Specialist Group on Use of Macrophytes in Water Pollution ... - IWA

Constructed wetlands are an attractive option for treatment of deicing runoff, because when
operated in a subsurface mode, the risk to airfield operations is minimal and the systems
require much less operation & maintenance than conventional systems.
PILOT TESTING
Pilot testing was carried out at Campus D‘Alfred of the University of Guelph in Ontario,
Canada. . The tests were carried out indoors in 1 m 3 vessels configured as mixing tanks
(containing mixers and heaters), open aerated basins (AB cells, simulating aerated tanks and
containing fine bubble aeration spargers), non-aerated vertical subsurface flow (VSSF)
constructed wetland cells and aerated VSSF intensified (IW) test cells. The wetland cells
were vegetated with common reed (Phragmites sp.) taken from ditches near the test unit. Test
runs were preceded by month-long calibration and acclimatization periods.
The pilot facility was configured as a mixing tank; two open-water AB cells; one non-aerated
VSSF CW cell containing gravel 0.3 m deep and; and two aerated gravel-bed VSSF
intensified wetland cells (IW1 and IW2) containing gravel 0.8 m deep. There were two
separate sets of cells which, after initial calibration and acclimation periods at room
temperature, operated in parallel at the two design basis target temperatures. The set-up for
high temperature operations consisted of a mixing tank and an AB cell followed by parallel
CW and IW cells. (These were considered as two separate trains.) The set up for low
temperature operations consisted of an AB Cell and one IW cell in series. These latter two
vessels were located inside a walk-in refrigerator at the Alfred Pilot Unit (Train 3). The initial
configuration of the pilot facility is shown in Figure 1.
SW from
Storage Tanks
ADF
Mixing Tank
AB Cell
Lo Temp
AB Cell
Hi Temp
Walk-in Refrigerator
IW Cell
Lo Temp
CW Cell
Hi Temp
IW Cell
Hi Temp
Figure 1. Pilot test facility schematic
Train 3
Train 2
Train 1
Results from the four testing periods (Runs A, B, C, D) and the three process trains (Trains 1,
2, 3) are summarized in Table 1 (Wallace et al., 2007).
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IWA <strong>Specialist</strong> <strong>Group</strong> on Use of Macrophytes in Water Pollution Control: Newsletter No. 38 37