Naima Rahman

Graduation Semester and Year

2018

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Civil Engineering

Department

Civil Engineering

First Advisor

Sahadat Hossain

Abstract

Solid waste is being generated at a record pace, and disposal of it requires advanced waste management services at a reasonable cost. Landfilling is the most suitable waste disposal and management technique currently available, and it is being used throughout the world. It is, however, the largest anthropogenic source of atmospheric methane, and it requires a lot of space. The primary objective of this study was to investigate an alternative sustainable solution to waste management by operating landfills as biocells. Biocells are cost effective, produce methane more rapidly, and accelerate space recovery. A laboratory scale study was conducted to investigate the effects of enzymes and manure on solid waste decomposition and gas production in a landfill biocell. To simulate the biocell, laboratory scale reactors were filled with municipal solid waste (MSW) and food waste, and the manganese peroxidase (MnP) enzyme, three types of manure (from cows, pigs and horses), and sludge were used as inoculum. MSW reactors with MnP produced the highest amount of methane, followed by reactors with pig manure. Among the food waste reactors, the highest methane volume was generated by reactors with cow manure. But all of the food waste reactors produced less methane than the MSW reactors, due to the long lag phase. Based on the results from the laboratory scale study, two field scale test cells (control cell and biocell) were installed in the City of Denton Landfill with MSW feedstock and were monitored for almost 14 months. Though reactors with MnP produced the highest amount of methane in the laboratory, it was not used in field. Instead, a combination similar to that of the MSW reactor with pig manure was used in the field biocell, where the control was simulated as a bioreactor landfill. The results from the field experiment revealed that the biocell test section that was fed with organic fractions of MSW, pig manure, and sludge produced nearly three times more the amount of methane (12,437 standard cubic feet) than the control section (4,644 standard cubic feet). The estimated decay rate of the biocell was considerably larger (1.32 year-1) than the decay rate of control cell (0.18 year-1) and the other values found in literature (0.003 to 0.21 year−1). The quality and amount of the landfill biogas and quality of the leachate showed that the pig manure enhanced the MSW biodegradation in both laboratory scale landfill simulation and field application. Thus, it can be concluded that operating a landfill as a biocell is a sustainable waste management system that results in enhanced methane production and waste decomposition.

Keywords

Sustainable waste management, Landfill, Biocell, Landfill gas, MSW decomposition

Disciplines

Civil and Environmental Engineering | Civil Engineering | Engineering

Comments

Degree granted by The University of Texas at Arlington

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