Emission of methane and carbon dioxide and earthworm survival during composting of pharmaceutical sludge and spent mycelia Deepanjan Majumdar * , Jigisha Patel, Neha Bhatt, Priyanka Desai Department of Environmental Science, Institute of Science and Technology for Advanced Studies and Research, Vallabh Vidyanagar, Gujarat 388 120, India Received 9 November 2004; received in revised form 14 March 2005; accepted 20 March 2005 Available online 19 May 2005 Abstract Emissions of methane (CH 4 ) and carbon dioxide (CO 2 ) from spent mycelia of the mold Penicilium notatum and sludge from the eﬄuent treatment facility (ETPS) of a pharmaceutical industry were estimated twice during a two-week composting before vermi- composting. These wastes are dumped in landﬁlls or sometimes used in agricultural ﬁelds and no reports are available on their green- house gas producing potentials. The solid wastes contained appreciable organic carbon and nitrogen while very high Fe, Mn and Zn were found in ETPS only. Pure wastes did not support germination of Vigna radiata L. while mixing soil with ETPS and spent myce- lia at the ratios of 12:1 and 14:1 led to 80% and 50% germination, respectively. The wastes were mixed with cowdung at the ratios of 1:1, 1:3 and 3:1 for composting. Carbon dioxide emissions were always signiﬁcantly higher than CH 4 emissions from all the treat- ments due to prevalence of aerobic condition during composting. From some treatments, CH 4 emissions increased with time, indi- cating increasing activity of anaerobic bacteria in the waste mixtures. Methane emissions ranged from 21.6 to 231.7 lgm 2 day 1 while CO 2 emissions were greater than thousand times at 39.8–894.8 mg m 2 day 1 . The amount of C emitted as CH 4 –C and CO 2 –C from ranged from 0.007% to 0.081% of total C composted. Cowdung emitted highest CH 4 followed by spent mycelia and ETPS while ETPS emitted more CO 2 than spent mycelia but lesser than cowdung. Global warming potential of emitted CH 4 was found to be in the range of 10.6–27.7 mg-CO 2 -equivalent on a 20-year time horizon. The results suggest that pharmaceutical wastes can be an important source of CH 4 and CO 2 during composting or any other stockpiling under suitable moisture conditions. The waste mixtures were found not suitable for vermicomposting after two weeks composting and earthworms did not survive long in the mixtures. Ó 2005 Elsevier Ltd. All rights reserved. Keywords: Carbon; Eisenia foetida; Germination; Global warming potential; Greenhouse gas; Solid waste 1. Introduction Methane (CH 4 ) and carbon dioxide (CO 2 ) are two of the most important greenhouse gases in atmosphere. Methane is radiatively, 62, 23 and 7 times stronger than CO 2 on a mass basis on a 20, 50 and 100-year time scales, respectively (IPCC, 2001). Anthropogenic emis- sions of CH 4 and CO 2 come from biogenic sources re- lated to agriculture and waste disposal, including enteric fermentation, animal and human wastes, rice paddies, biomass burning and landﬁlls. According to Khalil (2000), waste decomposition releases 61 Tg CH 4 per annum worldwide, comprising of 17% of total global CH 4 emissions. Industrial, agricultural, municipal and 0960-8524/$ - see front matter Ó 2005 Elsevier Ltd. All rights reserved. doi:10.1016/j.biortech.2005.03.015 * Corresponding author. Tel.: +91 02692 234955; fax: +91 02692 238355. E-mail addresses: joy_ensc@yahoo.com, joy_ensc@rediﬀmail.com (D. Majumdar). Bioresource Technology 97 (2006) 648–658