Source Separation and Recycling

There is global consensus for developing a circular economy and building green societies. As the two leading countries in their regions in this field, both China and Germany want to reduce the environmental impacts of waste and avoid the programme of “NIMBY” and have accumulated much experience in waste reduction and gradient utilisation of waste. “Pay As You Throw”, “Green Dot” system and “trade in policy (the new for old policy)” have all proven to lead to higher recycling rates and the minimisation of waste in the past 30–40 years. The article shows how German waste legislation developed to achieve the actual recycling rates. Though Germany follows the European laws, above this it has set a number of even stricter requirements, which are summarised in this paper. The main strategies for implementing source separation are described, while potentials are detected for certain waste fractions like plastics and textiles.

Separate collection of valuables from waste is of growing importance for the conservation of resources and the mitigation of greenhouse gas emissions from landfills. Moreover, the separation of certain waste fractions, such as food waste, is necessary to ensure that landfills and – more importantly – incinerators are managed properly. It is therefore necessary to examine the reasons and motivations for separating waste. Separation and recycling of waste fractions should decrease the overall cost of waste disposal for citizens and public bodies. This can only happen if the authorities take into consideration some important “stumbling blocks,” i.e. physical and socioeconomic indicators and prerequisites, when introducing a recycling system. Four examples (landfill tax as an incentive for separate collection, recycling of used paper and cardboard, collection of bio-waste, recycling of mixed packaging waste) have been investigated in order to evaluate the reasons for successful and unsuccessful attempts at resource recovery. Economic incentives for waste segregation are very important and should be tested in pilot studies or through simulation games, because major differences between opportunity costs and costs for alternative treatment options may lead to unwanted behavior by waste producers and/or citizens. Furthermore, citizens’ behavior regarding the separation of valuables, their cultural background with respect to waste management, and social norms must be taken into account when planning collection schemes. Obviously, convenient access to collection systems is essential. Citizens must become accustomed to these systems; long-term awareness raising helps to optimize the successful collection of recyclables.

Qingdao is an important economic center in eastern coastal China. With the rapid urbanization process, problems of municipal solid waste (MSW) management have become a new concern for the government. In Qingdao, MSW collection and transportation (MSW-CT) amounts increased from 0.81 × 10⁶ t/a in 1999 to 1.85 × 10⁶ t/a in 2015. The per capita MSW production was nearly 1.1 kg/(capita·d), higher than the Chinese average value of 0.70 kg/(capita·d). The MSW management system of Qingdao was dominated by the “Municipal Public Bureau of Qingdao.” Due to the continuous reform of the sanitation management system, an operation mechanism of separation for government and enterprise, unified management, orderly competition and a three-level management system of “City – District – Street” were established. MSW-CT mode was mainly based on the combination of “multi-way collection in early, transfer station compression in late” and “compression car direct transport.” MSW treatment was mainly located at the “XiaoJianXi Solid Waste Comprehensive Disposal plant of Qingdao,” including sanitary landfill, incineration, composting, and recycling. Qingdao was one of the earliest pilot cities of MSW source separation in China. Although some relevant achievements were achieved, many problems were also found. In the future, MSW source separation will be regarded as a key concern for government departments in Qingdao. MSW management of Qingdao had always been leading position in the Shandong Province. However, some problems cannot be ignored, such as multi-head management, inadequate market competition, and inconsistent power between supervision and law enforcement. In the future, Qingdao’s MSW management will be improved through structural reform, financial investment, and an increase in market competition and public environmental awareness. A “Qingdao model” in Chinese MSW management will be gradually established.

Most developing and transitional economies are faced with daunting challenges related to household waste segregation, climate protection, environmentally compatible treatments and the utilisation of the various waste fractions.

Source separation has a major impact on the effectiveness of waste management systems, as it causes significant changes in the quantity and quality of waste that reaches final disposal, which is the main factor in the generation of the greenhouse gas, methane. This environmental impact can be significantly reduced by the separate collection and recycling/use of organic waste.

The German Closed Cycle Management Act is aimed at turning waste management into resource management. The realisation that waste can be a useful source of raw materials and energy is not new; metals, glass, organic waste and textiles have been collected before and put in to new use. The waste management policy, which has been adapted in Germany over the past 20 years, is based on closed cycles and assigns disposal responsibilities to the manufacturers and distributors of products. This has made people even more aware of the necessity to separate waste, has led to the introduction of new disposal technologies and increased recycling capacities (Nelles et al., Proc Environ Sci 35:6–14, 2016).

Nowadays, Germany has great experience in terms of waste separation. Around 14% of the raw materials used by German industry are recovered waste, thus leading to a reduction in extraction levels and the related environmental impact. Modern closed-cycle management contributes, with a share of approximately 20%, to achieving the German Kyoto targets for the reduction of climate-relevant emissions.

The sustainable management of waste has attained increasing importance due to the rising total amounts of waste, as well as the high diversity of the waste fractions worldwide. Increased urbanization rates are resulting in changes in the economy and demography. The suitable management of generated waste streams and using the high potential of recyclables inside these waste streams are major topics communities have to deal with. Especially in Asian countries, the fast development of the society and the rising amounts of waste is resulting in significant problems in sustainable waste management. As the largest emerging country with the largest population in the world, China faces different waste treatment situations than other developing countries. Several technologies can be used for waste treatment depending on the amounts and compositions of the waste streams. Recycling processes should be used for material recovery, biological treatments for appropriate streams, as well as thermal treatments for energy recovery. Landfills for the disposal of residues generated by the other treatments are also necessary. In the challenge of avoiding the presence of biodegradable waste in landfills and increasing recycling, mechanical biological treatment (MBT) plants have seen a significant increase in number and capacity in the last two decades in Europe. Among the conditions and local challenges in countries in Asia, which are at the beginning in implementing a regulated waste management system, MBT technologies can be a promising approach.

The most relevant parameter for the profitability of a deposit is its raw materials concentration. With the view on secondary raw materials from municipal solid waste (MSW), the concentration depends on the population density and the specific waste generation rate. To recover a secondary raw material from MSW, collection is the first step and at the same time, the bottleneck, as typically the efficiency of the separate collection of recyclables decreases with increasing population density. Also, the effort of collecting many different recyclables as a single fraction, with each of these fractions making up a small specific amount per household, often only leads to collection costs being too high to be compensated by revenues from recycling or waste fees. As a compromise between losing recyclables due to high degrees of contamination when collected in mixed household waste, and exploding collection costs for too many single fractions, recyclables are often collected as a commingled fraction of selected materials, which can technically be efficiently separated, and then be directed to recycling plants. Local waste management structures, such as contractual periods and distribution of responsibilities, lead to specific collection and treatment systems with individual efficiencies, which is demonstrated by different examples, as implemented in Europe.

This chapter addresses the possibilities for recovering resources for material applications by thermal waste treatment. Two thermal routes are considered: Waste-to-energy (WtE) plants and pyrolytic disintegration approaches.

WtE enables the recovery of iron, nonferrous metals, and also minerals from bottom ash. Another opportunity for material recovery is flue gas utilization. The recovery and material utilization of HCl and sulfur (in the form of gypsum) has been industrially practiced for decades. In the last few years, the first approaches to recover metals from the filter dust were also industrially implemented.

Pyrolytic processes offer the chance to recover valuables from composite material parts, like carbon fiber-reinforced plastics (CFRP), or from metal-enriched fractions of other waste treatment processes like shredder residues. The containing plastics can be volatilized at high temperatures and the emerging pyrolysis gases can be utilized to supply the thermal energy for the process. The absence of oxygen and relatively low temperatures prevents the valuables in the composite matrix from damage.

The rapid urbanization progress and the continuous improvement of rural residents’ living standards are contributing to the increase in rural solid waste (RSW) in China. RSW generation rates range from 0.25 to 2.3 kg (capita d)⁻¹ in different rural areas, and the real total RSW generation amount was far higher than official data in 2014. RSW is dominated by food residue and coal ash/cinder/dust in rural China, and most of it is discarded randomly without any treatment. In this work, rural household behaviors toward RSW treatment and their perceptions in terms of awareness and attitudes on the source-separated collection of RSW are investigated with a questionnaire survey consisting of 518 valid samples. The results indicated that some rural households had spontaneously separated the recyclable waste and food waste to some extent. The public were aware of the importance of RSW separation through various media, and more than half of households were willing to participate in a separation program. The dominant barriers to participation were the lack of awareness of separation, inconvenience, and an insufficient separation facility (53.7%). 62.5% of rural households had a positive willingness to pay (WTP) for RSW separation and management, and the mean WTP was estimated to be 3.8 USD/year. Age, annual household income, and location significantly influenced the respondents’ WTP. More positive policy is necessary to encourage the local government to devote efforts to provide collection service and improve RSW management by combining the governmental financial budget and rural household payments.

Only cascading use can ensure higher sustainability in the recycling of biodegradable waste materials (biowaste) compared to pure thermal and/or energetic utilization types. Cascading use means, in a first stage, that energy is skimmed off by a fermentation process. In a second stage, products used as organic fertilizers and soil improvers are generated. This is usually done by composting. The separate collection of biowaste is a prerequisite for the production of high-quality organic fertilizers and soil improvers.

The anaerobic treatment of biowaste and green waste in Germany has not gained the importance it deserves by far, owing to its ecological advantages. This is also evidenced by the high expansion and development potential afforded by the anaerobic treatment. There is a need for action in two areas: (1) increase the amount of biowaste collected by establishing a tightly meshed nationwide expansion of the organic waste bin system and increase the collection rates and (2) channel a large proportion of the biowaste currently only undergoing composting into fermentation as well. The potential for increasing fermentation in Germany is estimated at 5.4 million tons.

MSW source separation is a key procedure for its later processing. Kitchen waste, the main contributor to moisture content, accounts for a very high proportion (~60%) in MSW composition. The feasible way to dispose of MSW before or after separation depends on the reasonable disposal of kitchen waste. Here, a case study from Hangzhou, China, is presented in terms of the source separation effect on the waste disposal process. In Hangzhou, three strategies, including direct digestion without separation, composting after separation, and co-digestion with fruit and vegetable waste, were explored. It indicates that:

E-waste is a complex waste stream with several categories of products, each of them requiring a specific treatment technology. This chapter analyses the status quo of e-waste management in three global regions, where the European Union represents a frontrunner in environmental legislation and implementation; China, catching up with recent legislation and large-scale investments in recycling infrastructure; and Vietnam, as an example for the numerous countries where an unregulated situation dominates. This chapter aims at giving an overview of the management of this waste stream focussing on two relevant stages in the material recovery chain: collection as the interface between consumers and waste management and treatment with an overview of technologies applied for the removal of hazardous materials and the recovery of valuable materials such as steel, copper, plastics and others. Challenges for these situations are identified.

The increase in waste generation amounts and its Greenhouse gas (GHG) emissions are two main pressures for the Chinese government. The development process of the waste management system was summarized. The corresponding GHG emissions pattern was studied, and the potential reduction measurements were also proposed based on the different steps for the waste management system. It was found that the total estimated GHG increased from 10.95 million tons (1991) to 72.4 million tons CO₂-equiv (2013) on the basis of the IPCC methods. Landfill was the main GHG source, as the corresponding percentage increased to the peak of 82% (1999) and finally to 69.5% (2013) in the period studied. Eastern China was the dominant CO₂ emission region, while the percentage decreased from 39.6% (2003) to 26.4% (2013). To get more detailed GHG emissions from landfills, the bottom-to-top method was applied to estimate the corresponding emissions and reduction potential from 1,955 landfills in 2012. The source reduction in MSW and the diversion alternatives for landfills are indirect, while useful GHG mitigation way for the reduction of the terminal disposal amounts and its GHG emissions through the implementation of “pay-as-you-throw” and an environmental protection tax.

The production of secondary materials from waste materials requires, in most cases, significantly lower energy amounts than the primary material production of raw materials. Along with lower energy demand, the greenhouse gas emissions produced are also lower. The duty of a modern waste management system should therefore be to collect and sort the waste materials in a way that the highest amounts of single material fractions with the highest qualities can be generated. In this contribution, the greenhouse gas balances of the theoretical treatment of the household waste, if collected as mixed waste in sanitary landfills, in waste incineration plants, or in mechanical-biological treatment plants, are compared to the existing separate waste collection and treatment in Germany in 2014. The results show that the treatment of the mixed collected household waste in sanitary landfills would lead to a significant release of greenhouse gases. The treatment in MBTs with the recovery of valuables and the further disposal of the biologically stabilized fraction on landfills, as well as the treatment of the high calorific fraction (also called refuse derived fuel – RDF) in RDF plants, coal-fired power plants, or cement kilns, would lead to small amounts of avoided greenhouse gas emissions. The thermal treatment in waste incineration plants would lead to moderate amounts of avoided greenhouse gases. Only with the actually practiced separate collection and treatment of household waste were significant amounts of greenhouse gas emissions avoided. In total, this is approximately 5.5 million tons of carbon dioxide equivalents for approximately 45.5 million tons of separate collected and treated household waste in Germany in 2014.

In the early 1970s of the last century, new sorting and pyrolysis plants as well as new ideas for landfills were introduced and constructed. The result of this was a separate collection, recycling and reuse of material, and energy recovery from waste of more than 90% in a number of cities and areas in Europe.

What kinds of problems are we facing that we should solve in the future sooner rather than later? Today in our modern society, we need more than 90% of all known elements in our consumer products and produce a severe environmental problem. This makes a proper recycling and reuse of especially rare elements very difficult and a real challenge.

Chemicals are ubiquitous. Once man-made chemicals enter the environment, they can move around regionally and worldwide through a variety of mechanisms. High toxic concentrations can be found (in predator species and human beings).

The new threat is coming from closing the loop at a global scale. Plastic, paper and cardboard, lubricants, electronic devices, nano-coated material, and other products undergo a recycling process and make their way into a recovered material with unpredictable and unforeseen health and safety problems.

This is what we have to solve in the future.

Within the symposium “Waste Reduction and Recycling: Challenges and Trends for Source Separation,” which was held from June 6 to 10, 2016, participants discussed the successful implementation of separate collection. The conclusions of this symposium are summarized in this chapter and consider some additional aspects. It is focused on the situation in China and Germany, but they are also applicable to different situations and regions around the world. For countries with rising waste management challenges, source separation has been proven to be one of the fundamental solutions for the sustainable handling of resources and achievement of a circular economy. The driving forces for establishing of efficient collection schemes are described in this chapter, referring back to the previous chapters of the book, where the challenges and possibilities for different fractions and separation technologies are presented.