Model for Economical and Sustainable Bioenergy Production under Greywater Irrigation Trial

Abstract

The present study focuses on sustainable utilization of greywater in short-rotation energy plantationEucalyptus hybrid, Populus deltoides, Salix alba and Melia azedarach. The dry matter produced by wastewater plots was 143%, 54%, 274% and 321% higher for Eucalyptus hybrid, Populus deltoides, Salix alba and Melia azedarach respectively, than the same plants in control plot. The calorific value of samples ranged from 4037 to 5190 Kcal kg -1 in greywater plots, and 3460 to 4469 Kcal kg -1 in control plots. The carbondioxide mitigation potential was 19, 13, 11 and 29 t ha -1 higher for E. hybrid, P. deltoides, S. alba and M. azedarach trees respectively, under wastewater irrigation.Keywords: Bioenergy production, calorific value, carbon dioxide mitigation potential, greywater irrigation.ACCORDING to the 2011 census, India's population has reached 1210 million. Around 833 million people reside in rural areas constituting 68.8% of the population. Approximately 44% of this rural population has no access to electricity and 85% still depends on firewood as a primary source of fuel. In India, bioenergy is the primary sources of energy for cooking, heating water, etc. About 76.3% of rural and 17.5% of urban population still depend on firewood for cooking purposes 1 . India is well bestowed with 450-500 million tonnes of biomass per year, which has a potential to generate 18,000-50,000 MW of power 2 . However, due to increasing population pressure, the consumption of firewood has by far exceeded its supply, thereby causing deforestation. Another problem faced is freshwater scarcity and increasing loads of wastewater. Grey fraction of domestic wastewater represents the largest potential source of water conservation 3 . The present study demonstrates a commercial model for plantation of short rotation bioenergy trees under the greywater irrigation trial and its impact on firewood and economic returns.The present study was conducted in a 1 ha fallow land at the G.B. Pant University of Agriculture and Technology, Pantnagar, Uttarakhand, India (Figure 1). The soil of the experimental site is sandy loam in texture with a slightly acidic pH ranging from 6.3 to 6.5 and electrical conductivity of 140-165 S cm -1 . It is a Tarai region with organic matter (OM) ranging from 1.42% to 1.49%, and bulk density and infiltration rate of 1.45 g cm -3 and 0.32 cm h -1 respectively. The experiment was initiated in November 2008; greywater used for the experiment was exclusively from the bathrooms and kitchens of two residential colonies of the University, having a population of approximately 5000 inhabitants. The control plot was irrigated with water from a shallow borewell which was installed in the experiment field.Two equal sub-plots of dimensions 60 m  80 m were prepared for treatment and control trials leaving a buffer zone of 20 m width between the two plots to prevent the mixing of wastewater and control water. Each plot was further subdivided into three replicated subplots of dimension 30 m  20 m having a buffer of 10 m between each...