Specific heat and thermal conductivity of municipal solid waste and its effect on landfill fires G.S. Manjunatha, Digambar Chavan, P. Lakshmikanthan, Lal Singh, Sunil Kumar ⇑ , Rakesh Kumar CSIR-National Environmental Engineering Research Institute (CSIR-NEERI), Nehru Marg, Nagpur 440 020, India article info Article history: Received 23 March 2020 Revised 28 June 2020 Accepted 19 July 2020 Keywords: Municipal solid waste Thermal conductivity Specific heat capacity Organic content Moisture content abstract Municipal Solid Waste (MSW) landfills are sources of physical, chemical and microbiological processes and as a result, gases and heat are generated as by-products. The generated heat flows from the higher to lower temperature regions within the landfill. Specific heat and thermal conductivities are two impor- tant properties that determine heat flow in MSW landfills. The goal of this study was to determine the thermal conductivity and specific heat capacity of MSW samples of Indian origin and to study its effect on landfill fires. Thermal conductivity and specific heat capacity of waste samples collected from dump- site at Bhandewadi landfill, Nagpur & Bellahalli landfill, Bangalore (India) and the synthetic MSW (pre- pared in the lab) were determined using newly designed and fabricated experimental set-up. Results showed that moisture and organic content of MSW are directly proportional to specific heat capacity and indirectly proportional to thermal conductivity. Thermal conductivity of MSW is directly propor- tional to its density and specific heat is indirectly proportional to the density of MSW. MSW with specific heat and thermal conductivity in the range 0.003 J/g. K  0.47 J/g. K and 0.35–3.6 J/s. m. K, respectively were found between 30 and 75 °C with 5% to 25% moisture content. As the temperature increases above 75 °C, decrease in thermal conductivity & increase in specific heat was observed and thermal conductivity of 0.07 J/s. m. K was observed at 130–140 °C. As a result of this, heat does not flow and gets concentrated in that region leading to landfill fire. Ó 2020 Elsevier Ltd. All rights reserved. 1. Introduction India is generating 531.53 X 10 5 million tons (MT) of municipal solid waste (MSW) per year (MNRE, 2018). Landfills are the final disposal points of MSW in India. MSW is a miscellaneous combina- tion of organic (food and vegetable) waste, paper & textile compo- nents, glass, plastic, rubber, wood, ferrous & non-ferrous metals, leather, stones and bones. MSW composition and its properties play a major role in its management, disposal and post disposal issues. While collection and transportation of MSW require only the compositional details but the disposal, utilization and treat- ment technology require other critical information like density, thermal properties and elemental composition (Vyacheslav et al., 2016). Although processes like gas extraction and leachate recircu- lation were implemented at few landfills (Huijie et al., 2018), the management of heat and landfill fires still remains a critical issue to be addressed. A large amount of heat is produced by the exothermic reaction in the landfill and remains undissipated. Bio- logical and chemical degradation of MSW components will lead to the temperature rise in MSW landfills. In addition, anaerobic decomposition releases methane gas that is explosive when its percentage in air varies in the range 5.3–13.9 (Margaret, 2004). Around 8400 landfill fires incidents per year were reported in the United States (National Fire Incident Reporting System, 2002). Delhi (India) fire station (DFS) reported that Bhalswa, Okhla, Gha- zipur had 69, 35, 27 times major landfill fire incidents per year, respectively (India Today, 2017). Causes for the fire incidents include chemical reactions, reactive materials, failure of landfill gas systems, smoking or sparks, landfill equipment, lightning strikes, hot load. Hot loads in the landfills are an important factor for the landfill fires (Jeff, 2018). It is necessary to avoid the landfill fire incidents by extracting the heat from the landfills and by avoiding the hot loads at one point in the landfill. It is necessary to maintain good heat dissipation in landfills so that hot load will not be stored at one place and landfill fire inci- dents can be avoided. Conduction is the major process through which heat transfer occurs in the landfilled waste with specific heat and thermal conductivity playing a major role in the heat con- duction process (Megalla, 2015). Thermal conductivity and specific heat are the two important thermal properties which need to be analysed for understanding the heat distribution in landfill and https://doi.org/10.1016/j.wasman.2020.07.033 0956-053X/Ó 2020 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail address: s_kumar@neeri.res.in (S. Kumar). Waste Management 116 (2020) 120–130 Contents lists available at ScienceDirect Waste Management journal homepage: www.elsevier.com/locate/wasman