Treating waste as a resource and the transformation from a linear towards a circular economy seems to be high on the political agenda as never before. Especially in the European Union where the European Commission published its Circular Economy Strategy that underlines the environmental, social and above all economic benefits of becoming more circular (European Commission, 2016). Against this background of potential cost-savings for companies, municipalities and the wider society of an estimated hundreds of billions of Euros, the question is raised as to why the reality is still so far away from perfectly closed loops in which generation and treatment of waste happens without any environmental burdens?
The five papers in this issue of Waste and Resource Management all address this issue from very different angles and especially against the background of very different spatial contexts. They cover the full range of the waste hierarchy from prevention to disposal and highlight the complexity and technological challenges of the circular economy.
Mwai et al. (2016) tackle the issue of environmentally sound disposal of waste and focus on the use of tyre-derived aggregates to be used as drainage media in leachate collection and drainage systems. Based on three case studies for tyre-derived aggregates sourced from processors in Alberta, Canada, they analysed the effects of overburden pressures and propose a reduction factor of 50% that should be taken into account as a minimum criterion for determining the initial (as-spread) thickness of a drainage layer.
The paper by Grimes and Thompson (2016) addresses the recovery of base oils from waste lubricant oils. Waste lubricant oils are classified as hazardous waste that can be managed by recovery for reuse and recycling, hydrocracking to produce fuels, incineration with energy recovery and, less satisfactorily, by direct incineration or disposal at a hazardous waste site. Hydrocracking and incineration give rise to only one second use for the waste oil, but recovery for recycling provides the opportunity to achieve multiple reuse stages for recycled oils and should, with the use of suitable technologies, be the preferred management option. According to the authors, recovery rates in Europe are below 40% and the paper describes two novel low-temperature ionic liquid processes that avoid the use of high-temperature adsorbents that have to be disposed of as hazardous materials or volatile organic solvents, all of which adversely affect their economic and/or environmental suitability.
Ahmed and Panwar (2016) provide a forecast for the generation of hazardous constituents contained in e-waste in India. According to their model, India's e-waste (for example, from obsolete laptops) is projected to increase by 300% until 2020 compared to the 2014 levels. Taking into account the amount of hazardous substances in e-waste, they draw the conclusion that reuse must be particularly boosted and promoted, thereby minimising recyclable component waste and hence disposal and dumping. Additionally, while repair and other ways of preparation for reuse are often covered by the informal sector – in India as well as in Europe – they conclude that more stress should be laid on refurbishment of reparable equipment so as to prevent disposal of hazardous material.
The final two papers address management and prevention of municipal solid waste in Morocco. Abouri et al. (2016) report that according to the World Bank in Morocco, before a recent reform in 2008, only 70% of urban municipal solid waste was collected and < 10% of collected waste was being disposed of in an environmentally and socially acceptable manner. There were 300 uncontrolled dumpsites and approximately 3500 waste pickers, of which 10% were children who were living in and around these open dumpsites. The lack of waste management infrastructure leads to burning of trash as an inexpensive form of waste disposal. This completely unregulated incineration of waste poses a significant threat to the environment and health of citizens, and more innovative approaches are urgently needed. Specifically with regard to fresh leachate with a high level of chemical oxygen demand (COD), Abouri et al. studied the removal of pollution from municipal solid waste fresh leachate using a technique of continuous and discontinuous aeration in order to predict the efficiency of a low-cost biological treatment for this type of effluent. The physicochemical characteristics of the leachate showed that the pollution load has high levels of COD, biological oxygen demand, phenol and surfactant. The authors report that a removal of 90 and 60% of surfactant was obtained during discontinuous and continuous aeration, respectively.
Maguiri et al. (2016) analyses the case of the city of Mohammedia, Morocco, which has to bear a significant cost for the treatment of its waste. To alleviate this problem, the city has been trying to reduce waste production by upstream sorting and recovery. The paper describes outcomes of a study on the waste arising through characterisation of household waste, including an analysis on how much waste is recyclable, the percentage of fermentable organic materials, the percentage of non-recyclable materials as well as the estimated cost of disposal of such waste. The results show that particularly for glass, plastic and cardboard/paper, the treatment costs could be reduced substantially. The authors also discuss the role of the informal sector and households as key stakeholders in the generation of waste. The analysis of these interlinkages between technical expertise and infrastructure systems on the one hand but also behavioural aspects and their underlying economic incentives on the other might be the key challenge for an in-depth understanding of the circular economy. And the rewarding lecture of all five papers in this issue points out some of the relevant research question at these interfaces that will require our continuous attention.
