Drinking Water Treatment TABLE 5.1 LOCATION
CAPACITY
YEAR
TURBIDITY
(m^/d)
COMPLETED
(NTU)
COLOUR
(TCU)
RAW
TREATED
RAW
TREATED
<15
Cat Lake First Nation
330
1995
3
0.2
50
Pic River First Nation
500
1998
1.0
<0.1
25
<5
Sheshegvyaning FN North Spirit Lake FN Wapekeka
130
1998
0.5
0.1
<5
<5
345
1999
3
0.2
40
<15
345
2000
1.5
0.2
30
<15
for a more thorough cleaning. The slow sand filter is cleaned using a hydraulic wet harrow method. Water is directed over the filter bed to a collection trough while the surface is sprayed with a high-pressure hose to dislodge the accumu lated schmutzdecke. This is required approximately once every two to twelve months depending on raw water qual ity. In over five years of operation the final GAC contactor has not required cleaning. The multi-stage filter process has been installed in five Northern Ontario communities. A summary of the existing installations is presented in Table 5.1.
■RINSE WATER TROUGH
DISTRIBUTION TROUGH
ROUGHING FILTER
RAW WATER
SLOW SAND
INLET
FILTER
Plants under construction in the summer of 2000 are:
• Brunswick House First Nation - Capacity 180 mVd; • Park Hotel and Resort, North of Peterborough - Capacity
CARBON CONTACTOR PLANT
EFFLUENT
85 mVd; and
-WASTE WATER/OVERFLOW
• Clarke County, Virginia, USA - Capacity 480 mVd.
CHANNEL
Figure 5-1 MuIti-Stage Filtration
Package Plant
FIBROTEX* also has
optional Vacuum Steam Pasteurization that destroys captured cryptosporidium and giardia.
The Park Hotel facility, an upscale resort, will utilize preozonation to achieve a very high quality of water both from a health and an aesthetic perspective. Summary Enhancement to the slow sand process has significantly extended the range of raw water quality that can be treated without sacrificing the simplicity of operation. The rough ing filter is capable of removing high levels of turbidity and algae and can be cleaned with a simple backflushing. Slow sand filters can be operated at higher hydraulic load ing rates due to the high quality of water being applied from the roughing filter. The hydraulic wet harrow method of cleaning is simple and requires little time. Very little sand is lost during cleaning, therefore there does not need to be an allowance for loss of bed depth. Filter boxes can be kept
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The only system that filters for iron/ manganese removal and cryptosporidium/ giardia. The IRONMANn"''" System hy Smith & Loveless packages FIBROTEX® with an integrated oxidation process. This system is particularly useful for Municipalities that rely on well water sources for potable water. FIBROTEX is
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RBROTEX®
tested and certified to ANSI/NSF
International Standard 61 and provides a cryptosporidium barrier of2 log. The FIBROTEX also has the optional Vacuum Steam Pasturization that destroys filtered crypto and giardia.
shallower and reduce costs.
The activated carbon contactor is effective at removing colour but carbon life limits this option alone to low to moderate coloured waters. However, pre-ozonation will effectively oxidize the long chain colour molecules and al low the biological processes that follow to remove the col our and the ozone by-products. The enhanced slow sand filter alternative offers the ad
Smith & Loveless, Inc. 14040 Santa Fe Trail Drive
Lenexa, Kansas 66215-1284 United States of America 913.888.5201
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vantage of simple operation and low operating costs which must he balanced against the size of the filters and some times the higher initial capital costs. For communities with a population of less than 1,500, the enhanced slow sand filtration option can he a practical and very effective alter native.
For more information, circle reply card No. 136 Environmental Science & Engineering, May 2000