Fe3+ and Cd2+ wastewater. The research we have done shows that the method by which the composite flocculant is used to treat the wastewater containing heavy metal ions or phosphorus provides important reference value for practical application. [ABSTRACT FROM AUTHOR]

The weathering of phosphorus-bearing mineral powder (PBMP) and calcium phosphate (CP) by Aspergillus niger was compared, and the mechanism involved was analyzed for the comprehensive utilization of PBMP. The concentration of water-soluble phosphorus (WSP), Mg, and Ca at different culture times, microstructures of particles, and mineral compositions was examined by ultraviolet-visible spectrometer (UV), atomic absorption spectrometry (AAS), scanning electron microscopy (SEM), and X-ray diffraction (XRD). Results showed that the change in the concentrations of WSP, Mg, and Ca were related to the growth of A. niger and the different mineral compositions. Compared with CP, PBMP was weathered harder by fungi. Traces of the weathered mineral were found through SEM. CP not only showed traces of erosion damage but also appeared as a rhombohedron-like substance. The XRD test indicated that the weathering minerals can form water calcium oxalate. Further analysis revealed that the mechanism of PBMP and CP weathering by A. niger was the collaborative result of mycelium biomechanical effects and the acid-soluble role of acidic metabolites. The phosphorus dissolution rate of PBMP after 20 d was 46.83%, whereas that of CP after 12 d was 91.01%. The findings of this study are significant to the effective use of waste PBMP and to the exploitation of low-grade phosphate rock resources. [ABSTRACT FROM AUTHOR]

The article presents abstracts of several studies on environmental geochemistry. Some of the abstracts presented include "Biogeochemical Cycling of Nutrients in Karstic Catchments, Southwestern China: Linkages to Changes of Eco-Environments," by Congqiang Liu and "Emerging Organic Contamination in China," by Guibin Jiang and colleagues.