Tokyo Metropolitan Government Practical Technology Certification: Aerobic Granular Sludge Continuous Sewage Treatment System 'AGSORⓇ'

Organo Corporation (Headquarters: Koto-ku, Tokyo; President: Masayuki Yamada) is pleased to announce that its continuous sewage treatment system using aerobic granular sludge, 'AGSORⓇ', has been certified as a practical technology by the Tokyo Metropolitan Government Bureau of Sewerage.

1. Background Biological treatment using activated sludge has long been widely used in sewage treatment due to its cost-effectiveness. However, conventional activated sludge methods face challenges such as slow solid-liquid separation in settling tanks and difficulties in maintaining high sludge concentrations, leading to unstable treated water quality and increased footprint requirements. To address these issues, Tokyo and Organo conducted collaborative research aimed at the practical application of a continuous sewage treatment system using aerobic granules.

2. What are Aerobic Granules? Aerobic granules are granular sludge formed by microorganisms self-granulating at high density, reaching a particle size of 200 μm or larger. They feature high sedimentation rates and excellent solid-liquid separation, allowing for high biomass maintenance in reaction tanks, which leads to improved treated water quality and equipment compacting.

3. Collaborative Research with the Tokyo Metropolitan Government Since 2020, we have conducted demonstration tests in collaboration with Tokyo by adding granular sludge to the reaction tanks of the Sunamachi Water Reclamation Center (Koto-ku, Tokyo). After more than four years of continuous operation in actual equipment, we stably achieved the following research goals (summary), leading to the certification as a practical technology by Tokyo in March 2026: (1) Treated water quality comparable to the control system at 1.5 times or more the treatment volume. (2) Electricity consumption for the granular system is equal to or less than the control system. (3) Water quality comparable to advanced treatment in nitrogen processing at standard activated sludge method treatment volumes (HRT of 6 hours or more).

4. Introduction Benefits of AGSORⓇ In this system, a portion of the incoming sewage is diverted to form aerobic granules without the need for carriers or chemical injection. By continuously supplying these granules to increase the sludge concentration in the reaction tank, the system achieves 1.5–2 times faster treatment compared to conventional methods, improved nitrogen/phosphorus removal, and stabilized solid-liquid separation in final settling tanks. Furthermore, it enables significant downsizing of biological reaction tanks and final settling tanks, allowing for cost reductions and lower maintenance requirements during facility renovations compared to conventional methods.