Miljøprojekt, 1137 – Nyttiggørelse af kommunal indsamlet PVC-affald

Nyttiggørelse af kommunal indsamlet PVC-affald

Summary and conclusions

This report describes the results that have been obtained in the study “Products from the Watech process by treatment of PVC waste collected by Danish municipalities”. RGS90 Watech with Uffe Rahbek as project manager has performed the study. The project has received financial support from Miljøstyrelsens “program for renere produkter”.

An important part of the study has been to supply technical, economic and environmental data to two different socioeconomic studies. The Socioeconomic studies describe and compare a number of different processes for the treatment of PVC waste.

The first study was ”PVC Recovery Options, Concept for Environmental and Economic System Analysis” initiated by Vinyl 2010, ref.1. This study has been finalized and the report can be seen on the Internet

The second study was a Danish Environmental- and Socioeconomic analysis of treatment methods for PVC waste, which was initiated by Miljøstyrelsen (the Danish EPA). In this study different treatment methods are compared. The methods chosen were Disposal, Incineration, the Watech process and the Stigsnæs process. This study has not been published yet.

Conclusions

The amount of PVC waste that was collected by the local recycling station in two Danish municipalities has been determined. The collected PVC waste has been characterized with respect to content of other materials and plastics than PVC and it has been analyzed for its lead and cadmium content. It proved to be difficult to find reasonably clean fractions of PVC waste since many municipalities currently are mixing all “waste to disposal site” in big containers in order to save space at the collection sites (recycling stations). In some municipalities PVC waste are mixed with other building waste and this will require further sorting before the PVC waste can be treated and converted into useful products.

PVC wastes that were used in this study were collected in containers, which were dedicated to collection of PVC waste. The containers were clearly marked and having a clear explanation to the users of which type of waste that was wanted in the containers. In spite of this marking the collected PVC waste still had a significant content of other materials than PVC. In particular high contents of other plastics and metals were found, but also wood, household waste and electronic waste were found. A better sorting and pretreatment scheme would be nice but not necessary in order to treat the PVC waste in the Watech process (WAPRO®). Sorting was performed briefly in order to remove large non-plastic fractions. Hereafter the PVC waste was comminuted to about ca. 8-10 mm grain size and separation (sorting) was done using the PLASTSEP® process. The PLASTSEP process is the pretreatment process used before further PVC waste treatment in the WAPRO®process.

The sorting and separation using the PLASTSEP® process gave the result that 65 % and 75 % of the PVC waste could be sorted out as “clean” PVC waste from the two municipalities. The “clean” PVC could be further treated in the WAPRO®process. The 25% (respectively 35%) materials that were separated out in the PLASTSEP® process were metals (Copper, Aluminium, Iron, Steel) that can be recycled and a “Light” plastic fraction (Polyetylene, Polypropylene etc.) that could be recycled either mechanically or by energy recovery.

The ”clean” PVC waste could be pyrolysed and intermediate products could be treated in the WAPRO®process. The products from treatment of PVC waste from municipally collected PVC waste have the same quality as products from treatment of other PVC waste (cable waste and building waste).

The municipally collected PVC waste had high contents of roof gutters and plasticized PVC (for example bathing basins, toys and rain clothing). By pyrolysis of this type of PVC waste more oil product is recovered compared to cable waste. Also less salt product and less coke product is recovered from this PVC waste. Pyrolysis was performed in the WAPRO® pilot plant with a mixture of municipal collected PVC waste and cable waste. This mixture was treated and products recovered without any process technical problems.

Roof gutters and plasticized PVC contains the metals cadmium and lead. The municipal collected PVC waste in this study consists of relatively ”new” PVC waste. It has been seen before that the content lead and cadmium can be up to 10 times higher in relatively “old” PVC waste such as cable waste. In the WAPRO® process these heavy metals are concentrated in a filter cake that can be send to metal recovery or to a specific disposal site.

Treatment of municipal collected PVC waste requires a special precipitation stage for cadmium from the salt product. The extra cost for this process stage is so low that it can be neglected. Pretreatment and reaction conditions can be set the same way as for treatment of PVC cable waste or PVC building waste. It has been shown that municipal collected PVC waste can be mixed with other types of PVC waste without any process technical problems.

The recovered salt product may contain other salts than calcium chloride. When an alkaline source such as Flue Gas cleaning Waste is used as an additive in the WAPRO® process other salts is also formed. It has been shown that is possible to produce calcium chloride salt, sodium chloride salt and potassium chloride salt in a quality that corresponds to commercial products and hereby increasing the value of the salt product.

The treatment cost for PVC waste has been calculated in connection with the Watech participation in the Environmental and Socioeconomic studies initiated by Miljøstyrelsen. From the Socioeconomic study assuming Danish amounts of PVC waste and co-treatment with Flue Gas Waste the treatment cost will be in the range 800 – 900 kr/ton.