Date of Award

Fall 1987

Document Type

Thesis - Restricted

Degree Name

Master of Science (MS)

Department

Civil and Environmental Engineering

Abstract

Literature concerning the principles governing cellulose degradation in soil was reviewed. Twenty-four reactors were incubated in the laboratory with soil, paper mill sludge, and seed, in order to study the influence of microbial seed on the degradation of cellulose wastes. The variables considered in the design of the experiment were: 1) Application rates of sludge-25 and 50 ton/ acre, and 2) Seed application as a percentage of the sludge loading - 0, 2.5, 5, and 10%. The reactors were run in duplicate, and incubated for 45 days at room temperature. Carbon dioxide evolution was periodically measured in each reactor to determine the rate of decomposition of the sludge and to produce an indirect measurement of the microbial activity. Other attempts of measuring the microbial activity in the reactors were made by running microbial counts and volatile solids tests on sludge-soil samples. At the end of the study, an estimated 63% of the added carbon was mineralized at the 2.5 and 50 ton/ acre sludge amendments, and differences between carbon dioxide evolution from reactors with different seed percentages were not observed. Statistical analysis confirmed the absence of influence of applied seed on degradation of sludge. High carbon dioxide evolution rates (about 30 mg 002/day for 25 ton/acre amendments and 80 mg C02/day for 50 ton/acre) were measured during the first five days of incubation. After these peaks, the rate decreased gradually and became stable. This trend is explained by the presence of readily and non-readily degradable organic matter in the sludge. The number of microbial colonies counted at different incubation days followed the same general trend observed in carbon dioxide evolution.

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