بهبود بهره وری در مراکز بازیافت زباله های جامد از طریق اجرای هدفمند شده با تحلیل تصمیم گیری چند معیاره Productivity improvement in solid waste recycling centres through lean implementation aided by multi-criteria decision analysis

1. Introduction Solid waste management has been an integral part of every human society (Shekdar, 2009) and is one of the most challenging issues in urban cities, which are facing serious pollutions problems due to the generation of huge amount of solid waste (Kumar et al., 2009). The influence of improper management practices for municipal solid waste (MSW) has attracted the attention of various entities, professionals and researchers in recent years (Catapreta and Heller, 1999; Agarwal et al., 2005; Mondelli et al., 2007; Taylan et al., 2008; Parrot et al., 2009), since these can cause serious threats to the public health and environment. MSW is the most complex solid waste stream, as opposed to more homogeneous waste streams resulting from industrial or agricultural activities (Troschinetz and Mihelcic, 2009). According to the Brazilian Institute for Geography and Statistics (IBGE, 2002), Brazil produces about 125,281 tons of MSW per day, 30.5% of which are disposed off in garbage dumps, 22.3% in controlled dumps and 47.1% in sanitary landfills. Although, the selectiveness of garbage disposal has improved in recent years, 63.6% of Brazilian towns still dispose off their solid waste in dumps. Effective planning of solid waste recycling programs is currently a substantial challenge in many solid waste management systems (Li et al., 2008). Despite some effort in order to develop sustainable solutions for municipal solid waste management systems (Shekdar, 2009), the management of MSW is going through a critical phase, due to unavailability of suitable facilities to treat and dispose of the larger amount of MSW generated daily in metropolitan cities (Sharholy et al., 2008; Taylan et al., 2008; Parrot et al., 2009; ChamizoGonzalez et al., 2016). Specifically in the case of Brazil, the existent technology for the recycling of MSW is simple and labour intensive (Nunes et al., 2007). While developed countries typically apply curbside recycling programs to collect and sort wastes for recycling processing (Troschinetz and Mihelcic, 2009), developing countries, such as Brazil, utilize the social sector known as scavengers to handle such activities, who are citizens with low-to noincome that collect materials either dispersed throughout the city or concentrated at dumpsites (Medina, 2004; Wilson et al., 2006; Fei et al., 2016). Furthermore, Nunes et al. (2007) report on their study that the majority of recycling centres in Brazil are badly administered by public authorities and their viability depend on continuity of operation and reaching expected production volumes. According to Krook and Eklund (2010b) there is a lack of affordable and accurate monitoring for providing the recycling centres with the necessary facts for improving waste. Javied et al. (2014) also mention that, among several critical success factors for improving efficiency at recycling centres, four main points are worth noticing: (i) proper funding for MSW management system, (ii) awareness and training of workers and people, (iii) increased pay of workers and related staff and (iv) proper production practices for daily activities’ demand. Thus, as the trend towards recycling grows, so does the need for increasing the effectiveness of recycling centres (Hemphala et al., 2010; Lino and Ismail, 2013).