NaCl盐度对A^2/O工艺缺氧区胞外聚合物及生物絮凝性的影响

Effect of NaCl Salinity on Extracellular Polymeric Substances and Bioflocculation of Anoxic Sludge in A^2/O Process

为了提高含盐废水的生物脱氮除磷效率和生物絮凝性,考察NaCl盐度对A^2/O工艺缺氧区脱氮除磷效率的影响,结合傅里叶变换红外光谱(fourier transform infrared spectroscopy,FTIR)与X射线光电子能谱(X-ray photoelectron spectroscopy,XPS)分析缺氧区活性污泥胞外聚合物(extracellular polymeric substances,EPS)组分与结构变化,以期揭示盐度对生物絮凝性的影响.结果表明,当NaCl盐度为0~5 g·L^(-1)时,A^2/O缺氧区生物絮凝性良好,重絮凝性(flocculation ability,FA)约为44%,污泥粒径约为45.5μm,EPS含量为52.3~62 mg·L^(-1),PN/PS维持在2.1左右;当NaCl盐度由10 g·L^(-1)增加至40g·L^(-1)时,A^2/O缺氧区生物絮凝性显著降低,FA由40%下降至22%,污泥粒径由43.7μm减小至32.1μm,EPS含量由76.5 mg·L^(-1)增加至101.0 mg·L^(-1),PN/PS由1.5下降至1.3.随着NaCl盐度的增加,通过FTIR分析可知,EPS主要组成基团未发生明显变化,以氨基、酰胺Ⅰ和羧基为主;由XPS分析可知,EPS和Na+相互作用过程中部分基团(如C、O、N基团)发生电荷转移,但其存在形态未发生变化.

In order to improve the biological removal efficiency of nitrogen and phosphorus and bioflocculation performance of saltcontaining wastewater,the effect of NaCl salinity on the efficiency of denitrification and phosphorus removal in the anoxic zone of an A-2/O process was investigated. Fourier transform infrared spectroscopy（FTIR） and X-ray photoelectron spectroscopy（XPS） were used to analyze the composition and structure of extracellular polymeric substances（EPS） in activated sludge of the anoxic zone,to discern the effect of salinity on bioflocculation. Results showed that when NaCl salinity was 0-5 g·L^-1,flocculation ability（FA） in A-2/O anoxic zone was about 44% and the sludge particle size was 45. 5 μm. EPS content increased from 52. 3 mg·L^-1 to 62 mg·L^-1 and protein（PN）/polysaccharide（PS） remained at 2. 1. When NaCl salinity increased from 10 g·L^-1 to 40 g·L^-1,bioflocculation of sludge significantly decreased. FA decreased from 40% to 22% and sludge particle size decreased from 43. 7 μm to 32. 1 μm. EPS content increased from 76. 5 mg·L^-1 to 101. 0 mg·L^-1 and PN/PS decreased from 1. 5 to 1. 3. Based on FTIR analysis,with increase in salinity,the main components of EPS were always amino,amideⅠ,and carboxyl. Based on XPS analysis,increasing salinity led to charge transfer of some groups（such as C,O,and N groups） during the interaction between EPS and Na＋,but its form did not change.