In Japan, Johkasou which are designed to remove the BOD of treated water below than 20 mg/L, are widely used as decentralized wastewater treatment facilities. In these facilities, maintenance and desludging are collectively called operation and maintenance (O&M). As of the end of fiscal year 2023, it has been reported that of the approximately 4.1 million units of Johkasou installed in Japan, the implementation ratio of maintenance was 81.2% and the desludging ratio was 67.4% (Reference: "Fiscal Year 2024 Survey Results on Guidance and Promotion of Johkasous"). Maintenance and desludging of Johkasou are carried out by specialized businesses, and it is a unique case in the world where the maintenance of decentralized wastewater treatment facilities has become a viable business, and a market has been formed.
The Johkasou Act is a law that specifically focuses on decentralized wastewater management and requires users to carry out O&M as their responsibility. This O&M must be carried out in accordance with the technical standards set out in the Johkasou Act. For example, if a business undertakes maintenance of Johkasou, the business must notify and be registered by the prefecture governor. One of the conditions for registration is the employment of staff who hold the national qualification of "Johkasou Operator". To obtain this qualification, one must either pass a national examination held once a year or complete a training course at a nationally designated training institution.
In this way, Japan has put in place a system to ensure that the capabilities of businessis responsible for O&M are systematically guaranteed, so that the expected performance of Johkasous, which are decentralized wastewater treatment facilities with high treatment performance, is reliably achieved.
On the other hand, with regard to decentralized wastewater treatment facilities such as septic tanks being common in Asian countries, users have had few opportunities to become aware of the importance of regular O&M, and thus it is assumed that there had not been much positive to introduce systems and standards for O&M.
However, to correspond to the restricting of effluent standard and environment regulation, the adoption of high-performance decentralized wastewater treatment facilities that meet effluent standard has been progressing in Special Economic Zones, factories, or large-scale facilities, etc. As these high-performance decentralized wastewater treatment plants become more widespread, attention is being paid to the importance of O&M, as well as the development of the human resources required to carry out the O&M.
In this workshop, we will share information on the current situation of O&M of decentralized wastewater plants treatment around the world, including Asia, and trends in developing the human resources required for such O&M, and will also discuss related challenges and necessary actions.
