Waste transfer system for a toilet of a public transport vehicle that discharges into an on-board aerated waste storage tank, comprising a waste intermediate tank, means for generating negative or positive pressure inside said waste intermediate tank so as to cause the waste to be transferred either to the said waste intermediate tank or to the aerated storage tank, and a discharge valve means (3,5,6,7) arranged to selectively regulate the waste flow, wherein; - said discharge valve means comprises; i. a multi-port discharge valve connected to a port (4, 4a, 4b) of the waste intermediate tank, said multi-port valve comprising a valve body with at least three ports (9, 10, 12) and a rotating valve element rotatably mounted inside a cavity of the valve body for selectively regulating the waste flow, and ii. driving means (5, 14) for said rotating valve element, characterised in that said rotating valve element comprises a tubular element provided with a first conduit as a waste passage which, when said rotating valve element is in a first working position connects a first port of the valve body to a second port of the valve body for allowing the passage of fluid between said toilet bowl and said intermediate tank, and provided with a second conduit as a waste passage which, when said rotating valve element is in a second working position connects the second port of the valve body with a third port of the valve body for allowing the passage of fluid between said intermediate tank and said aerated waste storage tank, - wherein the tubular element further being provided with an interior separation plate adapted to avoid the direct communication between the toilet bowl and the aerated waste storage tank when working in either said first or said second working positions, and - wherein said system includes a process and control unit configured to selectively activate the actuation of said rotating valve element from said first working position to the second working position, to provide, in said first working position, direct fluid communication between said toilet bowl and said waste intermediate tank when the pressure generating means generate negative inside said waste intermediate tank, and to provide, in the second working position, direct fluid communication between the waste intermediate tank and the aerated waste storage tank when the pressure generating means generate positive pressure in the said waste intermediate tank. - said discharge valve means comprises; i. a multi-port discharge valve connected to a port (4, 4a, 4b) of the waste intermediate tank, said multi-port valve comprising a valve body with at least three ports (9, 10, 12) and a rotating valve element rotatably mounted inside a cavity of the valve body for selectively regulating the waste flow, and ii. driving means (5, 14) for said rotating valve element, characterised in that said rotating valve element comprises a tubular element provided with a first conduit as a waste passage which, when said rotating valve element is in a first working position connects a first port of the valve body to a second port of the valve body for allowing the passage of fluid between said toilet bowl and said intermediate tank, and provided with a second conduit as a waste passage which, when said rotating valve element is in a second working position connects the second port of the valve body with a third port of the valve body for allowing the passage of fluid between said intermediate tank and said aerated waste storage tank, i. a multi-port discharge valve connected to a port (4, 4a, 4b) of the waste intermediate tank, said multi-port valve comprising a valve body with at least three ports (9, 10, 12) and a rotating valve element rotatably mounted inside a cavity of the valve body for selectively regulating the waste flow, and ii. driving means (5, 14) for said rotating valve element, - wherein the tubular element further being provided with an interior separation plate adapted to avoid the direct communication between the toilet bowl and the aerated waste storage tank when working in either said first or said second working positions, and - wherein said system includes a process and control unit configured to selectively activate the actuation of said rotating valve element from said first working position to the second working position, to provide, in said first working position, direct fluid communication between said toilet bowl and said waste intermediate tank when the pressure generating means generate negative inside said waste intermediate tank, and to provide, in the second working position, direct fluid communication between the waste intermediate tank and the aerated waste storage tank when the pressure generating means generate positive pressure in the said waste intermediate tank.