Solid Waste

Where Does Solid Waste Go?

Have you ever stopped to think about where solid waste goes after it leaves the facilities where it is no longer needed? Most people have vague notions of waste going to the 'dump', but don't really know where that is or what it looks like. Yet much of it gets dumped in rivers or landfills completely. Millions of pounds of solid waste are discarded every year. Until recently (the last few decades), the landfill was considered to be the best and most efficient option of waste disposal. Now there is more pressure to recycle waste, the landfill is rapidly losing favor especially as society realizes how much damage is done to the countryside through constantly opening new sites.

Waste from larger manufacturers goes to larger areas with more room for such materials. Here the waste is transferred from the dustcart to larger freighters that can accommodate much larger volumes of waste. 'Bulking up' in this way reduces the overall number of journeys needed. The freighter will then take the waste to the landfill site. On arrival, the trash isn't just dumped out of the truck into a hole in the ground. Landfill sites these days are highly engineered facilities, designed to maximize space and minimize the environmental impact on the surrounding countryside. The whole site is lined with a membrane, designed to keep water that flows down through the rubbish from entering the groundwater. This water,can be highly polluting as it carries away some of the chemicals in the rotting rubbish. Collecting the water allows it to be treated in a sewage works. Landfill sites are compartmentalized into 'cells' or areas of active disposal.

While the cell is active, garbage is tipped on to the top and is compacted by special vehicles to maximize the amount of space available. Compaction has the effect of driving out air pockets and reducing subsidence after the landfill has been restored. Over time, micro-bacteria begin to feed on the rubbish causing it to break down, rather like a very large compost heap. However, because of compaction most of the oxygen has been driven out of the site and rather than composting, the rubbish putrefies and releases methane gas. Methane is highly flammable and was responsible for many fires and explosions at old-style landfill sites where it was not properly managed. Some of these fires would burn for several weeks or months. Nowadays, methane is collected through a network of pipes running through the site and is either vented to the atmosphere, or more usually flared. At larger sites, methane gas is being used to generate electricity. Compaction also means that rubbish remains intact for a very long time. Even biodegradable waste can last several years and there are instances of newspapers being dug up that are perfectly readable even after being buried thirty years ago! Perhaps one day, landfill sites will be 'mined' for valuable materials such as metals and plastics. In the meantime, there is a better way of reclaiming these valuable materials. It's called recycling.