Advances in Water Purification Technology: Evolution from 1997 to the 2020s

Advances in Water Purification Technology: Evolution from 1997 to the 2020s

### The Early 1990s
In 1997, a groundbreaking purification plant utilizing membrane technology (membrane separation technology) began operations in Kariya City, Aichi Prefecture. This plant was capable of treating 10,000 tons of industrial wastewater per day, removing heavy metals (lead, cadmium), nitrogen compounds, and organic pollutants with an efficiency of over 90%. The concentration of heavy metals in the treated effluent was reduced to below the regulatory limit of 0.01 ppm, contributing significantly to the ecological restoration of the Yahagi River. For this project, the local government provided a subsidy of approximately 500 million yen, and the facility was completed at a construction cost of approximately 2 billion yen.

### What Is Membrane Separation Technology?
Membrane separation technology is a method that uses fine membranes to selectively separate and remove pollutants. Common types of membranes include reverse osmosis (RO) membranes, ultrafiltration (UF) membranes, and nanofiltration (NF) membranes, each of which removes different contaminants. For example, RO membranes have extremely fine pore sizes (0.0001 microns) and are highly effective at removing salts and heavy metal ions, making them suitable for seawater desalination and advanced water purification. The features of membrane separation technology are as follows:
- High purification performance: Efficiently removes harmful substances and microorganisms.
- Reduced environmental impact: Treatment is possible with minimal use of chemicals.
- Versatility: Suitable for a wide range of applications, including industrial wastewater, domestic wastewater, and seawater desalination.

While reducing operating costs was a challenge for this technology, improvements in membrane durability and energy efficiency since the 2000s have led to its widespread adoption.

### Developments in the 2000s
In the 2000s, membrane separation technology became even more widespread across the country. In Fuji City, Shizuoka Prefecture, a new purification facility capable of treating 12,000 tons of wastewater per day was installed in 2005, improving the removal efficiency of nitrogen compounds and phosphates to over 95%. Additionally, in Yokkaichi City, Mie Prefecture, specialized membranes were introduced to efficiently remove benzene and toluene from petrochemical industrial wastewater. Furthermore, driven by national environmental policies, Japan's total annual treatment capacity exceeded 10 million tons by 2008. During this period, energy-efficient membrane systems that reduced energy consumption were also developed, leading to cost reductions and increased efficiency.

### Globalization and Technological Innovation in the 2010s
In the 2010s, membrane separation technology spread beyond Japan, leading to global expansion. In 2013, a large-scale purification facility utilizing Japanese technology was completed in Jakarta, Indonesia, capable of treating 30,000 tons of domestic wastewater per day. Additionally, within Japan, membrane durability improved, extending the average service life to seven years and reducing annual maintenance costs by 20%. In 2015, a seawater desalination plant utilizing reverse osmosis (RO) membranes began operations in Kumamoto Prefecture, reaching a scale capable of supplying 10,000 tons of drinking water per day. This facility boasts a high desalination rate of 99.5% and has made a significant contribution to securing water resources for the region.

### Current Status and Outlook for the 2020s
In the 2020s, a state-of-the-art purification facility with a daily processing capacity of 15,000 tons was established in Fuji City, where technology capable of reducing the concentration of heavy metals (lead and arsenic) to 0.001 ppm or less was successfully implemented. Additionally, in Yokohama City, Kanagawa Prefecture, a seawater desalination facility capable of producing 30,000 tons of drinking water per day began operations, achieving greater efficiency with a production cost of 0.5 yen per liter. Furthermore, membrane separation technology has been adopted in Middle Eastern and African countries facing severe water shortages, contributing to the resolution of global water resource issues.

Membrane separation technology, which began with basic research in the 1990s, continues to evolve as a foundational technology supporting a sustainable society. Its importance is growing increasingly significant, particularly in addressing water resource issues caused by climate change and population growth.