 In the previous video, Limits to Recycling, we looked at the overall limits to recycling of materials. We touched on plastics in that video. You may be aware that the biggest problem in recycling plastics is they are not biodegradable. So that soft drinks bottle, or your wrappers that you just threw away, are not biodegradable. This means the fate of most plastics is to go into landfill sites, or our oceans, where it will take hundreds, possibly thousands of years for them to degrade. You may say what about recycling? Briefly, the problems with recycling plastics are, they have to be manually sorted, which is a labour and energy-intensive process. Mixed polymers are found in a range of materials, so cannot be recycled and are often dumped. Once a plastic has been recycled once, it can become downcycled, whereby its quality is decreased. The fact is that plastic recycling rates are far below other recycling rates, but the industry has improved in recent years. Worldwide, seven groups of plastic polymers have been given a plastic identification code that people use for recycling, these you can find on most packaging or plastic materials. Different types of plastics will be recycled by different municipalities, even by different countries in some instances. Generally, it's difficult to recycle plastics with numbers one and two. Plastics in these higher numbers are known as rigid plastics, so the disposal of plastics is a tricky one. Other than reducing their use, recycling or reusing them, what else do you think might be done to dispose of them? Pause the video and continue when you think you have an answer. One way is that the plastic can be incinerated or burnt. Whilst this produces useful energy, some plastics contain polymers that are halogenated. When these polymers are burnt for instance, PVC, toxic fumes like hydrochloric acid are released. This can cause severe respiratory distress and so is hugely problematic. In addition, burning of polymers produces CO2, the greenhouse gas, and so contributes to global warming. This is because about 10% of the oil is used as petrochemicals. If we then use the polymers again as a fuel for energy production, then at least we're using the oil twice. You may have heard the idea of using bioplastics as a solution, but these two can have problems. What do you think a bioplastic is? Pause the video and resume when you have an answer. A bioplastic is a biodegradable plastic. This means it's compostable and it can be broken down by the result of bacterial action when it is disposed of. Whilst this is a benefit, there are still issues with bioplastics that need solving. Bioplastics often come from renewable raw materials like starch, maize, cellulose and polylactic acids. These are plant-derived materials, and so the ethical question that arises is whether land should be used to grow crops for bioplastic manufacture instead of crops for food. Originally, we said that bioplastics are readily compostable, however bioplastics are not nearly as readily compostable as regular plant material. If you toss a bioplastic fork into your compost and assume it will be dirt in a few months, you'll be disappointed. Whilst a bioplastic fork is compostable, it requires high-intensity, high-heat commercial composting for that to happen quickly. In summary, plastic disposal has a number of issues with regards to landfills, recycling and incineration. However, bioplastics are slightly better, do not present themselves as the better alternative, because there are issues of land usage, the quality of the bioplastic and how it is composted. The best alternative is to reduce our usage and disposal of plastics altogether.