Daisen Membrane Systems Ltd. (Head Office: Minato-ku, Tokyo; President: Masanao Shiba) has announced that its MOLSEP® tubular membrane modules--developed, manufactured, and sold by the company--have been adopted as part of a reuse facility within the plant area of the Japan Pavilion at Expo 2025 Osaka Kansai. This plant transforms waste collected from the Expo site into water, a source of all life, through the action of microorganisms--demonstrating a contribution to building a circular society.
Note 1: Our company was responsible for the design and fabrication of the reuse facility under contract from Kanadevia Corporation, which received the order for the biogas plant.
Overview of the Japan Pavilion
The Japan Pavilion consists of three areas: the "Plant Area," "Farm Area," and "Factory Area." It is a facility where visitors can experience the concept of "circulation," which underpins Japanese culture, in various forms.
In the "Plant Area," waste generated at the Expo site is collected and decomposed into water and biogas through the power of microorganisms.
Features of the Biogas Plant Facility
Various pieces of equipment are efficiently arranged within a compact area of 1,500 m² inside the Japan Pavilion site. The facility enables a complete process within the pavilion--from receiving food waste, crushing, methane fermentation treatment, extracting and utilizing biogas for power generation, using CO₂, to wastewater treatment after sludge processing and reuse of treated water.
Main Features and Designed Processing Capacity
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Electricity utilization through power generation
- Processing capacity: up to 1 ton/day
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Reuse of treated water
- Treatment process: wet methane fermentation + biological denitrification
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Utilization of CO₂ in biogas
- Biogas production: 150 m³/day
- Power generation: 280 kWh/day
- Reused water volume: 1,000 L/day
Features of the Reuse Facility
The reuse facility separates treated wastewater using tubular membrane units and reuses it in the Japan Pavilion's "water basin."
The system consists mainly of:
- Tubular UF (ultrafiltration) membrane units
- Tubular RO (reverse osmosis) membrane units
- UV disinfection system
- RO permeate tank
- Concentrate storage tank
A two-stage treatment process using UF and RO membranes is employed to achieve water quality suitable for reuse. Specifically, substances such as COD* that cannot be fully removed by the UF membrane are separated by the RO membrane.
*COD (Chemical Oxygen Demand): A key indicator of water pollution representing the amount of oxygen required to oxidize organic matter in water.
Features of MOLSEP® Tubular Membrane Modules
The MOLSEP® tubular membrane module contains 18 separation membranes in a single module. Each membrane is coated on the inner surface of a cylindrical support tube (diameter: 10-15 mm, length: approx. 3 m), with a pressure-resistant outer tube forming a three-layer structure for strength.
- Filtration method: internal pressure cross-flow filtration
- Compared to hollow fiber and spiral membrane modules, the larger feed flow channel reduces clogging and makes it suitable for concentration and separation processes.
This tubular membrane is a unique product representing "Japan Quality," manufactured and sold only by our company in Japan (at our Aboshi Plant).
Wastewater discharged from biogas plants contains microorganisms, as well as various organic and inorganic contaminants. It cannot be purified by microbial action alone unless all such contaminants are removed.
The MOLSEP® tubular membrane modules, optimized for the characteristics of biogas plant wastewater, support the realization of the Japan Pavilion's concept of "diverse cycles surrounding life."
Additionally, MOLSEP® tubular membrane modules are available in both UF (ultrafiltration) and RO (reverse osmosis) types, enabling the removal of a wide range of substances in wastewater and restoring it to water--the source of life--through a unique, high water recovery rate.
Although the MOLSEP® tubular membrane modules fulfilled their role at the Japan Pavilion in line with the pavilion's concept--"once the Expo ends, everything will be dismantled and returned to the cycle"--their use has not stopped there. They have since been adopted in full-scale methane fermentation facilities operated by municipalities in Japan and continue to attract attention worldwide.
Our company will continue contributing to the development of a circular society originating from Japan and expanding globally, leveraging the MOLSEP® tubular membrane modules at the forefront of Japan's advanced recycling technologies.