Correspondence and reprint requests: Dr J.S. Pandey, National Environmental Engineering Research Institute (NEERI), Nagpur – 440 020 (Maharashtra), India; Phone: 91-712-2249753; E-mail: js_pandey@neeri.res.in Short Communication [Indian J Chest Dis Allied Sci 2010;52:60-61] Amongst all the greenhouse gases (GHG) present in the atmosphere methane has assumed considerable significance. Atmospheric concentration of methane has almost doubled after industrial revolution. It contributes to 20% of total GHG effect. In industrial countries, 15% of total GHG contribution comes as methane emission and it is expected to contribute to 18% of the total expected global warming over the next 50 years. Along with the warming effect, methane also participates in troposphere ozone formation, which amplifies methane’s direct infrared absorption by approximately 70 percent. 1 Ten percent of total methane emissions come from industrial and municipal wastewater. Anaerobic bacteria are the main factors behind methane emission. Therefore, biochemical oxygen demand (BOD) and chemical oxygen demand (COD) are two important water-quality parameters on the basis of which methane emission from a particular water-body can be determined. 2-4 The present analysis would be useful before planning any methane- mitigation or utilisation strategy. Per-capita Country-wise Methane Emission The BOD and COD values of wastewater are the parameters, which mainly determine potential for methane emission. Municipal and industrial wastewater having higher BOD or COD values emit more methane under the similar climatic conditions. Organic fractions present in the municipal wastewater are degraded to produce methane. 5,6 In this paper, a comparison was made between methane emissions from wastewater in various developed and developing countries. 7 It is observed that over the years there has been continuous increase in methane emission from wastewater in both the countries. In America, methane emission has increased from 24.85 million MT (CO 2 -eq.) in 1990 to 35.21 million MT (CO 2 -eq.) in 2005. During the same time in India, this increase was from 56.90 million MT (CO 2 -eq.) to 73.25 million MT (CO 2 -eq.), respectively (Figure 1). 7 Another analysis was carried out on the basis of per- capita emissions from municipal wastewater in different countries. 5 India, Pakistan and China turn out to be the lowest contributors in terms of per- capita methane How to Plan for Methane Mitigation and Utilisation Strategies? J.S. Pandey, A.P. Mishra, U.K. Sur, M. Tembhare, R. Kumar and S.R. Wate National Environmental Engineering Research Institute, Nagpur, India emissions (Figure 2). On the other hand, developed countries like Australia, Canada, France, Japan, Germany, and USA have 7.86, 8.57, 8.57, 8.57,10 and 10 times more per-capita contributions than that of India. While Mexico, Egypt, Brazil, Lebanon and Indonesia have 1.29, 1.29, 1.43, 1.43 and 2 times more than that of India. Figure 1. Year-wise methane emissions from wastewater treatment Figure 2. Per-capita methane emission (1997) [wise ranking: relative values] Country-wise BOD Comparisons Since BOD values of municipal wastewater are prime indicators of methane emission, a comparison was made on the basis of per-capita BOD in different countries (Figure 3). 6 This comparison shows that per-