铁强化微生物除磷的效能及机理

Efficiency and mechanism of ferric salt enhanced biological phosphorus removal

从深海菌中筛选出一株高效除磷菌，并研究了铁强化此除磷菌在高盐合成废水中的除磷效能及机理。通过批次试验研究了铁磷物质的量比、初始pH值对除磷效率的影响以及铁强化生物除磷的动力学，并利用扫描电镜和能谱分析对微生物表面形貌进行了研究。结果表明，与单独铁盐和生物除磷相比，铁强化微生物除磷效率更高效且稳定在95％以上。当n（Fe（Ⅲ））：n（P）=1：1时，铁强化微生物除磷的最大效率达98．50％，相比单纯生物除磷提高30％，而单独铁盐除磷n（Fe（Ⅲ））：n（P）=2：1-3：1时，除磷率仅90％；当n（Fe（Ⅲ））：n（P）≤1：1时，铁强化微生物除磷以微生物除磷为主，铁盐辅助，处理后水pH中性且稳定；当物质的量比n（Fe（Ⅲ））：n（P）〉1：1时，由于Fe（Ⅲ）水解造成pH降低至5．50以下，微生物生长受抑，磷的去除主要靠化学沉淀。废水初始pH在6．0-9．0范围内，铁强化生物除磷去除率均在95％以上。准一级动力学模型能够很好地模拟生物除磷过程；准二级动力学模型能够很好地模拟铁强化生物除磷，且较长时间内无磷释放现象。铁强化生物除磷的机理包括：（1）细菌生长除磷以及胞外聚合物对磷的吸附；（2）在混合液中形成了羟基磷酸铁络合物；（3）在细菌表面形成了由细菌诱导的铁磷微沉淀。

Abstract： An efficient phosphorus （P） removal bacterium strain was screened from deep-sea bacteria, and phosphorus removal efficiency and mechanism by iron enhanced biological treatment were studied in the high salinity synthetic wastewater. The effects of molar ratio Fe（ Ⅲ）/P, initial pH on phosphorus removal and kinetics of iron enhanced bio- logical phosphorus removal were investigated by batch tests, and the surface morphology of bacteria was studied by SEM-EDS （scanning electron microscopy-energy dispersive X-ray spectroscopy）. Results showed that the phosphorus removal efficiency of iron enhanced biological treatment was high and stable at more than 95 % compared to those of in- dependent iron and biological treatment. Removal efficiency of phosphorus reached the maximum of 98.5 % with molar ratio of Fe（Ⅲ） and P being 1, which increased 30% than that of the biological treatment, whereas the maximum phos- phorus removal was 90% with molar ratio of Fe（Ⅲ） and P ranging from 2 to 3 by independent iron treatment. Phos- phorus removal was mainly ascribed to bacterial growth and aided by iron, and pH was kept stable at about 7.2 when molar ratio of Fe（Ⅲ） and P being not more than 1. Phosphorus removal was mainly by chemical precipitation with mo- lar ratio of Fe（Ⅲ） and P being more than 1 because that the pH reduced to 5.5 or even lower by Fe（Ⅲ） hydrolysis and significantly influenced bacterial growth. Phosphorus removal was kept at above 95% at pH of 6 ~ 9 with molar ratio ofFe（Ⅲ） and P being 1. The dynamic pseudo-first-order model could fit the biological phosphorus removal process well, and the pseudo-second-order model could well describe the iron enhanced biological phosphorus removal without phos- phorus releasing for a long time. Except the uptake of part of the phosphorus by bacterial growth and bio-sorption by ex- tracellular polymeric substance, the hydroxyl phosphate iron complex compound and iron phosphorus precipitation in- duced by bacterium also contributed to the phosphorus removal.