Study design
At the request of the municipal assembly, mixed plastic collection in Muttenz has been carried out as a pilot collection with 35-liter bags since May 2020. Carbotech AG was commissioned to carry out a life cycle assessment study specifically for the Muttenz collection to evaluate the pilot phase. Raymond Schelker organized and carried out the manual sorting and analysis of the collection bags as an expert for realcycle GmbH (then REDILO GmbH).
In principle, the study should answer the following questions:
- Is the separate plastic collection in Muttenz worthwhile from an ecological point of view?
- Is the separate plastic collection in Muttenz worthwhile from an economic point of view?
- Do other scenarios (bring-in instead of pick-up collection, other recycling route) have a higher ecological benefit than the current scenario?
In order to answer these questions, a separate analysis of the plastic collection bags in Muttenz was carried out. On each of three collection days, 50 plastic collection bags were manually sorted, allocated to different plastic fractions and weighed. The quantities and types of plastic sorted served as the basis for the LCA calculation. The environmental impact was assessed using the ecological scarcity method (MöK). The incineration of the plastics in the Basel waste incineration plant (KVA) served as the reference scenario. The environmental benefit is expressed as a saving of environmental impact points (EPP).
Results of Carbotech's life cycle assessment study:
The results of the sorting show a very good collection quality. The collection bags contained only 1.5% foreign matter. However, 60% of the materials could not be assigned to any specific type of plastic, and experience has shown that around 25% of them may contain problematic additives (plasticizers, fire retardants, stabilizers). These substances can be found, for example, in office materials or garden furniture, but also in children's toys. These substances are problematic in recycling, as they remain in the material cycle and can therefore end up in the environment.
In the scenarios examined in the LCA study (bring or pick-up collection, disposal of the residual materials in a cement plant or in the waste incineration plant), the environmental benefits of plastics collection in Muttenz vary according to the assumptions made. Recycling the residual materials in a cement plant results in a higher ecological benefit than thermal recycling in the Basel waste incineration plant. On average, 75% of the residual materials are used for energy recovery in cement plants and 25% in waste incineration plants. The Muttenz plastics collection results in an environmental benefit of approx. 1.35 million UBP per ton.
What does this ecological benefit mean for the population of Muttenz?
A comparison: If a family of four in Muttenz collects plastics for a year and fills a 35-liter bag every four weeks, they will save around 25,000 UBP in that year. The family could achieve the same savings by avoiding the consumption of 220 grams of beef (55 grams/person) or a car journey of almost 50 km. Separate plastic collection can achieve an extremely modest ecological benefit, which answers the first question.
The cost analysis of plastic collection in Muttenz shows an annual deficit of around CHF 40,000, as only 45% of the costs are covered by the sale of collection bags. To fully cover costs, the price per bag would have to be doubled. The eco-efficiency of the collection, measured as the ratio of ecological benefits to costs, is low compared to other recycling systems such as PET bottles or aluminum cans. This means that high costs are incurred in order to reduce relatively little environmental impact.
In addition, the method of ecological scarcity was applied. It assesses the environmental impact by determining environmental impact points (EIP). Although the plastic collection in Muttenz achieves an ecological benefit, this remains low. Alternative collection scenarios such as bring systems or other recycling routes do not show a significantly higher ecological benefit. Despite the possible recycling of plastics in the cement plant, plastic collection remains economically in deficit and has a low eco-efficiency.
The entire study can be read here.
Contact person
Dr. Melanie Haupt(melanie.haupt@realcycle.ch,+41 44 537 82 80)
Project by Raymond Schelker
Clients
Carbotech AG
Municipality of Muttenz