苯酚对污水生物脱氮系统亚硝积累及污泥性能的影响

Effects of phenol on nitrite accumulation and sludge performance in biological nitrogen removal system

采用SBR缺氧/好氧反应工艺,研究了不同苯酚浓度对脱氮过程中亚硝积累与污泥性能的影响。结果表明,苯酚浓度在0～90mg·L-1变化时系统出现2次明显亚硝酸盐积累,最终稳定维持在70%±5%,低浓度(0～30mg·L-1)系统亚硝酸盐积累恢复是微生物改变自身结构及分泌胞外聚合物导致;高浓度(60～90mg·L-1)苯酚条件下亚硝积累是由于苯酚对AOB(ammonia-oxidizing bacteria,氨氮氧化细菌)和NOB(nitrite-oxidizing bacteria,亚硝酸氧化细菌)抑制作用引起的微生物种群改变形成。氨氮氧化速率和氮氧化物生成速率由10.85mg N.(g MLSS)-1.h-1和10.12mg N·g(MLSS)-1.h-1降低至2.79mg N·g(MLSS)-1.h-1和2.32mg N·g(MLSS)-1.h-1,亚硝酸盐积累率和氮氧化物生成速率呈现负相关性,与苯酚浓度呈正相关;荧光原位杂交表明苯酚的抑制使得硝化菌群结构发生了变化,AOB相对数量由2.80%增加为9.30%。苯酚的可降解性使得系统污泥浓度由2500mg·L-1左右上升至5870mg·L-1。当EPS(extracellular polymeric substances,胞外聚合物)总量由67.20mg.(g VSS)-1减少至32.10mg·g(VSS)-1时,SVI从165ml·g-1降到50ml·g-1。亚硝酸盐积累、丝状菌和胞外聚合物是引起活性污泥系统SVI变化的原因,其中NAR影响最大,丝状菌次之。

In the pre-denitrification of anoxic-aerobic reaction process,nitrite accumulation and sludge performance at different phenol concentrations were investigated.The results showed that there were two obvious nitrite accumulations finally stabilized at 70%±5% when phenol varied from 0 to 90 mg·L-1.At low phenol concentration（0 to 30 mg·L-1）,nitrite accumulation and recovery were caused by microbial structure varieties and secreting extracellular polymer.At high phenol concentration（60—90 mg·L-1）,nitrite accumulation was caused by microbial population changes of ammonia-oxidizing bacteria and nitrite-oxidizing bacteria was caused by phenol inhibition.Ammonia oxidation rates and nitrogen oxide production rates varied from 10.85 mg N·（g MLSS）-1·h-1 and 10.12 mg N·（g MLSS）-1·h-1 to 2.79 mg N·（g MLSS）-1·h-1 and 2.32 mg N·（g MLSS）-1·h-1,respectively.Nitrite accumulation rate had a negative correlation with nitrogen oxide production rate,whereas a positive correlation to phenol concentration.Fluorescence in situ hybridization showed that nitrifying bacteria communities changed due to phenol inhibition,with AOB relative quantity increasing from 2.80% to 9.30%.As carbon source,phenol caused sludge concentration increase from 2500 mg·L-1 up to 5870 mg·L-1.When total extracellular polymeric substances declined from 67.20 mg·（g VSS）-1 to 32.10 mg·（g VSS）-1,sludge volume index（SVI）accordingly changed from 165 ml·g-1 to 50 ml·g-1.Nitrite accumulation,filamentous bacteria and extracellular polymer contributed to SVI changes in the activated sludge system,and nitrite accumulation was the main reason followed by filamentous bacteria.