Odegaard H, Liao Z, Hansen A T
Department of Hydraulic and Environmental Engineering, Norwegian University of Science and Technology (NTNU), N-7491 Trondheim, Norway.
Water Sci Technol. 2003;47(12):81-8.
In this paper coarse media filtration has been analysed as an alternative to the traditional settling in primary, secondary and tertiary treatment of wastewater. Various filter media configurations were evaluated for enhanced primary filtration. It was found that a dual media configuration based on Kaldnes biofilm media (1 and K2modified) were most suitable when taking both separation efficiency as well as filter run time into consideration. SS removal efficiencies of around 75% were achieved in the dual Kaldnes primary filter at around 20 m/h without any chemical addition and around 85% at low dosage (1-2 mg/l) of a high MW cationic polymer FO4440SH. In the latter case COD was removed by around 70%. Further experiments were carried out on a multi-media Kaldnes-Filtralite-Sand (KFS) filter for enhanced primary treatment as well as for secondary filtration directly downstream of a high-rate moving bed biofilm reactor, resulting in an extremely compact secondary treatment process. The secondary KFS-filter gave SS-removal efficiencies around 90% (effluent SS < 15 mg/l) and filter run times of around 24 hrs at filtration rates of 10 m/h (sludge loading rates of around 1 kg/m2h) when a small dose (2 mg/l) of polymer was used. It is also demonstrated that the primary filter may also be utilised as a pre-denitrification reactor. A denitrification rate of 1.5 kg NO3-N(equiv.)/m3d was achieved when the filter was operated at a filtration rate of 5 m/h.
本文分析了粗介质过滤作为废水一级、二级和三级处理中传统沉淀法的替代方法。对各种过滤介质配置进行了评估，以增强一级过滤效果。结果发现，综合考虑分离效率和过滤运行时间，基于Kaldnes生物膜介质（1和K2改性）的双层介质配置最为合适。在不添加任何化学药剂的情况下，双层Kaldnes一级过滤器在约20 m/h的过滤速度下可实现约75%的悬浮物去除效率；在投加低剂量（1-2 mg/l）的高分子量阳离子聚合物FO4440SH时，悬浮物去除效率可达约85%。在后一种情况下，化学需氧量的去除率约为70%。还对Kaldnes-Filtralite-砂（KFS）多层过滤器进行了进一步实验，以增强一级处理效果，并直接在高速移动床生物膜反应器下游进行二级过滤，从而形成了一个极为紧凑的二级处理工艺。当使用少量（2 mg/l）聚合物时，二级KFS过滤器在10 m/h的过滤速度（污泥负荷率约为1 kg/m²h）下，悬浮物去除效率约为90%（出水悬浮物<15 mg/l），过滤运行时间约为24小时。研究还表明，一级过滤器也可作为预脱硝反应器使用。当过滤器以5 m/h的过滤速度运行时，脱硝速率可达1.5 kg NO₃-N（当量）/m³·d。
