Industry News » Mitsubishi Heavy Industries Ltd. Patent Issued for System And Method To Prevent Chemical Fouling On ...

2019 JUL 1 (VerticalNews) -- By a News Reporter-Staff News Editor at Journal of Engineering -- A patent by the inventors Ukai, Nobuyuki (Tokyo, JP); Suzuki, Hideo (Tokyo, JP); Nakashoji, Hiroshi (Tokyo, JP); Yoshioka, Shigeru (Tokyo, JP); Eda, Masayuki (Tokyo, JP), filed on January 28, 2015, was published online on July 1, 2019, according to news reporting originating from Alexandria, Virginia, by VerticalNews correspondents.

Patent number 10,322,951 is assigned to Mitsubishi Heavy Industries Ltd. (Tokyo, Japan).

The following quote was obtained by the news editors from the background information supplied by the inventors: "Conventionally, industrial waste water containing organic matter from various industries is treated by biological treatment processes such as standard activated sludge method. The standard activated sludge method is a biological treatment method of performing biological treatment of organic waste water aerobically.

Waste water from various factories is treated by the first-stage treatments, such as oil-water separation treatment and coagulation-sedimentation treatment, for example, followed by the second-stage treatments such as activated sludge treatment. Then, recycled water is obtained as permeate water from a water regeneration apparatus such as a reverse osmosis membrane apparatus, for example.

"Examples of the reverse osmosis membranes used in the reverse osmosis membrane apparatus include polyamide-based materials. However, there are problems that polyamide-based materials are prone to contamination by organic matters, resulting in the decrease of permeation flow rate.

"A method and an apparatus for treating water by an adsorbing means using an adsorbent that can prevent contamination of a reverse osmosis membrane and suppress reduction of permeation flow rate have been proposed to-date (Patent Document 1)."

In addition to the background information obtained for this patent, VerticalNews journalists also obtained the inventors' summary information for this patent: "Technical Problem

"However, in the proposal of the conventional art, there is a problem that a contaminant will leak through the adsorbing means and contaminate the reverse osmosis membrane, in the case of the absorbent breaking through against the contaminant.

"In the conventional art described in the Patent Document 1, though it is possible to analyze the contaminants adsorbed to the adsorption column, there is a problem that it is not possible to predict contaminant leak into processed water, unless the contaminant is known (identified) and capacity of the adsorbent for the contaminant is also known.

"Therefore, the conventional art is not sufficient as a countermeasure against reverse osmosis membrane contamination for industrial waste water which may contain unknown contaminants or sea water which may be mixed into waste water from nearby ocean or waters.

"Thus, the introduction of the system for preventing chemical fouling on reverse osmosis membranes is strongly desired, the system being able to prevent chemical fouling that clogs reverse osmosis membranes by identifying the contaminants prior to the introduction of raw water to a reverse osmosis membrane apparatus, when the treatment and recycling of the raw water such as industrial waste water, sea water and the like is performed.

"In light of the problem described above, the present invention addresses the problem of providing a system and a method to prevent chemical fouling on a reverse osmosis membrane, which is capable of identifying contaminants and implementing a countermeasure prior to the introduction of a reverse osmosis membrane apparatus.

"Solution to Problem

"The first invention of the present invention to solve the problems described above is a system to prevent chemical fouling on a reverse osmosis membrane, comprising a pre-treatment means that pre-treats raw water, a reverse osmosis membrane apparatus including a reverse osmosis membrane that yields recycled water having its salts removed and concentrated water having salts in raw water concentrated, from pretreated inflow water, a monitoring apparatus disposed at an inflow water line through which inflow water flows in and/or a concentrated water line through which concentrated water flows out, that monitors the presence of chemical fouling causal substances in the inflow water or the concentrated water, and a removal apparatus that removes the chemical fouling causal substances from the inflow water on the front stream side of the inflow into the reverse osmosis membrane apparatus, upon the presence of chemical fouling causal substances in the inflow water or the concentrated water being confirmed as a result of the monitoring by the monitoring apparatus.

"The second invention relates to the system that prevents chemical fouling on a reverse osmosis membrane according to the first invention, wherein the monitoring apparatus performs chemical monitoring to determine the chemical fouling causal substance.

"The third invention relates to the system that prevents chemical fouling on a reverse osmosis membrane according to the first invention, wherein the monitoring apparatus branches off a part of the inflow water and confirms degradation of membrane due to the presence of chemical fouling by a small membrane apparatus for chemical fouling monitoring.

"The fourth invention relates to a method to prevent chemical fouling on a reverse osmosis membrane, comprising a pre-treatment process that pre-treats raw water, a reverse osmosis membrane process that separates permeate water and concentrated water from pre-treated inflow water by a reverse osmosis membrane, salts being removed in the recycled water and salts in raw water being concentrated, a monitoring process that monitors the presence of chemical fouling causal substances in the inflow water of the reverse osmosis membrane process or the concentrated water of the reverse osmosis membrane process, and a removing process that removes the chemical fouling causal substances from the inflow water on the front stream side of the inflow into the reverse osmosis membrane apparatus, upon the presence of chemical fouling causal substances in the inflow water or the concentrated water being confirmed as a result of the monitoring in the monitoring process.

"Advantageous Effects of Invention

"According to the present invention, when recycled water is produced by the reverse osmosis membrane apparatus, it is possible to prevent inflow of a contaminant into the reverse osmosis membrane apparatus and protect the reverse osmosis membrane apparatus by monitoring chemical fouling causal substance by a monitoring apparatus and by performing the operation to reduce the cause of the chemical fouling in a control apparatus."

The claims supplied by the inventors are:

"The invention claimed is:

"1. A system to prevent chemical fouling on a reverse osmosis membrane, the system comprising: a pre-treatment unit that pre-treats raw water to yield inflow water; a reverse osmosis membrane apparatus that is provided downstream of the pre-treatment unit, including a reverse osmosis membrane that yields recycled water and concentrated water from the inflow water, salts being removed in the recycled water and salts in raw water being concentrated in the concentrated water; an inflow water line that is connected between the pre-treatment unit and the reverse osmosis membrane apparatus and through which the inflow water flows into the reverse osmosis from the pre-treatment unit; a concentrated water line that is connected from the reverse osmosis membrane apparatus and through which the concentrated water flows out; a monitoring apparatus, disposed at both or either of the inflow water line or the concentrated water line, which monitors the presence of chemical fouling causal substances in the inflow water or the concentrated water; and a removal apparatus that is connected to the pre-treatment unit and supplies a chemical to the pre-treatment unit to removes the chemical fouling causal substances from the inflow water on a front upstream side of the inflow thereof into the reverse osmosis membrane apparatus, upon the presence of chemical fouling causal substances in the inflow water or the concentrated water being confirmed as a result of the monitoring by the monitoring apparatus, wherein the pre-treatment comprises a first-step treatment unit including an oil-water separation section and a coagulation-sedimentation section, a second-step treatment unit including an activated sludge treatment section, and a solid-liquid separation section, and the removal apparatus is connected to the coagulation-sedimentation section, the activated sludge treatment unit, or a position therebetween to supply the chemical thereto.

"2. The system to prevent chemical fouling on a reverse osmosis membrane according to claim 1, wherein the monitoring apparatus performs chemical monitoring to determine the chemical fouling causal substance.

"3. The system to prevent chemical fouling on a reverse osmosis membrane according to claim 1, wherein the monitoring apparatus branches off a part of the inflow water and confirms the presence of the chemical fouling causal substances therein by a small membrane apparatus for chemical fouling monitoring."


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