Performance Comparison of Filters with Different Aggregates

摘要

Unplanted upflow filters, which were filled with different filter media (natural zeolite, blast furnace granulated slag, ceramsite, and walnut shells), were operated to assess their nutrient removal performances. Different preprocessing methods involving aerobic and anaerobic sludges were applied to the filters to accelerate the treatment processes. Tbe results indicated that preprocessing enhanced the soluble chemical oxygen demand (SCOD) removal, but had no obvious influence on the total nitrogen (TN) and total phosphorus (TP) removal efficiencies. Filters containing blast furnace granulated slag were independent with respect to SCOD loading rate variations in the range between 100 and 900 mg/d. A linear velocity equation was used to determine the nutrient removal velocities of blast furnace granulated slag-filled filters. The removal velocities were rapid, and highest for TP and lowest for TN. Compared with other filters, blast furnace granulated slag-filled filters performed best concerning nutrient removal and retention. Walnut shell-filled filters performed worst.