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– by Oliver Möllenstädt
© Denis Meyer/imagebroker/Lineair
A waste picker in Kolkata sorting recyclable plasticware
Economic growth always has downsides. One of them is that more consumption leads to more waste. All newly industrialising countries face this challenge. Household garbage includes a lot of used packaging and disposable plastic products that are not naturally degradable.
Most emerging economies still have no real system for recycling waste such as the lightweight packaging that is collected for re-use in Germany in specific yellow bins and bags. So litter – waste products disposed of improperly in public places – is a real problem in cities. Unfortunately, many residents also dispose of plastic waste in rivers and on shorelines or beaches.
The plastics industry is actively addressing these issues. National industry associations are increasingly cooperating across borders to extend waste collection schemes and introduce professional recycling. One example is cooperation between Germany and India (see box).
India currently has no official systems for collecting and recycling plastic waste; nor are there overarching initiatives by private or public sector. Nonetheless, some waste is collected and recycled very efficiently: waste pickers scour municipal dumps, and later sell plastic items to small local plastics processors or recyclers. It is estimated that millions of tonnes of plastic waste is reclaimed this way every year.
Plastic waste covers a broad spectrum of used products, including film packaging, carrier bags, beakers and consumer products. The bulk consists of recyclable thermoplastics, especially PE, PP, PVC and PS – polymers that become pliable or mouldable when heated. Only a small share is made of composites and thermosetting polymers, for which the production process is non-reversible.
At present, collection focuses mainly on thermoplastics and is confined to conurbations and industrial centres, where there are more recycling businesses. Much of the plastic waste is pre-sorted before recycling, but some of the waste is still mixed or contaminated. Small processors turn the waste into secondary raw materials that can be used for manufacturing new products. In most cases, the processing is done with the help of simple injection moulding and extrusion machines. The processes are labour-intensive and do not require much capital investment.
The downside is that these methods do not necessarily lead to secondary materials of the highest quality. Nor can the small-scale business guarantee a steady flow of recyclates of standard quality, which limits commercial use. Today, Indians are aware of the value of recycled plastic, but the potential has not been fully tapped, and only a fraction of the theoretically available waste is being recycled at all.
For small and medium-sized enterprises in India, recycling is certainly an attractive business. If its appeal could be enhanced and the business made even more lucrative, the problem of waste could be significantly reduced. To achieve that, improvements are needed on a number of fronts: policy and judicial measures can ensure that more waste is collected for recycling, processors can work more profitably if they acquire the necessary know-how and introduce up-to-date technology. Many chemical processes that are widely applied in Europe are not in use in India.
Quality management and control systems, for example, could guarantee that recycled material is of a uniform high standard. Automated sorting systems would be another major advance, because the plastics collected in India at present are still pre-sorted by hand. In up-to-date systems, different kinds of plastics are separated by machines.
Thermal and mechanical wastestream pre-treatment would also have considerable potential in India. Mechanical wet and dry processes, for example, can be used to separate mixed waste. Thermal treatment reduces the length of polymer chains and creates secondary raw materials such as the gases Ethen and Propen as well as different sorts of oil and wax. If processed appropriately, these materials can be substitutes for fossil raw materials.
India particularly offers scope for broadening the base of not just chemical but also feedstock recycling. In this case, plastic waste is not recycled as plastic, but as another raw material. Contaminated waste of heterogeneous composition that cannot otherwise be usefully reclaimed at present can be used for feedstock recycling. Heat is used to break down the polymer chains and turn the plastic into petrochemical feedstocks such as oils and gases, which can then be used for various purposes. One form of feedstock recycling relies on the gasification of plastic waste, where carbon monoxide and hydrogen are produced by the partial oxidation of hydrocarbons. This technique enables even high-grade polyolefin re-granulates to be produced from waste plastic packaging. They are used for the manufacture of long-life equipment.
For such technical systems and processes, Indian entrepreneurs naturally need the relevant expertise. It would also be very useful for them to know what other purposes the secondary raw materials can serve. Knowledge transfer from countries like Germany is particularly important in this context.
Policy-makers and administrations could help to improve the recycling sector. Waste collection and separation, in particular, could be significantly better. At the same time, however, the livelihoods of India’s waste pickers must not be jeopardised.