Biomass Production Through Grey Water Fertigation ...

Biomass Production Through Grey Water Fertigation in Eucalyptus Hybrid and Its Economic Significance Anil Kumar Shankhwar and R.K. Srivastava Department of Environmental Science, G.B. Pant University of Agriculture and Technology, Pantnagar, U.S. Nagar, Uttarakhand 263145, India; [email protected] (for correspondence) Published online 24 March 2014 in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/ep.11968 Bioenergy demand is accelerating day by day due to increase in population pressure whereas on other end worldwide water scarcity for irrigation is also becoming a challenge. This problem may be resolved through the fertigation with grey water for biomass production through short rotation intensive cultural plantation systems (SRICPS). The grey water generated from households constitutes the major portion of domestic wastewater with higher nutritive value. Reuse and recycling of grey water save natural water resources require for irrigation and moreover greywater use would be an added advantage to increase in the biomass due to its nutritive quality. Therefore, in present study, an experimental trial has been done for comparison of SRICPS biomass production within treatment (fertigated with greywater) and control (irrigated with bore well water) plots for biomass growth rate, biomass deficit and estimation of actual and potential biomass productivity with fertigation and control irrigation in same environmental condition by planting Eucalyptus hybrid (clone K-413). Eucalyptus hybrid (clone K-413) above ground biomass (AGBM) production per tree was observed to be 34.19 kg tree21 in treatment plots as compared to 25.69 kg tree21 in control plots during initial 2year of field observation and it envisages higher economic returns by fertigation due to higher biomass production per C 2014 Ameriunit area as compared to control irrigation. V can Institute of Chemical Engineers Environ Prog, 34: 222– 226, 2015 Keywords: biomass deficit, biomass growth rate, biomass productivity, fertigation, grey water

the U.S. Energy Information Agency projected that there will be a nearly threefold increase in worldwide biomass consumption from years 2005 to 2030, mainly for biofuel mandates and renewable portfolio standards [2]. However, in Indian scenario it is estimated that Energy demand will quadruple in another 25 years [3]. Short rotation forestry is renewable sources of energy that can be accomplished the energy demands currently met by fossil fuels [4]. In order to meet renewable energy by fuel wood plantation higher productivity is required so that it can be fired for combined heat and power (CHP) plants [5]. Therefore supply of nutrient through fertigation will be an advantageous to increase the yield of short rotation fuel wood biomass. Due to availability of fertilizers at higher cost, use of this domestic wastewater as fertigation may be an added benefit for yielding higher fuel wood biomass, natural water conservation, and recharge of the groundwater after phytoextraction of pollutants by plants for biomass production purposes [6]. The apparent benefits of combining Eucalyptus hybrid (clone K-413) biomass production under short rotation intensive cultural plantation systems (SRICPS) by wastewater fertigation and phytoremediation techniques depends upon the proper implementation of methodology that would allow to minimize the use of required freshwater resources and provide nutrient rich greywater for irrigation. Therefore, present field trial study focuses on comparative assessment of Eucalyptus hybrid (clone K-413) biomass production at different densities under SRICPS through greywater fertigation and using bore well water irrigation as control.

INTRODUCTION

Water is an essential, natural, inexorable, life-sustaining commodity for human beings in day to day life. But nowadays it is becoming inaccessible due to increasing water pollution as a consequence of accelerated industrial and urban growth. Therefore, this polluted water is required a proper treatment. Alternatively domestic wastewater can be reuse and recycle in a convenient way through fertigation technique. As grey water (generated from domestic activities such as laundry, dishwashing, and bathing) include about 60% of domestic wastewater [1]. One another aspect of present study is tremendously increasing demand of energy as

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MATERIALS AND METHODS

Experimental Site Description Geographically the site lies in Tarai plains about 30 km southwards of foothill of Shivalik range of Himalaya at 29 10 4900 N latitude, 79 290 5200 E longitude and at an altitude of 243.8 meter above the mean sea level. The study area site is a subhumid and the subtropical climatic zone with average annual rainfall of around 1350 mm [7]. The mean annual temperature ranges from minimum 5.5 C to maximum 41 C. The experimental site is situated in University premises along the drain which carrying generated domestic wastewater from residential colonies of G.B. Pant University of Agriculture and Technology, Pantnagar, India.

Environmental Progress & Sustainable Energy (Vol.34, No.1) DOI 10.1002/ep

Table 1. Physicochemical characteristics of grey water and bore well water used for irrigation in treatment and control plots. Water quality parameters pH Total solids Biochemical oxygen demands Chemical oxygen demands Total nitrogen Total phosphorus Total potassium Sodium

Grey water

Bore well water

7.5–8.1 450–670 mg L21 45–60 mg L21

8.05 117.50 mg L21 –

190–270 mg L21

–

30–45 mg L21 5.0–12 mg L21 0.5–6.0 mg L21 2.0–13 mg L21

1.75 0.90 0.55 2.80

mg mg mg mg

L21 L21 L21 L21

Short Rotation Intensive Cultural Plantation Systems This study was investigated for the Eucalyptus hybrid (clone K-413) biomass production rate irrigated with domestic wastewater under short rotation intensive cultural plantation systems (SRICPS). The saplings of Eucalyptus hybrid (clone K-413) were transplanted in Nov 2010 in experimental trial field of University farmland. In the experimental trial species Eucalyptus hybrid (clone K-413) was planted due to its hybrid nature and it is obtained after hybridization of two different Eucalyptus species considering variation in stem form, growth rate, branching patterns, and wood traits. Therefore the Eucalyptus hybrid (clone K-413) is hybrid product of E. camaldulensis and E. hybrid originated from ITC Bhadrachalam Ltd. Andhra Pradesh India. Selection of this tree was done keeping in view the wide adaptability in study area climatic conditions, phytoremediation potential, and timber wood yield as well as resistant against various insect, pest, and disease. SRICPS Management The increasing cost of fossil fuels such as diesel and gasoline, and a desire to curtail greenhouse gas emissions are driving expansion of short rotation bio-energy plantation [8]. Furthermore, grey water was applied as nutrients supplement for growth of Eucalyptus hybrid (clone K-413) in treatment plots and for removal of pollutant present in domestic wastewater by phytoremediation whereas bore well water was used in control plots which was without any additional nutrients supplement. Therefore in present study Eucalyptus hybrid (clone K-413) was planted at different densities for phytoremediation of grey water as well as to obtain more biomass as compared to control (ground water) irrigation per unit area by grey water fertigation system. Water Quality and Irrigation Schedule Effect of grey water feritigation on biomass productivity was examined into two irrigation regimes namely serpentine and channel irrigation regime as compared to irrigated with bore well water. In both treatment and control plots of Eucalyptus hybrid under SRICPS plantation into two irrigation regimes were used to provide the optimum use of water and nutrients. The irrigation frequency was kept twice in a week and physicochemical characteristics of grey water and control water used for irrigation are as shown in Table 1 [9]. Plants Spacing and Distance In each plots of 512 m2 the total 156 saplings of Eucalyptus hybrid were transplanted in 13 rows and each row is having 12 saplings in control as well as treatment in uniform pattern. The planting distance were kept 2 3 3 m2,

2 3 1.5 m2, and 2 3 0.5 m2 spacing in both serpentine and channel irrigation system. Tending operations such as weeding, cleaning, thinning, improvement felling, pruning, and climber cutting were practiced time to time for proper tree growth in each plots. Above Ground Biomass Measurement A mechanical caliper was used for collar diameter measurement of planted Eucalyptus hybrid stands as per the method previously presented [10,11]. The above ground biomass (AGBM) measurement of one foot Eucalyptus hybrid saplings was done at the interval of six months since January 2011 for the saplings transplanted in month of Nov 2010 in trial field. This AGBM were calculated for the vertical and radial growth on the basis of plant height and collar diameter. The collar diameter was used instead of diameter at breast height (DBH) as plant height was insufficient for DBH measurement during observation period. The allometric equation was used for AGBM estimation [12]. AGBM 50:15D2 3H where AGBM, above ground biomass in pound (lbs); D, collar diameter in inches; and H, height of the tree in feet. Further by multiplying conversion factor 0.45359 it could be changed from pound (lb) to kilogram (kg). Potential and Actual Aboveground Biomass Production The potential biomass is calculated for the biomass obtained at absolute survival rate whereas the actual biomass production might be always lesser due to not having 100% of transplanted plant survival rate. Therefore, actual biomass was specific for each plot and varies with number of survivalist. The potential and actual biomasses were calculated according to equation [13], which was modified for green above ground biomass estimation in nondestructive fashion for present study. PROD5

ðAGBM mean 2PAGBM mean Þ 1000

where PROD, green biomass production of the plot (tBMha21); AGBMmean, average above ground biomass (kgBMtree21) for a specific plots irrigated with control water and treatment water (grey water); PAGBMmean, mean planted above ground biomass (kgBMtree21), at transplanting time means November 2010; D, stem density of the plot (trees ha21); and 1000 is used as conversion factor from kg to tonne. However to get the value of actual and potential biomass production with the help of above formula can be used for potential biomass produced on the basis of plant density at planting time, Dini (in Jan 2011 after establishment of trees), which was specific for each plots as about 3023 and 3004 stems ha21 respectively as per given plant densities in experiment for control and treatment plots. The plant density Dact was specific for control water irrigated and treatment water fertigated plots as observed in Jan 2013. After 2 years it was observed 2946 and 2829 stems ha21 respectively. Consequently, the actual biomass production (PRODact) —varies due to the survival rate of Eucalyptus hybrid planted almost 2 years ago. However, survival rate of plants in experimental plots were calculated as the ratio of Dini and Dact which further turned into percentage by multiplying with 100. Tree Biomass Deficit In the present study biomass deficit was calculated and it may be defined as difference of potential and actual biomass


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Table 2. Comparative characteristics of soil at experimental field after 30 months of treatment with grey water

Soil characteristics Soil pH Total nitrogen (%) Available phosphorus (ppm) Available potassium (ppm) Total organic carbon (%) Water holding capacity (%) Soil texture CFU of bacteria/g of soil CFU of fungi/g of soil

At the time of project initialization

Treatment plots (fertigation with grey water)

Control plots (irrigation with bore well water)

7.47 6 0.8 0.0272 6 0.0012 6.1 6 1.6 89.26 6 2.4 0.4766 6 0.011 36.79 6 2.3 Silty Clay 8 6 3 3 106 4.5 6 1.5 3 104

6.92 6 0.9 0.098 6 0.0011 8.52 6 1.8 102.98 6 3.1 01.352 6 0.012 38.15 6 1.2 Silty Clay 17 6 12 3 106 9 6 2.5 3 104

7.48 6 0.6 0.0327 6 0.0012 6.4 6 1.6 93.12 6 2 0.6272 6 0.02 38.6 6 2.6 Silty Clay 14.5 6 1.5 3 106 7 6 1 3 104

production considering the survival rate in experiment trial field. Therefore, biomass deficit measurement can be considered as an indicator for the lower degree of silvicultural and tending operations adopted in biomass production management practices to know the actual biomass obtained from field in comparison to its potential biomass production. RESULTS AND DISCUSSION

Biomass Growth Rate The experimental soil is Silty clay in texture and other soil characteristics of experimental site are shown in Table 2. The observed data from experimental field revealed that incremental above ground tree biomass production per tree vary from approximately 10–19-fold in second year as compared to first year of experimental period. The average above ground biomass growth was recorded to be 34 kg tree21 with the treatment plot as compared to 25 kg tree21 of control irrigated plots after 2 years of experimental periods. Therefore result from experimental plantation signifies a clear cut variation in higher tree biomass growth of treatment plots as compared to control plots with previous year yield. However, this grey water mainly generated from domestic practice in study area and does not combine with any industrial wastewater. The heavy metals analyses of grey water were also done for Zn, Cu, Ni, Pb, and As before commencement of experimental work and only Pb is found in very traceable amount 0.06 mg L21 which are quite below than the permissible limit (0.1 mg L21) prescribed for inland surface wastewater discharge. The study conducted by various other authors have envisaged that the plant biomass growth increases faster in third and fourth year onwards compared to the yields of first year and second year due to its more leaves, fine root, and robust root growth [14]. Survival rate of Eucalyptus hybrid (clone K-413) after 2 years of transplantation has performed very high survival rate in control and treatment, i.e., 97.44 and 94.19%, respectively. Above Ground Biomass Production of Tree The observations of individual tree above ground biomass production (ABGM tree21) of Eucalyptus hybrid (clone K413) were taken at each 6 month interval as shown in Figure 1. The results show the AGBM from 0.73 to 25.68 kg tree21 and 0.87–34.19 kg tree21 increase significantly from January 2011 to 2013 for control and treatment plots respectively. The similar study has been done for effluent fertigation effect on the three different Eucalyptus species and result reveals higher incremental growth in above ground biomass production after 2 and 3 years as compared to control irrigation [4]. At the end of 3 years period and their results have shown incremental growth from 19 to 76% as compared to control due to the application of effluent as fertigation water. Moreover, it has been reported that Eucalyptus globulus is a 224

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suitable species for short-rotation pulpwood stands and achieved higher productivity through effluent fertigation [15]. Biomass Production and Deficit In general, the higher rate of biomass production depends upon species selection, nutrient supply, and the nutrient use efficiency [16]. In present study biomass production was assessed in terms of potential and actual above ground biomass production and results are given in Table 3. The observed results indicate a significant variation in potential and actual biomass production of treatment and control plots. A slight biomass deficit were recorded 1.93 and 5.81 ton ha21 respectively in control and treatment plots which was calculated 2.56 and 5.81% less of potential above ground biomass production. The deficit in biomass production from its potential biomass production in the present study has been measured maximum 5.81% with the fertigated treatment plots. This deficit is due to 94.19% of survival rate of tree species Eucalyptus hybrid (clone K-413). As stated earlier the various factors are responsible for governing the survival rate whereas in present case 94.19% with treatment plots and 97.44% with control are quite higher because achieving 100% survival is tedious due to various agroclimatic condition of field and other factors. Moreover, survival rate is also depend mainly due to mortality of sapling at initial stage of planting in treatment and this may be due to root damage and other disease problems with sapling because saplings of Eucalyptus hybrid clone K-413 planted in both treatment and control plots was on random basis and without any specific selection of sapling. However, overall biomass production per tree has

Figure 1. Above ground biomass per tree (AGBM, kg tree21) and growth pattern of Eucalyptus hybrid clone K-413 in initial 2-year study period. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary. com.]


5.81 94.28*

1.93 73.50

Biomass deficit(t ha21) )

PRODact(t ha21)

Test of Significance Interpretation of recorded data was analyzed statistically using Z test to determine different levels of significance at 0.05, 0.01, and 0.001 and observed Z calculated value was found to be 24.831. Therefore a significant biomass increment was recorded in treatment plots as compared to control plots (Table 3).

100.09* 96.75 12.83

*Significant at 1% level of significance.

146 155

94.19

75.43 75.68 6.29 97.44 152 156

Control (bore wellwater irrigated) plots Treatment (greywater fertigated) plots

Jan 2012

Jan 2013

Survivalrate(%)

Jan 2012

Jan 2013

PRODpot(t ha

21

Predicted AGBM production(t ha21) Number of plants(in 516 m2)

Types of irrigation water

Table 3. Observation of Eucalyptus hybrid clone K-413 biomass production, survival rate of saplings, predicted potential, actual biomass and deficit after initial 2-year study period

been observed higher in treatment plots in comparison to control plots. The higher biomass production in grey water fertigated plots are consequently due to higher nutrients contents, more microbial population and soil, plant, and water positive interaction and wide adaptability of Eucalyptus hybrid clone K-413.

Economic Returns from Eucalyptus Biomass Production The present study envisages that higher biomass of short rotation woody crop (Eucalyptus hybrid clone K-413) can be obtained in treatment plots by fertigating (grey water) in comparison to the control, i.e., bore well water irrigated plots. The Table 3, shows almost 25% more production of biomass in initial 2 years as compared to control (bore well irrigated) plots. Therefore, this will give return of 25% more money as compared to the biomass obtained in control plots. The variation in biomass production will further increase in treatment plots as compared to control plots over 2 years period of time. The comparison of actual AGBM in experimental trial field with potential AGBM shows that both the value of biomass is very close to each other. Therefore above described method for calculation of the biomass production can be further calculated for longer period of time to assess the actual production. Nowadays short rotation forestry is interrelated with land management and restoration system and are being looked upon as a potential source to enhance the farm income as well as to check the environmental disruption, degradation and deterioration towards sustainability. Moreover, the use of nonrenewable energy resources such as fossil fuels/coal etc. have to be preserved for our coming generations through use of renewable energy resources, such as biomass based gasifier, etc. and this may be an important area of research to provide power requirement in interior area and as well as also for small scale industry by adopting enhanced biomass production technology. Since agricultural production is always a prime importance due to food security therefore it will be impractical to convert the culturable and fallow land under short rotation forestry for biomass, fodder, and fuel purposes. However, an effort can be made for maximum AGBM production and productivity through the fertigation with grey water. Moreover, this biomass is organic matter and renewable source of energy resource and can be produced in abundant at cost competitive rate. The energy costs of biomass protect from volatility of gas and petroleum prices and its electricity generation cost and provide enhanced energy security. In spite of this, other environmental benefit of wood biomass also includes low NOx and SOx and no net increase in CO2 emissions as compared to nonrenewable energy resources, such as coal, petrol, and diesel, etc. CONCLUSION

The performance of SRICPS tree Eucalyptus hybrid (clone K-413) above ground biomass production with grey water fertigation has shown 25% higher biomass growth rate as compared to control irrigated with bore well water in initial 2 years of study period. Therefore this study advocates the use of grey water fertigation for biomass production of short rotation fuel wood species is an added advantage. Apart


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from the ecological significance of biomass production through fertigation with grey water it also fulfills the need of recycling and reuses domestic wastewater.

9.

ACKNOWLEDGEMENTS

This research was conducted in the framework of the RCUK-DST India Science Bridge, Bioenregy: Technology and Business Solutions for the UK and India, and authors extend special thanks to Dr. P.K. Sen, Department of Applied Mechanics, IIT Delhi, Dr. Padma Vasudevan, Retd. Professor, Centre for Rural Development and Technology, IIT Delhi, India and Dr. Philip Davies, Aston University, Birmingham, UK for their technical and financial support.

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