Transformation of spent broiler litter from exogenous matter to compost in a sub-tropical context Romeela Mohee a,1 , Marie-Francoise B. Driver b,2 , Nafiisa Sobratee b, * a Department of Sugar and Chemical Engineering, Faculty of Engineering, University of Mauritius, Re ´duit, Mauritius b Department of Agriculture and Production Systems, Faculty of Agriculture, University of Mauritius, Re ´duit, Mauritius Received 12 September 2006; received in revised form 17 November 2006; accepted 20 November 2006 Available online 30 January 2007 Abstract Composting, an environmentally-sound treatment option for confined animal feeding operations (CAFO)-derived wastes, provides opportunities for stabilisation and hygienisation. A 110-day systematic composting study investigated Salmonella presence and survival of total coliforms, faecal coliforms, Escherichia coli and faecal enterococci in three experimental windrows consisting of SBL/bagasse mixture in a close-sided roofed facility. Salmonella was absent throughout the experiment. Log 10 reductions of 6.98, 8.03, 8.18 and 5.96 occurred in TC, FC, E. coli and FE concentrations respectively. As expected, FE exhibited resistance to high temperature compared to E. coli especially for the first 21 days. Temperature histories revealed hygienisation attainment. Differences in mean, rep- resenting benchmark stages of composting, were highly significant (P < 0.05) for all pathogen indicators. VSRed (%) proved effective in depicting system progress. Final respiration rate of 0.000206 mg CO 2 g 1 organic-C day 1 with no phytotoxicity showed the stability achieved. Besides stabilisation, quantitative analysis of the sanitisation potential of composting is elemental for hygienic compliance. Ó 2006 Elsevier Ltd. All rights reserved. Keywords: Spent broiler litter (SBL); Total coliforms (TC); Faecal coliforms (FC); Faecal enterococci (FE); Volatile solids reduction (VSRed) 1. Introduction The poultry industry in Mauritius, representing the larg- est share of the local livestock sector, is fully developed with a production of 26,000 tonnes of processed chicken produced annually (Anon, 2003). This indicates a consider- able amount of waste generated from the poultry rearing facilities. Animal waste-related environmental problems, particularly regarding the poultry sector have been exacer- bated by the organisational structure of the industry, nota- bly its high degree of vertical integration (Shane, 1998). In line with the industrial ecology concept, clean practices that allow transformation and re-use of livestock waste need to be researched and applied to prevent environment and san- itation hazards associated with wastes presenting zoonotic significance. Uncontrolled disposal and land application of raw man- ure may potentially spread pathogens to non-target envi- ronments (Bach et al., 2002; Pell, 1997). Gagliardi and Karns (2000) demonstrated the possibilities for Escherichia coli to survive, replicate and move downwards in soil for up to two months through manure spreading. Likewise, Kudva et al. (1998) reported the survival of E. coli O157:H7 for more than one year in stockpiled non-aerated ovine manure pile that was exposed to environmental con- ditions. Such facts highlight the priorities associated with seeking efficient manure treatment processes. The main interest with composting as waste manage- ment option lies in its capacity to both lead to stabilisation of the exogenous organic matter and its potential for sani- tisation, resultant of the self-heating characteristic based 0960-8524/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.biortech.2006.11.040 * Corresponding author. Tel.: +230 242 1849; mobile: +230 912 6400. E-mail address: nsobratee@yahoo.com (N. Sobratee). 1 Tel.: +230 4541041x1540; fax: +230 4657144. 2 Tel.: +230 4541041x1545; fax: +230 4655743. Bioresource Technology 99 (2008) 128–136