Author

The Arabian Journal for Science and Engineering, Volume 30, Number 2C.December 2005 17

*To whom correspondence should be addressed.Ege University, Centre for Environmental StudiesE- Blok, Bornova, Izmir 35100, Turkeye-mail: munirozturk@hotmail.comTel: +90-0-232-3884000 / 2434Fax: +90-0-232-3881036

MULTIPURPOSE PLANT SYSTEMS FOR RENOVATION OF WASTE WATERS

Munir Ozturk*Centre for Environmental Studies, Ege University, Bornova, Izmir, Turkey

Ibrahim AlyanakConsultant and Engineering Company, PAP Ltd., Alsancak, Izmir, Turkey

Serdal SakcaliInstitute Science, Marmara University, Goztepe, Istanbul, Turkey

and

Aykut GuvensenBiology Department, Ege University, Bornova, Izmir, Turkey

الخالصــة

ايكرنيا وليمنا الصغيرة) الختبار قدرتها على المائية (كراسيـبس النباتات استخدمنا في عام ١٩٩٦م ١١٠ مترمكعب، اليومي الطفو معدل كان وقد مخارج. وثالثة واحد مدخل ذات الحمأءات برك تـنـقية و BOD5 = ١٣٠-١٧٠ مج / ل، pH = ١٣٫٥ . وزرعنا نبات الكراسيبس E ( ٥+٥ جذر وطول ٢٥ سم)

. pH في بركتين بينما زرعنا ليمنا الصغيرة في بركة واحدة. لم تـنم هذ� النباتات وذلك الرتفاع قيمة

وفي عام ١٩٩٦م خـفـضت قيمة pH إلى ٧-٦ قبل البدء بعملية الزراعة، رغم ذلك لم تنم ليمنا الصغيرة وذلك لكثرة األعشاب، بينما نمت الكراسيبس بشكل جيد وحصلنا على ٣٤٠٠ و ٣١٠٠ جذر نباتي بعد ٩٠ يوما بمعدل ارتفاع ٧٥-٧٠ سم. وقد أظهرت هذ� النباتات قدرة كبيرة على االمتصاص، وكانت الكتلة

الجافة للمحصول حوالي ٨٠٫١٦٠ كيلو غرام.

ك، وأن الماء الناتج عند المخرج كان نقيا حيث كانت والحظنا أن النبات يغطي ٪٩٠-٨٠ من سطح البرأيار ٢٠٠١) قمنـا بزراعة عشرين قيم BOD5 = ٤٠-٣٠ مج / ل و ٨٠ -٥٠ مج / ل. وفي وقت الحق (١٧٠ = COD نبتة من نوع ليمنا الصغيرة في خزان مائي يحتوي على عوالق بمقدار ٣٥٫٢ مج / ل وو BOD5 = ١٣٠. وبعد ٩٠ يوم حصلنا على ١١٠٠ نبتة في المتر المربع. وبعد جني المحصول أظهرت مج / ل، ٢ والفسفور= مج / ل، ٤٣ = النيتروجين ومحتوى ٣٩٫٢٧ = BOD5 أن الميا� تحليل نتائج مج / ل، ٠٫٠٠٥ = والكادميــــوم مج / ل، ٠٫٠٢ = والرصــــاص مج / ل، ١٫٦٧ = والبوتاسيــــوم الكروم = ٠٫٠٥ مج / ل. استخدمنا خليط من الميا� المـعـالجة وغير المعالجة لري المساحات الخضراء المغطاة باألعشاب مثل لوليم بيرين و ل. ايتاشيوم. وقد نمت هذ� االعشاب بشكل أفضل عند استخدام ميا�

معالجة فقط (نسبة ٪١٠٠).

M. Ozturk, I. Alyanak, S. Sakcali, and A. Guvensen

18 The Arabian Journal for Science and Engineering, Volume 30, Number 2C. December 2005

ABSTRACT

Two promising aquatic macrophytes Lemna minor (Duckweed) and Eichornia crassipes (Water Hyacinth); were used to test their cleaning ability for domestic waste waters in lagoons with one entry point and three outlets in 1996 (floatation rate 110 m3/day; BOD5 130–170 mg/l; pH 13.5). E. crassipes plants (5+ 5 roots, 25 cm long) were cultured in two lagoons and L. minor in one lagoon. Both species failed to grow due to a high pH. In 1997 the pH of water was neutralized to 6–7 before plant introduction in to the lagoons. L. minor plants did not grow due to overgrowth of rushes. However, E. crassipes grew very well and a total of 3100 and 3400 roots were counted after 90 days with average heights of 70–75 cm, during this year. These plants showed high absorptive capacity. The dry weight of the harvested plants showed a parallelism to the prevalence with 80.160 kg dry weight. Phenological observations revealed that 80–90% of the plants covering the lagoon surface bloomed and water coming from the outlet became clear enough with a BOD5 value of 30–40 and 50–80 mg/l. In a later experiment L. minor (20 plants) was cultured in a tank in May 2001(BOD5 130, COD 170, suspended matter 35.2 mg/l). In all 1100 plants/m2 were counted at the end of 90 days. After harvesting Lemna plants, water analysis showed that BOD5 was 39.27, total nitrogen content 43, phosphorus 2, potassium 1.67, Pb 0.02, Cd 0.005, and Cr 0.05 mg/l. Renovated and non-renovated waters were used for irrigation of lawns covered by the grass species like Lolium perenne and L. italicum. These species behaved better when sprayed with 100% renovated water than mixed or non-renovated waters.

Key words: Ecology, Environmental pollution, Eichornia crassipes, Lemna minor, wastewater treatment.

M. Ozturk, I. Alyanak, S. Sakcali, and A. Guvensen

December 2005 The Arabian Journal for Science and Engineering, Volume 30, Number 2C. 19

MULTIPURPOSE PLANT SYSTEMS FOR RENOVATION OF WASTE WATERS

1. INTRODUCTION

The wastewater problem due to population increase and industrialization is becoming more and more important in the world nowadays. A lot of work is being done on the renovation and reuse of wastewaters by many countries all over the world, in particular those facing a water shortage. Turbidity due to soil as well as other suspended particles resulting from land degradation processes like erosion and domestic and non-domestic wastes running into the water courses, and a load resulting from organic and inorganic pollutants vis-a-vis the bacteriological involvement are the main problems in this connection.

Sewage treatment systems in big cities have been developed to overcome this problem. However, these systems have high construction, energy, and labor costs. They can serve the purpose in densely populated metropolitan areas but not for cities with 5000–35 000 inhabitants. As such, treatment systems that require lower energy and labor costs are more attractive economically at such places. One of these systems is the use of shallow ponds that contain floating or emergent-rooted wetland vegetation, which depend on biological, chemical, and physical processes in a natural environment to treat wastewater [1–4]. These systems have been used for more than six decades for the treatment of wastewaters [5] and studies in this connection in Europe began in the 1950’s [6]. A major increase in the number of these systems was observed in 1990’s as the application expanded for use not only to treat municipal wastewaters [7], but also industrial, mining, and agricultural wastes [8, 9].

Biological processes are widely employed for treatment of industrial and municipal waste waters [10–13]. With proper analysis and environmental control, almost all waste waters can be treated biologically. In fact bioremediation has emerged and expanded as an industry now, and it is accepted as an effective alternative for cleaning surface and ground waters as well as soils, contaminated with a wide range of toxics [14]. Activated sludge treatment of industrial waste waters is by far the most popular biological treatment system used today [15]. Another program is waste water stabilization ponds [16–19]. The use of multipurpose plant systems, mainly aquatic macrophytes [20], seems to be economically viable in low populated areas because of lower constructional and operating costs, and depends on a turnover of organic and inorganic load of waste waters in to plant biomass. These systems are widely used for the renovation and reuse of waste waters by many industrializing countries all over the world [21, 22]. As such, aquatic macrophytes were tested in the Mediterranean climatic zone of Turkey [23] with the aim of looking at the possibilities of using this multipurpose low cost plant system in the areas, with warmer climatic conditions and population ranging between 10 and 30 thousand.

2. EXPERIMENTAL

2.1. Material and Methods

Lemna minor L. (Duckweed) collected locally and Eichornia crassipes Kunth (Water Hyacinth) specimens procured from Egypt were used to test the cleaning ability of domestic waste waters. L. minor was left in one lagoon and E. crassipes in two lagoons in the Selcuk city during 1996–1998; one of the cities with a great touristic potential in the Aegean region of Turkey and having a population of over 30 thousand. During the study period, maximum and minimum temperature, mean annual precipitation, and mean annual relative humidity in the study area were 32.8°C, 5.5°C, 691.5 mm, and 62–75% respectively. Each lagoon had an area of 400 (40×10×1) m3. Domestic waste water coming from the sewer system of Selcuk city (Figures 1(a), (b), (c)) (floatation rate 110 m3/day; BOD5 130–170 mg/l; pH 13.5) was connected directly to the first lagoon and three lagoons were filled up with this water, each having its own outlet. Waste water was pumped into the lagoons in the month of March. During 1996 5+ 5 stolons of 20 cm long E. crassipes plants (lagoon 1 and 2) and 20 individuals of L. minor plants (lagoon 3) were cultured but these failed to grow due to high pH. In 1997 the experiment was repeated with E. crassipes plants and their growth behavior followed. However, this time aeration was done to maintain the pH of the system between 6 and 7. Air temperature at the time of culturing was around 15–20 °C. L. minor plants failed to grow during this year as well due to an overgrowth of rushes in

M. Ozturk, I. Alyanak, S. Sakcali, and A. Guvensen

20 The Arabian Journal for Science and Engineering, Volume 30, Number 2C. December 2005

(a)

(b)

(c)

Figure 1. Map showing the location of study site Selcuk in Turkey (a), pumping station (b), and experimental design at the study site (c).

M. Ozturk, I. Alyanak, S. Sakcali, and A. Guvensen

December 2005 The Arabian Journal for Science and Engineering, Volume 30, Number 2C. 21

third lagoon. In a later experiment the plants of E. crassipes (5 stolons/per tank) taken from Ege University, Botanical Garden, were left in two tanks full of domestic waste water (BOD5 130, COD 170, suspended matter 35.2 mg/l) in the greenhouse in May 2001, for phenological studies under high temperature (30°C) and high light intensity (500 W.m–2) and low temperature (15°C) and low light intensity (250 W.m–2) conditions. The studies were continued till September, 2001. L. minor was cultured in a tank (20 individuals in 10×10×1 m) during the same period (BOD5 130, COD 170, suspended matter 35.2 mg/l). For biomass recording harvesting was done in September. Total nitrogen, phosphorus, and potassium content of the L. minor plants and water samples was determined using methods outlined in detail in Ozturk et al. [24] and APHA/AWWA/WEF [25], whereas lead and cadmium were determined according to the methods outlined in detail in Aksoy and Ozturk [26]. 100% renovated, 50% renovated + 50% non renovated, 25% renovated + 75% non-renovated, and 100% non renovated waters were sprayed on to grass lawns of Lolium perenne and L. italicum. These were harvested and fresh biomass calculated by weighing. The dry biomass of the plant samples was calculated after drying in an air blown oven at 80°C.

3. RESULTS

3.1. Lemna minor

Genus Lemna includes 15 species in total which are included in the family Lemnaceae. It is generally included with a group of aquatic macrophytes called duckweeds, inhabiting fresh water lakes or ponds all over the world. In Turkey this cosmopolitan genus is represented by 4 species, namely: L. minor; L. gibba; L. trisulca; and L. trionifera [27]. Out of these species the most commonly distributed one is L. minor, which has a very small thallus-like stem floating on the surfaces of lakes or ponds. The plants are flat and asymmetrical in shape. The plants (20 individuals) were transplanted to the lagoon in May but these failed to grow. Therefore, another set of plants was cultured in a tank full of domestic waste water (BOD5 150 mg/l, pH 6–7) in the greenhouse at 20°C. The plants showed a progressive growth and after 90 days the number reached 1100 individuals/m2, which is higher than our previous findings of 708 individuals/m2 when waste water from an industrial establishment was used [27]. These plants were all dark green in color.

After harvesting, the experimental plants and water were analyzed and the results are given in Table 1. The water was reasonably clean (quality II). These results coincide with our previous findings where the amounts of N varied between 0.0004–0.102%, P 70–650 ppm, K 800–1600 ppm, Pb 0.4–1.1 ppm, Cr 0.2–1.0 ppm, Cd 0–0.09 ppm [27].

The values of N, P, K, Pb, Cr, and Cd in Lemna minor plants analyzed by us earlier lay between 1.8–4.4%, 60–190 ppm, 150–500 ppm, 0.5–1.5 ppm, 0.5–2.2 ppm, and 0.02–0.1 ppm [27]. These coincide with our present findings.

Table 1. The Results of Chemical Analysis of Water and L. minor Plants after Harvesting.

BOD5

(mg/l ) Total N (mg/l )

P (mg/l )

K (mg/l )

Pb (mg/l )

Cd (mg/l )

Cr (mg/l ) Water

32.27 43 2 1.67 0.02 0.005 0.05

N (%)

P (ppm)

K (ppm)

Pb (ppm)

Cd (ppm)

Cr (ppm) Plant

1.5–5.3 50–200 100–456 0.2–2.5 0.8–2.7 0.05–0.2

3.2. Eichornia crassipes

This species belongs to family Pontederiaceae and is distributed in the warmer regions of the world, mainly Americas, Africa, South and Southeast Asia, Australia, and New Zealand, covering the still or slowly running waters but has never been recorded from Turkey [28]. The green glossy leaves and 5–15 cm long fibrous roots rise from the rhizome. The most attractive part of the plant is light bluish-pink flowers lying on an emergent flower stalk. This has been the reason for their introduction in to many areas of the world. Almost all flower stalks had flowers. The growth of this highly productive macrophyte takes place with the help of stolons arising from the rhizome. Air-filled spongy tissues with a moisture content of 80–90 percent are buoyant.

M. Ozturk, I. Alyanak, S. Sakcali, and A. Guvensen

22 The Arabian Journal for Science and Engineering, Volume 30, Number 2C. December 2005

E. crassipes plants cultured in two lagoons showed a progressive growth on monthly basis from May till September, when temperatures decreased and leaves started shriveling. Phenological observations showed that 80–90% of the 6500 plants covering the lagoon surface bloomed and water coming from the outlet became clear enough with a BOD5

value decreasing from 150 mg/l to 30–80 mg/l (Table 2). These plants show a high absorptive capacity [29]. The dry biomass is a good energy source, with great potential for heating of greenhouses lying in the vicinity of study area.

The studies carried out in the glasshouse in tanks full of domestic wastewater (Table 3) under different light conditions revealed that under high light intensity (500 W.m–2) and low temperature (15°C) leaves are dark green and flattened, but are thinner and lighter in color under low light intensity (250 W.m–2) and higher temperature (30°C). Upper few cm of rhizome are pinkish in color and very sensitive. Removal of this part resulted in death of plants.

Renovated and non-renovated waters used for irrigation of lawns with grass species like Lolium perenne and L. italicum gave promising results. The 100% renovated water proved more effective than 50%, 25%, and non-renovated waters. These results agree with those of other workers [30, 31]. The growth behavior and biomass values of Lolium perenne and L. italicum are presented in Figures 2, 3, and 4.

Table 2. Growth Behavior of E. crassipes.

Lagoon Number of

stolons cultured

Length of stolons

Length of plants after 90 days

Number of stolons after

90 days

BOD5 (mg/l )

Start - - - - 150

1 5 25 cm 75 cm 3100 50–80

2 5 25 cm 75 cm 3400 30–40

Table 3. Physico-Chemical Analysis of Water before Culturing and After Harvesting of Plants in the Greenhouse under Controlled Conditions.

Parameters Before

Culturing stolons

After Harvesting

pH 6.5

E.C (ds/m) 2.7

BOD5 (mg/l ) 130 21

COD (mg/l ) 170 63

Total suspended matter (mg/l ) 35.2 1.4

Total dissolved salts (mg/l ) 1723

Cl (mg/l ) 275

Total N (mg/l ) 38

P (mg/l ) 1.9

K (mg/l ) 2.7

Pb (mg/l ) 0.35

SAR (meq/l ) 7000

M. Ozturk, I. Alyanak, S. Sakcali, and A. Guvensen

December 2005 The Arabian Journal for Science and Engineering, Volume 30, Number 2C. 23

0 2 4 6 8

10 12 14 16

100% 50% 25%

(cm

)

Lolium perenne Lolium italicum

Figure 2. Growth behavior of lawn grasses sprayed with renovated (100%),

renovated–nonrenovated (50+50%) and renovated–nonrenovated (25+75%) wastewaters.

0

500

1000

1500

2000

100% 50% 25%

(kg

/ha)

Lolium perenne Lolium italicum

Figure 3. Fresh weight of lawn grasses sprayed with renovated (100%),

renovated–nonrenovated (50+50%) and renovated–nonrenovated (25+75%) wastewaters.

0 5

10 15 20 25 30 35 40

100% 50% 25%

(kg

/ha)

Lolium perenne Lolium italicum

Figure 4. Dry weight of lawn grasses sprayed with renovated (100%),

renovated–nonrenovated (50+50%) and renovated–nonrenovated (25+75%) wastewaters.

M. Ozturk, I. Alyanak, S. Sakcali, and A. Guvensen

24 The Arabian Journal for Science and Engineering, Volume 30, Number 2C. December 2005

4. DISCUSSION

The global concern over environmental issues is increasing the need to understand more the relationship between irrigation, environment, and public health. This triangle is therefore facing a paradox. In industrializing countries nearly 1.2 billion people do not find clean drinking water [32]. Every year about 3240 km3 of fresh water are drawn world over, 69% of which is used for agriculture, 23% for industries, and 8% for domestic uses [33]. In all 220×106 ha in the world are irrigated. It is 20% of the total area used for agricultural purposes, but production equals to 40% of the total [34].

The people in Asia use 86% of the water resources mainly for irrigation of their agriculture. However, since the start of the industrial revolution and the fast expanding agricultural activities water resources began to decrease with time. This has been particularly observed in industrializing southwest and central Asian countries (Figures 5, 6, 7). There is a great need to look towards the reuse of wastewaters.

0

50

100

150

200

250

300

350

Afg

hani

stan

Aze

baija

n

Bah

rain

Iran

Iraq

Jord

an

Kaz

akis

tan

Kirg

izis

tan

Kuw

ait

Leba

non

Pak

ista

n

Pal

etsi

ne

Qat

ar

Sau

di A

rabi

a

Syr

ia

Tajk

ista

n

Turk

ey

Turk

men

ista

n

UA

E

Uzb

ekis

tan

Yem

en

Countries

Bill

ion

met

er c

ube

Figure 5. Total internal renewable water in Southwest and Central Asian Countries.

0

20

40

60

80

100

120

140

160

180

Afg

hani

stan

Aze

baija

n

Bah

rain

Iran

Iraq

Jord

an

Kaz

akis

tan

Kirg

izis

tan

Kuw

ait

Leba

non

Pak

ista

n

Pal

etsi

ne

Qat

ar

Sau

di A

rabi

a

Syr

ia

Tajk

ista

n

Turk

ey

Turk

men

ista

n

UA

E

Uzb

ekis

tan

Yem

en

Countries

Bill

ion

met

er c

ube

Figure 6. Annual river inflow (□) and outflow (■) in Southwest and Central Asian Countries.

M. Ozturk, I. Alyanak, S. Sakcali, and A. Guvensen

December 2005 The Arabian Journal for Science and Engineering, Volume 30, Number 2C. 25

0

100

200

300

400

500

600

700

800

900

1000

Afg

hani

stan

Aze

baija

n

Bah

rain

Iran

Iraq

Jord

an

Kaz

akis

tan

Kirg

izis

tan

Kuw

ait

Leba

non

Pak

ista

n

Pal

etsi

ne

Qat

ar

Sau

di A

rabi

a

Syr

ia

Tajk

ista

n

Turk

ey

Turk

men

ista

n

UA

E

Uzb

ekis

tan

Yem

en

Countries

Ann

ual p

er c

apita

/yea

r

Figure 7. Renewable water m3/capita /year in 1990 (■) and 2025 (□) in Southwest and Central Asian Countries.

In Turkey approximately 2400×106 m3/year of wastewater is produced; only 100×106 m3/year are treated, and 0×106 m3/year is reused [34]. The naturally operating multipurpose plant systems, with lower constructional and operating costs, and depending on the conversion of organic load of nutritionally rich domestic waste waters into plant biomass as used in this study, seem to be a good solution in this connection. Presently 4000 constructed wetlands have started operating on selected sites in the western part of Turkey on an experimental basis.

Eichornia crassipes and Lemna minor appear to be the promising candidates for cleaning waste waters at a very low cost. Our observations showed that water after 20 days started becoming clear and was transparent at the end of the experiment. Water ponds created for waste waters coming from irrigation or domestic uses may provide a good habitat for these plants. Both taxa have high absorption ability and, for the growth of these plants, water should contain N, P, and K in high quantities. The waters used for agricultural irrigation and domestic purposes are suitable for their growth. Most wastewater treatment facilities monitor carbonaceous biochemical oxygen demand. Several investigators [1, 9] have mentioned that influent solids from lagoons are typically removed in the first 2–3 days of retention time in vegetated zones near the influent discharge point. Concentrations of TSS in effluent tend to increase during the summer months and decrease during the winter [9]. Nearly half of municipal wastewater nitrogen received at a treatment system is organic nitrogen. The remaining portion is converted to ammonium in the sewer [17, 35]. Plants can absorb ammonium or it can be held in sediments, remain in soluble form in water, be volatilized as ammonia, and under oxygenated (aerobic) conditions it can be nitrified. Nitrate may remain in the water or in sediment pore water, be absorbed by plants or microbes, or be denitrified [36].

Lemna species are playing an important role in treating waste waters. When compared under identical conditions duckweeds show higher production than soybean [27], particularly in the waters rich in N, P, and K. Post irrigation agricultural waters and domestic waters can be good source for the growth of these plants. They absorb macro and microelements very well [27]. Currently there is no long-term data on full-scale constructed wetlands for wastewater treatment to determine the effectiveness in removing metals and organic contaminants. Studies have shown that removal of these contaminants does occur in wetlands [8]. Metals may be sequestered by wetland soils and biota [37]. Organics may be taken up by plants but then returned to the system during decomposition. Some may be completely biodegraded or adsorbed in wetland soils. If the plants grown in waste waters lack heavy metals they can serve a good nutrient rich food for ducks and fish, or even salad for humans. The fish feeding on these plants show a 3 times increase in the

M. Ozturk, I. Alyanak, S. Sakcali, and A. Guvensen

26 The Arabian Journal for Science and Engineering, Volume 30, Number 2C. December 2005

production. Because of this, it has also been named as green gold by the farmers. These plants are cultured specially by some countries and exported for consumption as salad. The dry Lemna plants are reported to be a rich protein source (35–50%) [38, 39]. The growth of highly productive macrophyte E. crassipes takes place with the help of stolons arising from the rhizome. Stolons are longer at the beginning being 20–25 cm long, but become shorter (2–4 cm) when water surface gets covered fully.

Our findings enlighten the fact that use of such a system in the Mediterranean region of Turkey will to a great extent protect the ground waters from pollution [23, 27, 28, 40]. If waste waters renovated by these plants do not contain heavy metals and are not contaminated with bacteria it can be used to irrigate newly created landscapes, lawns, orchards, and forest nurseries. Plant biomass can additionally be used as a fertilizer. Plants also provide a mulch/litter layer that is a porous substrate for attachment of microbes that treat wastewater. Decomposing plant matter is also a rich carbon source for microbial communities. Treatment efficiencies in wetlands are dependent on the large surface area of the plant mulch layer for attachment of microbes. It has been suggested [41] that the most important role for plants in a constructed wetland for wastewater treatment are to grow and die, which is why treatment efficiencies between plant species are somewhat similar on a broad ecological basis. Emergent and floating-leaved plants are used most commonly in wetlands. Leaves, stems, and roots of these plants are adapted for growth in water or saturated soils. The more commonly used emergents include Scirpus (bulrush), Phragmites (giant reed) [42], Typha (cattail), Carex (sedges), and Iris (iris). Lemna (duckweed) is the most commonly found floating plant. These macrophytes can be used successfully in Turkey particularly in the areas where new irrigation schemes are developing at a fast speed and waste water potential is increasing at the same rate. Some special precautions are however, needed for Eichornia crassipes. It should not spread out of the lagoons to become a noxious weed. As such, species of Juncus, Phragmites, Typha, Potomogeton, and Trapa growing locally in Turkey should also be tried in such lagoons.

REFERENCES

[1] S.C. Reed, R.W. Crites, and E.J. Middlebrooks, Natural Systems for Waste Management and Treatment, 2nd edn. New York: McGraw-Hill Book Company, 1995.

[2] R.W. Crites and G. Tchobanoglous, Small and Decentralized Wastewater Management Systems. New York: McGraw-Hill Book Company, 1998.

[3] R.A. Gearheart, Free Water Surface Wetlands for Wastewater Treatment: A Technology Assessment. Phoenix, AZ: U.S. EPA, Office of Water Management, Bureau of Reclamation, 1999.

[4] D.A. Hammer, “Water Improvement Functions of Natural and Constructed Wetlands”, Proc. of Newman Teleconference Seminar Series, Protection and Management Issues for South Carolina Wetlands, Columbia, SC., 1990.

[5] EPA, Wastewater Treatment Facilities for Sewers of Small Communities. Washington, DC: US EPA, 1977.

[6] K. Seidel, “Macrophytes and Water Purification”, Biological Control of Water Pollution. Philadelphia, PA: University of Pennsylvania Press, 1976.

[7] G.W. Loomis, D.B. Dow, M.H. Stolt, L.T. Green, A.J. Gold, and E.T. Oppelt, Constructed Wetlands Treatments of Municipal Wastewaters. EPA Manual, 45268 EPA/625/R-99/010 2000, p.166.

[8] IWA, Constructed Wetlands for Pollution Control, Processes, Performance, Design and Operation (IWA Specialist Group on Use of Macrophytes in Water Pollution Control). London, England: IWA Publishing, 2000.

[9] R.H. Kadlec and R.L. Knight, Treatment Wetlands. Boca Raton, FL: CRC Press, 1996.

[10] Anonymous, “Wastewater Reuse and its Applications in Western Asia”, United Nations Economic and Social Commission for West Asia Rep. E/ESCWA/NR, 84 (1984), Rev. 1.

[11] J.M. Russel, J.M. Cooper, and S.R. Lindsey, “Reuse of Wastewater from Meat Processing Plant for Agricultural and Forestry Irrigation”, Water Science and Technology, 24 (1979), pp. 277–286.

[12] M. Ozturk, M. Pirdal, H. Mert, and S. Akgul, “Evaluation of Sewage Sludge in the Plant Growth”, Proceedings of International Symposium on Urban Ecology, Aydın-Turkey, 1991. ed. M. Ozturk et al. Bornova-Izmir, Turkey: Ege Univ. Press, 1991, pp. 266–270.

[13] WHO, Health Guidelines for the Use of Wastewater in Agriculture and Aquaculture. Geneva: WHO, Technical Series No. 778, 1989.

M. Ozturk, I. Alyanak, S. Sakcali, and A. Guvensen

December 2005 The Arabian Journal for Science and Engineering, Volume 30, Number 2C. 27

[14] R.L. Crawford and D.L. Crawford, Bioremediation: Principles and Applications. Cambridge: Cambridge University Press, 1996.

[15] G. Tchobanoglous and F. Burton, Wastewater Engineering, Treatment, Disposal and Reuse, 3rd edn. New York: McGraw-Hill Book, Inc., 1991.

[16] EPA, Constructed Wetlands Treatment of Municipal Wastewaters, US EPA/625/R/010, 1999.

[17] R.H. Wayland and E. Timothy Oppelt, USEPA Onsite Wastewater Treatment, Manual- US. EPA/625/R-00/008, 2002.

[18] M.J. Hammer, Water and Wastewater Technology, 2nd edn. New York: John Wiley & Sons, 1986.

[19] F. Kanbour, Technology of Wastewater Treatment and Reuse. IAS Publication, 1995, pp. 405–427.

[20] B. Talischer, “Water Treatment by Flocculent Compound of Higher Plants”, Plant Res. and Devt. (Inst. for Sci. Cooperation, Tübingen, Germany), 40 (1994), pp. 56–70.

[21] W.J. Mitch and J.G. Gosselink., Wetlands, 3rd edn. New York: John Wiley and Sons, 2000.

[22] M.A. Economopoulou and A.P. Economopoulos, “Expert System for Municipal Wastewater Management with Emphasis in Reuse”, Water Science and Technology, Water Supply, 3 (2003), pp. 79–88.

[23] UNEP, Wastewater Reuse for Irrigation in the Mediterranean Region, MAP Tech. Report 41, 1990.

[24] M. Ozturk, M. Pirdal, and F. Ozdemir, Applications in Plant Ecology. Bornova-Izmir: Ege University Press, 1997, p. 129.

[25] APHA/AWWA/WEF, Standard Methods for the Examination of Water and Wastewater. 20th edn. Washington, USA, 1998.

[26] A. Aksoy and M. Ozturk, “Nerium oleander as a Biomonitor of Lead and Other Heavy Metal Pollution in Mediterranean Environments”, The Sci. of the Total Environment, 205 (1997), pp. 145–150.

[27] M. Ozturk, T. Uysal, and A. Guvensen, “Role of Lemna in the Renovation of Waste Waters”, XII. Nat. Biol. Congress, Edirne, 1994, vol. 3, pp. 68–70.

[28] D.Gokmen, M. Ozturk, I. Alyanak, and M. Yuksel, “Renovation of Domestic Wastewaters by Plant Systems”, Kusadasi Coastal Problems Symposium, Municipality Publ., 1997, vol. 8, pp. 455–461.

[29] K.R. Reedy and W.F. DeBusk, “Nutrient Removal Potential of Selected Aquatic Macrophytes”, J. Environmental Quality, 19 (1985), p. 261.

[30] T. Kipinis, A. Feigin, I. Vaisman, and J. Shalhevet, “Wastewater Application, Dry Matter Production and Nitrogen Balance of Rhodes Grass Grown on Fine-Textured Soil or Sand Dunes”, Proc. of XIV. Int. Grassland Congress, Lexington, USA, 1983, pp. 288–291.

[31] Y. Pakfiliz, S. Ozcan, and M. Ozturk, “Possibilities for the Use of Waste Water from Treatment Systems for Watering of Plants”, Ekoloji, 15 (1995), pp. 9–13.

[32] R. Engelman and P. LeRoy, Sustaining Water-Population and the Future of Renewable Water Supplies, Population and Environment Program, Population Action International, Washington, USA, 1993.

[33] FAO, “Irrigation in the Near East Region in Figures”, Water Reports No. 9, Food and Agricultural Organization of UN, Rome, 1997, p. 281.

[34] M. Ergin, D. Altinbilek, and R.M. Zou’bi, “Water in the Islamic World: an Imminent Crisis”, IAS Publ., Varan Printing House, Ankara, Turkey, 1995, p. 544.

[35] R.W. Crites and G. Tchobanoglous, “Discussion of Nitrogen Removal in Experimental Wetland Treatment System, Evidence for the Role of Aquatic Plants”, Water Environment Research, 64 (1992), pp. 39–51.

[36] S.K. Liehr, “Constructed Wetlands Treatment of High Nitrogen Landfill Leachate”, US WERF Report, 94 - NCSU, 2000.

[37] A. Zayed, E. Lytle, and N. Terry, “Phytoaccumulation of Trace Elements by Wetlands Plants, I. Duckweed”, Environ. Quarterly, 27 (1998), p. 715.

[38] E. Robson, “Duckweed: A Lovely Plant Finds a Richer Role in Cleansing Waste and Creating Protein Source”, UNDP report, 1991, p. 22–26.

[39] P. Skillicorn, W. Spira, and W. Journey, Duckweed Aquaculture. A New Aquatic Farming System for Developing Countries. Washington, DC, USA: The World Bank Report, 1993.

[40] A. Saabye, I. Kruger, and H. Schwinnig, Treatment and Beneficial Use of Sewage Sludge in the European Union, ISWA Times, 3 (1994), 12 pp.

M. Ozturk, I. Alyanak, S. Sakcali, and A. Guvensen

28 The Arabian Journal for Science and Engineering, Volume 30, Number 2C. December 2005

[41] B.P. Pullin and D.A. Hammer, “Comparison of Plant Density and Growth Forms Related to Removal Efficiencies in Constructed Wetlands Treating Municipal Wastewaters”, Sixty-Second Annual Conference of the Water Pollution Control Federation, San Francisco, CA, USA, 1989.

[42] J.H. Peverly, J.M. Surface, and T. Wang, “Growth and Trace Metal Absorption by Phragmites australis in Wetlands Constructed for Landfill Leachate Treatment”, Ecological Engineering, 5 (1995), pp. 21–35.

Paper Received 11 December 2004; Revised 29 August 2005; Accepted 10 October 2005.