Graduation Semester and Year

2012

Language

English

Document Type

Thesis

Degree Name

Master of Science in Civil Engineering

Department

Civil Engineering

First Advisor

Sahadat Hossain

Abstract

The Enhanced Leachate Recirculation (ELR) landfills operation results in rapid waste stabilization, waste decomposition and increased rate of gas generation. However, operating landfill as an ELR landfill requires availability of sufficient amount of fresh water in close proximity to the landfill facility. In coastal regions, where fresh water supplies may be scarce, available saline water may be considered for ELR operation. However, the effects of saline water on the decomposition solid waste and landfill gas generation are unknown and need to be investigated., The objectives of the current research are to investigate the effects of adding and/or recirculating saline water on biodegradation and landfill gas generation of municipal solid waste (MSW) at the Cefe Valenzuela Landfill (Cefe), Corpus Christi, Texas. To accomplish the research objectives, four 6-gallon laboratory scale reactors, simulating ELR landfill, were built. The reactors were filled with fresh MSW collected from the Cefe Landfill. Reactors 1 and 3 were being operated with de-ionized water while the reactors 2 and 4 were being operated with saline water collected from Corpus Christi Landfill site. The physical characteristics of collected MSW samples have also been investigated. Based on 10 bags of fresh MSW sample, major MSW components are: Paper (38.27%), Plastic (14.15%), Food Waste (9.14%),and Others (Soil & Fines) (18.11%). The initial moisture content of MSW samples varied from 29.66% to 43.21%. Average compacted unit weight and permeability were found to be 35.34 pcf and 4.39 x 10-4 cm/sec, respectively. The volatile solids, pH, BOD, and COD tests were performed to evaluate the level of degradation of the solid waste in the bioreactor. It was observed that the fresh water reactors 1 and 3 started producing methane in significant amount after 20 days of operation. The total methane produced in this reactor 1 and 3 were 325.82 L and 923.89 L, and the methane yields were 39.83 L/lb and 100.53 L/lb dry weight, respectively. For the reactor 4 with saline water, there was a lag period of 60 days prior to methane generation. But the methane generation did not accelerate until 80 days. The cumulative methane generation of reactor 4 was 83.044 L/lb at the time of dismantling after 194 days, and reactor 4 was still producing gas. From the experimental results the increase in salt content causes a reduction in a volume of daily and total methane production and methane yield, and an increase in lag time, the time to reach the peak of daily methane production, and stabilization time. The addition of saline water for ELR operation might have delayed the methane generation in landfill. However, the rate and volume of gas production are similar to reactors that were operated with fresh water after an initial lag period. Considering the experimental results, it was determined that saline water can be utilized for ELR landfill operation.

Disciplines

Civil and Environmental Engineering | Civil Engineering | Engineering

Comments

Degree granted by The University of Texas at Arlington

Download

Share

COinS