Innovative Applications of O.R.
Official recycling and scavengers: Symbiotic or conflicting?

https://doi.org/10.1016/j.ejor.2011.11.030Get rights and content

Abstract

Nowadays, especially in developed countries, the traditional collection of end-of-use products by scavengers has been displaced by formal waste recovery systems. However, scavenging still exists, especially in places with collection capacity shortages and/or low living standards. Besides its obvious social implications, the financial and environmental aspects of scavenging are certainly not trivial. Informal recycling of waste electrical and electronic equipment (WEEE) by scavengers not only constrains profits of the formal system. In their effort to recover the value of end-of-use products, scavengers also pollute the environment if toxic substances leak when WEEE is not properly disposed of. We investigate the impact of scavenging on the operations of the formal recovery system of WEEE, under three regulatory measures, using system dynamics methodology. By using data from a real world closed-loop supply chain that operates in Greece extended numerical experimentation revealed that a legislation incorporating scavengers into the formal waste recovery system (instead of either ignoring or prohibiting their participation) is beneficial for economical, environmental and social sustainability.

Highlihgts

► We model the impact of scavenging on the operations of a formal recovery system. ► The formal system collects and recovers waste electrical and electronic equipment. ► We investigate the impact of 3 different regulatory measures on sustainability. ► We incorporate the economical, environmental and social aspects of sustainability. ► Incorporating scavengers into the formal system is beneficial for sustainability.

Introduction

Recently, mass consumption and shortening lifecycles of consumer products have increased worldwide production of goods and led to indiscriminate disposal habits. The usage rate of raw materials is increasing and available landfills are filling up. One of the major and fastest growing waste streams in the world is that from waste electrical and electronic equipment (WEEE), which also appears as one of the biggest sources of environmental footprint (Neto et al., 2010).

WEEE contains toxic substances such as lead, cadmium and mercury. While these toxins are embedded inside the appliance and separated from the user during usage, concerns have been raised regarding the environmental risk associated with toxic substances leaking when WEEE is disposed of in landfills (Williams et al., 2008). Nearly 40% of the lead disposed in landfills and 50% of the lead in incinerators comes from WEEE (Toffel, 2003). It is estimated that the amount of WEEE in Europe increases 16%–28% every year and by the end of 2010 it would be about 4 kilograms per resident totalling approximately 12 million tons (Widmer et al., 2005).

Despite stringent environmental regulations (Mitra, 2007) imposed by governments, through increased collection and recycling percentages (Directive 2002/96/EC, 2003; Chen and Monahan, 2010), informal waste recycling activities are still carried out by specific social groups. The informal recycling sector (“grey” recycling) refers to the waste recycling activities of scavengers (Medina, 2000) and covers a significant part of the total recycling sector both in developed [e.g. Germany by handicapped people (Tobias, 2009)] and developing countries [e.g. Mexico].

Scavenging is a widespread phenomenon with environmental, economical and social dimensions. Scavengers are usually people with limited employment potential who make their living by collecting all kinds of materials for reuse or recycling and by directly extracting recyclable and reusable materials from waste. However, the participation of scavengers often creates a barrier to formal waste recovery operations. In Greece it is estimated that about 90% of WEEE between 2003–2006 was processed by “grey” recycling (Antonopoulos and Karagiannidis, 2007).

Most researchers [with very few exceptions (Medina, 2000, Wilson et al., 2006)] have ignored scavenging in their studies of reverse supply chains and official waste streams. Therefore, many of these studies may be practically irrelevant, especially in countries where grey recycling is substantial.

The formal waste recovery system regards scavenging as potentially harmful to public health. Some regulatory authorities declare scavenging as illegal, while others ignore informal recycling hoping it will disappear in the foreseeable future (Medina, 2000). However, given the economical crisis, the limited employment opportunities and the living conditions of scavengers throughout the world, this hope could be considered idle.

Studies on scavenging concentrate on problem identification, driving forces, cause-effect and social impact, but from a qualitative point of view. In this paper we develop a holistic approach to comprehend the interactions of scavenging with formal waste recovery systems and to study the impact of scavenging on environmental, economical and social aspects of sustainability. We develop a comprehensive dynamic closed-loop supply chain (CLSC) model which enables the joint examination of formal and grey recycling operations. In particular, we consider a WEEE recovery system imposed by legislation and study the impact of the regulatory measures, the scavengers’ activities and the formal waste recovery system activities. The selected methodological tool is System Dynamics (SD). To estimate parameters we apply the model to recycling activities in Central Macedonia in Greece.

The innovative elements of our work are twofold. Firstly, we study the impact of scavenging on the operations of a WEEE recovery system through the environmental dimension (availability of natural resources and landfills, and pollution due to leaks from the scavengers’ uncontrollable disposal ignoring the pollution due to emissions), the economical dimension (CLSC profitability) and the social dimension of sustainability (number of unemployed scavengers). Secondly, we assess the efficiency of different regulatory measures in limiting the impact of informal recycling on the economical, environmental and social aspects of sustainability. We study the efficiency of three different regulatory measures; the current “real” system in which the legislation ignores scavenging, the “ideal” system where the informal recycling sector has disappeared as a result of the legislation, and the “symbiotic” system where the legislation supports scavenging as symbiotic to the formal system. The above analysis is performed by extended numerical investigation with parameter values at different levels in combination with Analysis of Variance (ANOVA) to analyse the sensitivity of the system.

The next section presents a literature review of studies describing the impact of scavenging on societies, along with a brief presentation of SD methodology. In Section 3 we present the structures of the “real”, the “ideal” and the “symbiotic” system. In Section 4 we implement the model in a real-world CLSC with recycling activities of EEE in Greece, while in Section 5 we conduct sensitivity analyses to study the impact of alternative regulatory measures on the sustainability of the CLSC. Section 6 suggests future research directions and the final section provides a summary of the results.

Section snippets

Literature review

Many studies have presented the impact of scavenging and the cause-effects at a city level. In cities within developing countries 50%–80% of the waste generated is usually collected, with open dumping as the only available disposal method. The World Bank has estimated that in developing countries about 1% of the population makes a living by scavenging. Scavengers usually live near landfills to have easy access to and reduce transportation costs of the discarded materials (Brunner and Fellner,

The system under study

We present three different structures of the system under study. In sub Section 3.1 we introduce the current system (“real” system) where the informal recycling sector constrains the activities of the formal waste recovery system. In sub Section 3.2 the “ideal” system is presented, where the informal recycling sector has disappeared, while in sub Section 3.3 we outline the structure of an alternative system where the scavengers are symbiotic to the formal system.

Empirical study

To study the dynamic behaviour of our model, we used data from Greece. In 2001, Greek legislation complied with the current European Directive 2002/96/EC (2003). The first collection and treatment targets should have been attained by December 2008. One of the difficulties the Greek formal waste recovery system (Appliances Recycling S.A.) had to face was grey recycling, which is still carried out mainly by Roma people (Karagiannidis et al., 2008).

In Europe the Roma population is estimated

Results of sensitivity analysis

In this section we investigate the impact of regulatory measures, scavengers’ activities and formal system activities on sustainability of the three systems. More specifically, regulatory measures refer to Legislative Collection Percentage and Legislative Recycling Percentage, scavengers’ activities to Initial Scavengers, Scavenger’s Capacity and Scavengers Collection Cost, formal waste recovery system activities to formal system’s collection capacity (System Collection Capacity), its Recycling

Future research

The SD model that we developed along with the results of the Anova sensitivity analyses revealed that the “symbiotic” system is more sustainable from the environmental, economical and social aspects of sustainability. However, according to Keating et al. (1999), despite the demonstrated benefits of improvement programs, such as the introduction of a new regulation that will promote the incorporation of the scavengers to the operations of the formal system, most improvement programs end in

Summary of results

In this manuscript we developed a SD model to study the impact of scavenging on the operations of a closed-loop supply chain with collection and recycling activities. Although most studies so far develop mathematical models ignoring scavenging, in most developing and in many developed countries informal recycling is still carried out affecting the operations of a closed-loop supply chain. Using our model we have shown that research should consider scavenging in order to correspond accurately to

Acknowledgments

The authors thank the mechanical engineers Georgia Boutzikoudi and Anastasios Mouzouris for the data collection. The first and third author would like to thank the European Project ZeroWIN that is grant funded by the European Commission Framework Programme 7 for funding part of this work.

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