... during backwashing.Commercially available activated carbons usually have a small percentage of materialsmaller than the smallest sieve and larger than the largest sieve, which significantlyaffects ... testing activated carbon are given in ASTM Stan-dards (American Society for Testing Materials, 1988) available from ASTM, 1916 Race St., Philadelphia, PA19103, as well as in AWWA Standards B604-96 ... relativeamounts of different-size particles that are part of a given sample, or lot ,of carbon,andhas an important impact on the filtration properties of GAC in GAC columns that areused both as...