Thesis-1993-Aydin.pdf (48.14 MB)
An investigation into the influence of sand size, bed depth, rates of filtration and temperature on the quality of filtrate from a slow sand filter
thesis
posted on 2010-11-23, 10:57 authored by Mehmet Emin AydinThe objective of this research project was to investigate the influence
of the principal design and operational parameters on the quality of
the filtrate from a slow sand filter. These parameters are sand effectivc
size, depth of sand bed, rate of filtration, water temperature and
influent quality. Attempts were then made to establish relationships
between the variables employed by means of regression analyses of the
experimental data.
To carry out the investigation three laboratory scale filter columns
were constructed each measuring 150 mm in diameter and 3010 mm
height. The filtration medium in each column consisted of a 1.2 m
depth of sand on a 0.3 m depth of gravel. For the three individual
columns three different sand sizes were employed. These were 0.17
mm effective size (ES), 0.35 mm ES and 0.45 mm ES. Water to be
filtered was abstracted from the Burleigh Brook, adjacent to the Civil
Engineering laboratories. As required small amounts of settled sewage,
obtained from the Loughborough Water Reclamation Works, were
added to increase both the turbidity and the count of indicator
bacteria.
The filters were operated at five different filtration rates at three
different temperatures. These temperatures were 25 degrees C, 15 degrees C, 5 degrees C
and the filtration rates repeated for each temperature were 0.1, 0.2, 0.3, 0.4, 0.5 m/h. The filters were operated for not less than one
month at each filtration rate.
In order to assess the efficiency of the filters water samples were
taken and analysed from the influent and from the filtrate and also
from a series of sampling taps positioned at various depth down the
sand media. These water samples were tested for total coliform
bacteria, for faecal coliform bacteria, suspended solids and turbidity.
Regression analyses were then carried out on the data obtained and
regression models were developped for 100 mm and 1200 mm sand
depths of each filter for each period. Occasional tests (i. e. at least once
for each flow rate) were also carried out for nitrate and ammoniacal nitrogen, colour, pH, conductivity, total organic carbon (TOC) and
dissolved oxygen.
Following the completion of the filtration operation at three
temperatures and five filtration rates the sands of the filtration media
were also examined. Sand samples were taken for examination from 0,
50, 100, 150, 200, 300, 400, 600, 800, 1000 and 1200 mm below
the sand surface of each filter. Then in order to assess both the
penetration of the removed solids into the filter bed and to investigate
the concentration of the biological film developed within the sand bed,
sand samples were analysed for suspended solids, turbidity, standard
plate count bacteria and particulate organic carbon. Regression
analyses were also carried out on these data and variation of each
parameter against each filter bed was modelled. The solid and
biological deposits on the sand samples were also viewed with a
Scanning Electron Microscope.
History
School
- Architecture, Building and Civil Engineering
Publisher
© Mehmet Emin AydinPublication date
1993Notes
A Doctoral Thesis. Submitted in partial fulfillment of the requirements for the award of Doctor of Philosophy of Loughborough University.EThOS Persistent ID
uk.bl.ethos.334368Language
- en