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A sludge dehydration method includes a recovery process of recovering specific material as a dewatering aid from sludge generated in a sewage treatment process and a dewatering process of performing solid-liquid separation on sludge in which the dewatering aid recovered in the recovery process and dewatering target sludge are mixed.


Patent
Ishigaki Company Ltd | Date: 2013-08-14

The present invention relates to a sludge thickening method of a differential rate rotary thickener in which a screw is disposed in a rotatable outer cylinder screen; raw slurry sludge is fed into a feed end of the outer cylinder screen; filtered liquid is separated from the outer cylinder screen with rotating the screw at a different speed; and thereafter thickened sludge is discharged from a discharge end of the outer cylinder screen, the sludge thickening method comprising the steps of:setting in advance an upper limit of the chemical feed rate max of flocculant, a lower limit min of chemical feed rate of flocculant, an upper limit X max of the thickened sludge concentration, a lower limit X min of the thickened sludge concentration, an upper limit C max of the rotational speed of the outer cylinder screen, a lower limit C min of the rotational speed of the outer cylinder screen, an upper limit S max of the rotational speed of the screw, and a lower limit S min of the rotational speed of the screw;when a thickened sludge concentration X of thickened sludge, which is discharged from the differential rate rotary thickener, has been increased to not less than the upper limit X max of the thickened sludge concentration, decreasing a chemical feed rate of flocculant stepwise until the thickened sludge concentration X becomes not greater than the upper limit X max of the thickened sludge concentration or until the chemical feed rate of flocculant becomes equal to the lower limit min of chemical feed rate of flocculant; and, when the flocculant has become equal to the lower limit min of chemical feed rate , increasing a rotational speed S of the screw stepwise; andwhen the thickened sludge concentration X of thickened sludge, which is discharged from the differential rate rotary thickener, has been deceased to not greater than the lower limit X min of the thickened sludge concentration, decreasing the rotational speed S of the screw stepwise until the thickened sludge concentration X becomes not less than the lower limit X min of the thickened sludge concentration or until the rotational speed S of the screw becomes equal to the lower limit S min of the rotational speed; and, when the rotational speed S of the screw has become equal to the lower limit S min of the rotational speed, increasing the chemical feed rate of flocculant stepwise.


Patent
ISHIGAKI COMPANY Ltd | Date: 2012-09-21

An indefinite form filter medium layer includes filter media configured to capture suspended solids contained in a liquid to be treated and filtering aids configured to allow the suspended solids contained in the liquid to be treated to pass through the filtering aids. The filter media and the filtering aids are mixed together and the liquid to be treated is filtered by being passed through the filter media and the filtering aids as mixed together. A filter device includes the indefinite form filter medium layer and a filter tank configured to accommodate the indefinite form filter medium layer.


Patent
Ishigaki Company Ltd | Date: 2013-08-21

The present invention relates to a concentration detection device for a differential rate rotary thickener in which a screw is disposed in a rotatable outer cylinder screen; raw slurry sludge is fed into a feed end of the outer cylinder screen; filtered liquid is separated from the outer cylinder screen with rotating the screw at a different speed; and thereafter thickened sludge is discharged from a discharge end of the outer cylinder screen, the concentration detection device comprising:a cylindrical detecting body which is suspended down into the thickened sludge, a lower end thereof being open and on a top end thereof an air hole being formed;a driving motor having a rotary axle which is connected to the cylindrical detecting body; anda power detector configured to detect a change in an electric current value of the driving motor, and output the change in the electric current value in the form of an electric signal.


Patent
Ishigaki Company Ltd | Date: 2016-08-24

A sludge dehydration method includes a recovery process of recovering specific material as a dewatering aid from sludge generated in a sewage treatment process and a dewatering process of performing solid-liquid separation on sludge in which the dewatering aid recovered in the recovery process and dewatering target sludge are mixed.


A filter medium includes: a core yarn and a binder yarn twisted together, at least one of the core yarn or the binder yarn being weldable; and a filament yarn being fuzzy and weldable, the filament yarn being welded to at least one of the core yarn or the binder yarn while being placed between the core yarn and the binder yarn as twisted together. A filtering device for filtering a liquid to be treated with a filter medium layer including includes the filter medium. A method of manufacturing the filter medium is also disclosed.


Patent
Ishigaki Company Ltd | Date: 2012-01-25

A concentrator-integrated screw press includes: a continuous concentrator configured to continuously concentrate sludge and discharge the sludge as concentrated sludge, and including a discharge amount equalization unit configured to equalize an amount of concentrated sludge to be discharged per unit time; a positive displacement pump installed consecutively to the concentrator, and configured to continuously transport the concentrated sludge discharged from the concentrator; and a screw press installed consecutively to a discharge side of the positive displacement pump, and configured to compress and dewater the concentrated sludge.


Patent
ISHIGAKI COMPANY Ltd | Date: 2014-10-10

A pair of filter cloths is wound around a first roll a plurality of times by being wound around the first roll, then being wound around a second roll to return to a space between the first roll and the pair of filter cloths wound around the first roll, and being wound around the first roll again. The pair of filter cloths wound around the first roll the plurality of times applies a pressing force to the first roll.


A recovery device is configured to recover specific material as a dewatering aid from sludge generated in a sewage treatment process. The recovery device includes: a grinder configured to fragment a solid in the sludge to obtain prepared sludge; a separator configured to separate hardly decomposable organic matter and easily decomposable organic matter from the prepared sludge; and an extractor configured to continuously extract hardly decomposable organic matter having specific properties as the dewatering aid from the hardly decomposable organic matter separated by the separator.


Patent
ISHIGAKI COMPANY Ltd | Date: 2016-01-06

A sludge dehydration method includes a recovery process of recovering specific material as a dewatering aid from sludge generated in a sewage treatment process and a dewatering process of performing solid-liquid separation on sludge in which the dewatering aid recovered in the recovery process and dewatering target sludge are mixed.

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