体积溶氧传递系数在好氧颗粒污泥系统中的变化特性初步分析

取成熟的好氧颗粒污泥,在同一测试装置中采用相同的曝气条件进行体积溶氧传递系数(kLa)的测试,当传统活性污泥和成熟好氧颗粒污泥浓度MLSS为2 000、4 000、6 000、8 000 mg·L-1时,其kLa(min-1)值分别为0.586 1±0.009 5、0.586 1±0.027 2、0.555 6±0.016 8、0.533 8±0.026 8和0.645 5±0.027 6、0.632 0±0.075 5、0.618 5±0.062 5、0.640 6±0.055 5,表明颗粒污泥kLa值高于同浓度条件下的絮体污泥,且随浓度增加,絮体污泥氧传递效率下降而颗粒污泥无明显变化.对好氧颗粒污泥进行筛分后,大颗粒和小颗粒在污泥浓度相同、体积相同、表面积相同以及个数相同的情况下二者的kLa值均无明显差别,由此可以推断,这些因素对好氧颗粒污泥kLa的影响可以忽略.研究结果对于污水处理厂节能运行具有一定的参考价值.

Preliminary Study on Characteristics of Volumetric Oxygen Transfer Coefficient in Granular Sludge Systems

The volumetric oxygen transfer coefficient (k_La) was tested with mature aerobic granules in the same aeration measurement device and under the same aeration conditions. The k_La (min^-1) was 0.5861±0.0095, 0.5861±0.0272, 0.5556±0.0168, 0.5338±0.0268 for floc sludge, and 0.6455±0.0276, 0.6320±0.0755, 0.6185±0.0625, 0.6406±0.0555 for aerobic granules, when the sludge concentration MLSS (mg·L^-1) was controlled at 2000, 4000, 6000, 8000, respectively. This indicated that granular sludge exhibited higher k_La values than the flocs, and the k_La value of floc sludge decreased with the increase of the sludge concentration; however, insignificant decease was found for granular sludge. After screening of granules with different diameter, the k_La values of the aerobic granular sludge with different sizes which had the same MLSS, volume, surface area and particle number were compared, and insignificant difference was found, suggesting that the effects of these factors on the k_La of granular sludge were negligible. The findings of this work may have significance for the energy-saving operation of wastewater treatment plants.