Other than recycling how can the sustainability of glass bottles be improved?

Hi! Other than traditional recycling, glass can be reused to improve the sustainability. A good example of this is Heineken's attempt at a square bottle, which was designed to be used as a brick after it had been used to build housing in developing countries (see here). It didn't take off but it's an interesting idea.

A lot of the improvements that can be made come from the manufacturing process - e.g. reducing waste materials by investing in new, more efficient machines. Glass packaging is about 50% lighter today than it was in the past (source), which has made it more sustainable because we are using less energy to produce the same number of products. Hope that helps!