Rakib Ahmed

Graduation Semester and Year

2019

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Civil Engineering

Department

Civil Engineering

First Advisor

Sahadat MD Hossain

Abstract

Landfilling is the most popular waste disposal system worldwide; however, with increasing scarcity of materials, increases in land values, and the presence of non-engineered landfill sites in both the developing and developed world, landfill mining has been the recipient of special interest in today’s waste management practices. Therefore, the motivation of the current study was to evaluate the energy potential of mined landfill waste and develop a statistically significant mathematical model to predict its energy potential (calorific value). The current study was conducted by using the municipal solid waste (MSW) samples collected from the City of Denton landfill and the City of Irving landfill Texas. Mined waste was collected from conventional cell (cell 0) and ELR operated cell (cell 2) from City of Denton Landfill, and the calorific value of the collected MSW was investigated, using an oxygen bomb calorimeter. The fine/degraded fraction made up 48% of the mined waste at the City of Denton landfill. The average calorific value of mined waste was found to be 3586.97 Btu/lb. The calorific value was also determined for fresh MSW collected from the working phase of the landfill. Based on the results, 52% of the energy value is still available in the mined waste compared with the energy potential of fresh waste. Different parameters, such as depth, landfill operation, moisture content, volatile solid, age of waste, precipitation, and fine fraction were analyzed to understand the behavior of mined solid waste. It was observed that the fine fraction had a decreasing trend, and the volatile solid had an increasing trend with the increase of calorific value. Moisture content and depth of the landfill did not exhibit any significant correlation with the calorific value. Based on the degradation nature of the solid waste components, a universal energy index, based on the composition of the waste, was introduced and found to be a very good predictor the for calorific value of MSW. Proximate analysis (Volatile solid determination) and elemental analysis 2343 determined by a muffle furnace and an elemental analyzer, respectively. Carbon was found to be the most significant element for energy value. Three simple linear regression (SLR) models, based on three different analyses (physical composition, proximate analysis, and elemental analysis), were developed to predict calorific value, using the statistical tool R. The physical model, which used the energy index, was validated with mined solid waste collected from the City of Irving landfill, and showed excellent agreement between the predicted calorific value and the measured calorific value of the MSW collected from the landfills. The model-based elemental analysis was in good agreement with the experimental values found in literature. Overall, this study will enhance the understanding of the physical characteristics and energy potential of landfill mined waste and will provide two universal mathematical models for better predictions of calorific value from any waste composition.

Keywords

Landfill mining, Energy from MSW

Disciplines

Civil and Environmental Engineering | Civil Engineering | Engineering

Comments

Degree granted by The University of Texas at Arlington

Download

Share

COinS