Search

The grains of a rapid water filter are best cleansed by washing upward with water consistently at a rate sufficient to fluidize the entire bed and for a period sufficient to wash the dislodged floc particles out of the bed and into the wash water gutters. Effective washing cannot be accomplished in operation unless the means are provided in the design and construction of the filter plant. Mathematical relationships are developed for beds fluidized by water, beds fluidized by an air-water mixture, and fluidized multi-media beds. Experimental procedures and data are presented, which were used to develop and substantiate the mathematical relationships, or both, and provide useful design information. Suggestions are given for the design of the bed and filter bottom to achieve effective washing. The value of surface wash and air wash is analyzed. It is noted that when air is applied to a bed which is fluidized with water, the bed expansion is reduced.

Increasing evidence is accumulating which indicates that immunological abnormalities contribute to the development of liver disease and its signs and symptoms. Platelet-associated IgG (PAIgG) levels were quantified in 42 patients with biopsy-proven liver disease of various etiologies to determine the relationship of thrombocytopenia to immunologic abnormalities in these disorders. Five of six nonthrombocytopenic patients with acute viral hepatitis B had elevated PAIgG. Six of ten patients with chronic active hepatitis had elevated PAIgG and thrombocytopenia. In contrast, only one of six patients with chronic persistent hepatitis had elevated PAIgG. Nine of ten patients with alcoholic hepatitis had elevated PAIgG; seven of the nine were thrombocytopenic. Seven of ten alcoholic patients with cirrhosis had elevated PAIgG; six of seven were thrombocytopenic. Thus the increase in PAIgG may be present without thrombocytopenia in acute liver injury, while patients with chronic persistent hepatitis do not usually exhibit this abnormality. Severe chronic active liver disease is accompanied by thrombocytopenia and an increase in PAIgG levels.