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Toray to Globally Offer Sewage Treatment Chemical RWI-8000 that Inhibits Scaling

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Dec. 16, 2021

Toray Industries, Inc.

Tokyo, Japan, December 16, 2021 – Toray Industries, Inc., announced today that it will start globally marketing RWI-8000. Low doses of this water treatment chemical can significantly reduce sewage treatment costs by suppressing struvite scale formation in dewatering sludge. Struvite is a mineral derived from bacteria in the urinary tract.

Swiss subsidiary Toray Membrane Europe AG developed this offering, which it has pre-sold to some European customers since April this year. Toray decided to offer this product worldwide because users acclaimed its performance in cutting operating costs and stabilizing quality.

Struvite scales form on dewatering centrifuge surfaces and inside pipes when removing water from sewage sludge. Strong mechanical force can remove this mineral if only a micrometer or so thick. However, it tends to build up rapidly, and becomes hard to remove once a millimeter thick, necessitating pipe and centrifuge cleaning. Severe buildups may oblige operators to dismantle and replace piping at considerable expense. Long-term operational shutdowns are inevitable for piping inside buildings.

Struvite precipitation stems primarily from magnesium crystallization. Toray Membrane Europe developed RWI-8000 by drawing on its expertise in techniques for inhibiting calcium scaling, which is similar to magnesium scaling, from more than 30 years of developing and manufacturing scale inhibitors for water treatment.

Tests of sludge samples from dewatered sewage confirmed that struvite particle formation plunged 99.4% immediately after adding several drops of RWI-8000 per cubic meter of sludge. A daily dosing of 25 to 50 parts per million of RWI-8000 at operational sewage treatment facilities prevented struvite precipitation and lowered cleaning costs to 75% below those of conventional techniques, lifting operational stability and operating rates.

The global market for water treatment scale inhibitors is worth an estimated $US330 million, and is expanding 5% to 7% annually. Toray offers scale inhibitors for diverse raw water treatment needs. It looks to further expand its business by applying expertise from developing this product to other applications.

Toray will draw on more than four decades of experience in the water treatment sector to keep developing and delivering high-quality scale inhibitors in keeping with its corporate philosophy of contributing to society by creating new value.
Centrifuge before adding scale inhibitor  After adding scale inhibitor

Toray Membrane website