Date of Award

1995

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

First Advisor

Gary A. Britenbeck

Abstract

The stringent environmental regulations, rising cost, public concerns, and the limited availability of landfills for disposal of organic wastes have stimulated efforts to identify cost-effective, environmentally sound, alternative waste disposal technologies. The value of organic wastes as soil amendments is limited by their low nutrient value, occasional strong odors and high costs of transportation. The primary goal of this investigation was to develop a process to enrich the N content and to reduce the water content of organic wastes in order to enhance the value of these wastes for use in fertilization and oil spill remediation. A chemical process was developed to enrich the N contents of cellulosic wastes by employing a thermally induced high pressure reaction with NH$\sb3$ in an oxidative environment. This process increased the total N content of cellulosic wastes by 5.1-17.1 times, resulting in organic products containing 50-90 g N kg$\sp{-1}.$ Generally, the capacity of this process to enrich N content was related to the organic C content of the cellulosic material. For all of the cellulosic materials studied, optimal reaction pressure was about 7000 kPa and optimal reaction temperature varied between 80 and 180$\sp\circ$C. Optimal reaction time was 90 min. Carbonyl-containing aliphatic and aromatic compounds in cellulosic wastes offered reactive sites for N enrichment. Major N-containing compounds formed were aliphatic and aromatic amides, nitriles, nitro compounds, and heterocyclic compounds. These N enriched materials have little odor, low salts, neutral pH and an attractive, dark-brown organic appearance. These characteristics and the high level of N greatly increased the value of the N enriched products to serve as an environmentally-friendly, slow-release organic N fertilizer. The leaching losses of N were negligible when applied at moderate rates. Nitrogen enriched cellulosic materials were effective oil absorbents even when crude oil was spilled on coastal sand or marsh soil several days before application. Furthermore, surface applied N enriched cellulosic materials stimulated the bioremediation of soils contaminated with south Louisiana crude resulting in oil losses of 68-74% during 90 d incubation period. Oil losses were about 30% from untreated soils under natural conditions.

Pages

158

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