Plant for aquaculture and outlet for aquaculture tanks and other uses thereof

Plant for aquaculture, for farming of fish or other aquatic species, comprising a closed or semi-closed tank, at least one inlet for water to the tank and an outlet for water from the tank, wherein the outlet comprises two pipes, an outer pipe and an inner pipe, wherein the outer pipe is arranged outside the inner pipe,

• wherein the outer pipe extends from a bottom of the tank up to an outer pipe upper end, and the outer pipe comprises openings distributed along an immersed part of the outer pipe,
• wherein the inner pipe extends from the bottom of the tank up to an inner pipe upper end, and the inner pipe comprises an outlet opening at the inner pipe upper end and/or outlet openings at elevation below the inner pipe upper end, and
• wherein a main outlet from the tank is arranged in the tank bottom in a position inside the inner pipe,
• further comprising:
• a primary sludge outlet, arranged in the tank bottom outside the outer pipe, and
• a secondary sludge outlet, arranged in the tank bottom outside the inner pipe but inside the outer pipe, and
• wherein water brought into the tank through the at least one inlet comprises circular and radial and laminar and/or diverging flow, into and through the openings distributed along the immersed part of the outer pipe, into an annular water column formed between the inner and outer pipe, upwards through the annular water column, into and through the inner pipe outlet, down the inner pipe and out through the main outlet, whilst sludge is separated and brought out from the tank through the primary sludge outlet and the secondary sludge outlet.