A water-treating ceramic filter unit comprising a filter having pluralities of flow paths partitioned by porous ceramic cell walls and plugs alternately sealing the one-side or other-side ends of the flow paths; a housing containing the filter such that water to be treated is supplied from one end of the filter, and that the treated water is discharged from the other end of the filter; and seal members disposed on the outer edge portions of both end surfaces of the filter for longitudinally sandwiching and fixing the filter to the housing; the maximum of a gap between a side surface of the filter and the housing being equal to or less than the equivalent diameter of the flow paths.

A pillar shaped honeycomb structure includes: a porous partition wall that defines a plurality of cells, the cells forming flow paths for a fluid, the cells extending from an inflow end face to an outflow end face; and an outer peripheral wall located at the outermost circumference. The cells include: a plurality of cells A wherein a side of the inflow end face is opened and the outflow end face has a plugged portion; and a plurality of cells B wherein a side of the outflow end face is opened and the inflow end face has a plugged portion, the cells B being arranged alternately with the cells A. One or both of the plugged portion of the cells A and the plugged portions of the cells B contain a magnetic substance and glass.

A pillar shaped honeycomb structure includes: a porous partition wall that defines a plurality of cells, the cells forming flow paths for a fluid, the cells extending from an inflow end face to an outflow end face; and an outer peripheral wall located at the outermost circumference. The cells include: a plurality of cells A wherein a side of the inflow end face is opened and the outflow end face has a plugged portion; and a plurality of cells B wherein a side of the outflow end face is opened and the inflow end face has a plugged portion, the cells B being arranged alternately with the cells A. One or both of the plugged portion of the cells A and the plugged portions of the cells B contain a magnetic substance and glass.

A pillar-shaped honeycomb structure including an outer peripheral side wall, a plurality of first cells provided on an inner peripheral side of the outer peripheral side wall, the first cells extending from a first end surface to a second end surface, each opening on the first end surface and having a sealing portion with an average void ratio of 4% or less on the second end surface, and a plurality of second cells provided on the inner peripheral side of the outer peripheral side wall, the second cells extending from the first end surface to the second end surface, each having a sealing portion with an average void ratio of 4% or less on the first end surface and opening on the second end surface, the first cells and the second cells being alternately arranged adjacent to each other with a partition wall interposed therebetween.

A pillar-shaped honeycomb structure including an outer peripheral side wall, a plurality of first cells provided on an inner peripheral side of the outer peripheral side wall, the first cells extending from a first end surface to a second end surface, each opening on the first end surface and having a sealing portion with an average void ratio of 4% or less on the second end surface, and a plurality of second cells provided on the inner peripheral side of the outer peripheral side wall, the second cells extending from the first end surface to the second end surface, each having a sealing portion with an average void ratio of 4% or less on the first end surface and opening on the second end surface, the first cells and the second cells being alternately arranged adjacent to each other with a partition wall interposed therebetween.

A method of plugging a honeycomb body is disclosed herein, the method comprising: contacting a first end of the honeycomb body comprising a plurality of channels with a light curable sealing mixture such that an infiltrate of the light curable sealing mixture flows into the plurality of channels proximate the first end; emitting a light toward a first portion of the infiltrate within the plurality channels of the filter; and curing the first portion of the infiltrate within the channels with the light to form a plurality of seals.

A method of plugging a honeycomb body is disclosed herein, the method comprising: contacting a first end of the honeycomb body comprising a plurality of channels with a light curable sealing mixture such that an infiltrate of the light curable sealing mixture flows into the plurality of channels proximate the first end; emitting a light toward a first portion of the infiltrate within the plurality channels of the filter; and curing the first portion of the infiltrate within the channels with the light to form a plurality of seals.

A method for producing a honeycomb structure including producing an unfired pillar shaped honeycomb body; placing the unfired pillar shaped honeycomb body on a receiving table such that the unfired pillar shaped honeycomb body stands thereon; conveying the unfired pillar shaped honeycomb body placed on the receiving table; drying the unfired pillar shaped honeycomb body after the conveying step, or drying the unfired pillar shaped honeycomb body during the conveying to obtain a honeycomb dried body; and firing the honeycomb dried body to obtain a honeycomb structure. The receiving table includes at least one protrusion. In the honeycomb formed body conveying step, the unfired pillar shaped honeycomb body is conveyed while supporting it by inserting the at least one protrusion of the receiving table into a bottom surface of the unfired pillar shaped honeycomb body placed on the receiving table.

A method for producing a honeycomb structure including producing an unfired pillar shaped honeycomb body; placing the unfired pillar shaped honeycomb body on a receiving table such that the unfired pillar shaped honeycomb body stands thereon; conveying the unfired pillar shaped honeycomb body placed on the receiving table; drying the unfired pillar shaped honeycomb body after the conveying step, or drying the unfired pillar shaped honeycomb body during the conveying to obtain a honeycomb dried body; and firing the honeycomb dried body to obtain a honeycomb structure. The receiving table includes at least one protrusion. In the honeycomb formed body conveying step, the unfired pillar shaped honeycomb body is conveyed while supporting it by inserting the at least one protrusion of the receiving table into a bottom surface of the unfired pillar shaped honeycomb body placed on the receiving table.

A honeycomb filter includes a pillar-shaped honeycomb structure having porous partition walls provided, surrounding a plurality of cells which serve as fluid through channels extending from an inflow end face to an outflow end face, and porous plugging portions provided either at the ends on the inflow end face or the outflow end face of the cells, wherein the plugging portions are composed of a porous material, the honeycomb structure has a central region and a circumferential region and a ratio of an area of the circumferential region with respect to that of the central region ranges from 0.1 to 0.5, and a plugging length L1 in the cell extending direction of a central plugging portion in the central region is smaller than a plugging length L2 of a circumferential plugging portion in the circumferential region, L1 ranges from 3 to 6 mm, and L2 from 7 to 9 mm.