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Partial denitrification(PD) can reduce nitrate to nitrite, and is an important way to provide substrates steadily in anaerobic ammonia oxidization(ANAMMOX) reaction. PD has great potential in energy-efficient biological nitrogen removal of wastewater, and has become a research hotspot in recent years. In this work,the mechanism of PD was introduced from the aspects of its biological process and functional microorganisms. Then the key factors affecting the PD process, such as carbon source, carbon-nitrogen ratio, environmental conditions, and heavy metals, etc. were summarized. Moreover, the research on PD in biological nitrogen removal process in recent years was also reviewed. Finally, the problems existing in the current research and the aspects for further research of PD were discussed. This work is expected to provide theoretical supports for the development and application of PD in biological nitrogen removal of wastewater.

A strain D5 with excellent partial denitrification performance was screened from paddy soil. The bacteria were identified as Klebsiella pneumoniae by morphological observation and 16S r DNA sequence analysis. The denitrification ability of strain D5 under different environmental factors （carbon source，C/N ratio and temperature） were investigated using single-factor experiments. The results showed that various environmental factors had obvious influence on partial denitrification of strain D5. The optimal conditions for partial denitrification activity of strain D5 were carbon source of sodium citrate， C/N ratio of 3，temperatures of 25 ℃ and 35 ℃. The results showed that strain D5 had excellent partial denitrification performance，and the optimal partial denitrification effect could be achieved by regulating environmental conditions.

Three kinds of end group with double bonds (IVm) were synthesized by esterification reaction, etherification reaction and hydrolysis reaction, using methyl 4-hydroxybenzoate as the main raw material. And the double bonds were oxidized by 3-chloroperoxybenzoic acid as an oxidizing agent to get three kinds of epoxy-functional groups liquid crystal monomers (Vm). The molecular structures of the liquid crystal monomers were characterized by Fourier infrared absorption spectrometer (FT-1R) and proton nuclear magnetic resonance (NMR) spectroscopy, and the target product was identified. The performance of the product was characterized by differential scanning calorimetry (DSC) and thermal polarizing microscope (POM). The results shows that all the products were with the correct molecular structure and had liquid crystal properties under certain conditions with enantiotropic nematic mesophase. [ABSTRACT FROM AUTHOR]