Greg Forbes (Agri-Food & Biosciences Institute)

Performance of the Greenmount
Constructed Wetland in treating farmyard
dirty water
Summary based on AFBI research monitoring and
QUB post-graduate research.
Greg Forbes (AFBI), Bob Foy (AFBI), Martin Mulholland
(CAFRE).
Contributors; Sally Kidd, Deborah Stephenson, Brian Reid (CAFRE).
Vanessa Woods, Colm McKenna, Zoe McKervey, Phil Dinsmore, Elaine
Sayers, Peter Scullion, Jennifer Meeke, Louise Davis (AFBI).
Largely funded by DARD
P 5
GW 3
P 4
P 3
GW 2
P 2
GW 1
Total pond area = 1.25ha
P 1
Inlet
manhole

WATER LEVEL
Pond 1
INFLOW
200mm
150mm
400mm
SOIL
WATER LEVEL
450mm
1700mm fall, Pond 1 to Pond 5
OUTLET
Species %
survival
Typha latifiola 93
Phragmites
australis.
82
Carex riparia. 80
Iris pseudacorus. 88
Sparganium
erectum.
No FDW for first year
82
INFLOW
200mm
150mm
450mm
SOIL
400mm
OUTLET
Pond 5

•
–
–
• !
–
–
• " #
– $
• % & ''
– ( ) ! $
–
– * +*,%- .
Greenmount rainfall 2006 - 2009
Annual
Rainfall (mm)
' /0/
. /'/
/ 0 /
0 )

Flows and Potential evapotranspiration (pET)
FDW inflow
Average rainfall to
Ponds ~ 11,500m 3 /yr
BUT
1 2
pET
mm/month
(mean)
JAN 5.4
FEB 13.5
MAR 30.7
APR 52.0
MAY 79.3
JUN 88.7
JUL 87.5
AUG 70.1
SEP 43.5
OCT 22.4
NOV 6.7
DEC 3.7
Summer pET loss ~450mm yr
~ 50% of total inflow & rainfall
FDW & summer rainfall insufficient to sustain pond
water levels

32 + 4 - 567 ) $ %8 9
+:* -
Inlet P1 P2 P3 P4 P5 sed P
BOD 1773 168 75 35 52 8.3 128 **
TP 61.4 15.9 10.3 7.5 3.6 1.8 3.1 **
Free
NH 3
6.21 5.29 1.78 3.06 0.48 0.23 0.02 **
BOD- Biochemical oxygen demand
Discharge limit 40 mg/l
Mean annual TP concentrations
2006-2009
Mean annual BOD concentrations
2006-2009

Mean annual NH3 concentrations (2007)
Mean annual conductivity values (2006-2009)
High rainfall episodes affect TP concentration
Flow
No flow

Each year over 90% of TP load retained in CW
" 567 )

Pond 4 BOD 5 limit exceedence
Without pond 5 the CW would breach BOD levels
Pond 4 BOD 5 monthly mean concentrations 2009
Pond 4

8 7 ; "
% 8 7 139
• ? !
• @ !< 5
A "
8 2 B $ C=5
Kai Cai found that wetland efficiently removed naturally occurring female (estrogens)
and male (androgens) hormones originating from the dairy farm
EEQs concentration (ng L -1 )
TEQs concentration (ng L -1 )
150
100
50
0
1200
1000
800
600
400
200
0
January
January
V-notch pond 1a pond 1b pond 2 pond 3 pond 4 pond 5
February
February
March
March
Apirl
Apirl
May
May
July
July
August
August
September
September
Ocotober
Ocotober
Novermber
Novermber
December
December

Janette Bretell also found that wetland efficiently removed microbiological
load present in dirty water inflow including: faecal coliforms, total coliforms,
Enterococcus faecalis and Escherichia coli. Wild birds may have been source
of low levels of Campylobacter found in pond 5 but not in ponds 2, 3 or 4.
Log10CFU/ml
5
4
3
2
1
0
20/08/2007
03/09/2007
17/09/2007
Coliforms levels (CFU log 10 /ml) in wetland ponds
01/10/2007
15/10/2007
29/10/2007
12/11/2007
26/11/2007
10/12/2007
24/12/2007
07/01/2008
21/01/2008
04/02/2008
18/02/2008
03/03/2008
17/03/2008
Sampling dates
This Masters thesis on the Greenmount wetland was judged
best student project in NI section Chartered Institution of
Water and Environmental Management
" 8 ,
3
31/03/2008
14/04/2008
28/04/2008
12/05/2008
26/05/2008
09/06/2008
23/06/2008
07/07/2008
21/07/2008
04/08/2008
18/08/2008
! " # ! !
$ % & '
( ) & * +
Inflow
Pond 1A
Pond 1B
Pond 2
Pond 3
Pond 4
Pond 5

• , 2
2
2 D
•1
•8
– : (
– 2
• "
• 8
• E
2 567
Faecal coliform (presumptive) counts
(‘000 cfu/100 ml)
7 1 8 8 8 8 8 )
4 )4 ' 0 >' F > F > F > F > GG
'4 04 ' . > F > F > F > F > GG
4 )4 . H > >. > F > F > GG
4 4 0 I '>' > F > F > F > GG
)4 /4 0 /' >0 F > /> F > F > GG
Courtesy of Northern Ireland Environment Agency (NIEA)

CW Pathogen reduction
Total coliform (presumptive) and enterococci* counts (‘000 cfu/100 ml)
Date Inlet Pond 1 Pond 2 Pond 3 Pond 4 Pond 5 Significance
31/05/06 500 22 0.3 0.1