An apparatus for mass flow (100; 400; 700), comprising: a housing (150; 750); an inlet (159; 759) disposed at a first end of the housing; an outlet (158; 758) disposed at a second end of the housing, wherein the housing comprises a first section (151; 751) and a second section (154; 754), wherein the first section has a cylindrical inner surface and the second section has a frustoconical inner surface; and a divider (102; 302; 402; 600; 900) disposed at least partially within the first and second sections of the housing, wherein the divider comprises: one or more plates (412, 414; 616, 618; 912, 914, 916, 918) radially extending from a pipe, wherein an edge (103; 403; 603) of the one or more plates is located between the first section and a point in the second section where a ratio of a diameter of the second section to a diameter of the outlet is about 3:1 or less; and at least one tapered surface disposed proximate the frustoconical inner surface of the second section; the apparatus further comprising two or more fluid distribution conduits (630, 632) extending from the pipe; wherein the fluid distribution conduits have one or more aeration holes (1081, 1082, 1083, 1084) defined through sidewalls thereof configured to direct fluid into the second section of the housing and wherein the two or more fluid distribution conduits extend radially from the pipe along edges of two or more of the plates. a housing (150; 750); an inlet (159; 759) disposed at a first end of the housing; an outlet (158; 758) disposed at a second end of the housing, wherein the housing comprises a first section (151; 751) and a second section (154; 754), wherein the first section has a cylindrical inner surface and the second section has a frustoconical inner surface; and a divider (102; 302; 402; 600; 900) disposed at least partially within the first and second sections of the housing, wherein the divider comprises: one or more plates (412, 414; 616, 618; 912, 914, 916, 918) radially extending from a pipe, wherein an edge (103; 403; 603) of the one or more plates is located between the first section and a point in the second section where a ratio of a diameter of the second section to a diameter of the outlet is about 3:1 or less; and at least one tapered surface disposed proximate the frustoconical inner surface of the second section; one or more plates (412, 414; 616, 618; 912, 914, 916, 918) radially extending from a pipe, wherein an edge (103; 403; 603) of the one or more plates is located between the first section and a point in the second section where a ratio of a diameter of the second section to a diameter of the outlet is about 3:1 or less; and at least one tapered surface disposed proximate the frustoconical inner surface of the second section; the apparatus further comprising two or more fluid distribution conduits (630, 632) extending from the pipe; wherein the fluid distribution conduits have one or more aeration holes (1081, 1082, 1083, 1084) defined through sidewalls thereof configured to direct fluid into the second section of the housing and wherein the two or more fluid distribution conduits extend radially from the pipe along edges of two or more of the plates.