FILTER MEDIUM USING GRANULAR ACTIVATED COAL FOR PURIFYING EUTROPHIC SEWAGE CAUSED BY NITROGEN OR PHOSPHORUS, WATER PURIFICATION PLANT UTILIZING SAME, METHOD OF TREATING SLUDGE WITH FINE ACTIVATED-COAL POWDER AS ION-EXCHANGE MATERIAL, AND VARIOUS RECYCLE MATERIALS PRODUCED BY THE METHOD

摘要

A filter medium for purifying eutrophic sewage, the filter medium comprising granular activated coal which is obtained by subjecting low-grade coal unsuitable for use as a fuel to an oxidation treatment to remove ash therefrom and thereby make the whole structure microporous and has an average particle diameter of 5 mm or lager, wherein the proportion of silicon to carbon in the constituent elements has been regulated to a value within a given range. As a result, the excellent ability of the granular activated coal obtained by subjecting inexpensive low-grade coal to an oxidation treatment and the purifying ability of microorganisms or nitrogen- or phosphorus-absorbing ability of a plant are effectively utilized in the filter medium for purifying eutrophic sewage. A water purification plant utilizing the filter medium can be provided.