Method for cleaning separation membrane

A washing method and separation membrane technology, applied in semi-permeable membrane separation, chemical instruments and methods, membrane technology, etc., can solve the problems of decreased activated sludge activity, low device operation efficiency, long stop filtration time, etc. The effect of shortening, suppressing drug costs, and reducing equipment costs

CN100421773CActive Publication Date: 2008-10-01NGK INSULATORS LTD
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Publication Date
2008-10-01

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Abstract

Pulse back washing for applying a back pressure from the filtrate side to the raw water side of the membrane is repeated plural times for recovering a TMP during usual main back washing applied by suspending membrane filtration, when the TMP is increased when tank water extracted out of a biological treatment tank 1 is filtrated through the membrane by a cross-flow method. Pulse back washing is applied at a stage when the TMP is 80% or less of the permissible TMP to peel the deposits on the membrane surface, and the peeled deposits are returned to the biological treatment tank concomitantly with a circulating flow. Clogging substances on the separation membrane is removed in a direction opposite to the direction of pulse back washing by selecting the destination of discharge of back wash drain to be the inlet side of the separation membrane in the main back wash step.
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Description

technical field

[0001] The present invention relates to a method for washing a separation membrane, and more specifically, to a method for washing a separation membrane used in a membrane bioreactor method or the like. Background technique

[0002] Membrane separation activated sludge method is a method in which the water in the biological treatment tank for activated sludge treatment is filtered by a separation membrane to produce treated water. Compared with the conventional method of using a sedimentation tank, the space can be reduced, so We attract attention mainly on urban sewage treatment plants.

[0003] The separation membrane used includes an immersion type separation membrane installed inside the biological treatment tank and a separation membrane installed outside the biological treatment tank disclosed in Patent Document 1 (JP-A-9-136021). As for the immersion type separation membrane, as shown in Patent Document 1, there is known a method in which floating sol...

Examples

Embodiment

[0028] Such as figure 1As shown, the water in the activated sludge treatment tank of sewage is led out and circulated to the outside, and cross-flow filtration is performed through an internal pressure ceramic membrane. The separation membrane used is a monolithic membrane (membrane micropore diameter 0.1 μm, membrane pore diameter 4 mm) manufactured by the applicant company. As a result of operating under the conditions of circulating water volume of 1.0m / s and membrane filtration flow rate of 2.4m / d, the membrane permeation pressure rises rapidly, and stable operation cannot be performed even if original backwashing is performed every 45 minutes. In addition, 0.11m / s air was supplied from the gas supply device to make the raw water side of the membrane a gas-liquid mixed phase flow, but it still could not operate stably. In contrast, under the conditions of circulating water volume of 1.0m / s, membrane filtration flow rate of 2.4m / d, and gas flow rate of 0.11m / s, pulse backw...