PVC Plastic: a Looming Waste Crisis

PVC Industry does a U-turn in Thinking

The recycling potential of PVC appears to be seriously limited. A study concluded that for more than 70-85% of PVC waste already discarded or to be discarded by 2005, there is no recycling option (Moller and Jeske 1995). But even this figure seems to be far too optimistic, as most reported mechanical recycling rates for post consumer PVC are below 1% and chemical recycling is almost non-existent.

Since PVC cannot be recycled in any significant quantities or at competitive cost, the most likely disposal route for almost all PVC will be landfilling or incineration. Both options cause environmental problems and should be phased out. PVC presents particular problems because of its additives and high chlorine content, as discussed in previous chapters.

Furthermore, incineration and landfilling shift the risks as well as the costs onto communities. In Germany, incinerator air purification for future quantities of PVC would involve additional costs amounting to DM 1.5 billion (Lahl 1997). To prevent PVC entering the incineration waste stream would involve complicated separation processes. Apart from logistical difficulties, there is the question of who would pay for this.

Despite industry’s recycling claims, it is actively lobbying for incineration and landfill as disposal options. These are by far the cheapest for the industry, because disposal costs are shouldered by municipalities and local governments, and because they do not require expensive separation and collection processes. The German PVC industry is now even proposing incineration in a mono-incinerator for PVC which has been separately collected, which illustrates the problems with mechanical recycling of PVC.

Mechanical recycling is favoured by the European plastics industry only for clean, single pipes, ducts and windows which are collected separately. Otherwise incineration with energy recovery is preferred (APME 1996b). Preferred recovery options (derived from APME 1996b) are as follows:

Product	primary recovery option
Fixed floor coverings	energy recovery
Cables	energy recovery
Pipes and ducts	mechanical recycling*
Profiles	energy recovery
Lining	energy recovery
Wall coverings	energy recovery
Windows	mechanical recycling*

*only preferred when clean, single products are collected

The plastics industry is now also lobbying for the use of packaging waste in steel industry blast furnaces as material recycling, replacing coal or oil as a reducing agent. The burning of waste plastics in cement kilns is also being promoted by industry as a "recovery" option. But this may only have a low PVC content, in the order of 1% or less (Lahl 1997).

So the plastics industry’s own political agenda seems to acknowledge the difficulties of recycling. It is pressing governments to accept incineration, labelled as energy recovery. The plastics industry’s prediction is that, as a result of energy recovery, the amount of plastic wastes entering European incinerators and other combustion processes will increase 3-4 times between 1994 and 2000. It also claims that by the year 2000 about 50-60% of the approximately 20 million tonnes of plastics waste should be incinerated annually in Europe for energy recovery (Mader 1997).

PVC: incineration loses energy. Proposed incineration with energy recovery is highly inefficient and does not recoup the calorific value of waste. Because most, if not all, of the energy content of the waste is lost in incineration and all of the carbon dioxide is emitted, it can never be regarded as ‘closing a loop’. Even with energy recovery, 80% of the energy is lost and with mono-incineration 20% is lost (Pohle 1997). Moreover, all the energy used to manufacture the product is lost in incineration. For PVC, the net energy balance with energy recovery is likely to be negative (Moller and Jeske 1995, Pohle 1997). Industry claims that PVC incineration with energy recovery saves energy are therefore not true.

Incineration generates dioxin and other persistent, toxic compounds in both air emissions and solid waste residues. With incineration there is always the problem of the formation of dioxin and other toxic substances and their release into the environment. Even though atmospheric emissions from incinerators can be partially filtered, modern filtering and operating technologies do not prevent dioxin and persistent toxic compounds from forming. They merely shift the problem from being one of atmospheric emissions to one of waste disposal. Emissions and ash residues are further contaminated by additives such as heavy metal stabilisers. This presents inevitable leachate problems for the future. Moreover, PVC has a negative impact on the energy efficiency of a municipal waste incinerator, because the steam pressure must be kept relatively low to prevent corrosion of the heat recovery boiler by hydrochloric acid. For this reason the energy efficiency is only 25%, compared to 40% in a power plant. PVC contributes significantly to this negative impact on the energy efficiency (VA 1997).

PVC also increases the leaching of heavy metals from bottom ash. Around 25% of the chlorine ends up in the bottom ash in the form of salts such as cadmium chloride, which enhances leachability. PVC contributes significantly to this (VA 1997).

In addition, immobilisation techniques may be used to improve the quality of bottom ash prior to disposal or re-use. Prior to immobilisation, the bottom ash needs to be washed and the high chlorine content will contribute to excessive amounts of residual waste from such washing operations (VA 1997).

Incineration of PVC increases waste mass. Incineration of PVC also leads to the formation of hydrochloric acid, which is corrosive to the equipment and hazardous when emitted. In most modern incinerators, hydrochloric acid from PVC incineration is neutralised with calcium carbonate (lime) and/or sodium hydroxide (caustic soda) into salts. These salts are usually contaminated and must be disposed of in special landfills, at considerable cost (Lahl 1997, TNO 1996). In Germany, an insignificant proportion is cleaned and re-used (Pohle 1997).

According to the PVC Information Council in Denmark, incineration of 1kg PVC creates 2-5kg of neutralisation residue that needs to be disposed of as hazardous waste (PVC Information Council Denmark 1997). The amount of waste salt from 1kg of PVC in a municipal incinerator is calculated to be 1.7kg for a wetscrubber in Germany (Lahl 1997). The Danish EPA’s estimates, on the basis of incineration studies, are 1.7-2.0kg solid waste for a semi-dry process and 2.6-3.0kg for a dry process, in Denmark (Rasmussen et al. 1995). This increase in the amount of waste in PVC incineration has led to an agreement between the Danish Government and the Danish PVC industry to prevent PVC from entering incinerators.

The myth of the salt loop. The German PVC industry promotes the recycling of hydrochloric acid into salt as closing the PVC loop - salt into salt, that can be given back to "mother nature" or "re-used" for PVC production. However, this salt is contaminated and it is doubtful whether it is economically viable for the PVC industry to use the salt as a feedstock in their production processes on a large scale, even though a few incinerators in Germany are equipped to produce an insignificant amount of salt for the chlorine industry (Pohle 1997).

When hydrochloric acid is neutralised with caustic soda, the caustic soda used to neutralise the hydrochloric acid is produced by the chlor-alkali industry as a by-product of chlorine production from salt. In other words, an equivalent amount of chlorine will be produced from salt to neutralise the hydrochloric acid. This "recycling concept" cannot close the loop, regardless of emissions and waste production, because it involves the use of an equivalent amount of salt and the production of chlorine.

The PVC industry also promotes the direct use of hydrochloric acid for the oxychlorination process in vinyl chloride monomer production (AgPU (undated)). But oxychlorination with hydrochloric acid is known to produce dioxins and other organochlorine wastes in large quantities (Stringer et al. 1995, OSPAR 1995). It is also very doubtful whether the PVC industry could use the hydrochloric acid from incinerators directly to produce vinyl chloride monomer, because it is contaminated with heavy metals and other additives, and must first be cleaned (Pohle 1997). This PVC recovery scheme leads to the formation and/or release of hazardous substances throughout the various processes involved, and cannot be regarded as a closed system.

Chlorine input is dioxin output: PVC is a major precursor to dioxin formation in incinerators. The contribution of PVC to dioxin formation in incinerators is still hotly debated and challenged, especially by the chlorine industry (Costner 1997a). However, a significant proportion of studies that have researched the correlation between chlorine in waste feed and dioxin generation from incinerators show a positive association (Costner 1997b) and PVC has been documented in several studies as the predominant chlorine source in incinerators (Green 1993, Moller et al. 1996, VROM 1997).

The PVC industry has put a significant effort into challenging the correlation between chlorine input - and therefore PVC input - and dioxin output in incinerators. Greenpeace recently analysed a study by the American Society for Mechanical Engineers (ASME) which evaluated 1,900 test results world-wide and came to the conclusion that there is no relationship between chlorine input and dioxin formation (Rigo et al. 1995). It was found that the data supported no such conclusions (Costner 1997a). The study, commissioned by the PVC industry, is now being widely used by the industry to lobby for incineration with energy recovery as a recycling method.

Mono-incineration: excessive costs and insufficient environmental gains. The mono-incineration process simply treats plastic waste - with a typical energy value of 30 mJ/kg (somewhat lower than oil) - as a fuel for power plants. The mixed plastics are incinerated in a circulating fluidised bed, with energy recovery of up to 90%. Pilot plants are being tested in Finland and Japan, but have not yet proved economic. A monocombustion unit would substantially increase costs because plastic waste would have to be separated from mixed household waste (Chemical Week 1996).

Chlorine needs to be kept to a minimum in these pilot plants. However, in Germany there is a plan for mono-incineration of PVC, in which PVC waste is first shredded and then incinerated in a mono-incinerator, with hydrochloric acid being recovered. Recycling of hydrochloric acid from PVC in mono-incineration facilities could fail because of the excessive costs and insufficient environmental gains (Moller and Jeske 1995). Another disadvantage of mono-incineration is the energy needed to transport all the PVC to the central disposal site.

PVC and landfills - PVC’s additives will eventually leach, posing a risk to groundwater. The bulk of petrochemical-based plastics - such as PVC, PP and PE - are durable and have a long lifetime. After disposal, they do not decompose readily or quickly. Moreover, the use of many different chemical additives in some plastics results in their leaching out of landfills to contaminate soil and groundwater. This is especially true for PVC, which has the highest content of additives, most of which are hazardous to the environment.

Considerable quantities of PVC are present in landfills, as a result of the disposal of municipal solid wastes (MSW), and construction and other wastes. In Europe 7,480,000 tonnes of plastic waste was landfilled in 1994 as MSW. This contains 13% PVC - therefore almost 1 million tonnes of PVC was landfilled in Europe as MSW. If plastic waste from other sectors, such as agriculture, the car industry, construction and distribution is included, the amount of plastic entering landfills almost doubles to thirteen million tonnes (based on APME 1996b).

PVC is unique because it contains large quantities of additives which are mixed rather than chemically bound with the polymer, and may leach out of landfills. However, little research has been carried out on the behaviour of PVC in landfills. It has been assumed that PVC and other plastics will behave as inert solids when landfilled. But a Danish report (DTI 1993) suggests that it degrades through a combination of microbial, chemical and mechanical influences. This could increase the release of phthalic acid esters, heavy metals and other additives.

A number of researchers have considered the leaching of plasticisers from landfills. While there is no dispute that leaching occurs, estimates of the amounts vary considerably. Cadogan et al. (1993) suggest that the leaching of plasticisers in Europe may vary from 7.5 to 250 tonnes a year. Wams (1987) estimates that 1,000 tonnes of the plasticiser DEHP could be released as leachate in Dutch landfills each year. Global emissions from such sources have been estimated at up to 200,000 tonnes/year (Lundberg et al. 1992).

The leaching of additives from PVC and other plastics, such as the metals that are used as stabilisers, may ultimately destabilise the polymer. PVC entering landfills at the end of its useful life may be in a partially degraded state. Photochemical and oxidative degradation during the product’s useful life may considerably change the properties of the polymer, leading to an increased susceptibility to further chemical or physical breakdown, and the release of additives after disposal.

As an example, experience has shown that PVC roof-lights, if weathered in cool, well-ventilated situations, tend to whiten, indicating photo-oxidation processes. PVC barrel roof vaults can become excessively hot in sunlight and cause PVC to undergo rapid degradation by loss of hydrogen chloride (DoE 1996). Nevertheless, the possibility of PVC degradation in landfills has never been comprehensively checked.

Landfill fires become particularly toxic with PVC waste. Landfill fires are a common occurrence, with the potential to pyrolyse and combust PVC, leading to the release - either in smoke or as leachate - of a range of pollutants, including heavy metal additives and dioxins. A four-year survey of 63 landfills in Germany revealed that 13 fires occurred, requiring the attendance of the fire services. Some fires deep in the landfill may require several months to be brought under control.

In some cases, fires are deliberately started at landfills as a way of reducing waste volumes, or for recovery of scrap metals - for instance, copper recovery from PVC cable (Feliubadalo and Relea 1995). Smoke from these fires contains a wide range of products of incomplete combustion, including dioxins, aromatic hydrocarbons and aldehydes. PVC may be expected to contribute to these emissions since its pyrolysis and combustion are known to produce dioxin. However, this aspect has not been comprehensively investigated and the potential contribution of PVC remains unknown. In addition, contaminants produced and released by the fire may mobilise into the leachate.