石油类物质环己烷对活性污泥沉降性能的影响

炼油废水中石油类物质容易影响活性污泥沉降性能、干扰处理效果.为了定量分析石油类物质对活性污泥沉降性能的影响，采用定量图像分析技术，通过图像采集、图像处理、图像分析和数据处理流程，考察了不同浓度环己烷影响下活性污泥絮体微观参数变化情况及参数间的相关性，并分析了微观参数与宏观参数SV（污泥沉降比）、SVI（污泥容积指数）和MLSS（污泥浓度）]间的相关性.结果表明:①絮体微观参数值随环己烷投加浓度的变化规律具有明显的分组现象，同组参数间相关性强，可据此将参数分为大小类、规则性类和密实性类.②环己烷在低于1 g/L浓度条件下使活性污泥沉降体积增大，此时密实性参数与环己烷投加浓度、SV和SVI分别具有一定相关性.③环己烷投加浓度≥ 1 g/L时会导致污泥上浮流失，此时大小类和规则性类参数均分别与SV和MLSS具有一定相关性，其中，孔率与环己烷投加浓度呈负相关（R2为0.91），分形维数与SV和MLSS分别呈负相关（R2分别为0.75和0.89）.研究显示，利用定量图像分析技术检测孔率和分形维数等污泥絮体微观参数，能够反映石油类物质对活性污泥沉降性能的影响，当孔率降至0.98以下预示着污泥流失，并且分形维数越大，流失越严重. 

Effects of Petroleum Substance Cyclohexane on the Activated Sludge Settling Ability

The petroleum substances in refinery wastewater influence the settling ability of activated sludge and decrease the efficiency of biotreatment systems. To achieve quantitative understandings of this influence, quantitative image analysis (QIA) was adopted to measure the microscopic parameters of floc morphology through the process of image collection, image processing, image analysis and data processing. Changes of the microscopic parameters were investigated under different concentrations of a typical petroleum substance, cyclohexane. The correlations among different microscopic parameters, and between microscopic and macroscopic parameters (SV, SVI and MLSS) were analyzed respectively. The results show that:(1) The microscopic parameters of flocs were changed with the concentration of cyclohexane in several different patterns, which provides a basis to classify the parameters into size, regularity and density groups. Correlations were found to be significant between the parameters in each group. (2) Cyclohexane less than 1 g/L caused an increase of the settling volume of activated sludge, and certain correlations were found between the parameters in density group and the macroscopic parameters SV and SVI, respectively. (3) When cyclohexane concentration was above 1 g/L, sludge losses by floating up were observed, and correlations of parameters in size and regularity groups were significant with SV and MLSS, respectively. Two of the microscopic parameters were changed typically under the high concentration conditions. The hole ratio of the flocs presented a negative correlation with the concentration of cyclohexane (R²=0.91). The fractal dimension was found to be negatively correlated with SV and MLSS (R² was 0.75 and 0.89, respectively). The impact of petroleum substance on the activated sludge settling ability could be analyzed by the determination of microscopic parameters such as hole ratio and fractal dimension by QIA:hole ratio below 0.98 would indicate a sludge-loss problem caused by petroleum substances; and the higher the fractal dimension value was, the more the sludge loss.