Gas diffuser

A gas diffuser (10) comprising a grid of aeration pipes (12, 12′, 12″, 12″′) spaced apart and in parallel alignment with each other within a common horizontal plane and a manifold (14) in fluid communication with the aeration pipes,

• wherein an aeration pipe (12) comprises:
• a length (L) extending between two ends (16, 18) and defining an axis (Z),
• a hydrodynamic diameter (Dh),
• an elliptical cross-sectional area defining a vertical plane comprising a vertical (Y) and horizontal (X) axis intersecting through a center (C) which are perpendicular to axis (Z),
• an outer circumference defined by a first arc (20) comprising 30° located below the (X) axis and bisected by the (Y) axis, and a second arc (22) comprising 330° which is non-overlapping with the first arc (20) and wherein the second arc (22) comprises four non-overlapping 15° sectors,
• a plurality (N) of discharge holes (26, 28, 30, 32) spaced along the length (L) at four or more distinct positions about the second arc (22) within said sectors and a plurality (M) of drainage holes (34) spaced along the length (L) within the first arc (20);
• wherein each of the four sectors of the second arc (22) comprise:
• at least 10 discharge holes having a minimum hydraulic diameter (dmin) of equal to or greater than 0.001 m,
• a value (y) equal to the average position along the Y axis of all discharge holes within the sector measured in meters, and
• a value (F) equal to the mean value of the hydraulic diameter (d) to the forth power for all discharge holes within the sector measured in meters;
• wherein the following relationship applies for any two the four sectors:
• Abs[1−Fi/Fii+2.6×108m−5N2(yii−yi)Fi)]≦0.5
• wherein “i” and “ii” refer to higher and lower sectors along the Y axis, respectively.