#Japan #Wakayama #Nachikatsuura #Taiji #Watering Engineering

Major Sanitation Infrastructure Revamp in Wakayama Prefecture

On March 27, 2026, Watering Engineering Co., a subsidiary of Watering Inc., officially entered into a contract with the Nachikatsuura and Taiji Environmental Health Facility Joint Council. This ambitious project focuses on the renovation of the core equipment at the Ōura Wastewater Treatment Plant, located in the municipalities of Nachikatsuura and Taiji in Wakayama Prefecture. The primary aim is to enhance the aging sewage treatment facilities while maintaining the community's sanitation infrastructure and reducing environmental impact.

Background of the Project

The Ōura Wastewater Treatment Plant commenced operations in 1996 and has been a vital component in maintaining the area's sanitary environment for nearly 30 years. However, the facility has faced significant challenges due to aging infrastructure as it approaches its 30-year milestone.

In recent years, there has been a shift in households transitioning from non-flush toilets to septic tanks, primarily in areas lacking sewer systems. This shift has changed the composition of the waste being treated, significantly increasing the amount of sludge from septic tanks compared to traditional sewage.

Due to this change in waste composition, the treatment facility has experienced higher processing loads, which has, in turn, led to decreased efficiency under existing operational conditions. Furthermore, ensuring stable processing capabilities, minimizing maintenance costs (like electric bills, chemical expenses, and repair costs), and enhancing resilience against increasingly severe natural disasters have become crucial priorities for the municipalities.

Recognizing these challenges, the Nachikatsuura and Taiji Environmental Health Facility Joint Council aims to upgrade the essential equipment without a complete facility overhaul. Instead, they are opting for a strategy that maximizes the use of existing infrastructure while renewing key components. The project is supported by the Ministry of the Environment's grant system for promoting a circular economy, which facilitates the careful and systematic upgrades needed.

During the construction period, waste management services will continue uninterrupted, ensuring minimal impact on the daily lives of residents and the operations of the local government.

Project Details

• - Contract Name: Ōura Wastewater Treatment Plant Core Equipment Renovation Project
• - Client: Nachikatsuura and Taiji Environmental Health Facility Joint Council
• - Constituent Towns: Nachikatsuura and Taiji in Wakayama Prefecture
• - Bidding Method: Proposal-based
• - Project Type: Design and Build (DB) method
• - Processing Method: Denitrification processing with high ratios of septic tank sludge
• - Processing Capacity: 35 kL/day (4 kL/day sewage, 31 kL/day effluent sludge)
• - Contract Amount: ¥2,519,000,000 (tax included)
• - Construction Period: March 27, 2026, to March 21, 2029

Our Role in This Project

Watering Engineering will oversee the design and construction phases of this project. We will utilize our proprietary Denilight System®, a direct dewatering denitrification processing method that integrates a shaft sliding screw press. This state-of-the-art method is designed to handle processing conditions with high ratios of septic tank sludge, ensuring stable operations even amid fluctuating treatment loads.

Moreover, the incorporation of pre-dewatering steps will help reduce energy consumption across the treatment processes, allowing us to cut down on CO2 emissions. This approach not only bolsters efficiency but also prepares the facilities to withstand increasingly severe natural disasters without compromising functionality.

Leveraging our extensive know-how in design and construction, we aim to support the long-term stability of the Ōura Wastewater Treatment Plant while enhancing the region's sanitary and environmental standards.

About the Watering Group

Watering Group, under the philosophy of contributing to society through “water,” is committed to comprehensive services related to water treatment facilities (including water purification plants, sewage treatment plants, and sludge recycling facilities) from design, construction, to ongoing management. With approximately 300 operational management locations across the country, we remain focused on tackling community challenges by ensuring reliable water environments, ultimately supporting the future of urban living.

For more information, visit our official website.