The recycling of PET bottles generates process water that can be treated with eco-friendly methods: modern recycling operations first clean the process water biologically in their in-house water treatment plant and then treat it with modern membrane filter systems. This makes it possible to reuse up to 75 percent of the water as process water in production.
For the biological cleaning to work reliably, the pH of the water must be right. This is achieved with carbon dioxide, which reacts as a mild acid in the water. The gas is very easy to handle and store – and also less expensive to use than chemicals. Moreover, it leaves no salts behind in the water treatment process, which would otherwise increase the salt load of the water.