|
" A Laboratory Study on a Biochar-Amended Biosand Filtering System for Escherichia coli Removal from Lake Water "
Guan, Peining
Afzal, Muhammad T.
| Document Type
|
:
|
Latin Dissertation
|
| Language of Document
|
:
|
English
|
| Record Number
|
:
|
1058900
|
| Doc. No
|
:
|
TL58017
|
| Main Entry
|
:
|
Guan, Peining
|
| Title & Author
|
:
|
A Laboratory Study on a Biochar-Amended Biosand Filtering System for Escherichia coli Removal from Lake Water\ Guan, PeiningAfzal, Muhammad T.
|
| College
|
:
|
McGill University (Canada)
|
| Date
|
:
|
2019
|
| Degree
|
:
|
M.Sc.
|
| student score
|
:
|
2019
|
| Note
|
:
|
87 p.
|
| Abstract
|
:
|
Surface water contamination has been a global concern for years, especially in the developing world where high-quality centralized water treatment systems are often lacking. An alternative point-of-use household water treatment technology widely adopted in many developing countries, the biosand filter (BSF) generally shows poor removal efficiency for fæcal indicator bacteria (Escherichia coli). However, amendment of some filtering systems with biochar has been shown to enhance the E. coli removal. As the role of biochar as an amendment in a BSF remains unknown, the present research sought to investigate the performance of a laboratory-scale biochar-amended biosand filtering system for the removal of E. coli from lake water. In the first of two laboratory experiments, the effect of hardwood biochar (< 1 mm diameter) and its placement in the filtering column [independent layer in the middle (biochar filter); thoroughly mixed with sand (mixture filter)] on E. coli removal from lake water was investigated. A 3-week pre-filtration of lake water, without E. coli inoculation, was conducted to promote filter maturation. Filters were then daily dosed with one pore volume of E. coli -inoculated lake water over a period of two weeks. Throughout the experiment, no significant difference in E. coli removal was found between the biochar filter and control filter with no biochar. With significantly greater E. coli removal observed on two different days, the biochar filter showed a generally better performance than the mixture filter. For both types of biochar-amended filters (the biochar filter and the mixture filter), the soil hydraulic conductivity was dramatically reduced compared to the non-amended filters. In the second experiment, the effect on E. coli removal on type of biochar was investigated. Biochars, produced from feedstocks of willow wood and wheat straw, were sieved to a size of 1-4 mm and added as an independent layer in the filters - filters without biochar served as a control. The pattern of filter operation and concentrations of E. coli were maintained as in the first experiment, but no pre-filtration step was carried out. Compared to the control, both biocharamended filters showed reduced E. coli removal, the filter amended with wheat straw biochar achieving a greater mean E. coli removal (0.88 log10) than the willow wood biochar-amended filter (0.73 log10). Both biochars increased the pH, electrical conductivity and phosphorus content of the effluent. In the first experiment, Scanning Electron Microscope observations indicated the presence of biofilm (schumuzekecke) on the surface of the coarse sand near the columns’ water inlets. These filters achieved a higher E. coli removal rate than the filters employed in the second experiment, showing that filter maturation improved filter performance. Formation of biofilm on the biochar’s surface could not be confirmed, so the effect of biochar-associated biofilm on E. coli removal remains unclear. Since biochar-amended filters showed no enhancement of E. coli removal in either experiment, biochar may not be an ideal medium for amending BSFs. Investigations on the performance of biochar-amended biosand filter on E. coli removal using a downward filtering system, E. coli removal by other types of biochar, the effect of filter maturation on E. coli removal by biochar, and the influence of biochar amendment on removal of other contaminants are recommended for the future research.
|
| Descriptor
|
:
|
Bacteria
|
|
|
:
|
Civil engineering
|
|
|
:
|
Drinking water
|
|
|
:
|
E coli
|
|
|
:
|
Environmental protection
|
|
|
:
|
Environmental science
|
|
|
:
|
Pathogens
|
|
|
:
|
Sanitation
|
|
|
:
|
Soil contamination
|
|
|
:
|
Water shortages
|
|
|
:
|
Water supply
|
| Added Entry
|
:
|
Afzal, Muhammad T.
|
| Added Entry
|
:
|
McGill University (Canada)
|
| |