Sewage treatment machine

A sewage treatment machine, comprising:

• a closed container into which a liquid to be treated is brought to boil;
• a vacuum-generating apparatus, which is adapted to maintain an inside of the closed container at a given pressure having a value lower than an environmental and/or external pressure;
• a supply line for the liquid to be treated, which is adapted to channel the liquid to be treated to the inside of the closed container;
• a heat-pump assembly, which is connected to the closed container so as to be able to transfer heat to the liquid present on a bottom of the closed container thus to bring said liquid to boil, and simultaneously remove heat from the vapours that reach a top of the closed container thus to condense the vapour and obtain a distilled liquid, wherein said heat-pump assembly contains a refrigerant fluid including one or more gases of the family of the hydro-fluoroolefins in a percentage greater than 3%;
• a first drain line that branches off and/or departs from a bottom part of the closed container and is adapted to channel, outside of the closed container, the liquid that accumulates and/or stagnates on the bottom of the closed container;
• and
• a second drain line that branches off and/or departs from the upper part of the closed container and is adapted to channel, outside of the closed container, the vapours that form inside the closed container and/or the distilled liquid resulting from condensation of said vapours, wherein said second drain line comprises a tank adapted to contain the vapour and/or the distilled liquid arriving from the closed container, and wherein said heat-pump assembly additionally comprises a third heat-exchanger which is located inside the tank of the second drain line, so as to be able to cool down the distilled liquid and/or vapour located inside the tank.