Plastics in municipal waste: what are the recovery options ?
Plastics in municipal waste: what are the recovery options ?
| Author: Patrick Semadeni
In Switzerland, between 175,000 and 212,000 tons of plastics are disposed of with municipal waste per year1 . What is to be done with these plastics? An exciting discussion has flared up on this subject. The FOEN (Federal Office for the Environment) held a conference on 14 November 2017.
What recovery methods exist?
There are basically three disposal methods, which lead to different forms of recycling:
- Mechanical recycling: processing of plastic wastes into plastic granulate;
- Thermal recycling: using the calorific value of plastics through incineration;
- Energetic recycling: using the energy in plastic to manufacture cement.
In Switzerland, the proportions are as follows2:
- Thermal recycling: 83.3%
- Material recycling: 10.3%
- Energy recycling: 6.4%
In various countries, waste is also disposed of at landfill sites. This is the least advantageous method of disposal. In Switzerland, combustible waste has not been disposed of in landfills since 2000.
What collection systems do we have in Switzerland?
The most widespread is still collection together with the normal household waste for energy recycling.
There are, however, also special collection systems for plastics3:
- Plastic waste bags (4,740 tons/year collection amount)
- Public/private collection sites (1,181 tons/year collection amount)
- Collections at retail businesses (5,396 tons/year)
The mechanical recycling rate in these systems is 53%. Even with this kind of collection, 36% is thermally/energetically recycled, and another 11% is accounted for by a loss of moisture, which leads to a discrepancy between the input weight of the collected waste and its output weight after disposal.
A further study of EMPA4 has examined the mechanical recycling rate with the plastic waste bag KUH Bag. KUH Bag is joint pilot project of the waste recycling associations Zweckverband Abfallverwertung Bazenheid ZAB and Verband KVA Thurgau. The catchment area covers 4.6% of the Swiss population. In the second year of the KUH Bag, 502 tons of plastic were collected from households, corresponding to a collection rate of 10% of the quantity regarded as collectable in the catchment area. The collected quantity in the second year nevertheless doubled compared with the starting year. The study shows a value of 47% for the technical recycling rate (kg recyclate/100 kg collected material) and is therefore within the range of the HSR study.
The KuRVe Study (Plastic Recycling)
The company Carbotech AG and the university institute UMTEC have carried out a study for the rating of plastic collection systems, on behalf of eight cantons, various associations and the Federal Office for the Environment BAFU. The KuRVe study was published in the middle of July 2017.
The study comes to the following conclusion5: “Compared with the collection of PET bottles, plastic collections from households have low cost/benefit efficiency. They involve high costs and produce a relatively small ecological benefit. The potential ecological benefit of a new plastic collection per person per year is roughly equivalent to that of refraining from one 30-kilometre car journey per person per year.” The study estimates the costs of disposal: in normal household waste with incineration in the refuse incinerator: CHF 250/ton, by means of a new plastic separate collection CHF 750/ton. This evaluation does not include the existing collection system for PET drinks bottles (PRS system).
The KuRVe study was intended as a basis for further discussions and as a contribution to supporting the political decision-making process.
The attitude of the federal government, cantons and municipalities
The joint approach of the federal government, cantons, and municipalities (Federal Office for the Environment BAFU, Cercle Déchets CD, Organisation of Communal Infrastructure OKI) was stated at the BAFU Conference of 14.11.176:
- BAFU, CD and OKI can understand the population’s desire to collect as much plastic waste separately as possible. A collection is only useful, however, if cost and benefit are in an appropriate ratio to each other.
- From the point of view of the BAFU, CD and OKI, the pure, separate collection of PET drinks bottles is useful. It should absolutely be retained because high-quality “bottle-to-bottle” recycling is possible with PET drinks bottles.
- BAFU, CD and OKI welcome the Switzerland-wide, blanket coverage collection of plastic bottles offered by the retail trade. This is usually a case of PE plastic, which is easy to recycle. In addition, this collection has no cost for the consumer.
- Regarding the separate collection of mixed plastic wastes, BAFU, CD and OKI are sceptical, because of the low proportion of high-quality recycling materials obtained from this waste fraction.
- Depending on how the situation develops in the next few years due to technical innovations, BAFU, CD and OKI will carry out a reappraisal.
Our position
As a processor with high levels of rigid packaging we welcome the attitude of the authorities. This argues clearly in favour of a high quality of the collected material. To some extent, selective plastic collection. This in turn allows us as a processor to manufacture the same product again from the discarded plastic packaging. We thus keep the material in a “closed loop” for as long as possible. If the quality deteriorates after x material recycling cycles, there is still always the option of thermal or energetic recovery.
We favour “bottle-to-bottle” recycling. The aim here is to use high-quality recycled material instead of new material. The manufacturing of one kg virgin polyethylene (PE-HD) requires 76.7 MJ7, with a calorific value of 54.3 MJ/kg7. The difference of around 22 MJ/kg is not used. In the processing, around 0.5 MJ/kg is required for melting a kg of polyethylene. One must also not forget that the incineration of 1 kg polyethylene produces 3.14 kg CO2.
We achieve very good recycling rates with a collection system that gathers selectively picked batches with high quality. An excellent example of this is the well-functioning PRS system for PET drinking bottles, which achieves a collection rate of 83%. Thanks to the good quality of the recyclate, “bottle-to-bottle” recycling is possible. At the same time, the further disposal methods of thermal and energy recycling still remain.
A survey8 of 485 processors from 28 – carried out by the EuPC (European Plastic Converters), has essentially shown that there is a lack of high-quality recycled material.
If mechanical recycling is to be expanded, then good quality of the collected material is a basic condition of this. Furthermore, however, there must be a willingness, on the part of retailers, bottlers, brand owners and others, to buy products made of post-consumer recycling materials.
(please click to enlarge)
Bottles made of 100% Post Consumer Recycling PE-HD (Logo Plastic).
1 Kunststoffmengen im Hauskehricht, Kunststofftagung 14.11.17, BAFU (ohne PET Getränkeflaschen im PRS System, ohne Verbundwerkstoffe und ohne Textilien).
2 BAFU, https://www.bafu.admin.ch/bafu/de/home/themen/abfall/abfallwegweiser-a-z/kunststoffe.html
3 Übersicht der verschiedenen Sammelsysteme der Schweiz, HSR Hochschule für Technik Rapperswil, UMTEC Institut für Verfahrens- und Umwelttechnik, 14.11.17
4 Zusammensetzung und Recyclingquoten von gemischten Kunststoffsammlungen - Erfahrungen aus dem KUH-Bag System, EMPA, 14.11.17
5 KURZBERICHT –KuRVe (Kunststoff Recycling und Verwertung) - Ökonomisch-ökologische Analyse von Sammel- und Verwertungssystemen von Kunststoffen aus Haushalten in der Schweiz, Carbotech AG, 13.07.17
6 Haltung BAFU, CD und OKI zur Sammlung von Kunststoffabfällen aus Haushalten, Bundesamt für Umwelt (BAFU),Cercle Déchets (CD),Organisation Kommunale Infrastruktur (OKI),14. November 2017
7 Stoffliche Nutzung nachwachsender Rohstoffe: Grundlagen - Werkstoffe – Anwendungen, Türk, 2013, Springer Verlag
8 The Usage of Recycled Plastics Materials by Plastics Converters in Europe - A qualitative European industry survey October 2017, EuPC, Brüssel