Technical Bulletin No. 0004: Trickling Filter Report
During 1945 certain equipment and operational changes were made in the fifteen-foot trickling filter and in the test runs during the summer and fall moderately increased efficiencies were realized. Certain experimental work, in connection with the thirty-inch filter which, being housed indoors, can be operated the year round, was conducted simultaneously with the fifteen-foot -filter trials. The results of these experiments with the small filter will be applied in the future operation of the fifteen-foot filter. The progress made during 1945 both in connection with the thirty-inch laboratory filter and the fifteen-foot filter is summarized in the attached report.