Complex sentence: Although they are often the preferred technology in many developing countries because of their low energy requirements and robust performance, they are also used to treat water in some of the most developed countries such as the UK where they are used to treat water supplied to London.
Split into simpler sentences: Although they are often the preferred technology in many developing countries because of their low energy requirements and robust performance. They are also used to treat water in some of the most developed countries such as the UK where they are used to treat water supplied to London.