Green Packaging: Environmental Issues for PVC (7)

The possible relationship between the incineration of PVC and the corrosion of incineration devices has long been debated. Some operators claim that steam pressure and subsequent energy efficiency will be higher in the presence of low chlorine in the waste stream. Therefore, the absence of PVC will make the recovery and recovery system more efficient. This issue requires further study. It should be noted that due to the higher calorific value of PVC wastes, the incineration of PVC waste energy recovery generates more energy than the incineration of ordinary municipal solid waste. 

Due to the neutralization of acid flue gas and the additional cost of waste disposal of the final residue, the incineration of the PVC waste increases the operating cost of the incinerator. The overall additional costs associated with the incineration of PVC vary depending on the waste treatment of Member States, neutralization processes and residues. It is estimated that the additional costs of incineration of PVC relative to municipal solid waste range from approximately €20 per ton for wet systems to €300 per ton for dry systems. It varies depending on the technology used and the type of incinerated PVC (rigid or flexible). Currently these additional costs are not particularly burdened by new PVC products or PVC waste, but are included in the overall waste incineration costs.

Research has been authorized to evaluate the economics of converting PVC waste from incineration. The report analyzes three scenarios and compares the basic scenario. With the appropriate reduction in the number of PVCs sent to incineration and landfills, the recovery rates for the first option and the second option will increase by 15% and 22% respectively by 2020. Taking into account the incineration, this means that the first program (mainly construction waste) accumulated 1.7 million tons during the period from 2000 to 2020, and the second option accumulated 3.8 million tons. The third option has not changed the recovery rate from the basic plan, but as a result of the separation of building materials into landfills, the incineration rate is estimated to be 28% instead of the 45% predicted in the basic plan. This corresponds to a separation of about 10.3 million tons between 2000 and 2020.方案 Option One: The fiscal costs considered in Section 2 include the cost of incineration (including “special costs”) and the net cost of the conversion process that is incurred depending on the separation of waste streams. The specific costs of incineration vary greatly depending on the type of flue gas cleaning system. The calculations in the report have already proposed an "average" system distribution consisting of 25% semi-dry systems, 25% wet systems, and 50% semi-wet systems. The results showed that except for rigid building products (pipes, windows, cable trays, and other rigid profiles) and cables, the net increase in cost was caused by the transfer of PVC waste from incineration to recycling. The estimated cost per ton of transfer plan is about 50 Euros per ton, Option 2 is about 190 Euros per ton, and Option 3 is the result of net savings of around 90 per ton. These latter savings are mainly due to the low cost of landfills and the separation of construction wastes in the case of waste generators. Converting other waste streams to landfills (such as domestic and commercial waste) will result in higher costs. 

Major environmental factors including the impact of the three options on related human health have been evaluated. Where possible, with the prejudice against the effects of air pollution, the objective costs associated with each scenario have been evaluated. Calculations for all scenarios show environmental benefits. Taking into account the “best” estimate of each evaluated factor in the study, the estimates for the benefits of the three scenarios will be converted from 2000 to 2020 tons of waste respectively. Around 190, 140 and 50 euros, the main contributions of these results are primarily from avoidance of emissions in raw PVC processing (in the case of high-quality recycling), and secondly from avoidance of emissions from incineration (including indirect emissions associated with the processing of neutralizing agents). ). 

From the comparison of fiscal and environmental analysis, we can see that, based on the best estimate, both scheme 1 and scheme 3 show the overall interest, because the cost per ton is lower than the benefit. Scheme 2 is indeed the opposite. Its environmental benefits (though higher than Option One and Three) are always lower than estimated costs. 

Some assumptions have been made to accomplish these calculations. Especially considering the financial aspect, the cost factor must be based on the experience of the existing post-consumer waste recycling mechanism of PVC. These mechanisms are still in the preliminary research stage. These uncertainties are high in scenario two.

Since the price of the recycling agent is closely related to the price of the original PVC, the latter's price increase will result in a lower overall cost. As indicated, environmental analysis tends to study the effects of air pollution. However, most of the external neglect (such as residue disposal) may increase the benefits of converting PVC from incineration. The main exception is related to the plasticizers of orthobromide. Landfilling with flexible PVC will form a storage site for these chemicals that slowly seep out over time, while incineration shows the advantage of burning them. Incineration can also recover the caloric value of the bromide. This factor has been included in the environmental analysis. 

Future developments and policy tend to fall into the basic scenario. Compared with the current 600,000 tons, the waste of incinerated PVC will increase to 2.5 million by 2020. While the number of factories using the dry process has decreased, the number and processing capacity of plants using the wet, semi-wet and semi-dry flue gas neutralization technologies will increase. 

4.6 Landfill Plants

Landfill disposal is the most common waste disposal method for PVC waste. The amount of PVC waste that is used for landfill disposal is still inaccurate, and there are large differences in various estimates. The largest estimate is 2.9 million tons of PVC waste that is landfilled in the year. It is estimated that several thousand in the past 30 years. Million tons of PVC waste have been disposed of and disposed of. 

Member states must begin implementing the provisions of 1999/31/EC Act on Landfill Disposal in 2001. The Act stipulates that in order to protect soil and water resources, the establishment and operation of landfills must follow certain technical standards, including leachate collection, bottom osmosis control at the landfill, and emission gas control. 

Various materials, including PVC, in landfills are affected by different reaction conditions, which are constrained by a number of parameters such as: temperature, humidity, aerobic/anoxic, microbial activity, and landfilling at different stages The interaction of various parameters. This can be divided into four phases: initial short-term aerobic phase, anaerobic acid production process (sustained at different times, longer than aerobic stage), and oxygen-free methanogenic process (up to several centuries) The final aerobic stage. 

Investigations on various rigid and flexible PVCs have been widely carried out, mainly through laboratory research, studies on the effects of biological treatments, and microbiological experiments.

It is generally believed that PVC polymers cannot be decomposed in landfills. However, an elongated packaging sheet that can attack the polymer has been discovered. This is still an isolated result. This attack occurs in the absence of oxygen at 80 degrees Celsius, but this condition is very short for the landfill. 

The loss of plasticizers in PVC has been mentioned in some literatures, especially the loss of phthalates. Phthalates and its decomposition products can be detected in the leachate. Moreover, long-chain phthalates, such as DEHP, are only partially degraded in the leachate and sewage of ordinary disposal sites and aggregate on the suspended solid particles. Loss of phthalates in landfills can also lead to gas release. Compared to the gas released from other landfills, the gas released due to phthalate losses can last long enough to exceed the deadline for technical quality assurance, and there is no evidence to prove this release process. After a period of time, you can stop it. 

The rigid PVC waste matrix contains stabilizers. Therefore, the transfer is small and affects the surface of the PVC waste rather than its host material. When considering the flexibility of flexible PVC materials, a long-term study of the characteristics of PVC in landfill conditions revealed that lead stabilizers could leak out of container tanks containing several plastic mixtures. 

In the event of an occasional fire in a landfill, PVC in landfills will form dioxins. However, because it is difficult to obtain the necessary related data, quantitative quantities are still difficult to estimate. 

In order to further evaluate the impact of landfill PVC on the environment, it is necessary to further study the potential decomposition of PVC polymers, the release of plasticizers and stabilizers, leachate from landfills, and the release of phthalates from gases. Impact on the environment and other issues.

The cost of a member's landfill for PVC waste refers to the cost of landfill municipal solid waste, and this cost has a long list of prices. Landfill prices are constrained by factors such as landfill standards, competition for various disposal methods, types and nature of waste received. In general, there will be no increase in the cost of landfills because of the presence of PVC in municipal solid waste. 

Further development and policy orientation

According to the basic plan, it is expected that the number of PVC landfills will stabilize at 2.8 million tons in 2020.

Source: China Plastics Association