Al-Jasser A O
Civil Engineering Department, College of Engineering, King Saud University, P.O. Box 800, Riyadh 11421, Saudi Arabia.
Water Environ Res. 2009 Sep-Oct;81(9):849-57. doi: 10.2175/106143008x390799.
Solids in aeration tank effluents contribute to the total organic content and suspended solids concentration, and violates disposal and reuse standards. Therefore, improving the settling properties of sludge helps produce an effluent with a quality that conforms to effluent standards, assuming all other conditions for good settling in the sedimentation tank are favorable. In this paper, seven chemicals that are all cationic polyelectrolytes were tested individually as additives to improve the settling properties of aeration tank effluent from a full-scale wastewater treatment plant. Pilot settling columns designed and constructed at a local wastewater treatment plant were used in this project. Batch settling tests were performed on fresh activated sludge samples that were collected before the secondary sedimentation tank and mixed with different concentrations of the additives without cumulative additions. Each additive was accessed based on its particular sludge settling properties, that is, the shape of the settling curves, the values of the hindered zone settling rate or zone settling velocity, and the stirred sludge volume index. Each additive result was compared with the corresponding properties of a plain sludge sample collected on the same day and used as a control. Substantial and dissimilar improvements were obtained and are presented in the form of graphs and values using 92 settling runs. Shorter lag-times, quicker descending speed of sludge-water interface, higher descending distance, and lower stirred sludge volume indices values were attained with the use of these additives.
曝气池流出物中的固体物质会增加总有机含量和悬浮固体浓度，并且不符合处置和再利用标准。因此，假设沉淀池内所有其他有利于良好沉降的条件都具备，改善污泥的沉降性能有助于产生符合排放标准的出水。在本文中，单独测试了七种均为阳离子聚电解质的化学品作为添加剂，以改善一座大型污水处理厂曝气池流出物的沉降性能。本项目使用了在当地污水处理厂设计和建造的中试沉降柱。对在二次沉淀池之前收集的新鲜活性污泥样品进行间歇沉降试验，并将其与不同浓度的添加剂混合，且不进行累积添加。根据每种添加剂特定的污泥沉降性能进行评估，即沉降曲线的形状、受阻区沉降速率或区域沉降速度的值以及搅拌污泥体积指数。将每种添加剂的结果与同一天收集的用作对照的普通污泥样品的相应性能进行比较。通过92次沉降试验获得了显著且不同的改善，并以图表和数值的形式呈现。使用这些添加剂可实现更短的延迟时间、更快的污泥 - 水界面下降速度、更高的下降距离以及更低的搅拌污泥体积指数值。
