Plasma-based water treatment apparatus

A plasma reactor, comprising:

• a liquid pump, which recirculates a liquid flow between a first liquid outlet port and a first liquid inlet port, wherein the first liquid inlet port supplies liquid water to a liquid drop or a droplet generator;
• an upper liquid electrode and a lower liquid electrode, the plasma reactor configured for electrical breakdown between said electrodes and plasma gas and liquid phase interactions treating water and producing plasma activated water;
• and the liquid drop or droplet generator generating water droplets, wherein the water drop or droplets act as the upper liquid electrode;
• a housing defining an interior space having the liquid drop or droplet generator positioned at an upper end;
• and a reservoir for water to accumulate at the lower end, wherein water in the reservoir acts as the lower liquid electrode, wherein the housing comprises the first liquid inlet port, the first liquid outlet port, and a liquid recirculation pathway connecting between the first liquid outlet port and the first liquid inlet port;
• and
• a high-voltage power supply connecting to both the upper and lower liquid electrodes to bias the liquid water supplied to the drop or droplet generator and the lower liquid electrode, such that plasma discharge filaments in the plasma reactor extinguish and regenerate continuously as the liquid water drop or droplets fall to the surface of the lower liquid electrode;
• wherein there are no non-liquid electrodes within the interior space connected to the high-voltage power supply, to prevent toxic metal contamination of treated water due to electrode erosion.