Landfill Leachate Sorption Potential of Kate Valley Soils

Type of content
Theses / Dissertations
Publisher's DOI/URI
Thesis discipline
Civil Engineering
Degree name
Master of Engineering
Publisher
University of Canterbury. Civil Engineering
Journal Title
Journal ISSN
Volume Title
Language
Date
2014
Authors
Chu, Kuang-Chi Kevin Yelias
Abstract

Kate Valley is a municipal waste landfill situated in Waipara, Northern Canterbury. It is a joint venture between the 6 local regional councils and Transwaste Canterbury Ltd to help dispose of waste quantities generated in the wider Canterbury region. Landfill waste disposal also generates waste streams. Major waste streams can include methane gas production and liquid leachate. One practice which can turn liquid leachate waste streams into a nutrient source for plants is land irrigation. It is important to have a thorough understanding of the interactions involved with leachate, soil structure, soil microbiology, flora. This thesis investigates the sorption mechanisms between Kate Valley soil and leachates, through batch and column experiments. Sorption mechanisms between leachate and soil were investigated through batch and column tests. Ex-situ soil samples were extracted from Kate Valley, along with raw leachate samples for batch tests at a soil to liquid ratio of 30 g vs. 70 ml respectively. Tested dilution leachate strengths ranged from raw to 50x raw leachate dilution; meanwhile soil samples were categorized into 3 groups based on soil depth: 0-20 cm, 20-40 cm, and 40-60 cm. Column tests were conducted on 3 extracted in-situ soil column monoliths. Column test irrigation conditions included: control case, 2x and 10x raw leachate dilution, and 200 mg/L KBr (bromide column), where the same soil column was used for bromine testing after control testing had ceased. Batch results suggest deeper soils are less effective at sorption of ammonia, where partitioning coefficient ranged from 9.5x10-7 to 6.410-7 L/mg for 0-20 cm soil to 40-60 cm soil respectively. Column results generally showed lower partitioning capacity than batch results, at 410-8 and 510-8 L/mg for 10x and 2x dilution leachate irrigation respectively. Discrepancies in experimental data have been attributed to: different dilution leachates tested between batch and column tests, making it difficult for direct comparison; extreme soil to liquid ratios employed in experiments; direct data comparison between the “full-contact” experimental data (between leachate and soil), obtained from batch tests with column results, where not all soil may have been fully exposed for shrinkage of boundary layers of soil particles; and oxygen exposure of samples during testing and sampling, possibly encouraging nitrification.

Description
Citation
Keywords
landfill, leachate, sorption, adsorption, batch test, column test, partitioning coefficient, nitrate, ammonia, total-nitrogen, porosity, bromide test
Ngā upoko tukutuku/Māori subject headings
ANZSRC fields of research
Rights
Copyright Kuang-Chi, Kevin Yelias Chu