反硝化生物膜对PBS表面形态及化学组分的影响

PBS是一种新型的可生物降解聚合物(BDPs),可以用做反硝化碳源和生物膜载体,去除饮用水源水中的硝酸盐.利用红外光谱和扫描电子显微镜对反硝化生物膜生长前后PBS颗粒表面形态、化学组成的变化进行了分析.结果表明,PBS仅在微生物作用下降解并为反硝化菌提供碳源.PBS颗粒可以在12 h内使进水中53 mg·L^-1的硝态氮降低到10 mg·L^-1以下(我国饮用水水质标准为:NO₃^--N<15 mg·L^-1).红外光谱表明,反硝化微生物附着生长后其PBS在2 925 cm^-1和2 850 cm^-1附近的吸收带以及3 200 cm^-1～3 410 cm^-1处峰值减弱,说明PBS材料中甲基、羟基官能团比例下降,而其它官能团没有发生明显的变化,PBS的主要单体组分淀粉和乙烯都可以被反硝化微生物用作碳源.扫描电子显微镜观察结果表明,反硝化生物膜附着生长后,PBS颗粒表面会出现空洞,扩大了生物膜生物附着生长的表面积,有利于形成致密的反硝化生物膜,对反硝化菌形成保护作用.

Effect of Denitrifying Biofilm Development on the Surface Configuration and Chemical Composition of PBS Polymer

PBS, a new kind of biodegradable polymers (BDPs), can be used as carbon source and biofilm carrier to remove nitrate from drinking water source. The effect of denitrification on the surface configuration and chemical composition of PBS was analyzed by using IR spectrum and SEM observation. The results showed that PBS could be only decomposed under attack of microbial enzymes and provided the carbon source for biomass. Influent nitrate concentration (53 mg x L- 1) can be reduced to less than 10 mg x L(-1) within 12 h. The IR spectrum showed that under development of denitrifying biofilm, absorption band at 2 925 cm(-1),2 850 cm(-1), 3200 cm(-1) -3410 cm-1 became weak, which suggested that the content of methyl or hydroxyl group in PBS decreased slightly, and the other functional groups were not influenced apparently. The main monomer gradients of PBS, such as starch and ethylene, could all be utilized as carbon source by denitrifiers. The SEM observation indicated that the cavity could be formed on the PBS granular surface, which increased the area for denitrifiers to attach. The formation of the cavity structure on the PBS surface was beneficial to further development of compact biofilm, which can protect denitrifiers.