Chemical-free water purification

Researchers at Siemens are developing a process that can turn waste water into drinking water without the need for chemicals.

The process will ensure that germs cannot develop a resistance to the treatment, and will also do away with the need to transport or store large amounts of disinfectant chemicals.

The first commercial system should be available in two to four years’ time, while the process will grow to play an increasingly important role in water treatment within 15 years.

Pulsed electrical fields are used to kill bacteria, viruses, algae and even mussel larvae. If left, mussels can grow to clog piping or spoil water passing through it after they die.

During purification, untreated water flows through a chamber containing two electrodes positioned a few centimetres apart. A pulsed voltage of around 100 kilovolts with a pulse length of less than a microsecond is applied, producing very high electric field strengths between the electrodes. The field sets two processes in motion.