Masters Theses


"The purpose of this research study was to investigate methods for the disposal of activated sludge containing metal-precipitated phosphorus. To accomplish this objective, chemically-treated activated sludge or a mixture of the secondary sludge with primary sludge were thickened and dewatered by vacuum filtration and centrifugation. The putrescibility of the dewatered secondary sludge was also evaluated, and since anaerobic digestion is the usual method of sludge treatment, a digestion study was conducted. Secondary sludge for these studies was produced in five 38-gpd (144-1/day) activated sludge pilot plants operated at the Rolla Southeast Treatment Plant. Ferric chloride and alum were added directly to the aeration chambers of four of the plants, while the fifth served as a control; and the effectiveness of Fe⁺⁺⁺ and Al⁺⁺⁺ in removing phosphorus from wastewater was evaluated. The addition of chemical precipitants to the activated sludge aeration chamber had a beneficial effect on the treatability of the sludge from the standpoint of vacuum filtration, but did not significantly alter its thickening and centrifuging characteristics; Al⁺⁺⁺ had a greater effect than Fe⁺⁺⁺ on all the sludge characteristics studied. The putrefactive characteristics of the dewatered metal-precipitated sludges were similar to those of a control sludge. Very little difference in gas production and composition was experienced during the anaerobic digestion of the chemically-treated sludges and the control sludge. Addition of either Al⁺⁺⁺ or Fe⁺⁺⁺ to the activated sludge system effectively reduced the concentration of phosphorus released in the effluent; however, greater removals were achieved with Al⁺⁺⁺ than with Fe⁺⁺⁺ when both were applied at equal M/P ratios"--Abstract, page ii.


Grigoropoulos, Sotirios G.

Committee Member(s)

Jennett, J. Charles
Nicholson, Larry M.


Civil, Architectural and Environmental Engineering

Degree Name

M.S. in Civil Engineering


United States. Environmental Protection Agency


University of Missouri--Rolla

Publication Date



viii, 107 pages

Note about bibliography

Includes bibliographical references (pages 80-81).


© 1971 Lyle Wayne Merritt, All rights reserved.

Document Type

Thesis - Open Access

File Type




Subject Headings

Sewage -- Purification -- Activated sludge process
Sewage sludge
Water -- Phosphorus content

Thesis Number

T 2597

Print OCLC #


Electronic OCLC #