1. Haddad, M., (2006). Evaluation Of Constructed Wetland
As Secondary Wastewater Treatment, Source For Tertiary
Wastewater Treatment; And Reuse System. ASCE and
World Water and Environmental Resources Congress In
Omaha, Nebraska, USA (May 21-25, 2006). The paper
Awarded Visiting International Fellowship

2. Evaluation of Constructed Wetland as Secondary Wastewater
Treatment, Source for Tertiary Wastewater Treatment; And Reuse
System
By: Marwan Haddad
Abstract
This paper describes an investigation into the treatment effectiveness and feasibility of
constructed wetland (CW) system as a secondary wastewater treatment system, as an
economic agricultural producer, and as a pretreatment phase for an ultrafitration/reverse
osmosis UF/RO tertiary treatment plant.
The treatment system consists of one vertical-flow infiltration CW cell (150 m2
in surface
area, 112.5 m3
in volume) and two settling basins (one before and one after the CW);
gravel, coastal sand, and almond shells were used as CW media. The CW was vegetated
with various plants including spineless cactus. Samples were analyzed for total plate
count, turbidity, total nitrogen, total phosphorus, total suspended solids, biochemical
oxygen demand, chemical oxygen demand, temperature, conductivity, and pH.
The CW operation indicated a significant reduction in influent water quality and proved
to be of suitable for smooth operation of the UF/RO pilot plant. High biomass growth
was observed on the spineless cactus and banana and little or negative growth was
obtained on other planted crops.
Keywords: Constructed Wetland, Wastewater treatment, Wastewater Reuse,
Environmental Management Systems for Agriculture, Palestine
Introduction
Wastewater collection and disposal in Palestine continues to be one of the most public
health and environmental hazards. However, the status of wastewater treatment and
collection services varies from one locality to another. Wastewater collection systems
are available in most of the cities of the West Bank and Gaza Strip with 50-85%
collection levels (Approximately 60% of the houses in the urban communities are
connected to sewage systems – PWA 2003).
Few wastewater treatment plants have been constructed in the past 10 years for a number
of cities in the West Bank and Gaza while untreated wastewater still flows in the wadis
from many other cities including major urban centers as the city of Nablus. However,
more than half of the population of the West Bank lives in more than 500 villages. Most

Marwan Haddad, Professor, An-Najah National University, Nablus Palestine, Tel. + 970-9-2381115, Fax
+070-9-2386982 , email: haddadm@email.com, haddadm@najah.edu

3. of these village lack wastewater collection systems and rarely have wastewater treatment
systems. In most of these villages, wastewater is disposed through cesspools. Due to the
spread of the rural population in the West Bank in a large number of villages and the high
cost of wastewater conveyance system, decentralized wastewater treatment plants are of
great value for the local population and are expected to be the only feasible alternative for
wastewater treatment in the West Bank.
The situation in the refugee camps can only be classified as very poor. Wastewater is
channeled into open drains until it flows into either a sewage network in a nearby city or
is simply transported to outside camp boundaries. Most of the Israeli settlements in the
West Bank have sewage networks and most of these settlements discharge the wastewater
into Wadis without any treatment.
Because there is very little wastewater treatment systems in rural areas of Palestine and
the economic situation is very bad, there is a high interest in testing and evaluating the
use of CW systems as a secondary treatment level benefiting from there low-cost, good
efficiency and minimum maintenance properties.
Current study will present and detail the results of the CW - UF/RO treatment and reuse
experiment indicating and emphasizing the lessons learned including costs, operation
and maintenance problems, and reuse and treatment efficiency.
Background
Wetlands have been used for secondary and tertiary wastewater treatment in different
parts of the world since the 1950s and research over the last half century has accumulated
much quantitative information on the performance of these systems (Verhoeven and
Meuleman 1999, Sukais and Tanner 2004),
Wetland beds contain plant species including cattails, reeds, bulrush, bamboo, blueberry,
cranberry, watercress, wild rice, alder, bald, cypress, river birch, swamp white oak, water
oak, white cedar, and black gum or tupelo (Wynn 2003).
Constructed wetlands (CW) for water pollution control are becoming an accepted
technology world-wide. Recent inventories have indicated that there are more than 7000
CW in Europe and North America, with the number increasing in central and south
America, Australia and Newzealand as well as Africa and Asia (Senzia et al 2002).
Although CW proved to be low in cost, easily managed, good for atural habitat, and good
in performance without the use of chemicals still some how controversial because there is
no agreed upon design criteria for the various CW systems (OEMC, 2001). In addition,
appropriate vegetation and uniform flow through the cells have been difficult to establish.
It was found that while data from some sources have indicated very good treatment
efficiencies, the performance of typical wetlands have been very erratic (Langston and
VanDevender, 1998).

4. Constructed wetlands are artificial wetlands. According to U.S. EPA (1993), a
constructed wetland is defined as “a wetland specifically constructed for the purpose of
pollution control and waste management, at a location other than existing natural
wetlands.”
Constructed wetlands are efficient at transforming pollutants such as nitrogen
phosphorus, suspended solids and biological oxygen demand found in wastewater, into
essential nutrients for plant growth or harmless bi-products. This was due to high level of
biological productivity created during filling and draining processes(Kadlec & Knight
1996).
Experience with infiltration wetlands in Europe has shown that systems loaded
with 800 PE:ha of domestic wastewater had a long-term removal capacity of
80–95% for COD and BOD, 99% for bacterial pollution; 35% for N; and 25% for
P. The removal of nutrients can be optimized up to about 50% for N and 40% for
P at these loading rates (Schierup et al., 1990; Meuleman, 1994).
Methods
A wastewater treatment system consisting of a vertical flow CW as a secondary level
and UF/RO pilot plant as a tertiary level was used.
The treated effluent was directed to various reuse schemes. The treatment and reuse site
is located in a land area of 1.8 ha on the eastern open wastewater channel about 13 km
east of the city of Nablus towards the Jordan Valley. Nablus is located on the northern
parts of the West Bank – Palestine. The West Bank is part of the Palestinian territory
under the administrative control of Israel. The population of the West Bank is estimated
at 2,304,825 (Palestinian Central Bureau of Statistics, 2003). The wastewater flow from
eastern parts of Nablus contains domestic and industrial liquid waste.
In this paper, the CW results only will be presented and discussed.
As shown in Figure 1 bellow, the treatment and reuse system consist of:
 A diversion canal built of reinforced concrete transporting raw wastewater from
the open channel to a settling tank (50 cm wide and 50 cm deep),
 A raw wastewater collection and settling tank built of reinforced concrete from
which settled wastewater is being pumped to a CW basin (4.5 m wide, 16,0 m
long, and 3.0 m deep),
 A CW basin built of reinforced concrete where gravel, almond shells, and coastal
sand represent the media (5 m wide, 30m long, and 0.75 m deep, see Table 1).

5. The CW was vegetated with economic crops of local importance such as spineless
cactus, pecans, bananas, apricot, peaches, and apples.
 A final settling tank built of reinforced concrete from which settled wastewater is
being pumped to UF/RO pilot plant or to reuse (5 m wide, 10 m long, and 2.0 m
deep),
 A UF/RO pilot plant for tertiary treatment of wastewater
 A 1.8 ha reuse site. The site has small green house (~60 m2
), small open area for
vegetable growth (~250 m2
), and the reminder mostly planted with various trees.
The hydraulic regime of the CW was vertical flow with intermittent wetting and draining.
The flow to the CW was introduced through a perforated PVC pipe located along the
upper-inner edges of the CW. After being filled the CW was allowed to drain at the
preset rate controlled by three check valves located at the lower end of the discharge side
(see Figure 1). CW filling was done twice per week. Due to controlled discharge and CW
size, variations in water movement and mixing in the CW was ignored. Between
September 2003 and September 2005, the average flow through the CW was 13.5 m3
/day.
Flow characteristics are given in Table 1.
To assess treatment effects, wastewater was sampled once a week at several pointes
through the system in 2-year period. Samples were analyzed for total nitrogen, total
phosphorus, total suspended solids, chloride, biochemical oxygen demand, chemical
oxygen demand, temperature, conductivity, turbidity, and pH. All analysis were
conducted according to Standard Methods for the examination of water and wastewater
(APHA-AWWA-WEF, 1998).
Table 1 CW Characteristics and Operating Parameters of Importance
Characteristic or Parameters Unit Value
Bottom Length m 30
Bottom Width m 5
Bottom Slope to Outlet % 1.67
Surface Area m2
150
Mid-Length Depth m 0.75
Volume m3
112.5
Bed Porosity % 42
Effective Volume m3
47.5
Detention Time* days 3.5
BOD Loading* kg/m2
-d 0.029
TSS Loading* kg/m2
-d 0.063
Hydraulic Loading* m3
/m2
-d 0.09
* = Average Measured During the Study

6. Figure 1 Wastewater Treatment and Reuse Site
To Reuse
To Reuse
UF/RO
CW
Settling
Basin 1
Settling
Basin 2
Perforated
PVC PipeDiversion
Channel
Wastewater
Channel
Pump 2
Pump 1

7. Results and Discussion
Performance data were collected for two year period and a summary is presented in
Figures 2-a to 2-h and Table 2. Although the results include the UF/RO pilot plant
results, the following discussions will emphasize the CW only.
As shown in Figure 2, the BOD, TSS varied considerable over the two years including
clear seasonal variations. However, it was noticeable that these variation of various
quality parameters were relatively repeated in the second year (with small exceptions).
Very little maintenance works has been required for the CW over the two year period.
Maintenance issues included clearing openings of the perforated influent pipe
to prevent clogging, cleaning and/or harvesting of the wetland plants, and checking the
discharge valves. No problem was faced concerning mosquitoes and other insects.
It is apparent from the data collected that the CW was able to produce effluent with very
good quality.
Influent BOD concentrations to the CW were ranging between 130 and 540 mg/l with an
overall average of 319 mg/l which is considered high in western countries. This is due to
water scarcity and low dilution of waste. Average organic loading rate was 28.7
gm/m2/d. Effluent BOD concentrations to the CW were ranging between 20 and 190
mg/l with an overall average of 85 mg/l which is reasonable compared to influent
concentrations. Average BOD removal rate was 73.4%. Although BOD removal was
somehow uniform which gives reliability to the treatment process, BOD removal rate was
a little higher in summer months than winter months.
Influent TSS concentrations to the CW were ranging between 550 and 900 mg/l with an
overall average of 699 mg/l which is also considered high in western countries and due to
the same reason as for BOD. Average organic loading rate was 28.7 gm/m2/d. Effluent
BOD concentrations to the CW were ranging between 20 and 190 mg/l with an overall
average of 85 mg/l which is reasonable compared to influent concentrations. Average
BOD removal rate was 73.4%. Although BOD removal was somehow uniform which
gives reliability to the treatment process, BOD removal rate was a little higher in summer
months than winter months.
The pH difference between influent and effluent water to the CW was little ranging
between 7.2 – 7.4 in thee influent and about 7.3 in the effluent.
Average influent Chloride concentration to the CW was 330 mg/l with low removal rate
of 12%. Chloride concentrations were higher in summer in raw wastewater and in CW
effluent than winter probably due to dilution factor. This represent a typical secondary
treatment efficiency.

8. Average TPC removal was 99.2 % which still less than acceptable for unrestricted
irrigation water quality standards.
Reasonable average removal rates of TP (65.2%) , TN (48.6%) , and turbidity (62.5%)
were observed in the CW (See Table 2).
The performance of the UF/RO pilot plant was very good in term of effluent water
quality (see Figure 2 and Table 2). However, fouling of membranes started shortly after
the start of plant operation and continued allover the experimental period. Most of the
fouling was permanent despite the various methods used in cleaning the membranes. The
cost of treatment per meter cubic using the UF/RO was 5.65 US$, which considered very
high and unacceptable by local farmers. In addition to the need of cleaning chemicals, a
trained technician presence was obligatory every time the plant is operated and/or
maintained which resulted in increasing the cost of produced water.
Vegetative growth in the CW was good for cactus and bananas, while orchards trees
(apples, apricots, plum, and pecans) mostly dried by the end of the second season. The
growth of cactus in CW was steady positive all over the last two years of about 670
gm/m2
(presented in Figure 3). This indicate the advantage of CW in reusing raw
wastewater for small (as well as large system) and in producing fodder and fruit crop in
economic quantities such as spineless cactus.
Table 2 Average Performances of CW and UF/RO
Description Quality Parameter
TSS BOD COD Cl TN TP TPC Turbidity
CW
In
Out
Loading rate
% Removal
699
126
62.9
82.0
319
85
28.7
73.4
641
252
57.7
60.7
330
291
29.7
12.0
14.4
7.4
1.3
48.6
20.7
7.2
1.9
65.2
5 E-6
4.2 E-4
--------
99.2
48
18
-------
62.5
UF/RO
In
Out
% Removal
126
0
100
85
1-3
96-99
252
3-5
98-99
290
2-8
97-99
7.4
2-3
60-73
7.2
0
100
4.2 E-4
0
100
18
0-3
83-100
Loading Rate in gm/m2-d, In, Out in mg/l, TPC in #/100 ml, and Turbidity in NTU
Conclusions
In conclusion and based on the results of this study, CW proved to deliver:
 Reasonable effluent quality but not complying with quality standards
 Good in reuse
 Cost is minimal
 O&M costs are minimal and need no chemical use or high tech personal for O&M

9. And therefore, could be recommended as a secondary level treatment for small systems
such as rural communities and/or remote areas in Palestine and elsewhere. Combination
of CW with an additional extended treatment system is necessary to attain accepted water
quality standards.
The data collected indicated that vegetation of CW with spineless cactus and bananas was
successful and feasible while orchard trees were problematic.
Additional treatment of the wastewater using The UF/RO would provide excellent
effluent quality which is very suitable for any class of reuse, however fouling is a real
problem, flow dropped to 25-30% of original and cost for small systems is very high per
cubic meter produced and will not be accepted by farmers. Furthermore, O&M of UF/RO
pilot plant need to be conducted by specialized personal and time and material
consuming. Accordingly, such treatment system is not recommended for small
communities.
Acknowledgements
This study was conducted as part of a MERC project No. M22-006. The author would
like to acknowledge and thank MERC, the Palestinian Research Group, and the Grand
Water Research Institute for their support and cooperation in conducting this study.
References
APHA-AWWA-WEF. (1998). ‘Standard methods for the examination of water and
wastewater’, 20th edition, eds L. S. Clesceri, A. E Greenberg, A. D. Eaton, American
Public Health Association, American Water Work Association, Water Environment
Federation, Washington DC.
Kadlec, R. H., & Knight, R. L. 1996. Treatment Wetlands, Boca Raton: CRC Press,
Lewis Publishers.
Langston, J., and VanDevender, K., (1998). Constructed Wetlands: An Approach
for Animal Waste Treatment. University Of Arkansas, Division Of Agriculture,
Cooperative Extension Service Report, Found In http://www.uaex.edu, accesses June
2005.
Meuleman, A.F.M., 1994. Waterzuivering door moeras-systemen: onderzoek naar de
water- en stofbalansen van het rietinfiltratieveld Lauwersoog. RIZA Nota 94.011, 1–134.
OEMC, (2001). Colorado Governor’s Office of Energy, Management, and Conservation.
Colorado Constructed Wetland Inventory, Denver, March 2001.

10. Palestinian Central Bureau of Statistics . (2003). Press conference about the results of
Local Community Survey in the Palestinian Territory , September, 2003, Ramallah –
Palestine.
PWA, Palestinian Water Authority. (2003). Water Supply Status in Palestine. Accessed
on February, 2004 at http://www.pwa-pna.org/status/supply.php.
Schierup, H.H., Brix, H., Lorenzen, J., 1990. Wastewater treatment in constructed reed
beds in Denmark; state of the art. In: Cooper, P.F., Findlater, B.C. (Eds.), Constructed
Wetlands in Water Pollution Control. Pergamon Press, Oxford, pp. 495–504.
Senzia, M., Mashauri, A., and Mayo, W., (2002). Suitability of Constructed Wetlands
and Waste Stabilisation Pond in Wastewater. 3rd WaterNet/Warfsa Symposium 'Water
Demand Management for Sustainable Development', Dar es Salaam, 30-31 October 2002
Sukais, J., and Tanner, C., (2004). Evaluation of the Performance of Constructed Wetland
Treaing Domestic Wastewater in the Waikato Region, NIWA Client Report : HAM2004-
015 for Environment Waikato, Hamilton East , March 2004.
U.S. Environmental Protection Agency. 1993. Subsurface Flow Constructed
Wetlands for Wastewater Treatment: A Technology Assessment. EPA Report 832-R-
93-008.
Verhoeven, J., and Meuleman, A., (1999), Wetlands for wastewater treatment:
Opportunities and limitations. Ecological Engineering 12 (1999) 5–12
Wynn, J., (2003). Innovative And Alternative On-Site Treatment Of Residential
Wastewater. Prepared For TERRAFORMS, Athens, Ohio, September 2003.

11. Figure 2-a Suspended Solids Concentration in Raw Wastewater, CW, and UF/RO
Figure 2-b Chloride Concentration in Raw Wastewater, CW, and UF/RO
Ave = 699 mg/l
Ave = 126 mg/l
Ave = 0 mg/l
Chloride Concentration
0
100
200
300
400
500
600
700
8009/3/2003
11/3/2003
1/3/2004
3/3/2004
5/3/2004
7/3/2004
9/3/2004
11/3/2004
1/3/2005
3/3/2005
5/3/2005
7/3/2005
Time
Clinmg/l
Raw Wastewater Constructed Wetland UF/RO

12. Water Turbidity
0
10
20
30
40
50
60
70
9/3/2003
10/3/2003
11/3/2003
12/3/2003
1/3/2004
2/3/2004
3/3/2004
4/3/2004
5/3/2004
6/3/2004
7/3/2004
8/3/2004
9/3/2004
10/3/2004
11/3/2004
12/3/2004
1/3/2005
2/3/2005
3/3/2005
4/3/2005
5/3/2005
6/3/2005
7/3/2005
8/3/2005
Time
Turbidity[NTU]
Constructed Wetland Effluent UF/RO Effluent Raw Wastewater
Ave = 85 mg/l
Ave = 319 mg/l
Figure 2-d BOD Concentration in Raw Wastewater, CW, and UF/RO
Figure 2-c Turbidity Levels in Raw Wastewater, CW, and UF/RO
Ave = 48 NTU
Ave = 18 NTU
Ave = 0-3 NTU

13. Ave = 641
mg/l
Ave = 252
mg/l
Ave = 3-5 mg/l
Total Plate Count (TPC)
0
2000000
4000000
6000000
8000000
10000000
12000000
14000000
9/3/2003
11/3/2003
1/3/2004
3/3/2004
5/3/2004
7/3/2004
9/3/2004
11/3/2004
1/3/2005
3/3/2005
5/3/2005
7/3/2005
Time
TPC
Raw Wastew ater Constructed Wetland UF/RO
Ave = ~0 Ave = 42045
Ave = 5,050000
Figure 2-e Total Plate Count Concentration in Raw Wastewater, CW, and UF/RO
Figure 2-f COD Concentration in Raw Wastewater, CW, and UF/RO

14. Total Phosphouros
0
5
10
15
20
25
30
9/3/2003
11/3/2003
1/3/2004
3/3/2004
5/3/2004
7/3/2004
9/3/2004
11/3/2004
1/3/2005
3/3/2005
5/3/2005
7/3/2005
Time
TPinmg/l
Raw Wastew ater Constructed Wetland UF/RO
Ave = 20.7 mg/l
Ave = 7.2 mg/l
Ave = 0.0 mg/l
Total Nitrogen (TN) Concentration
0
5
10
15
20
25
9/3/2003
11/3/2003
1/3/2004
3/3/2004
5/3/2004
7/3/2004
9/3/2004
11/3/2004
1/3/2005
3/3/2005
5/3/2005
7/3/2005
Time
TNinmg/l
Raw Wastew ater Constructed Wetland UF/RO
Ave = 14.4 mg/l
Ave = 7.4 mg/l
Ave = 2-3 mg/l
Figure 2-g Total Phosphorous Concentration in Raw Wastewater, CW, and UF/RO
Figure 2-h Total Nitrogen Concentration in Raw Wastewater, CW, and UF/RO

15. 0
2000
4000
6000
8000
10000
12000
14000
16000
18000
30/8/200330/10/200325/2/200430/6/200430/8/200428/2/200530/5/200530/8/2005
Time
Figure 3 Change in CW of Cactus aboveground biomass with Time
CactusBiomass
usBiomassin
Biomassin
assingm/m2
gm/m2
m2