About Seisui Industries’s

Seisui Industries Inc.

Seisui Industries Inc.

Seisui Industries’s business domain is all fields where wastewater is generated. 

Seisui means “clean water”, Kogyo means “industrial”. The company name Seisui (pronounced say-swi) indicates the business domain and its technological services.  

We are a small company with 15 employees, each with engineering and solution providing skills to make our clients’ “mission impossible” possible at over 2,500 locations. Our strong focus has been treating wastewater generated at construction and civil engineering sites, factories, sewage treatment facilities, oil tanks, hydroelectric power plants, and any other places where people live. 

  • Company name: Seisui Industries Inc.
  • Established: 1974
  • Location: 424-18 Kami-izumicho, Wakaba Ward, Chiba, 265-0045 Japan 
  • TEL: +81-(0)43-312-0895
  • E-MAIL: mizu@seisui-kk.com
  • Capital: JPY 20 million
  • President and CEO: Kenichi Imoto

Our Philosophy

“Contributing to the global environment with the best movable wastewater treatment technology in Japan”.

Japan is a top country facing flood disaster. In the past 10 years, more than 98% of cities, towns, and villages have experienced flooding or landslides. Seisui has contributed greatly to the recovery from flood damage throughout Japan including Tohoku Earthquake and Tsunami in 2011. 

Our Uniqueness

We build movable temporary water treatment facilities at the site where wastewater is generated. We customize implement innovative ideas for waste separation, coordination of various equipment and technologies, and chemical treatment to meet the regulatory requirements of the Waste Disposal and Public Cleansing Law, while also reducing the cost up to 80% (Please refer to our “case study” on page 3 which shares an example of our unique ways to provide solution at minimal cost). 

Our Work

Since its establishment in 1974, Seisui has completed more than 2,500 construction projects by 2022, and has experience in all regions of Japan, from Hokkaido in mid-winter (cold areas) to Okinawa in mid-summer (subtropical areas). 

Our Five Main Areas of Business:  

  1. Supporting water treatment during repairs or renovations of water treatment facilities in manufacturing industries
  2. Supporting restoration of sewage treatment facilities 
  3. Restoration from flood damage caused by natural disasters
  4. Treating sewage and sludge from oceans and rivers, environmental improvement such as treatment of contaminated water from nuclear power plants  
  5. Contracting for oil tank cleaning  


We would also like to further invest in the R&D of temporary water treatment solution to make it accessible to everyone, which means treating sludge and wastewater of all sizes in any kind of environment around the world. This would make it possible to effectively utilize precious water resources while also reducing the amount of waste in all situations.

Photo Gallery

Temporary water treatment plants consist of a combination of various pieces of equipment, such as dewatering machines, pumps, and water storage tanks. The combination can be customized according to the purpose. The plant can be assembled in about three days at the site where you want to do the treatment.

By using a temporary water treatment plant, sludge can be separated into water and solids in this way. This dramatically reduces the amount of waste ultimately disposed of and allows for the reuse of water.

What makes our water treatment unique is that it not only breaks down sludge into water and solids, but can also treat sludge containing heavy metals and oil. It can also be used for decontamination of contaminated soil.

[Case study]
Drainage of a power plant submerged by floodwaters

In October 2019, a large typhoon to the Tohoku region caused rivers to overflow, submerging the power plant’s water turbines and generators. Stockpiled lubricating oil and other oils mixed with the water and accumulated as oil-containing drainage. The volume is roughly 10,000 cubic meters, more than 20 times the volume of a standard swimming pool. Because it contains oil, it cannot be discharged into the river. Since the site is deep in the mountains, it would cost 300 million yen to transport the wastewater by vacuum truck. We thought about the best way to dispose of the water and decided to scoop water with a beaker and observed the turbidity, density, and the odour of the floating and settled substances. The supernatant and pooled water showed that it was sludge that tended to settle out. Running it through a sludge concentration measuring device confirmed this. The solids concentration was as low as 2,000 mg/ℓ. If it is dewatered, it will be less than one-tenth. The solid sludge would be treated as industrial waste, and the treated water would be discharged into the river. The policy was decided.

We built a movable dewatering and volume reduction plant inside the power plant and brought our water treatment equipment into the power plant deep in the mountains; tanks, centrifuges, dosing equipment, agitators, pumps, and hoses. A pump conducts oil-containing wastewater into the reaction tank for agitation. In the secondary treatment, the sludge is subjected to a centrifugal dehydrator to separate it into dewatered cake and water. The sludge with 70% water content looks like coffee powder after dripping. The separated treated water was clean and could be discharged into the river. Of the 10,000 m3 of wastewater, 90% was discharged into the river and 10% was treated as oil. The cost was only 60 million yen, or 20% of the expected 300 million yen. The staff at the power plant was overjoyed.

“Our Wastewater Mission is accomplished!”