Sonia Samir

Graduation Semester and Year

2011

Language

English

Document Type

Thesis

Degree Name

Master of Science in Civil Engineering

Department

Civil Engineering

First Advisor

Sahadat Hossain

Abstract

At present, there are more than 40 closed municipal solid waste (MSW) landfills around DFW and North Texas. A closed landfill might have potential benefits for gas recovery and utilization due to the presence of organic components in the MSW. The decomposition of organic components of MSW produces gas. The decomposition process after landfill closure may continue for 20 to 100 years depending on the operational practice of the landfill. However, to evaluate the methane potential of a closed landfill it is important to have the understanding of the characteristics of the existing or decomposed landfill wastes. The current study presents the characteristics of municipal solid waste samples, collected from a closed section (phase zero) of the City of Denton landfill, Texas. The phase zero section of landfill was operated as a pre subtitle-D conventional landfill. Twelve MSW samples were collected from the landfill using 3ft diameter bucket auger sampler from two boreholes in November, 2010. The estimated age of collected MSW samples ranged from 9 to 25 years. Physical composition was determined by manual sorting of the samples. The average composition for landfilled waste found was as Paper (31%), Plastic (10%), Food Waste (0%), Textile and Leather (2%), Wood and Yard Waste (8%), Metals (3%), Glass (1%), Styrofoam and Sponge (1%), C & D (5%), Degraded Fines (14%) and Soils (25%). The composition had very high percentage of soils and degraded fines. There was no food waste in the samples. The moisture content varied from 11% to 34%. The average moisture content of the landfilled samples was determined to be 24.93%. The average compacted unit weight of the samples was determined both using standard proctor method and using Tensile Compression machine applying overburden pressure. Average compacted unit weight was determined to be 58.76 lb/ft3 and 49.14 lb/ft3 for standard proctor and tensile compression respectively. The permeability was found in the range of 10-4 to 10-5 cm/sec. The average permeability was determined 2.3X10-4 cm/sec. The particle size distribution of the samples were determined and compared to previous study that indicated the degradation phase of samples. Approximate half of the samples were as phase I degraded samples and other half of the samples were between phase I and phase IV degradation level.The volatile solids (VS) tests were being performed to evaluate the level of degradation of the collected solid waste. Based on the test results, average volatile solids (VS) of all landfilled samples is determined 63.08%. The biochemical methane potential (BMP) was predicted from correlation with volatile solids tests results. Gas generation of the closed landfill section of City of Denton landfill was predicted using first order gas generation model. The predicted maximum gas generation volume was determined as 9.37X109 ft3, when Lo was used as140 m3/Mg. However the predicted gas volume was determined as 6.69 X109 ft3, when Lo was used as 100m3/Mg. The future gas generation potential of the existing landfilled solid waste varies between 65% and 20%.

Disciplines

Civil and Environmental Engineering | Civil Engineering | Engineering

Comments

Degree granted by The University of Texas at Arlington

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