Discharges from Phnom Penh Cambodia Successes and Future Challenges

Natural Wetlands Treatment of Sewage
Discharges from Phnom Penh, Cambodia:
Successes and Future Challenges
Kim N. Irvine, Buffalo State, State University of
New York

Wetlands Treatment Increasingly
Accepted Throughout the World

Constructed Wetland for Industrial Park,
Rayong, Thailand

AIT- An Important Regional
Resource for Wetlands Studies

Scenes from Phnom Penh

Phnom Penh is Growing and Developing

Background to Study
City of Phnom Penh serviced by a
combined sewer system, with ~160
km of concrete sewer pipe ranging
in diameter from 0.3-1.5 m
Concrete sewers discharge to larger
open channels that are connected
via pumping stations to the
treatment wetlands that ring the city

Peri-urban agriculture

Project Objective
Primary Objective: Determine How Effective
Phnom Penh’s Current Wetland Configuration is
in Sustainably Treating Sewage Discharge

Principal Team Members
Va Dany
Yim Mongtoeun
Kok Sothea
Chea Eliyan
Saneth Vathna
Tiev Visoth
Sovann Channsopheaktra
Im Nara
Department of Environmental Science, Royal University of Phnom Penh
Ratchadawan Ngoen Klan
Department of Parasitology, Faculty of Medicine, Chiang Mai University

Team Coordination and Additional Collaboration
Thammarat Koottatep – Asian Institute of Technology, Team Coordinator
Kim Irvine – Buffalo State, State University of New York, Team Mentor
Mickey Sampson and Ung Mengieng, Resource Development International – Cambodia
Doug Graber Neufeld, Eastern Mennonite University and Royal University of Phnom Penh
Thong Sokvongsa, Bun Kla, Ministry of Environment
Juha Sarkkula and Matti Kummu, MRC WUP-FIN (Mekong River Commission, Water Utilization
Program – Finland)
Drs. K and K. Sukontason, Chiang Mai University
10 undergraduate students from Royal University of Phnom Penh, as well as undergraduate and
graduate students from Buffalo State , AIT, and Chiang Mai University

Analytes of Interest
E. coli
O. viverrini
Cr
Cu
Zn
Nitrates
Total phosphorus
Dissolved oxygen
pH
Temperature
Conductivity
Turbidity
Total suspended solids
Detergents
Flow

Sample Locations

Sampling Trabek Channel

Sampling Meanchey Channel

Sampling in Boeng Cheung Ek

Installation of YSI Continuous Monitoring Units

RESULTS

Cr, ug/L
Mean Dry Weather Results, 14 Sample
Dates, 3/30/07-4/20/08
80.00
70.00
60.00
50.00
40.00
30.00
20.00
10.00
0.00
Trabek up
Trabek
down
Mean up Mean Down Middle Outlet
Cambodian effluent standards for protected public water
areas: Cr – 50 μg/L

Cu, ug/L
Mean Dry Weather Results, 14 Sample
Dates, 3/30/07-4/20/08
180.00
160.00
140.00
120.00
100.00
80.00
60.00
40.00
20.00
0.00
Trabek up
Trabek
down
Mean up Mean Down Middle Outlet
Cambodian effluent standards for protected public water
areas: Cu – 200 μg/L

Total P, mg/L
Mean Dry Weather Results, 14 Sample
Dates, 3/30/07-4/20/08
6.00
5.00
4.00
3.00
2.00
1.00
0.00
Trabek up
Trabek
down
Mean up Mean Down Middle Outlet

Detergents, mg/L
Geometric Mean E. Coli/100 mL
10000000
1000000
100000
10000
1000
Geometric Mean E. coli for dry
weather samples, dry seasons,
3/30/07-4/20/08, n=14 (left)
100
10
1
Trabek
Down
Meanchey
Down
Iron
Bridge
Middle
Outlet
14
WHO standard, unrestricted
irrigation for crops eaten raw –
1,000 E. coli/100 mL
12
Mean detergents levels for dry
weather samples, dry seasons,
3/30/07-4/20/08, n=14 (right)
10
8
6
4
Cambodian standard – 5 mg/L
2
0
Trabek
Down
Meanchey
Down
Iron Bridge Middle Outlet

Results of Spatially-Intensive
Sampling, 2008

Dye Testing Near Trabek Pump Station, November 2007

Tumpun Pump Station/Trabek Channel Dye Testing

Intensive Sample Collection in Boeng
Cheung Ek, 2008
58 samples were collected between April 22 and
25, 2008 for E. coli analysis
45 samples were collected between June 4 and 6,
2008 for E. coli and detergents analysis

Innovative Sampling

E. coli Results, June, 2008
Sampling
E. coli were reduced by 99.9%
within 200 m from the point of
entry to the wetland
Flow travels approximately
another 2,500 m before it reaches
the Middle sample site
Small increases in E. coli were
recorded at some of the further
sample sites due to discharges
from local homes and factories

E. coli Results, April, 2008
Sampling
The E. coli levels entering the
wetland were higher for the April
sampling, at around 6.1 x 10 6 /100
mL (compared to 3.8 x 10 6 /100 mL
in June)
It took approximately 350 m to
observe a 99.5% decrease in levels

Detergents (anionic surfactants)
Results, June, 2008 Sampling
Detergents levels were reduced by
87% within 200 m from the point
of entry to the wetland
Small increases in detergents levels
were recorded at some of the
further sample sites due to local
discharges
The primary industrial activity in
Phnom Penh is textiles and anionic
surfactants are used in various
processes including cleaning, cotton
desizing, and dye dispersant

Additional Observations
April and June results generally are consistent, as a progressive
decrease in E. coli level occurred prior to the flow reaching the
Middle site
Based on all 2007and 2008 sample results, the geometric mean
level of E. coli was in the range of 275-3,409/100 mL by the
mid-point of the wetland
This range of E. coli meets or nearly meets the level of
1,000/100 mL recommend by WHO (2006) as the maximum for
unrestricted irrigation of crops eaten raw

Wet Weather vs. Dry Weather

Mean Dry Weather Values vs. Average EMC
200.00
180.00
160.00
140.00
120.00
100.00
80.00
60.00
40.00
20.00
0.00
D
D
D
Trabek Up, Dry
Trabek Up, Storm
Cr, ug/l Cu, ug/l Zn, mg/l Nitrate, mg/l Tot P, mg/l Detergent,
mg/l
TSS, mg/l
400.00
350.00
300.00
250.00
200.00
150.00
100.00
50.00
0.00
D
Cr, ug/l Cu, ug/l Zn, mg/l Nitrate, mg/l Tot P, mg/l Detergent,
mg/l
TSS, mg/l
n = 14 for mean dry weather values; n = 8 for average EMC; D=Different, α=0.05
D
D
Mean Up, Dry
Mean Up, Storm

Trabek Channel, Dry Weather
Trabek Channel, Wet Weather

Cool Things We Can See with the
YSIs

D.O., mg/L
Dissolved Oxygen Dynamics
12
10
8
6
4
2
0
31-Mar 1-Apr 2-Apr 3-Apr 4-Apr 5-Apr 6-Apr 7-Apr 8-Apr 9-Apr
Time, 15 minute steps, 2007
JICA, 1999 – sewer
d.o. – 0.1-4.6 mg/L;
Irvine et al., 2007 –
1.5-2.0 mg/L; MOE,
2003/2004 – 1.7-2.1
mg/L
Meanin
Outlet

Cond. mS/cm
D.O., mg/L
Weekly Mean YSI Results, Outlet Site
1.000
0.900
0.800
0.700
0.600
12.0
10.0
8.0
0.500
0.400
0.300
0.200
0.100
0.000
6.0
4.0
2.0
0.0
Cond.
D.O.

Other Analyses

PCSWMM.NET Model of Sewer System and Wetland
•Meanchey and Trabek
sewersheds divided into 52
sub-catchments for modeling in
PCSWMM.NET
•Three design storms
examined, small (27 mm),
medium (77 mm) and large
(392 mm) events
•Storms were 1-3 hours in
duration and had exceedance
probabilities of 10%, 2.8% and
0.0002%, respectively

Flooded Duration (mn)
Flooded Duration (mn)
Design Storms and Duration of Surface Flooding
100
80
60
40
20
0
1 6 11 16 21 26 31 36 41 46 51
160
140
120
100
80
60
40
20
0
Duration of low
and medium
storm
corresponds to
left axis.
Junction
Low Storm Medium Storm High Storm

Surface Flooding in Phnom Penh

Contaminant Mass Loading Estimates
for Large Modeled Storm
Location
Mass Loading (kg)
Cr Cu Zn Nitrate T.P.
Meanchey
Up 16.57 104.02 133.99 2,327.29 881.55
Trabek
Down 16.44 115.67 3,572.10 1,190.70 623.70
Cu and Cr loads above are of the same order of magnitude as an entire
month of dry weather flow. Nitrate and phosphorus loadings were much
smaller than a month of dry weather flow due to stormwater dilution.

Fishing in Boeng Cheung Ek

Fish Species
Jullien’s mud carp
Cirrhina jullieni
Indian river barb???
Cyclocheilichthys apagon
Moonlight gourami
Trichogaster microlepis
Weight of
fish (g)
Number of
found metacercariae
50 3
683 56
18 1
Red-cheek barb
Hampala dispar
Giant featherback
Chitala lopis
Smith barb
Puntioplites protozysron
Commom silver barb
Puntius gonionotus
Small scale mud carp??
Cirrhina microlepis
430 171
161 0
30 2
162 5
420 2
??? 159 13

Food Stuff Sampling
Two rounds of sampling done (one dry season, one wet
season)
3 sites on wetland
Analyses of morning glory, herbs, corn, tomato, fish,
snails, sediment and water
Cu, Cr, Zn done by AAS

Food Stuff Sampling
Metals levels are higher in fish and snails than vegetables
Based on a survey more than 200 families, consumption
of morning glory was highest
Risk assessment predicted that Zn, Cu and Cr originating
from consumption of morning glory grown in the
treatment wetland still does not pose any serious health
risk to the community

Conc. of Cr (mg/kg) WW
Heavy Metals Concentrations Near
Wetland Outlet
10
8
6
4
2
0
Green bean
Morning glory
Pumpkin stem
Spiny plant
Pumpkin flower
Pumpkin
Tomato
Corn
Snail
Krach fish
Snakehead fish
Tylapya
Eel
Cat fish
Chpin fish
Kachoush fish
Slate fish
Reil fish
Type of Foodstuff
Dry Season
Rainy Season
A potential health risk was identified for children consuming
snails, specifically with respect to Cr.

Conclusions
The wetlands are providing treatment!!!
There are some potential health risks to the periurban
community living on the wetland, based on
biological indicators and for snail consumption
for children
This is the first data set of its kind collected in
Cambodia

Challenges of Development
Infilling of wetlands – reduces
capacity to treat waste, yet the
growing population increases
demand for treatment
Could Boeng Cheung Ek treatment
be optimized? Yes, but there are
other considerations – flood control,
peri-urban community, ecosystem
functions
Phnom Penh Post, January 16, 2009

Importance of Capacity Building