A Comparison of Expanded-Bed and Packed-Bed Adsorption Systems

摘要

The overall objective of the program was to evaluate the feasibility of the expanded-bed technique for contracting granular activated carbon with biologically treated sewage effluent, and to provide a rigorous comparison between this technique and the conventional packed-bed mode of operation. The evaluations and comparisons were to be made with pilot scale adsorbers under actual field operating conditions. Although secondary effluent without further pretreatment was of primary interest, the effects of additional clarification were also to be determined. Clarification methods included dual media filtration and chemical treatment followed by dual media filtration. The packed-bed and expanded-bed adsorption systems, operating under comparable conditions, were found essentially equivalent in their effectiveness for removal of soluble organic material from a secondary sewage effluent. Suspended solids, present to some degree in all the wastewaters tested, were more effectively removed by the packed beds. The expanded beds did, however, removed some suspended material. Accumulation of suspended solids caused rapid increase in head loss in the packed beds, necessitating frequent cleaning of the carbon in these beds. Because the expanded beds are not subject to clogging from accumulated solids, their pumping power and maintenance requirements are lower than for a packed bed of the same size. Where the improved suspended solids removal provided by a packed bed is not required, the expanded-bed adsorber may be preferred. (Author)