Bioresource Technology 101 (2010) 833–835

Contents lists available at ScienceDirect

Bioresource Technology

journal homepage: www.elsevier .com/locate /bior tech

Short Communication

Biomass production of papyrus (Cyperus papyrus) in constructed wetlandtreating low-strength domestic wastewater

Thaneeya Perbangkhem a,1, Chongchin Polprasert b,*

a School of Environmental Engineering, Institute of Engineering, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailandb Department of Sanitary Engineering, Faculty of Public Health Mahidol University, Bangkok 10400, Thailand

a r t i c l e i n f o

Article history:Received 31 March 2009Received in revised form 14 August 2009Accepted 18 August 2009Available online 15 September 2009

Keywords:Energy-capturing efficiencyPapyrusConstructed wetlandBiomass productivity

0960-8524/$ - see front matter � 2009 Elsevier Ltd. Adoi:10.1016/j.biortech.2009.08.062

* Corresponding author. Tel.: +66 23548540.E-mail addresses: annita_p2004@hotmail.com (T. P

dol.ac.th (C. Polprasert).1 Tel.: +66 17339150.

a b s t r a c t

In this study, the pilot-scale constructed wetlands were fed with low-strength domestic wastewater toinvestigate the energy-capturing efficiency and plant productivity. Papyrus was a selected emergentmacrophyte planted in the systems. The wastewater was intermittently fed to the systems, correspond-ing to the organic loading rates of 10, 16, 31, and 63 kg BOD/ha-d.

With abundant sunshine in the tropical-climate area, papyrus converted solar radiation to biomass ofabout 2200–3100 g dry weight/m2 from the two-month period of the experiments. Furthermore, theenergy contents of papyrus are 16.2, 17.2, and 16.8 MJ/kg for culms, umbels, and total above-groundparts, respectively. From the plant productivity and the energy contents of papyrus obtained from thisstudy, the energy capturing efficiencies can be estimated to be in the range of 4.4–6.0%, which are rela-tively high, compared with those of other plants.

� 2009 Elsevier Ltd. All rights reserved.

1. Introduction

Constructed wetland (CW) is a system engineered for treatingwastewaters by using plants, soil and microorganisms, to improvethe water quality and is an effective treatment system alternativewhere suitable land is available at low cost (Neralla et al., 2000;Vymazal, 2005). Several advantages can also be obtained fromthe use of CW for wastewater treatments; for examples, removalof both organic matter, use minimal energy input, etc. (Kiwangoand Wolanski, 2008). The aquatic macrophyte grown in the CWsystem is one of the main components used for wastewater treat-ment. The plant itself also provides the surface areas for bacterialgrowth, uptakes the nutrients and add oxygen to the water (Liet al., 2008). In addition to the water quality improvement, plantproductivity is one of the CW added values because the biomassobtained can be further utilized as food, medicine, paper, biofuel,etc. (Polprasert, 2007).

Plant growth depends on many factors but the most importantone is sunlight because the energy for growth requirement derivesfrom sunlight through photosynthesis, in general, 1–5% of solar en-ergy falling on a plant is converted to organic matter (Chrispeelsand Sadava, 2003). The actual yield of energy in plant depends

ll rights reserved.

erbangkhem), phcpp@mahi-

on the product of solar input and efficiency with which the solarenergy is transformed into the harvested product.

Because in Thailand, there are many small communities locatedin the tropical area with abundant sunshine, it is appropriate fromthe solar energy utilization to grow plants for use of both biomassproduction and waste recovery and recycling. Aquatic plant thathas high potential of converting solar energy into the plant produc-tivity should be selected for plantation in CW. Papyrus is one of themost interesting one because it can grow well in the subtropicaland tropical climate and is among the most productive plants ofwetlands (Boar et al., 1999; Kansiime et al., 2005; Mnaya et al.,2007). Therefore, this study was carried out with the objectives:(1) to assess the plant productivity of papyrus and (2) to estimatethe energy capturing efficiencies in CW fed with low-strengthdomestic wastewater.

2. Methods

Two sets of the experimental pilot-scale CW, each with thedimensions of 1 m � 3 m � 1.2 m (width � length � depth), wereoperated to treat domestic sewage generated from dormitoriesand office buildings in the Suranaree University of Technology(SUT) campus. The CW units were intermittently fed with primarysewage pumped directly from the effluent weir of the primary sed-imentation tank, resulting in the organic loading rates of 10, 16, 31,and 63 kg BOD/ha-d for Run No. 1, Run No. 2, Run No. 3, and RunNo. 4, respectively. The experiments were carried out between

834 T. Perbangkhem, C. Polprasert / Bioresource Technology 101 (2010) 833–835

January 2005 and March 2006 with the 2-month period for eachexperimental run.

Papyrus was selected to plant in the CW. Before cultivating thepapyrus, the CW beds were prepared with gravel at the bottom andsandy loam at the top. Outlet valve of the CW’s tank was positionedto maintain the water level of 35 cm above the bed, resulting in thefree water surface volume of 1.05 m3. At the beginning, they werecut down to 0.60 m in height above ground, signaling the first dayof the experiment. Afterwards, effluent sampling and analyseswere carried out every drainage days to determine for biochemicaloxygen demand (BOD), chemical oxygen demand (COD), total sus-pended solid (TSS), ammonia-nitrogen (NH3-N), and orthophos-phate phosphorus (o-PO3�

4 ) (Franson et al., 1998). Every 10 days,a stem of plant was randomly cut so as to determine plant heightand biomass. Measurements of standing biomass and above-ground productivity were made in quadrant of 0.5 m � 0.5 m afterthe end of each experimental run. Finally, energy contents of papy-rus were determined, using bomb calorimeter.

20

40

60

80

100

120

140

m/g(etar

htworg

gnisaerced2 -d

)

Run 1

Run 2

Run 3

Run 4

3. Results and discussion

The average concentrations of the wastewater fed to all the CWunits are shown in Table 1; in comparison with those of Thailand’smunicipal sewage (Kanabkaew and Puetpaiboon, 2004). Becausethe SUT buildings were equipped with septic tanks as a wastewaterpre-treatment unit, prior to being discharged into the sewer, or-ganic solids would be partly removed, resulting in lower concen-trations of BOD and SS.

The net plant biomass and productivity including the productiv-ity of each part of papyrus (culm and umbel) are summarized inTable 2. This plant growth has a tendency to be in the transitionalphase of sigmoid curve for normal population growth rate so thatthe papyrus growth rate was derived to Eq. (1). Then the Thomasmethod was used to determine the ultimate plant biomass (mu)and rate constant (k) (Lee and Lin, 2000):

mt ¼ muð1� e�ktÞ ð1Þ

where mt is the biomass at time (g dry weight/m2), mu is the ulti-mate biomass (g dry weight/m2), k is the rate constant (1/d) and tis the time (d).

Table 1The influent concentrations of the constructed wetlands and typical domesticwastewater in Thailand.

Parameter Influent concentrations (mg/L)

This study Typical domestic wastewater in Thailand

COD 65.4–92.4 192–700BOD 18.4–22.1 110–400NH3 10.7–21.5 12–51

o-PO3�4

3.03–5.75 2.8–10.5

SS 10.9–16.4 100–350

Table 2Biomass and primary productivity of papyrus in each constructed wetland units.

Run Plant biomass(g dryweight/m2)

Plant productivity(g dryweight/m2 d)

Culmproductivity(g dryweight/m2 d)

Umbelproductivity(g dryweight/m2 d)

1 2341 39.02 15.99 23.032 2359 39.32 14.28 25.043 2538 42.30 15.87 26.434 3115 51.91 20.26 31.65

The above-ground biomass of the papyrus in this study was rel-atively lower to previous studies because of the shorter plantingduration and low-strength wastewater (Kansiime et al., 2007;Mnaya et al., 2007). However, their differences in various siteshave been attributed to prevailing climatic conditions. FromFig. 1, the optimum period for harvesting can be found to be 41–50 days. Plant cutting before the optimum period previously statedwill need more unnecessary manpower to do the work, therebyincreasing the cost of treatment wetland operation. At the opti-mum point, the growth rate of the plant is lowest. Subsequently,further allowance for plant growth is useless and, in the commer-cial sense, the opportunity for exploitation of the value-addedmaterial is lost. Therefore, determination of the optimum periodof plant harvest would be one of the very significant parametersin the design and operation of CW for wastewater treatment sothat associated workforces and tools can be properly provided.

The energy capturing efficiencies of papyrus are in the range of4.52–6.02% for CW as shown in Fig. 2. Umbels represented thehigher energy-capturing efficiency parts than culms because theyserve also as main photosynthetic surface. Papyrus has higherrange of energy-capturing efficiency (4.41–6.02%). The resultsshows that this plant likes to grow in full sun so that it can capturemore energy from the sun and transform into the plant productionand it has a high photosynthetic and productive potential due tothe presence of C4 photosynthesis. Moreover, the heating valuesof papyrus in this study fall within a wide range of biomass mate-rials such as field crop residues, food and fiber processing wastes,forest residues and energy crops (Chanthunyagarn et al., 2004, Gar-cía et al., 2008; Rosillo-Calle et al., 2008). Accordingly, papyrus isappropriate to use as biomass fuels which is the most suitable

0

1

2

3

4

5

6

7

1 2 3 4Run no.

ener

gy c

aptu

rin

g ef

fiec

ien

cies

(%)

culm

umbel

total

Fig. 2. Energy capturing efficiencies of papyrus in each CW.

0

1-10

11-2

021

-30

31-4

041

-50

51-6

0

time period (d)

Fig. 1. The decreasing growth rates of papyrus in CW.

T. Perbangkhem, C. Polprasert / Bioresource Technology 101 (2010) 833–835 835

and available renewable energy resource. Furthermore, their har-vest will help to re-grow the new culms density rapidly and canprobably reach original productivity within nine months to a yearin the natural condition. If they are planted in the wastewatertreatment unit, they will grow and reach to the ultimate growthrate more rapidly than those in the nature; so they need to be har-vested frequently for more productivity. This result obviouslypoints to the possibility of the plant to be used, more than justtreating wastewater, as an alternative energy source and other va-lue-added matter for further utilization of fibrous materials; suchas pulp in paper industry and weaving materials for handicraft. Fi-nally, in order to maintain high yields and good quality papyrus forcontinuous harvesting, suitable management programs must beplaned for successful operation to obtain the optimum period forharvesting so as to achieve sustainable yields.

4. Conclusion

Operation of the pilot-scale free water surface wetland in thisstudy indicates the feasible use of papyrus as a potential plant usedto treat domestic wastewater. More than just treating the waste-water, the plant harvest gives the value-added materials, whichcould reduce or even offset the treatment costs. The papyrus gavethe plant biomass of about 2590 g dry weight/m2 with the growthrate constant of 0.040 (d�1) and its energy-capturing efficiency ofabout 4.3%. The optimum period for plant harvesting was foundto be about 41–50 days. Appropriate plant cutting would helpmaintain a high growth rate all the time.

Acknowledgements

The authors greatly appreciate The Thailand Research Fund forthe financial support of this research given to Thaneeya Perbangk-hem through The Royal Golden Jubilee Ph.D. Scholarship Program.

References

Boar, R.R., Harper, D.M., Adams, C.S., 1999. Biomass allocation in Cyperus papyrus ina tropical wetland, Lake Naivasha, Kenya. Biotropica 31 (3), 411–421.

Chanthunyagarn, S., Garivait, S., Gheewala, S.H., 2004. Bioenergy Atlas ofAgricultural Residues in Thailand, Presented at Sustainable Energy andEnvironment (SEE), Hua Hin, Thailand, December 2004.

Chrispeels, M.J., Sadava, D.E., 2003. Plants, Genes, and Crop Biotechnology, seconded. Jones and Bartlett Publishers International, Massachusetts.

Franson, M.A.H., Clesceri, L.S., American Public Health Association, 1998. StandardMethods for the Examination of Water and Wastewater, 20th ed. AmericanPublic Health Association, Washington, DC.

García, M., Soto, F., González, J.M., Bécares, E., 2008. A comparison of bacterialremoval efficiencies in constructed wetlands and algae-based systems.Ecological Engineering 32 (3), 238–243.

Kanabkaew, T., Puetpaiboon, U., 2004. Aquatic plants for domestic wastewatertreatment: Lotus (Nelumbo nucifera) and Hydrilla (Hydrilla verticillata) systems.Songklanakarin Journal of Science and Technology 26 (5), 749–756.

Kansiime, F., Oryem-Origa, H., Rukwago, S., 2005. Comparative assessment of thevalue of papyrus and cocoyams for the restoration of the Nakivubo wetland inKampala, Uganda. Physics and Chemistry of the Earth 30 (11–16 SPEC. ISS.),698–705.

Kansiime, F., Saunders, M.J., Loiselle, S.A., 2007. Functioning and dynamics ofwetland vegetation of Lake Victoria: an overview. Wetlands Ecology andManagement 15 (6), 443–451.

Kiwango, Y.A., Wolanski, E., 2008. Papyrus wetlands, nutrients balance, fisheriescollapse, food security, and Lake Victoria level decline in 2000–2006. WetlandsEcology and Management 16, 89–96.

Lee, C.C., Lin, S.D., 2000. Handbook of Environmental Engineering Calculations.McGraw-Hill.

Li, L., Li, Y., Biswas, D.K., Nian, Y., Jiang, G., 2008. Potential of constructed wetlands intreating the eutrophic water: evidence from Taihu Lake of China. BioresourceTechnology 99 (6), 1656–1663.

Mnaya, B., Asaeda, T., Kiwango, Y., Ayubu, E., 2007. Primary production in papyrus(Cyperus papyrus L.) of Rubondo Island, Lake Victoria, Tanzania. WetlandsEcology and Management 15 (4), 269–275.

Neralla, S., Weaver, R.W., Lesikar, B.J., Persyn, R.A., 2000. Improvement of domesticwastewater quality by subsurface flow constructed wetlands. BioresourceTechnology 75 (1), 19–25.

Polprasert, C., 2007. Organic Waste Recycling Technology and Management. IWA,London.

Rosillo-Calle, F., Groot, P.d., Hemstock, S., Woods, J., 2008. The Biomass AssessmentHandbook: Bioenergy for a Sustainable Environment. Earthscan PublicationsLtd., London.

Vymazal, J., 2005. Natural and Constructed Wetlands Nutrients, Metals andManagement. Backhuys, Leiden.